Just-DataInspector/Components/PlotView/Src/PlotView.cpp

#include "PlotView.hpp"

#include <algorithm>
#include <cmath>
#include <limits>

#include "Utf8Util.hpp"

namespace jdi
{

	namespace
	{
		const int kTimeTickTarget = 10;				/**< 时间轴期望刻度数。 */
		const int kYTickTarget = 6;					/**< 幅值轴期望刻度数（网格较高时）。 */
		const int kYTickTargetMin = 3;				/**< 幅值轴最少刻度数（网格很矮时也要保证可读数）。 */
		const int kYTickTargetMax = 8;				/**< 幅值轴最多刻度数。 */
		const float kYTickSpacing = 28.0f;			/**< 幅值刻度之间的理想间距（逻辑像素）。 */
		const float kYLabelMinGap = 15.0f;			/**< 幅值标签的最小行距（逻辑像素）。 */
		const int kMinorDivisions = 5;				/**< 相邻主刻度之间的等分数（用于估读）。 */
		const unsigned int kMinorLineAlpha = 0x9Au;	/**< 辅助等分线的透明度（越高越清晰）。 */
		const float kScrollBarThickness = 9.0f;		/**< 滚动条宽度（逻辑像素）。 */
		const float kLanePadding = 8.0f;			/**< 网格内边距。 */
		const size_t kMaxPolylinePoints = 20000;	/**< 单条折线最大顶点数（上限保护）。 */
		const size_t kPolylinePointsPerPixel = 2;	/**< 每个像素列允许的折线顶点数（上/下包络两顶点）。 */
		const size_t kMinPolylinePoints = 512;		/**< 折线最少顶点数（窗口很窄时仍保留细节）。 */
		const float kEnvelopeMinPixelSpan = 0.5f;	/**< 包络纵向跨度小于该像素值时合并为单个顶点。 */
		const size_t kMaxScatterPoints = 2500;		/**< 单条散点最大绘制点数。 */
		const size_t kPolylineCacheLimit = 64;		/**< 折线顶点缓存条目上限。 */
		const float kMinScatterRadius = 1.6f;		/**< 散点最小半径（逻辑像素）。 */
		const float kMaxScatterRadius = 12.0f;	/**< 散点最大半径（逻辑像素）。 */
		const float kScatterRadiusScale = 1.5f;	/**< 散点半径相对线宽的增长系数。 */
		const double kMinTimeSpan = 1.0e-12;		/**< 允许的最小时间跨度。 */
		const float kPlotSidePadding = 8.0f;		/**< 绘图区左右留白（逻辑像素）。 */
		const float kLaneDividerWidth = 2.0f;		/**< 网格之间分界线的宽度。 */
		const float kSignalHitTolerance = 6.0f;	/**< 信号曲线命中容差（逻辑像素）。 */
		const float kCursorSnapMinPixels = 6.0f;	/**< 光标吸附采样点的最小采样间隔（逻辑像素）。 */
		const float kLaneLabelPad = 6.0f;		/**< 网格内侧标尺带的内边距。 */
		const float kLegendHeight = 19.0f;		/**< 图例条目高度（逻辑像素）。 */
		const float kLegendPad = 5.0f;			/**< 图例相对网格左上角的内缩。 */
		const float kLegendSwatchSize = 8.0f;	/**< 图例色块尺寸。 */
		const float kLegendItemGap = 14.0f;		/**< 图例条目之间的间距。 */
		const float kLegendMaxTextWidth = 200.0f;	/**< 图例条目的文本宽度上限（超出则省略）。 */

		/**
		 * @brief 将数值限制到合法区间。
		 * @param [IN] value 输入值。
		 * @param [IN] low 下限。
		 * @param [IN] high 上限。
		 * @return 限制后的数值。
		 */
		double ClampDouble(double value, double low, double high)
		{
			if (value < low)
			{
				return low;
			}
			if (value > high)
			{
				return high;
			}
			return value;
		}

		/**
		 * @brief 组装图例文本：使用信号当前显示名（用户重命名后立即生效）。
		 * @param [IN] data 信号数据。
		 * @return 图例文本。
		 */
		std::wstring BuildLegendText(const SignalData& data)
		{
			return data.Title();
		}

		/**
		 * @brief 将信号样式颜色按不透明度换算为实际绘制颜色。
		 * @param [IN] style 信号样式。
		 * @return 叠加不透明度后的 0xAARRGGBB 颜色值。
		 */
		std::uint32_t StyleColor(const SignalStyle& style)
		{
			double opacity = static_cast<double>(style.opacity);
			if (opacity < 0.0)
			{
				opacity = 0.0;
			}
			if (opacity > 1.0)
			{
				opacity = 1.0;
			}
			return WithAlpha(style.color, static_cast<unsigned int>(opacity * 255.0 + 0.5));
		}
	}

	PlotView::PlotView() = default;

	void PlotView::Setup(const UiFonts* fonts, const Theme* theme)
	{
		m_fonts = fonts;
		m_theme = theme;
	}

	void PlotView::SetContext(DataSet* dataSet, TabConfig* tab)
	{
		m_dataSet = dataSet;
		m_dataSetWritable = dataSet;
		m_tab = tab;
		m_hoverLane = -1;
		m_dragMode = PlotDragMode::NONE;
		// 重新绑定数据源后旧的几何键不再有意义，必须清空折线缓存。
		InvalidatePolylineCache();
		RefreshLanes();
	}

	void PlotView::SetScale(float scale)
	{
		m_scale = (scale > 0.1f) ? scale : 1.0f;
	}

	bool PlotView::CursorEnabled() const
	{
		return Tab().CursorEnabled();
	}

	double PlotView::CursorTime() const
	{
		return Tab().CursorTime();
	}

	double PlotView::ViewMinTime() const
	{
		return Tab().ViewMin();
	}

	double PlotView::ViewMaxTime() const
	{
		return Tab().ViewMax();
	}

	bool PlotView::HasDrawableContent() const
	{
		return (m_dataSet != nullptr) && !m_dataSet->Empty() && (m_tab != nullptr) && m_tab->AnyVisible();
	}

	void PlotView::TimeBounds(double& low, double& high) const
	{
		low = 0.0;
		high = 1.0;

		if (m_dataSet == nullptr || m_dataSet->Empty())
		{
			return;
		}

		// 优先使用可见信号所覆盖的范围，使视图随勾选内容自适应。
		if (m_tab != nullptr && m_tab->ComputeVisibleTimeBounds(*m_dataSet, low, high))
		{
			return;
		}

		low = m_dataSet->MinTime();
		high = m_dataSet->MaxTime();
		if (!(high > low))
		{
			high = low + 1.0;
		}
	}

	PlotView::ResolvedSignal PlotView::ResolveSignal(const SignalRef& ref) const
	{
		ResolvedSignal result;
		if (m_dataSet == nullptr)
		{
			return result;
		}
		result.data = m_dataSet->Resolve(ref);
		result.file = m_dataSet->FileAt(ref.fileIndex);
		result.style = m_dataSet->Style(ref);
		result.visible = (m_tab != nullptr) && m_tab->IsVisible(ref);
		return result;
	}

	void PlotView::Layout(const gd::RectF& area)
	{
		m_area = area;

		m_labelBandWidth = 66.0f * m_scale;
		m_timeAxisHeight = 34.0f * m_scale;
		m_minLaneHeight = 54.0f * m_scale;

		// 先为时间轴保留固定高度，剩余空间才交给网格，保证时间轴不会被挤压。
		const float topPadding = 6.0f * m_scale;
		const float availHeight = std::max(0.0f, area.Height - m_timeAxisHeight - topPadding);

		// 预估是否需要纵向滚动条：仅取决于网格数量与最小网格高度（网格之间不再留间隔）。
		std::size_t laneCount = (m_tab != nullptr) ? m_tab->Lanes().size() : 0;
		if (laneCount > 0)
		{
			const float needed = static_cast<float>(laneCount) * m_minLaneHeight;
			m_scrollBarVisible = (needed > availHeight);
		}
		else
		{
			m_scrollBarVisible = false;
		}

		const float sidePadding = kPlotSidePadding * m_scale;
		const float rightReserve = m_scrollBarVisible
		                              ? (kScrollBarThickness * m_scale + sidePadding)
		                              : sidePadding;
		const float plotWidth = std::max(0.0f, area.Width - sidePadding - rightReserve);

		m_plotRect = gd::RectF(area.X + sidePadding, area.Y + topPadding, plotWidth, availHeight);
		m_timeAxisRect =
		    gd::RectF(m_plotRect.X, m_plotRect.Y + m_plotRect.Height, m_plotRect.Width, m_timeAxisHeight);
		m_scrollBarRect = gd::RectF(area.X + area.Width - kScrollBarThickness * m_scale - 3.0f * m_scale,
		                            m_plotRect.Y, kScrollBarThickness * m_scale, m_plotRect.Height);

		BuildLaneVisuals();
	}

	void PlotView::RefreshLanes()
	{
		BuildLaneVisuals();
	}

	const SignalRef& PlotView::SelectedRef() const
	{
		static const SignalRef fallback;
		return (m_dataSet != nullptr) ? m_dataSet->Selected() : fallback;
	}

	void PlotView::SelectSignal(const SignalRef& ref)
	{
		if (m_dataSetWritable != nullptr)
		{
			m_dataSetWritable->SetSelected(ref);
		}
	}

	void PlotView::ClampLaneScroll()
	{
		const float maxOffset = std::max(0.0f, m_laneContentHeight - m_plotRect.Height);
		Tab().LaneScroll() = static_cast<float>(ClampDouble(Tab().LaneScroll(), 0.0, maxOffset));
	}

	bool PlotView::LaneSpansMultipleFiles(int laneIndex) const
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return false;
		}

		int firstFile = -1;
		for (const SignalRef& ref : m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].signals)
		{
			const SignalStyle* style = m_dataSet->Style(ref);
			if (style == nullptr || !m_tab->IsVisible(ref))
			{
				continue;
			}
			if (firstFile < 0)
			{
				firstFile = ref.fileIndex;
			}
			else if (ref.fileIndex != firstFile)
			{
				return true;
			}
		}
		return false;
	}

	void PlotView::BuildLaneVisuals()
	{
		m_lanes.clear();

		if (m_tab == nullptr || m_dataSet == nullptr || !HasDrawableContent())
		{
			m_laneContentHeight = 0.0f;
			return;
		}

		const std::vector<Lane>& lanes = m_tab->Lanes();
		const std::size_t count = lanes.size();
		if (count == 0)
		{
			m_laneContentHeight = 0.0f;
			return;
		}

		const float gap = 0.0f;
		float laneHeight = m_plotRect.Height / static_cast<float>(count);
		if (laneHeight < m_minLaneHeight * m_scale)
		{
			laneHeight = m_minLaneHeight * m_scale;
		}
		m_laneContentHeight = laneHeight * static_cast<float>(count);
		ClampLaneScroll();

		const float scrollOffset = Tab().LaneScroll();

		m_lanes.resize(count);
		for (std::size_t index = 0; index < count; ++index)
		{
			LaneVisual& visual = m_lanes[index];
			visual.rect = gd::RectF(
			    m_plotRect.X,
			    m_plotRect.Y + static_cast<float>(index) * (laneHeight + gap) - scrollOffset,
			    m_plotRect.Width, laneHeight);
			m_tab->ComputeLaneRange(*m_dataSet, static_cast<int>(index), visual.yMin, visual.yMax);
			if (!(visual.yMax > visual.yMin))
			{
				visual.yMin = 0.0;
				visual.yMax = 1.0;
			}
		}
	}

	float PlotView::TimeToX(double time) const
	{
		const double viewMin = Tab().ViewMin();
		const double viewMax = Tab().ViewMax();
		const double span = viewMax - viewMin;
		if (!(span > 0.0) || m_plotRect.Width <= 0.0f)
		{
			return m_plotRect.X;
		}
		return m_plotRect.X + static_cast<float>((time - viewMin) / span * m_plotRect.Width);
	}

	double PlotView::XToTime(float x) const
	{
		const double viewMin = Tab().ViewMin();
		if (m_plotRect.Width <= 0.0f)
		{
			return viewMin;
		}
		const double ratio = static_cast<double>(x - m_plotRect.X) / static_cast<double>(m_plotRect.Width);
		return viewMin + ratio * (Tab().ViewMax() - viewMin);
	}

	float PlotView::ValueToY(double value, const LaneVisual& lane) const
	{
		const double span = lane.yMax - lane.yMin;
		if (!(span > 0.0))
		{
			return lane.rect.Y + lane.rect.Height * 0.5f;
		}

		double ratio = (value - lane.yMin) / span;
		ratio = ClampDouble(ratio, -50.0, 50.0);
		return lane.rect.Y + lane.rect.Height * static_cast<float>(1.0 - ratio);
	}

	double PlotView::YToValue(float y, const LaneVisual& lane) const
	{
		if (lane.rect.Height <= 0.0f)
		{
			return lane.yMin;
		}
		const double ratio = 1.0 - static_cast<double>(y - lane.rect.Y) / static_cast<double>(lane.rect.Height);
		return lane.yMin + ratio * (lane.yMax - lane.yMin);
	}

	int PlotView::LaneAtY(int y) const
	{
		const float fy = static_cast<float>(y);
		for (std::size_t index = 0; index < m_lanes.size(); ++index)
		{
			const gd::RectF& rect = m_lanes[index].rect;
			if (fy >= rect.Y && fy <= rect.Y + rect.Height)
			{
				return static_cast<int>(index);
			}
		}
		return -1;
	}

	void PlotView::ClampTimeView()
	{
		if (m_dataSet == nullptr || m_dataSet->Empty())
		{
			return;
		}

		double span = Tab().ViewMax() - Tab().ViewMin();
		if (!(span > 0.0))
		{
			span = kMinTimeSpan;
		}

		double dataMin = 0.0;
		double dataMax = 1.0;
		TimeBounds(dataMin, dataMax);

		const double pad = span * 2.0;
		const double minAllowed = dataMin - pad;
		const double maxAllowed = dataMax + pad;

		if (Tab().ViewMin() < minAllowed)
		{
			Tab().ViewMin() = minAllowed;
			Tab().ViewMax() = Tab().ViewMin() + span;
		}
		if (Tab().ViewMax() > maxAllowed)
		{
			Tab().ViewMax() = maxAllowed;
			Tab().ViewMin() = Tab().ViewMax() - span;
		}
	}

	void PlotView::ZoomTimeAt(double factor, double anchorTime)
	{
		if (m_dataSet == nullptr || m_dataSet->Empty() || !(factor > 0.0))
		{
			return;
		}

		double dataMin = 0.0;
		double dataMax = 1.0;
		TimeBounds(dataMin, dataMax);
		const double dataSpan = std::max(dataMax - dataMin, kMinTimeSpan);

		const double span = Tab().ViewMax() - Tab().ViewMin();
		double newSpan = ClampDouble(span / factor, dataSpan * 1.0e-9, dataSpan * 100.0);

		const double ratio = (span > 0.0) ? (anchorTime - Tab().ViewMin()) / span : 0.5;
		Tab().ViewMin() = anchorTime - ratio * newSpan;
		Tab().ViewMax() = Tab().ViewMin() + newSpan;
		ClampTimeView();
	}

	void PlotView::ZoomTimeStep(double factor)
	{
		const double anchor = (Tab().ViewMin() + Tab().ViewMax()) * 0.5;
		ZoomTimeAt(factor, anchor);
	}

	void PlotView::PanTimeByFraction(double fraction)
	{
		const double span = Tab().ViewMax() - Tab().ViewMin();
		const double delta = span * fraction;
		Tab().ViewMin() += delta;
		Tab().ViewMax() += delta;
		ClampTimeView();
	}

	void PlotView::ScrollLanesByFraction(double fraction)
	{
		Tab().LaneScroll() += static_cast<float>(fraction * static_cast<double>(m_laneContentHeight));
		// 立即重建几何，避免命中测试使用旧位置。
		BuildLaneVisuals();
	}

	void PlotView::FitAll()
	{
		if (m_dataSet == nullptr || m_dataSet->Empty())
		{
			Tab().ViewMin() = 0.0;
			Tab().ViewMax() = 1.0;
			Tab().ViewInitialized() = true;
			return;
		}

		double low = 0.0;
		double high = 1.0;
		TimeBounds(low, high);
		if (!(high > low))
		{
			const double padding = std::max(1.0e-6, std::fabs(low) * 0.01);
			low -= padding;
			high += padding;
		}

		Tab().ViewMin() = low;
		Tab().ViewMax() = high;
		Tab().ViewInitialized() = true;
		Tab().LaneScroll() = 0.0f;
		// 自适应即回到初始状态：退出拖拽缩放模式并放下进行中的选区与拖拽。
		Tab().ZoomMode() = PlotZoomMode::NONE;
		m_rubberRect = gd::RectF();
		m_dragMode = PlotDragMode::NONE;
		m_dragSignal = SignalRef();
		m_dragTargetLane = -1;
		m_hoverSignal = SignalRef();

		if (m_tab != nullptr)
		{
			for (Lane& lane : m_tab->Lanes())
			{
				lane.autoRange = true;
			}
		}
		BuildLaneVisuals();
	}

	void PlotView::DisableCursor()
	{
		Tab().CursorEnabled() = false;
		m_cursorHover = false;
		if (m_editTarget == PlotEditTarget::CURSOR_TIME)
		{
			EndEdit(false);
		}
		if (m_dragMode == PlotDragMode::CURSOR_MOVE)
		{
			m_dragMode = PlotDragMode::NONE;
		}
	}

	bool PlotView::CancelDrag()
	{
		if (m_dragMode == PlotDragMode::NONE)
		{
			return false;
		}

		// 放弃当前拖拽：清空拖拽状态与尚未生效的缩放选区，不改动任何视图范围。
		// 调用方仍持有鼠标捕获，松开左键时会走 OnLButtonUp，
		// 此时拖拽模式已是 NONE，选区不会被应用到时间轴/幅值轴上。
		m_dragMode = PlotDragMode::NONE;
		m_dragLane = -1;
		m_dragMoved = false;
		m_rubberRect = gd::RectF();
		m_dragSignal = SignalRef();
		m_dragTargetLane = -1;
		return true;
	}

	void PlotView::InvalidatePolylineCache()
	{
		m_polylineCache.clear();
	}

	bool PlotView::FitTimeToLane(int laneIndex)
	{
		if (m_dataSet == nullptr || m_tab == nullptr)
		{
			return false;
		}

		const std::vector<Lane>& lanes = m_tab->Lanes();
		if (laneIndex < 0 || laneIndex >= static_cast<int>(lanes.size()))
		{
			return false;
		}

		double low = std::numeric_limits<double>::infinity();
		double high = -std::numeric_limits<double>::infinity();
		for (const SignalRef& ref : lanes[static_cast<std::size_t>(laneIndex)].signals)
		{
			const DataFile* file = m_dataSet->FileAt(ref.fileIndex);
			if (file == nullptr)
			{
				continue;
			}
			low = std::min(low, file->minTime);
			high = std::max(high, file->maxTime);
		}

		if (!std::isfinite(low) || !std::isfinite(high) || !(high > low))
		{
			return false;
		}

		Tab().ViewMin() = low;
		Tab().ViewMax() = high;
		Tab().ViewInitialized() = true;
		// 与“适应视图”保持一致：退出选区缩放模式，避免模式按钮与实际状态不符。
		Tab().ZoomMode() = PlotZoomMode::NONE;
		m_rubberRect = gd::RectF();
		BuildLaneVisuals();
		return true;
	}

	bool PlotView::SampleSpacingPixels(const DataFile& file, double time, double& pixels) const
	{
		pixels = 0.0;

		const std::vector<double>& samples = file.time;
		if (samples.size() < 2 || m_plotRect.Width <= 1.0f)
		{
			return false;
		}

		const double viewSpan = Tab().ViewMax() - Tab().ViewMin();
		if (!(viewSpan > 0.0))
		{
			return false;
		}

		const int index = FindNearestSample(file, time);
		if (index < 0)
		{
			return false;
		}

		double spacing = 0.0;
		if (index > 0)
		{
			spacing = samples[static_cast<std::size_t>(index)] - samples[static_cast<std::size_t>(index) - 1];
		}
		else
		{
			spacing = samples[1] - samples[0];
		}
		// 时间轴非单调时前后差值可能为负，此时不做吸附。
		if (!(spacing > 0.0) || !std::isfinite(spacing))
		{
			return false;
		}

		pixels = spacing / viewSpan * static_cast<double>(m_plotRect.Width);
		return true;
	}

	bool PlotView::SnapTimeToSample(double time, double& snapped) const
	{
		if (m_dataSet == nullptr)
		{
			return false;
		}

		const double minPixels = static_cast<double>(kCursorSnapMinPixels) * static_cast<double>(m_scale);

		bool found = false;
		double bestDistance = std::numeric_limits<double>::infinity();
		double bestTime = 0.0;

		for (const DataFile& file : m_dataSet->Files())
		{
			// 只有采样点在屏幕上足够稀疏时才吸附，否则缩小视图后光标会“跳格”。
			double pixels = 0.0;
			if (!SampleSpacingPixels(file, time, pixels) || pixels < minPixels)
			{
				continue;
			}

			const int index = FindNearestSample(file, time);
			if (index < 0)
			{
				continue;
			}
			const double candidate = file.time[static_cast<std::size_t>(index)];
			if (!std::isfinite(candidate))
			{
				continue;
			}

			const double distance = std::fabs(candidate - time);
			if (distance < bestDistance)
			{
				bestDistance = distance;
				bestTime = candidate;
				found = true;
			}
		}

		if (found)
		{
			snapped = bestTime;
		}
		return found;
	}

	bool PlotView::ToggleCursor()
	{
		if (Tab().CursorEnabled())
		{
			DisableCursor();
			return true;
		}

		Tab().CursorEnabled() = true;
		// 启用时光标居中放置，随后可用鼠标靠近拖拽或双击指定精确时间。
		Tab().CursorTime() = (Tab().ViewMin() + Tab().ViewMax()) * 0.5;
		m_cursorHover = true;
		return true;
	}

	PlotZoomMode PlotView::CurrentZoomMode() const
	{
		return Tab().ZoomMode();
	}

	bool PlotView::ToggleZoomMode(PlotZoomMode mode)
	{
		const PlotZoomMode current = Tab().ZoomMode();
		Tab().ZoomMode() = (current == mode) ? PlotZoomMode::NONE : mode;
		return true;
	}

	float PlotView::CursorX() const
	{
		return TimeToX(Tab().CursorTime());
	}

	gd::RectF PlotView::CursorLabelRect() const
	{
		if (m_fonts == nullptr || m_fonts->monoSmall == nullptr)
		{
			return gd::RectF();
		}

		const std::wstring text = FormatValue(Tab().CursorTime());
		const float width =
		    std::max(64.0f * m_scale, UiMeasureTextWidth(m_fonts->monoSmall, text) + 16.0f * m_scale);
		const float height = 20.0f * m_scale;

		// 读数标签固定在绘图区顶部，避免遮挡底部时间轴刻度尺。
		float left = CursorX() - width * 0.5f;
		left = std::max(m_plotRect.X, std::min(left, m_plotRect.X + m_plotRect.Width - width));
		const float top = m_plotRect.Y + 2.0f * m_scale;

		return gd::RectF(left, top, width, height);
	}

	bool PlotView::IsOnCursorLine(int x) const
	{
		if (!Tab().CursorEnabled() || m_plotRect.Width <= 0.0f)
		{
			return false;
		}
		const float cursorX = CursorX();
		const float tolerance = 6.0f * m_scale;
		return (static_cast<float>(x) >= cursorX - tolerance) && (static_cast<float>(x) <= cursorX + tolerance);
	}

	bool PlotView::ApplyTimeSelection(float x0, float x1)
	{
		if (m_plotRect.Width <= 0.0f)
		{
			return false;
		}

		float left = std::min(x0, x1);
		float right = std::max(x0, x1);
		left = std::max(left, m_plotRect.X);
		right = std::min(right, m_plotRect.X + m_plotRect.Width);
		if (right - left < 8.0f * m_scale)
		{
			return false;
		}

		double timeA = XToTime(left);
		double timeB = XToTime(right);
		if (timeB < timeA)
		{
			std::swap(timeA, timeB);
		}
		if (!(timeB - timeA > 0.0))
		{
			return false;
		}

		Tab().ViewMin() = timeA;
		Tab().ViewMax() = timeB;
		ClampTimeView();
		return true;
	}

	bool PlotView::ApplyValueSelection(int laneIndex, float y0, float y1)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return false;
		}

		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		if (visual.rect.Height <= 0.0f)
		{
			return false;
		}

		float top = std::min(y0, y1);
		float bottom = std::max(y0, y1);
		top = std::max(top, visual.rect.Y);
		bottom = std::min(bottom, visual.rect.Y + visual.rect.Height);
		if (bottom - top < 10.0f * m_scale)
		{
			return false;
		}

		const double valueTop = YToValue(top, visual);
		const double valueBottom = YToValue(bottom, visual);
		if (!(std::fabs(valueTop - valueBottom) > 0.0))
		{
			return false;
		}

		Lane& lane = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)];
		lane.autoRange = false;
		lane.yMin = std::min(valueTop, valueBottom);
		lane.yMax = std::max(valueTop, valueBottom);
		return true;
	}

	int PlotView::LaneIndexAt(int x, int y) const
	{
		if (!UiPointInRect(m_plotRect, static_cast<float>(x), static_cast<float>(y)))
		{
			return -1;
		}
		return LaneAtY(y);
	}

	bool PlotView::LaneRangeIsAuto(int laneIndex) const
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return true;
		}
		return m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].autoRange;
	}

	bool PlotView::ResetLaneRange(int laneIndex)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return false;
		}

		Lane& lane = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)];
		if (lane.autoRange)
		{
			return false;
		}
		lane.autoRange = true;
		BuildLaneVisuals();
		return true;
	}

	void PlotView::ScaleLaneRange(int laneIndex, double factor, double anchorValue)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return;
		}
		if (!(factor > 0.0) || !std::isfinite(anchorValue))
		{
			return;
		}

		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		const double span = visual.yMax - visual.yMin;
		if (!(span > 0.0))
		{
			return;
		}

		const double magnitude = std::max(std::fabs(visual.yMax), std::fabs(visual.yMin));
		const double minSpan = std::max(magnitude * 1.0e-9, 1.0e-12);
		const double newSpan = ClampDouble(span / factor, minSpan, magnitude * 100.0 + 1.0);
		const double ratio = (visual.yMax - anchorValue) / span;

		Lane& lane = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)];
		lane.autoRange = false;
		lane.yMin = anchorValue - ratio * newSpan;
		lane.yMax = lane.yMin + newSpan;
		BuildLaneVisuals();
	}

	void PlotView::ShiftLaneRange(int laneIndex, double deltaValue)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()) ||
		    !std::isfinite(deltaValue) || deltaValue == 0.0)
		{
			return;
		}

		// 首次纵向拖动时先把当前自适应范围固化下来，再进行偏移。
		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		Lane& lane = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)];
		if (lane.autoRange)
		{
			lane.autoRange = false;
			lane.yMin = visual.yMin;
			lane.yMax = visual.yMax;
		}
		lane.yMin += deltaValue;
		lane.yMax += deltaValue;
		BuildLaneVisuals();
	}

	bool PlotView::BeginLaneValueEdit(int laneIndex, bool editMax, const gd::RectF& anchorRect)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return false;
		}
		if (m_lanes.empty())
		{
			BuildLaneVisuals();
		}
		if (laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return false;
		}

		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		const double current = editMax ? visual.yMax : visual.yMin;
		return BeginEdit(editMax ? PlotEditTarget::LANE_Y_MAX : PlotEditTarget::LANE_Y_MIN, laneIndex,
		                 FormatValue(current), anchorRect);
	}

	bool PlotView::LaneRange(int laneIndex, double& yMin, double& yMax) const
	{
		if (laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()))
		{
			// 菜单弹出时几何可能尚未建立，回退到配置内的自适应范围。
			if (m_tab == nullptr || m_dataSet == nullptr || laneIndex < 0 ||
			    laneIndex >= static_cast<int>(m_tab->Lanes().size()))
			{
				return false;
			}
			m_tab->ComputeLaneRange(*m_dataSet, laneIndex, yMin, yMax);
			return true;
		}

		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		yMin = visual.yMin;
		yMax = visual.yMax;
		return true;
	}

	SignalRef PlotView::HitTestSignal(int x, int y) const
	{
		SignalRef empty;
		if (m_tab == nullptr || m_dataSet == nullptr || !HasDrawableContent())
		{
			return empty;
		}
		if (!UiPointInRect(m_plotRect, static_cast<float>(x), static_cast<float>(y)))
		{
			return empty;
		}

		const int laneIndex = LaneAtY(y);
		if (laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return empty;
		}

		const LaneVisual& lane = m_lanes[static_cast<std::size_t>(laneIndex)];
		const float tolerance = kSignalHitTolerance * m_scale;
		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);

		SignalRef best;
		float bestDistance = tolerance;

		// 只为当前网格内的可见信号做精确的点到线段距离检测，避免跨网格误命中。
		for (const SignalRef& ref : m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].signals)
		{
			const ResolvedSignal resolved = ResolveSignal(ref);
			if (resolved.data == nullptr || resolved.style == nullptr || !resolved.visible)
			{
				continue;
			}

			// 复用绘制阶段的折线顶点：悬停检测通常与上一帧几何完全相同，
			// 不再为“鼠标移动但命中结果未变”重复扫描全量采样点。
			const PolylineCacheEntry* cached = AcquirePolyline(ref, resolved, lane);
			if (cached == nullptr)
			{
				continue;
			}
			const std::vector<gd::PointF>& points = cached->points;
			const std::vector<std::size_t>& breaks = cached->breaks;
			if (points.size() < 2)
			{
				continue;
			}

			// 横向先行裁剪：点到线段的距离必然不小于横向距离本身，
			// 因此只有横向落在容差范围内的顶点才可能命中。
			// 时间单调时折线顶点按 x 递增，可二分定位后只扫描这一小段；
			// 否则每次鼠标移动都要遍历上万个顶点（悬停卡顿的来源之一）。
			std::size_t windowFirst = 0;
			std::size_t windowLast = points.size();
			if (resolved.file->timeMonotonic)
			{
				const auto byX = [](const gd::PointF& point, float limit) { return point.X < limit; };
				windowFirst = static_cast<std::size_t>(
				    std::lower_bound(points.begin(), points.end(), fx - tolerance, byX) - points.begin());
				windowLast = static_cast<std::size_t>(
				    std::upper_bound(points.begin(), points.end(), fx + tolerance,
				                     [](float limit, const gd::PointF& point) { return limit < point.X; }) -
				    points.begin());
			}
			if (windowFirst >= windowLast)
			{
				continue;
			}

			// 散点模式下把采样点本身也视为可命中目标。
			if (resolved.style->mode == DrawMode::SCATTER)
			{
				for (std::size_t index = windowFirst; index < windowLast; ++index)
				{
					const gd::PointF& point = points[index];
					const float dx = point.X - fx;
					const float dy = point.Y - fy;
					const float distance = std::sqrt(dx * dx + dy * dy);
					if (distance <= bestDistance)
					{
						bestDistance = distance;
						best = ref;
					}
				}
				continue;
			}

			for (std::size_t k = 0; k < breaks.size(); ++k)
			{
				const std::size_t start = breaks[k];
				const std::size_t stop = (k + 1 < breaks.size()) ? breaks[k + 1] : points.size();
				const std::size_t scanBegin = std::max(start + 1, windowFirst);
				const std::size_t scanEnd = std::min(stop, windowLast);
				for (std::size_t index = scanBegin; index < scanEnd; ++index)
				{
					const gd::PointF& a = points[index - 1];
					const gd::PointF& b = points[index];

					const float vx = b.X - a.X;
					const float vy = b.Y - a.Y;
					const float wx = fx - a.X;
					const float wy = fy - a.Y;

					const float lengthSquared = vx * vx + vy * vy;
					float t = 0.0f;
					if (lengthSquared > 1.0e-6f)
					{
						t = (wx * vx + wy * vy) / lengthSquared;
						t = std::max(0.0f, std::min(1.0f, t));
					}

					const float dx = wx - t * vx;
					const float dy = wy - t * vy;
					const float distance = std::sqrt(dx * dx + dy * dy);
					if (distance < bestDistance)
					{
						bestDistance = distance;
						best = ref;
					}
				}
			}
		}

		return best;
	}

	gd::RectF PlotView::EditFieldRect() const
	{
		if (m_editTarget == PlotEditTarget::NONE || m_fonts == nullptr || m_fonts->monoSmall == nullptr)
		{
			return gd::RectF();
		}

		const float height = 22.0f * m_scale;
		float width = std::max(90.0f * m_scale,
		                       UiMeasureTextWidth(m_fonts->monoSmall, m_edit.Text()) + 24.0f * m_scale);

		if (m_editTarget == PlotEditTarget::CURSOR_TIME)
		{
			// 与显示态标签取相同宽度，避免进入编辑时框体跳动。
			const gd::RectF displayRect = CursorLabelRect();
			width = std::max(width, displayRect.Width);
			float left = CursorX() - width * 0.5f;
			left = std::max(m_plotRect.X, std::min(left, m_plotRect.X + m_plotRect.Width - width));
			return gd::RectF(left, m_plotRect.Y + 2.0f * m_scale, width, height);
		}

		if (m_editTarget == PlotEditTarget::SIGNAL_NAME)
		{
			// 图例改名：输入框直接落在被双击的图例条目位置上。
			if (m_editFieldRect.Width <= 0.0f)
			{
				return gd::RectF();
			}
			const float nameWidth = std::max(width, m_editFieldRect.Width);
			return gd::RectF(m_editFieldRect.X, m_editFieldRect.Y, nameWidth, height);
		}

		// 网格 Y 轴上下限输入框：优先落在被点击的菜单条目位置，保证"就地编辑"的观感。
		if (m_editFieldRect.Width > 0.0f && m_editFieldRect.Height > 0.0f)
		{
			float left = m_editFieldRect.X;
			float top = m_editFieldRect.Y;
			left = std::max(m_area.X + 2.0f * m_scale,
			                std::min(left, m_area.X + m_area.Width - width - 2.0f * m_scale));
			top = std::max(m_area.Y + 2.0f * m_scale,
			               std::min(top, m_area.Y + m_area.Height - height - 2.0f * m_scale));
			return gd::RectF(left, top, width, height);
		}

		if (m_editLane < 0 || m_editLane >= static_cast<int>(m_lanes.size()))
		{
			return gd::RectF();
		}
		const LaneVisual& lane = m_lanes[static_cast<std::size_t>(m_editLane)];
		const float left = lane.rect.X + kLaneLabelPad * m_scale;
		const float top = lane.rect.Y + kLaneLabelPad * m_scale;
		return gd::RectF(left, top, std::min(width, lane.rect.Width - 2.0f * kLaneLabelPad * m_scale), height);
	}

	bool PlotView::BeginEdit(PlotEditTarget target, int laneIndex, const std::wstring& initialText,
	                         const gd::RectF& anchorRect)
	{
		if (target == PlotEditTarget::NONE)
		{
			return false;
		}
		// 切换编辑目标时清掉上一轮残留（图例改名需由调用方在进入前先设置 m_editSignal）。
		if (target != PlotEditTarget::SIGNAL_NAME)
		{
			m_editSignal = SignalRef();
		}
		// 调用方可以用锚点矩形指定输入框位置（如菜单条目、图例条目）；
		// 未提供锚点时由 EditFieldRect() 按目标类型自动推导。
		if (anchorRect.Width > 0.0f && anchorRect.Height > 0.0f)
		{
			m_editFieldRect = anchorRect;
		}
		else if (target != PlotEditTarget::SIGNAL_NAME)
		{
			m_editFieldRect = gd::RectF();
		}
		m_editTarget = target;
		m_editLane = laneIndex;

		// 名称与数值均不限长度（数值在提交时会做范围夹取）。
		const bool nameField = (target == PlotEditTarget::SIGNAL_NAME);
		m_edit.Begin(initialText, true, nameField ? EditFilter::ANY : EditFilter::NUMBER, 0u);
		return true;
	}

	bool PlotView::TakePendingRename(SignalRef& ref, std::wstring& name)
	{
		if (!m_pendingRename)
		{
			return false;
		}
		ref = m_pendingRenameRef;
		name = m_pendingRenameName;
		m_pendingRename = false;
		m_pendingRenameRef = SignalRef();
		m_pendingRenameName.clear();
		return true;
	}

	bool PlotView::EndEdit(bool commit)
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}

		const PlotEditTarget target = m_editTarget;
		const int laneIndex = m_editLane;
		const SignalRef editSignal = m_editSignal;
		const std::wstring text = Trim(m_edit.Text());

		m_editTarget = PlotEditTarget::NONE;
		m_editLane = -1;
		m_editSignal = SignalRef();
		m_editFieldRect = gd::RectF();
		m_edit.End();

		// 信号改名：交给宿主窗口落到数据层，绘图区只持有只读数据。
		if (target == PlotEditTarget::SIGNAL_NAME)
		{
			if (commit && !text.empty() && editSignal.IsValid())
			{
				m_pendingRenameRef = editSignal;
				m_pendingRenameName = text;
				m_pendingRename = true;
			}
			return true;
		}

		double parsed = 0.0;
		bool parsedOk = false;
		if (commit && !text.empty())
		{
			wchar_t* stop = nullptr;
			parsed = std::wcstod(text.c_str(), &stop);
			parsedOk = (stop != text.c_str()) && (parsed == parsed) && std::isfinite(parsed);
		}

		if (!parsedOk)
		{
			return true;
		}

		if (target == PlotEditTarget::CURSOR_TIME)
		{
			double low = 0.0;
			double high = 1.0;
			TimeBounds(low, high);
			const double span = std::max(high - low, kMinTimeSpan);
			Tab().CursorTime() = ClampDouble(parsed, low - span * 10.0, high + span * 10.0);
			return true;
		}

		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return true;
		}

		// 直接输入上下限：先固化当前范围，再用新值替换对应端点（保证 max > min）。
		if (laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return true;
		}
		const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
		Lane& lane = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)];
		if (lane.autoRange)
		{
			lane.autoRange = false;
			lane.yMin = visual.yMin;
			lane.yMax = visual.yMax;
		}

		const double magnitude = std::max(std::fabs(lane.yMin), std::fabs(lane.yMax));
		const double minimumGap = std::max(magnitude * 1.0e-6, 1.0e-12);

		if (target == PlotEditTarget::LANE_Y_MAX)
		{
			if (parsed <= lane.yMin)
			{
				parsed = lane.yMin + minimumGap;
			}
			lane.yMax = parsed;
		}
		else
		{
			if (parsed >= lane.yMax)
			{
				parsed = lane.yMax - minimumGap;
			}
			lane.yMin = parsed;
		}

		BuildLaneVisuals();
		return true;
	}

	bool PlotView::OnEditChar(wchar_t character)
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}

		// 剪贴板与全选快捷键经 WM_CHAR 送达（Ctrl+C/X/V/A 分别对应 3/24/22/1）。
		switch (character)
		{
		case 0x03: // Ctrl+C
			m_edit.CopyToClipboard(m_host);
			return false;
		case 0x18: // Ctrl+X
			return m_edit.CutToClipboard(m_host);
		case 0x16: // Ctrl+V
			return m_edit.PasteFromClipboard(m_host);
		case 0x01: // Ctrl+A
			m_edit.SelectAll();
			return true;
		default:
			break;
		}

		if (character == L'\r' || character == L'\n')
		{
			return EndEdit(true);
		}
		// 退格/删除已由 WM_KEYDOWN 的 OnEditKey 处理，此处忽略控制字符避免重复删除。
		if (character < 0x20 || character == 0x7F)
		{
			return false;
		}
		return m_edit.Insert(character);
	}

	bool PlotView::CollapseEditSelectionToEnd()
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}
		return m_edit.DeselectToEnd();
	}

	bool PlotView::OnEditMouseDown(int x, int y)
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}
		const gd::RectF rect = EditFieldRect();
		if (rect.Width <= 0.0f)
		{
			return false;
		}
		return UiEditFieldMouseDown(m_fonts->uiSmall, rect, m_edit, m_scale, x, y);
	}

	bool PlotView::OnEditMouseMove(int x)
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}
		const gd::RectF rect = EditFieldRect();
		if (rect.Width <= 0.0f)
		{
			return false;
		}
		return UiEditFieldMouseMove(m_fonts->uiSmall, rect, m_edit, m_scale, x);
	}

	bool PlotView::OnEditMouseUp()
	{
		if (!m_edit.Dragging())
		{
			return false;
		}
		m_edit.EndDrag();
		return true;
	}

	bool PlotView::OnEditKey(WPARAM key)
	{
		if (m_editTarget == PlotEditTarget::NONE)
		{
			return false;
		}

		const bool shift = (GetKeyState(VK_SHIFT) & 0x8000) != 0;
		const bool control = (GetKeyState(VK_CONTROL) & 0x8000) != 0;

		switch (key)
		{
		case VK_RETURN:
			return EndEdit(true);
		case VK_ESCAPE:
			return EndEdit(false);
		case VK_BACK:
			return m_edit.Backspace();
		case VK_DELETE:
			return m_edit.DeleteForward();
		case VK_LEFT:
			return m_edit.MoveCaret(-1, shift);
		case VK_RIGHT:
			return m_edit.MoveCaret(1, shift);
		case VK_HOME:
			return m_edit.MoveHome(shift);
		case VK_END:
			return m_edit.MoveEnd(shift);
		case 'A':
			if (control)
			{
				m_edit.SelectAll();
			}
			return true;
		default:
			break;
		}
		return true;
	}

	bool PlotView::HitTest(int x, int y) const
	{
		return UiPointInRect(m_area, static_cast<float>(x), static_cast<float>(y));
	}

	HCURSOR PlotView::QueryCursor(int x, int y) const
	{
		switch (m_dragMode)
		{
		case PlotDragMode::PAN:
			return LoadCursorW(nullptr, IDC_SIZEALL);
		case PlotDragMode::RUBBER_TIME:
			return LoadCursorW(nullptr, IDC_SIZEWE);
		case PlotDragMode::RUBBER_VALUE:
			return LoadCursorW(nullptr, IDC_SIZENS);
		case PlotDragMode::SCROLL_LANES:
			return LoadCursorW(nullptr, IDC_SIZENS);
		case PlotDragMode::CURSOR_MOVE:
			return LoadCursorW(nullptr, IDC_SIZEWE);
		case PlotDragMode::MOVE_SIGNAL:
			return LoadCursorW(nullptr, IDC_SIZEALL);
		default:
			break;
		}

		if (m_scrollBarVisible &&
		    UiPointInRect(m_scrollBarRect, static_cast<float>(x), static_cast<float>(y)))
		{
			return LoadCursorW(nullptr, IDC_SIZENS);
		}

		if (IsOnCursorLine(x) && UiPointInRect(m_area, static_cast<float>(x), static_cast<float>(y)))
		{
			return LoadCursorW(nullptr, IDC_SIZEWE);
		}

		if (UiPointInRect(m_plotRect, static_cast<float>(x), static_cast<float>(y)))
		{
			// 命中信号曲线时给出可拖拽提示光标（仅在常规模式下）。
			if (Tab().ZoomMode() == PlotZoomMode::NONE && HitTestSignal(x, y).IsValid())
			{
				return LoadCursorW(nullptr, IDC_SIZEALL);
			}

			// 仅在缩放模式下才切换到对应的缩放光标，常规模式保持箭头（不出现十字指针）。
			const PlotZoomMode mode = Tab().ZoomMode();
			if (mode == PlotZoomMode::TIME)
			{
				return LoadCursorW(nullptr, IDC_SIZEWE);
			}
			if (mode == PlotZoomMode::VALUE)
			{
				return LoadCursorW(nullptr, IDC_SIZENS);
			}
		}
		return nullptr;
	}

	bool PlotView::OnMouseMove(int x, int y)
	{
		m_mouseX = x;
		m_mouseY = y;

		if (!HasDrawableContent())
		{
			return false;
		}

		const float fx = static_cast<float>(x);

		switch (m_dragMode)
		{
		case PlotDragMode::PAN:
		{
			if (m_plotRect.Width <= 0.0f)
			{
				return false;
			}

			// 横向拖动平移时间轴；纵向拖动偏移当前网格的幅值显示位置。
			const double span = Tab().ViewMax() - Tab().ViewMin();
			const double delta =
			    -static_cast<double>(x - m_dragLastX) / static_cast<double>(m_plotRect.Width) * span;
			if (delta != 0.0)
			{
				Tab().ViewMin() += delta;
				Tab().ViewMax() += delta;
				ClampTimeView();
			}

			const int laneIndex = m_dragLane;
			if (laneIndex >= 0 && laneIndex < static_cast<int>(m_lanes.size()) && y != m_dragLastY)
			{
				const LaneVisual& visual = m_lanes[static_cast<std::size_t>(laneIndex)];
				if (visual.rect.Height > 0.0f)
				{
					const double valueSpan = visual.yMax - visual.yMin;
					const double deltaValue = static_cast<double>(y - m_dragLastY) /
					                          static_cast<double>(visual.rect.Height) * valueSpan;
					ShiftLaneRange(laneIndex, deltaValue);
				}
			}

			m_dragLastX = x;
			m_dragLastY = y;
			if (std::abs(x - m_dragStartX) > 3 || std::abs(y - m_dragStartY) > 3)
			{
				m_dragMoved = true;
			}
			return true;
		}
		case PlotDragMode::RUBBER_TIME:
		{
			// 竖向选区贯穿整个绘图区高度，只取横向区间用于时间轴缩放。
			const float left = static_cast<float>(std::min(x, m_dragStartX));
			const float width = static_cast<float>(std::abs(x - m_dragStartX));
			m_rubberRect = gd::RectF(left, m_plotRect.Y, width, m_plotRect.Height);
			m_dragMoved = true;
			return true;
		}
		case PlotDragMode::RUBBER_VALUE:
		{
			// 横向选区限定在按下时的网格内，只取纵向区间用于幅值轴缩放。
			if (m_dragLane < 0 || m_dragLane >= static_cast<int>(m_lanes.size()))
			{
				return false;
			}
			const gd::RectF& laneRect = m_lanes[static_cast<std::size_t>(m_dragLane)].rect;
			const float top = static_cast<float>(std::min(y, m_dragStartY));
			const float bottom = static_cast<float>(std::max(y, m_dragStartY));
			m_rubberRect = gd::RectF(laneRect.X, top, laneRect.Width, bottom - top);
			m_dragMoved = true;
			return true;
		}
		case PlotDragMode::SCROLL_LANES:
		{
			if (m_plotRect.Height <= 0.0f || m_laneContentHeight <= m_plotRect.Height)
			{
				return false;
			}
			const double travel =
			    static_cast<double>(y - m_dragLastY) / static_cast<double>(m_plotRect.Height);
			Tab().LaneScroll() += static_cast<float>(travel * m_laneContentHeight);
			m_dragLastY = y;
			m_dragMoved = true;
			BuildLaneVisuals();
			return true;
		}
		case PlotDragMode::CURSOR_MOVE:
		{
			// 放大到采样点可分辨时吸附到最近的数据点，便于精确对比取值。
			double target = XToTime(fx);
			double snapped = target;
			if (SnapTimeToSample(target, snapped))
			{
				target = snapped;
			}
			Tab().CursorTime() = target;
			m_dragMoved = true;
			m_cursorHover = true;
			return true;
		}
		case PlotDragMode::MOVE_SIGNAL:
		{
			const int target = LaneAtY(y);
			m_dragMoved = true;
			m_dragMouseX = x;
			m_dragMouseY = y;
			if (target != m_dragTargetLane)
			{
				m_dragTargetLane = target;
			}
			return true;
		}
		case PlotDragMode::NONE:
		default:
			break;
		}

		bool changed = false;

		const int lane = LaneAtY(y);
		if (lane != m_hoverLane)
		{
			m_hoverLane = lane;
			changed = true;
		}

		// 时间光标不再跟随鼠标移动，仅在鼠标覆盖光标时才显示具体时间读数。
		const bool hover = Tab().CursorEnabled() && IsOnCursorLine(x);
		if (hover != m_cursorHover)
		{
			m_cursorHover = hover;
			changed = true;
		}

		// 常规模式下精确检测鼠标是否贴近某条信号曲线，用于给出可拖拽提示。
		// 图例优先于曲线：图例条目本身就是信号的可点选目标（与左侧信号列表一致）。
		SignalRef hoverSignal;
		if (Tab().ZoomMode() == PlotZoomMode::NONE && !m_cursorHover)
		{
			hoverSignal = LegendAtPoint(x, y);
			if (!hoverSignal.IsValid())
			{
				hoverSignal = HitTestSignal(x, y);
			}
		}
		if (hoverSignal != m_hoverSignal)
		{
			m_hoverSignal = hoverSignal;
			changed = true;
		}
		return changed;
	}

	bool PlotView::OnLButtonDown(int x, int y)
	{
		if (!HasDrawableContent())
		{
			return false;
		}

		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);

		m_dragStartX = x;
		m_dragStartY = y;
		m_dragLastX = x;
		m_dragLastY = y;
		m_dragMoved = false;
		m_rubberRect = gd::RectF();

		if (m_scrollBarVisible &&
		    UiPointInRect(m_scrollBarRect, static_cast<float>(x), static_cast<float>(y)))
		{
			m_dragMode = PlotDragMode::SCROLL_LANES;
			return true;
		}

		// 内联输入中：输入框之外的点击视为提交（与线宽输入一致）。
		if (IsEditing())
		{
			if (!UiPointInRect(EditFieldRect(), fx, fy))
			{
				EndEdit(true);
			}
			return true;
		}

		// 靠近时间光标线时优先进入拖动，避免误触发平移或缩放选区。
		if (Tab().CursorEnabled() && IsOnCursorLine(x) && UiPointInRect(m_area, fx, fy))
		{
			m_dragMode = PlotDragMode::CURSOR_MOVE;
			m_cursorHover = true;
			return true;
		}

		if (!UiPointInRect(m_plotRect, fx, fy))
		{
			m_dragMode = PlotDragMode::NONE;
			return false;
		}

		const PlotZoomMode mode = Tab().ZoomMode();
		if (mode == PlotZoomMode::TIME)
		{
			m_dragMode = PlotDragMode::RUBBER_TIME;
			m_rubberRect = gd::RectF(fx, m_plotRect.Y, 0.0f, m_plotRect.Height);
			return true;
		}
		if (mode == PlotZoomMode::VALUE)
		{
			const int laneIndex = LaneAtY(y);
			if (laneIndex < 0)
			{
				m_dragMode = PlotDragMode::NONE;
				return false;
			}
			m_dragLane = laneIndex;
			m_dragMode = PlotDragMode::RUBBER_VALUE;
			const gd::RectF& laneRect = m_lanes[static_cast<std::size_t>(laneIndex)].rect;
			m_rubberRect = gd::RectF(laneRect.X, fy, laneRect.Width, 0.0f);
			return true;
		}

		// 常规模式下：点击图例条目等价于在左侧列表中选中该信号（样式区随之切换目标）。
		if (mode == PlotZoomMode::NONE)
		{
			const SignalRef legendHit = LegendAtPoint(x, y);
			if (legendHit.IsValid())
			{
				SelectSignal(legendHit);
				m_dragMode = PlotDragMode::NONE;
				return true;
			}
		}

		// 常规模式下：先检测是否落在信号曲线上；只有命中提示时才允许拖拽该信号。
		const SignalRef hit = HitTestSignal(x, y);
		if (hit.IsValid())
		{
			m_dragSignal = hit;
			m_dragTargetLane = Tab().LaneOfSignal(hit);
			SelectSignal(hit);
			m_dragMouseX = x;
			m_dragMouseY = y;
			m_dragMode = PlotDragMode::MOVE_SIGNAL;
			return true;
		}

		m_dragLane = LaneAtY(y);
		m_dragMode = PlotDragMode::PAN;
		return true;
	}

	bool PlotView::OnLButtonUp(int x, int y)
	{
		bool changed = (m_dragMode != PlotDragMode::NONE);

		switch (m_dragMode)
		{
		case PlotDragMode::RUBBER_TIME:
			if (m_dragMoved &&
			    ApplyTimeSelection(m_rubberRect.X, m_rubberRect.X + m_rubberRect.Width))
			{
				changed = true;
			}
			break;
		case PlotDragMode::RUBBER_VALUE:
			if (m_dragMoved &&
			    ApplyValueSelection(m_dragLane, m_rubberRect.Y, m_rubberRect.Y + m_rubberRect.Height))
			{
				changed = true;
			}
			break;
		case PlotDragMode::CURSOR_MOVE:
			m_cursorHover = true;
			break;
		case PlotDragMode::MOVE_SIGNAL:
		{
			const int target = LaneAtY(y);
			const int source = (m_tab != nullptr) ? m_tab->LaneOfSignal(m_dragSignal) : -1;
			if (m_dataSet != nullptr && m_tab != nullptr && m_dragSignal.IsValid() && target >= 0 &&
			    target != source && m_dragMoved)
			{
				m_tab->MoveSignalToLane(*m_dataSet, m_dragSignal, target);
				changed = true;
			}
			m_dragSignal = SignalRef();
			m_dragTargetLane = -1;
			break;
		}
		default:
			break;
		}

		m_dragMode = PlotDragMode::NONE;
		m_dragLane = -1;
		m_dragMoved = false;
		m_rubberRect = gd::RectF();
		(void)x;
		return changed;
	}

	bool PlotView::OnMouseWheel(int x, int y, int delta, bool shift)
	{
		if (!HasDrawableContent() || delta == 0)
		{
			return false;
		}

		const double notches = static_cast<double>(delta) / 120.0;

		// 滚轮不再承担缩放：默认纵向滚动网格，按住 Shift 时水平平移时间轴。
		if (shift)
		{
			const double span = Tab().ViewMax() - Tab().ViewMin();
			const double sweep = -notches * span * 0.15;
			Tab().ViewMin() += sweep;
			Tab().ViewMax() += sweep;
			ClampTimeView();
			return true;
		}

		if (m_plotRect.Height <= 0.0f || m_laneContentHeight <= m_plotRect.Height)
		{
			return false;
		}

		Tab().LaneScroll() -= static_cast<float>(notches * 48.0 * m_scale);
		BuildLaneVisuals();
		(void)x;
		(void)y;
		return true;
	}

	bool PlotView::OnDoubleClick(int x, int y)
	{
		if (!UiPointInRect(m_area, static_cast<float>(x), static_cast<float>(y)))
		{
			return false;
		}

		// 命中时间光标：进入精确时间输入（交互与线宽输入框一致）。
		if (Tab().CursorEnabled() && IsOnCursorLine(x))
		{
			return BeginEdit(PlotEditTarget::CURSOR_TIME, -1, FormatValue(Tab().CursorTime()));
		}

		// 命中图例条目：进入信号改名（与左侧列表双击改名的交互一致）。
		const SignalRef legendHit = LegendAtPoint(x, y);
		if (legendHit.IsValid())
		{
			const ResolvedSignal resolved = ResolveSignal(legendHit);
			if (resolved.data != nullptr)
			{
				SelectSignal(legendHit);
				m_editSignal = legendHit;

				// 先把输入框位置落在被双击的条目上，再进入编辑态。
				for (const LegendHit& hit : m_legendHits)
				{
					if (hit.ref == legendHit)
					{
						m_editFieldRect = hit.rect;
						break;
					}
				}
				return BeginEdit(PlotEditTarget::SIGNAL_NAME, -1, resolved.data->Title());
			}
		}

		// 其它位置：回到初始状态（自适应 + 退出缩放模式）。
		FitAll();
		return true;
	}

	bool PlotView::OnMouseLeave()
	{
		bool changed = false;
		if (m_hoverLane != -1)
		{
			m_hoverLane = -1;
			changed = true;
		}
		if (m_hoverSignal.IsValid())
		{
			m_hoverSignal = SignalRef();
			changed = true;
		}
		if (m_cursorHover)
		{
			m_cursorHover = false;
			changed = true;
		}
		return changed;
	}


	const PlotView::PolylineCacheEntry* PlotView::AcquirePolyline(const SignalRef& ref,
	                                                             const ResolvedSignal& resolved,
	                                                             const LaneVisual& lane) const
	{
		if (resolved.data == nullptr || resolved.file == nullptr)
		{
			return nullptr;
		}

		// 键 = 构建折线时实际读取的全部输入：
		// 信号（引用 + 文件内容 + 采样点数）、时间轴显示范围、绘图区横向几何、网格纵向几何。
		// 这些值全部相同时，BuildPolyline 的输出必然完全一致，可直接复用。
		const std::size_t sampleCount = std::min(resolved.file->time.size(), resolved.data->values.size());
		const double viewMin = Tab().ViewMin();
		const double viewMax = Tab().ViewMax();

		for (const PolylineCacheEntry& entry : m_polylineCache)
		{
			if (entry.ref == ref && entry.file == resolved.file && entry.sampleCount == sampleCount &&
			    entry.viewMin == viewMin && entry.viewMax == viewMax && entry.plotX == m_plotRect.X &&
			    entry.plotWidth == m_plotRect.Width && entry.laneY == lane.rect.Y &&
			    entry.laneHeight == lane.rect.Height && entry.laneYMin == lane.yMin &&
			    entry.laneYMax == lane.yMax)
			{
				return &entry;
			}
		}

		// 未命中：重建并写入缓存（deque 保证已有元素的引用在追加后依然有效）。
		// 缓存只用于消除重复计算，容量上限约等于“网格数 × 每网格信号数”的两倍。
		if (m_polylineCache.size() >= kPolylineCacheLimit)
		{
			m_polylineCache.clear();
		}
		m_polylineCache.push_back(PolylineCacheEntry());
		PolylineCacheEntry& entry = m_polylineCache.back();
		entry.ref = ref;
		entry.file = resolved.file;
		entry.sampleCount = sampleCount;
		entry.viewMin = viewMin;
		entry.viewMax = viewMax;
		entry.plotX = m_plotRect.X;
		entry.plotWidth = m_plotRect.Width;
		entry.laneY = lane.rect.Y;
		entry.laneHeight = lane.rect.Height;
		entry.laneYMin = lane.yMin;
		entry.laneYMax = lane.yMax;

		BuildPolyline(resolved, lane, entry.points, entry.breaks);
		// BuildPolyline 通过引用填充，push_back 过程中不会再次进入本函数，引用安全。
		return &m_polylineCache.back();
	}

	void PlotView::BuildPolyline(const ResolvedSignal& resolved, const LaneVisual& lane,
	                             std::vector<gd::PointF>& points, std::vector<std::size_t>& breaks) const
	{
		points.clear();
		breaks.clear();

		if (resolved.data == nullptr || resolved.file == nullptr)
		{
			return;
		}

		const std::vector<double>& time = resolved.file->time;
		const std::vector<double>& values = resolved.data->values;
		const std::size_t count = std::min(time.size(), values.size());
		if (count == 0 || m_plotRect.Width <= 1.0f)
		{
			return;
		}

		const double viewMin = Tab().ViewMin();
		const double viewMax = Tab().ViewMax();

		std::size_t begin = 0;
		std::size_t end = count;

		if (resolved.file->timeMonotonic)
		{
			const std::vector<double>::const_iterator first = std::lower_bound(time.begin(), time.end(), viewMin);
			begin = static_cast<std::size_t>(first - time.begin());
			if (begin > 0)
			{
				--begin;
			}
			const std::vector<double>::const_iterator last = std::lower_bound(time.begin(), time.end(), viewMax);
			end = static_cast<std::size_t>(last - time.begin());
			if (end < count)
			{
				++end;
			}
		}

		if (end <= begin)
		{
			return;
		}

		const float limitTop = lane.rect.Y - lane.rect.Height * 4.0f;
		const float limitBottom = lane.rect.Y + lane.rect.Height * 5.0f;

		const std::size_t visibleCount = end - begin;

		// 顶点预算由绘图区宽度决定（而不是固定值）：折线顶点数直接决定
		// GDI+ 抗锯齿折线的绘制耗时，百万级采样文件若按固定 20000 顶点绘制，
		// 会把大量顶点堆在同一个像素列上（画出来完全重合），纯粹浪费 CPU。
		std::size_t budget = static_cast<std::size_t>(std::max(1.0f, m_plotRect.Width)) * kPolylinePointsPerPixel;
		budget = std::max(budget, kMinPolylinePoints);
		budget = std::min(budget, kMaxPolylinePoints);

		// 采样点密度远超像素分辨率时改用“像素列上下包络”抽稀：
		// 每个像素列只保留最小/最大两个顶点（按出现先后排序），
		// 既不会漏掉尖峰（等间隔抽样会整段跳过），又把顶点数压到像素量级。
		if (visibleCount > budget && resolved.file->timeMonotonic && m_plotRect.Width > 1.0f)
		{
			const double viewSpan = viewMax - viewMin;
			const float plotLeft = m_plotRect.X;
			const float plotWidth = m_plotRect.Width;
			const std::size_t columns = std::max<std::size_t>(1, budget / 2);
			const float columnWidth = plotWidth / static_cast<float>(columns);

			const std::vector<double>::const_iterator rangeBegin = time.begin() + static_cast<std::ptrdiff_t>(begin);
			const std::vector<double>::const_iterator rangeEnd = time.begin() + static_cast<std::ptrdiff_t>(end);

			bool inSegment = false;
			for (std::size_t column = 0; column < columns; ++column)
			{
				const double t0 = viewMin + viewSpan * (static_cast<double>(column) / static_cast<double>(columns));
				const double t1 =
				    viewMin + viewSpan * (static_cast<double>(column + 1) / static_cast<double>(columns));

				const std::size_t i0 = static_cast<std::size_t>(
				    std::lower_bound(rangeBegin, rangeEnd, t0) - time.begin());
				const std::size_t i1 = (column + 1 == columns)
				                           ? end
				                           : static_cast<std::size_t>(
				                                 std::lower_bound(rangeBegin, rangeEnd, t1) - time.begin());
				if (i1 <= i0)
				{
					// 该列没有采样点：说明数据在此处存在时间间隙，断开当前折线。
					inSegment = false;
					continue;
				}

				double low = std::numeric_limits<double>::infinity();
				double high = -std::numeric_limits<double>::infinity();
				std::size_t lowIndex = 0;
				std::size_t highIndex = 0;
				bool broken = false;
				for (std::size_t index = i0; index < i1; ++index)
				{
					const double value = values[index];
					if (!std::isfinite(value))
					{
						// 该列含无效值：包络绘制到本列结束，后续另起一段。
						broken = true;
						continue;
					}
					if (value < low)
					{
						low = value;
						lowIndex = index;
					}
					if (value > high)
					{
						high = value;
						highIndex = index;
					}
				}

				if (!(low <= high))
				{
					// 本列全是无效值。
					inSegment = false;
					continue;
				}

				const float x = plotLeft + (static_cast<float>(column) + 0.5f) * columnWidth;
				const float yTop =
				    static_cast<float>(ClampDouble(ValueToY(high, lane), limitTop, limitBottom));
				const float yBottom =
				    static_cast<float>(ClampDouble(ValueToY(low, lane), limitTop, limitBottom));

				if (yBottom - yTop < kEnvelopeMinPixelSpan)
				{
					// 波动不足半个像素：只留一个顶点，避免无意义的重复顶点。
					if (!inSegment)
					{
						breaks.push_back(points.size());
						inSegment = true;
					}
					points.push_back(gd::PointF(x, yTop));
				}
				else
				{
					if (!inSegment)
					{
						breaks.push_back(points.size());
						inSegment = true;
					}
					// 按采样点出现的先后顺序连接上下包络，保持走线方向一致。
					if (lowIndex <= highIndex)
					{
						points.push_back(gd::PointF(x, yBottom));
						points.push_back(gd::PointF(x, yTop));
					}
					else
					{
						points.push_back(gd::PointF(x, yTop));
						points.push_back(gd::PointF(x, yBottom));
					}
				}

				if (broken)
				{
					inSegment = false;
				}
			}

			return;
		}

		std::size_t stride = 1;
		if (visibleCount > budget)
		{
			stride = (visibleCount + budget - 1) / budget;
		}

		bool inSegment = false;

		for (std::size_t index = begin; index < end; index += stride)
		{
			const double t = time[index];
			const double value = values[index];
			if (!std::isfinite(t) || !std::isfinite(value))
			{
				inSegment = false;
				continue;
			}

			const float x = TimeToX(t);
			float y = ValueToY(value, lane);
			y = static_cast<float>(ClampDouble(y, limitTop, limitBottom));

			if (!inSegment)
			{
				breaks.push_back(points.size());
				points.push_back(gd::PointF(x, y));
				inSegment = true;
			}
			else
			{
				points.push_back(gd::PointF(x, y));
			}
		}
	}

	void PlotView::PaintEmptyState(gd::Graphics& g)
	{
		std::wstring message;
		if (m_dataSet == nullptr || m_dataSet->Empty())
		{
			message = L"打开 CSV 文件以查看仿真数据波形";
		}
		else
		{
			message = L"请在左侧勾选需要查看的信号（可同时加载多个文件进行对比）";
		}
		UiText(g, message, m_fonts->ui, m_area, m_theme->textMuted, TextAlign::CENTER);
	}

	void PlotView::Paint(gd::Graphics& g)
	{
		if (m_theme == nullptr || m_fonts == nullptr)
		{
			return;
		}

		UiFillRect(g, m_area, m_theme->plotBg);

		BuildLaneVisuals();

		if (m_lanes.empty())
		{
			PaintEmptyState(g);
			return;
		}

		const double viewMin = Tab().ViewMin();
		const double viewMax = Tab().ViewMax();
		const double span = viewMax - viewMin;
		const double timeStep = NiceStep((span > 0.0) ? span : 1.0, kTimeTickTarget);
		std::vector<double> timeTicks;
		BuildTicks(viewMin, viewMax, timeStep, timeTicks);

		// 波形区域底色。
		UiFillRect(g, m_plotRect, m_theme->cardBg);

		// 图例命中矩形每帧重建，避免残留已消失的信号。
		m_legendHits.clear();

		for (std::size_t index = 0; index < m_lanes.size(); ++index)
		{
			PaintLane(g, static_cast<int>(index), m_lanes[index], timeTicks);
		}

		PaintTimeAxis(g, timeTicks, timeStep);
		PaintRubberBand(g);
		PaintCursor(g, m_lanes);
		PaintSignalInteraction(g);

		// 网格 Y 轴上下限的输入框绘制在最上层。
		if (m_editTarget == PlotEditTarget::LANE_Y_MAX || m_editTarget == PlotEditTarget::LANE_Y_MIN)
		{
			PaintEditField(g);
		}

		PaintScrollBar(g);

		// 绘图区外框（比网格内部分界线更重，形成明确整体边界）。
		gd::Pen borderPen(ToGdiColor(m_theme->axisLine), 1.6f);
		g.DrawRectangle(&borderPen, m_plotRect.X, m_plotRect.Y, m_plotRect.Width, m_plotRect.Height);
	}

	void PlotView::PaintRubberBand(gd::Graphics& g)
	{
		if (!m_dragMoved || m_rubberRect.Width <= 0.0f || m_rubberRect.Height <= 0.0f)
		{
			return;
		}

		const bool timeMode = (m_dragMode == PlotDragMode::RUBBER_TIME);
		const bool valueMode = (m_dragMode == PlotDragMode::RUBBER_VALUE);
		if (!timeMode && !valueMode)
		{
			return;
		}

		// 时间轴缩放用强调色，Y 轴缩放用警示色，便于区分两种模式。
		const std::uint32_t band = timeMode ? m_theme->accent : m_theme->danger;
		UiFillRect(g, m_rubberRect, WithAlpha(band, 0x24));
		UiDrawRoundRect(g, m_rubberRect, 2.0f * m_scale, band, 1.2f);

		// 选区跨度提示（时间用秒/数值用幅度量纲），放在选区顶部。
		std::wstring text;
		if (timeMode)
		{
			text = FormatValue(std::fabs(XToTime(m_rubberRect.X + m_rubberRect.Width) -
			                             XToTime(m_rubberRect.X)));
		}
		else if (m_dragLane >= 0 && m_dragLane < static_cast<int>(m_lanes.size()))
		{
			const LaneVisual& lane = m_lanes[static_cast<std::size_t>(m_dragLane)];
			text = FormatValue(std::fabs(YToValue(m_rubberRect.Y + m_rubberRect.Height, lane) -
			                             YToValue(m_rubberRect.Y, lane)));
		}
		if (text.empty())
		{
			return;
		}

		const float textWidth = UiTextWidth(g, text, m_fonts->monoSmall) + 12.0f * m_scale;
		const float textHeight = 18.0f * m_scale;
		float labelX = m_rubberRect.X + m_rubberRect.Width * 0.5f - textWidth * 0.5f;
		labelX = std::max(m_plotRect.X, std::min(labelX, m_plotRect.X + m_plotRect.Width - textWidth));
		const gd::RectF labelRect(labelX, m_rubberRect.Y + 3.0f * m_scale, textWidth, textHeight);

		UiFillRoundRect(g, labelRect, 3.0f * m_scale, band);
		UiText(g, text, m_fonts->monoSmall, labelRect, m_theme->textOnAccent, TextAlign::CENTER);
	}

	void PlotView::PaintLane(gd::Graphics& g, int laneIndex, const LaneVisual& lane,
	                         const std::vector<double>& timeTicks)
	{
		// 网格内容必须裁剪在绘图区之内：纵向滚动时网格会部分移出可视范围，
		// 若不与 m_plotRect 求交，波形就会溢出到工具栏与时间轴区域。
		const float clipTop = std::max(lane.rect.Y, m_plotRect.Y);
		const float clipBottom =
		    std::min(lane.rect.Y + lane.rect.Height, m_plotRect.Y + m_plotRect.Height);
		if (clipBottom <= clipTop)
		{
			return;
		}

		const int saveState = g.Save();
		g.SetClip(gd::RectF(m_area.X, clipTop, m_area.Width, clipBottom - clipTop));

		// 悬停高亮。
		if (laneIndex == m_hoverLane && m_dragMode == PlotDragMode::NONE)
		{
			UiFillRect(g, lane.rect, MixColor(m_theme->cardBg, m_theme->accent, 0.035));
		}

		// 幅值网格线（先画线，标尺稍后作为覆盖层绘制，避免被波形遮挡）。
		// 刻度密度随网格高度自适应：所有网格高度相同 → 各网格的刻度数量一致，
		// 不会出现“有的网格只有 1 条标签、有的有 3 条”的不一致观感。
		int yTickTarget = static_cast<int>(std::lround(lane.rect.Height / (kYTickSpacing * m_scale)));
		yTickTarget = std::max(kYTickTargetMin, std::min(yTickTarget, kYTickTargetMax));
		const double yStep = NiceStep(lane.yMax - lane.yMin, yTickTarget);
		std::vector<double> yTicks;
		BuildTicks(lane.yMin, lane.yMax, yStep, yTicks);

		// 五等分估读线：在相邻主刻度之间再细分，便于目视读取中间值。
		const double yMinorStep = yStep / static_cast<double>(kMinorDivisions);
		std::vector<double> yMinorTicks;
		BuildTicks(lane.yMin, lane.yMax, yMinorStep, yMinorTicks);
		for (const double tick : yMinorTicks)
		{
			// 与主刻度重合的位置跳过（主刻度会以更重的线条绘制）。
			const double majorIndex = tick / yStep;
			if (std::fabs(majorIndex - std::floor(majorIndex + 0.5)) < 1.0e-6)
			{
				continue;
			}

			const float y = ValueToY(tick, lane);
			if (y < lane.rect.Y - 1.0f || y > lane.rect.Y + lane.rect.Height + 1.0f)
			{
				continue;
			}
			UiDrawLine(g, lane.rect.X, y, lane.rect.X + lane.rect.Width, y,
			           WithAlpha(m_theme->gridWeak, kMinorLineAlpha), 1.0f);
		}

		for (const double tick : yTicks)
		{
			const float y = ValueToY(tick, lane);
			if (y < lane.rect.Y - 1.0f || y > lane.rect.Y + lane.rect.Height + 1.0f)
			{
				continue;
			}

			const bool zeroLine = (tick == 0.0);
			UiDrawLine(g, lane.rect.X, y, lane.rect.X + lane.rect.Width, y,
			           zeroLine ? m_theme->gridStrong : m_theme->gridWeak, 1.0f);
		}

		// 时间网格线（同样补充五等分估读线）。
		const double timeSpan = Tab().ViewMax() - Tab().ViewMin();
		const double timeMajorStep = NiceStep((timeSpan > 0.0) ? timeSpan : 1.0, kTimeTickTarget);
		const double timeMinorStep = timeMajorStep / static_cast<double>(kMinorDivisions);
		std::vector<double> timeMinorTicks;
		BuildTicks(Tab().ViewMin(), Tab().ViewMax(), timeMinorStep, timeMinorTicks);
		for (const double tick : timeMinorTicks)
		{
			const double majorIndex = tick / timeMajorStep;
			if (std::fabs(majorIndex - std::floor(majorIndex + 0.5)) < 1.0e-6)
			{
				continue;
			}

			const float x = TimeToX(tick);
			if (x < lane.rect.X || x > lane.rect.X + lane.rect.Width)
			{
				continue;
			}
			UiDrawLine(g, x, lane.rect.Y, x, lane.rect.Y + lane.rect.Height,
			           WithAlpha(m_theme->gridWeak, kMinorLineAlpha), 1.0f);
		}

		for (const double tick : timeTicks)
		{
			const float x = TimeToX(tick);
			if (x < lane.rect.X || x > lane.rect.X + lane.rect.Width)
			{
				continue;
			}
			UiDrawLine(g, x, lane.rect.Y, x, lane.rect.Y + lane.rect.Height, m_theme->gridWeak, 1.0f);
		}

		// 波形绘制。
		const std::vector<SignalRef>& laneSignals = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].signals;
		if (laneSignals.empty())
		{
			const gd::RectF visibleRect(lane.rect.X, clipTop, lane.rect.Width, clipBottom - clipTop);
			UiText(g, L"（空网格）", m_fonts->uiSmall, visibleRect, m_theme->textMuted, TextAlign::CENTER);
		}
		else
		{
			const int waveSave = g.Save();
			g.SetClip(lane.rect, gd::CombineModeIntersect);

			for (const SignalRef& ref : laneSignals)
			{
				const ResolvedSignal resolved = ResolveSignal(ref);
				if (resolved.data == nullptr || resolved.style == nullptr || !resolved.visible)
				{
					continue;
				}

				const DrawMode mode = resolved.style->mode;
				// 顶点由“几何键”缓存提供：同一视图下重复绘制不再重算全量采样。
				const PolylineCacheEntry* cached = AcquirePolyline(ref, resolved, lane);
				if (cached == nullptr)
				{
					continue;
				}
				const std::vector<gd::PointF>& points = cached->points;
				const std::vector<std::size_t>& breaks = cached->breaks;

				const bool drawLine = (mode != DrawMode::SCATTER);
				const bool drawScatter = (mode == DrawMode::SCATTER || mode == DrawMode::LINE_SCATTER);

				// 悬停命中的信号先画一层浅色光晕，作为“可拖拽”的视觉提示。
				const bool highlighted = (ref == m_hoverSignal) || (ref == m_dragSignal);
				if (highlighted && drawLine && !breaks.empty())
				{
					gd::Pen halo(ToGdiColor(WithAlpha(m_theme->accent, 0x66)),
					             (resolved.style->lineWidth + 4.0f) * m_scale);
					halo.SetLineJoin(gd::LineJoinRound);
					halo.SetStartCap(gd::LineCapRound);
					halo.SetEndCap(gd::LineCapRound);
					for (std::size_t k = 0; k < breaks.size(); ++k)
					{
						const std::size_t start = breaks[k];
						const std::size_t stop = (k + 1 < breaks.size()) ? breaks[k + 1] : points.size();
						if (stop <= start + 1)
						{
							continue;
						}
						g.DrawLines(&halo, points.data() + start, static_cast<INT>(stop - start));
					}
				}

				if (drawLine && !breaks.empty())
				{
					gd::Pen pen(ToGdiColor(StyleColor(*resolved.style)),
					            resolved.style->lineWidth * m_scale);
					pen.SetLineJoin(gd::LineJoinRound);
					pen.SetStartCap(gd::LineCapRound);
					pen.SetEndCap(gd::LineCapRound);

					for (std::size_t k = 0; k < breaks.size(); ++k)
					{
						const std::size_t start = breaks[k];
						const std::size_t stop = (k + 1 < breaks.size()) ? breaks[k + 1] : points.size();
						if (stop <= start + 1)
						{
							continue;
						}
						g.DrawLines(&pen, points.data() + start, static_cast<INT>(stop - start));
					}
				}

				if (drawScatter && !points.empty())
				{
					// 散点半径随线宽线性增长（达到上限前不过早触顶），使“线宽”直观控制数据点大小。
					const float radius = static_cast<float>(
					    ClampDouble(static_cast<double>(resolved.style->lineWidth) * kScatterRadiusScale,
					                kMinScatterRadius, kMaxScatterRadius) *
					    m_scale);
					const std::size_t scatterStride =
					    std::max<std::size_t>(1, points.size() / kMaxScatterPoints);
					gd::SolidBrush brush(ToGdiColor(StyleColor(*resolved.style)));
					for (std::size_t k = 0; k < points.size(); k += scatterStride)
					{
						g.FillEllipse(&brush, points[k].X - radius, points[k].Y - radius, radius * 2.0f,
						              radius * 2.0f);
					}
				}
			}

			g.Restore(waveSave);
		}

		// 网格分界线：网格之间不再留间隔，改用较重的横线明确分隔相邻网格。
		const float dividerY = lane.rect.Y;
		if (dividerY >= m_plotRect.Y - 1.0f && dividerY <= m_plotRect.Y + m_plotRect.Height)
		{
			UiDrawLine(g, lane.rect.X, dividerY, lane.rect.X + lane.rect.Width, dividerY,
			           (laneIndex == 0) ? m_theme->axisLine : m_theme->borderStrong,
			           (laneIndex == 0) ? 1.6f : kLaneDividerWidth);
		}

		// 内侧纵轴标尺作为覆盖层绘制：每个刻度数值带半透明底，保证在波形之上仍清晰可读，
		// 同时只在数值背后遮挡波形，不牺牲波形本身的可见范围。
		{
			const bool showLabels = (lane.rect.Height >= 34.0f * m_scale);
			float lastLabelY = -1.0e9f;

			// 网格较矮时同步收紧标签行距，让密度随可用高度提升而不是整片被过滤掉。
			const float labelMinGap =
			    std::min(kYLabelMinGap * m_scale,
			             lane.rect.Height / static_cast<float>(yTickTarget + 1));

			for (const double tick : yTicks)
			{
				if (!showLabels)
				{
					break;
				}

				const float y = ValueToY(tick, lane);
				if (y < lane.rect.Y - 1.0f || y > lane.rect.Y + lane.rect.Height + 1.0f)
				{
					continue;
				}
				if (std::fabs(y - lastLabelY) < labelMinGap)
				{
					continue;
				}
				lastLabelY = y;

				const std::wstring raw = FormatTick(tick, yStep);
				const float textWidth = UiMeasureTextWidth(m_fonts->monoSmall, raw);
				const float pillHeight = 17.0f * m_scale;
				const gd::RectF pill(lane.rect.X + kLaneLabelPad * m_scale, y - pillHeight * 0.5f,
				                     std::min(textWidth + 8.0f * m_scale,
				                              lane.rect.Width - 2.0f * kLaneLabelPad * m_scale),
				                     pillHeight);
				if (pill.Width <= 0.0f)
				{
					continue;
				}
				// 与图例重叠时不再跳过：标尺值先绘制，随后绘制的图例会盖在其上层
				// （顶层始终为图例），因此两者都不丢失。
				// 但仍要求数值完整落在可见区内——否则会在网格分界处露出被截断的半行数字，
				// 且 GDI 文本不受 GDI+ 裁剪约束会越过绘图区（改用 UiTextAtClipped 兜底）。
				if (!IsFullyVisible(pill, clipTop, clipBottom))
				{
					continue;
				}

				UiFillRoundRect(g, pill, 3.0f * m_scale, WithAlpha(m_theme->cardBg, 0xF0));
				const std::wstring text = UiEllipsize(g, raw, m_fonts->monoSmall, pill.Width - 6.0f * m_scale);
				UiText(g, text, m_fonts->monoSmall,
				       gd::RectF(pill.X + 4.0f * m_scale, pill.Y, pill.Width - 8.0f * m_scale, pill.Height),
				       (tick == 0.0) ? m_theme->text : m_theme->textMuted, TextAlign::LEFT);
			}
		}

		if (lane.rect.Height >= 24.0f * m_scale)
		{
			PaintLaneLegend(g, laneIndex, lane, clipTop, clipBottom);
			if (Tab().CursorEnabled() && lane.rect.Height >= 40.0f * m_scale)
			{
				PaintLaneReadout(g, laneIndex, lane, clipTop, clipBottom);
			}
		}

		g.Restore(saveState);
	}

	SignalRef PlotView::LegendAtPoint(int x, int y) const
	{
		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);
		for (const LegendHit& hit : m_legendHits)
		{
			if (UiPointInRect(hit.rect, fx, fy))
			{
				return hit.ref;
			}
		}
		return SignalRef();
	}

	void PlotView::PaintLaneLegend(gd::Graphics& g, int laneIndex, const LaneVisual& lane, float visibleTop,
	                               float visibleBottom)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return;
		}

		// 图例固定在网格左上角：网格被滚动出可视区时整体跳过，避免文字溢出到工具栏。
		const gd::RectF legendBand(lane.rect.X + kLegendPad * m_scale,
		                           lane.rect.Y + kLegendPad * m_scale, lane.rect.Width,
		                           kLegendHeight * m_scale);
		if (!IsFullyVisible(legendBand, visibleTop, visibleBottom))
		{
			return;
		}

		const std::vector<SignalRef>& laneSignals = m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].signals;
		const bool multiFile = LaneSpansMultipleFiles(laneIndex);

		const float top = legendBand.Y;
		const float height = kLegendHeight * m_scale;
		float cursorX = legendBand.X;
		const float maxX = lane.rect.X + lane.rect.Width - kLanePadding * m_scale;

		bool anyVisible = false;
		int visibleCount = 0;
		int drawnCount = 0;

		// 先测量图例总宽度，再用半透明底板掠开底下的网格线，提升可读性。
		float legendWidth = 0.0f;
		for (const SignalRef& ref : laneSignals)
		{
			const ResolvedSignal resolved = ResolveSignal(ref);
			if (resolved.data == nullptr || resolved.style == nullptr || !resolved.visible)
			{
				continue;
			}

			std::wstring label = BuildLegendText(*resolved.data);
			if (multiFile && resolved.file != nullptr)
			{
				label += L" · " + resolved.file->Title();
			}
			const float itemWidth = kLegendSwatchSize * m_scale + 5.0f * m_scale +
			                        std::min(UiTextWidth(g, label, m_fonts->uiSmall),
			                                 kLegendMaxTextWidth * m_scale) +
			                        kLegendItemGap * m_scale;
			if (cursorX + legendWidth + itemWidth > maxX)
			{
				break;
			}
			legendWidth += itemWidth;
		}
		if (legendWidth > 0.0f)
		{
			UiFillRoundRect(g, gd::RectF(cursorX - 4.0f * m_scale, top - 2.0f * m_scale,
			                             legendWidth + 6.0f * m_scale, height + 4.0f * m_scale),
			                3.0f * m_scale, WithAlpha(m_theme->cardBg, 0xE8));
		}

		// 记录本次绘制命中的条目矩形，供点击选中与双击改名使用。
		for (auto iterator = m_legendHits.begin(); iterator != m_legendHits.end();)
		{
			if (m_tab->LaneOfSignal(iterator->ref) == laneIndex)
			{
				iterator = m_legendHits.erase(iterator);
			}
			else
			{
				++iterator;
			}
		}

		// 绘制图例条目（与测量阶段保持一致的裁剪条件）。
		float drawnWidth = 0.0f;
		for (const SignalRef& ref : laneSignals)
		{
			const ResolvedSignal resolved = ResolveSignal(ref);
			if (resolved.data == nullptr || resolved.style == nullptr || !resolved.visible)
			{
				continue;
			}
			anyVisible = true;
			++visibleCount;

			std::wstring label = BuildLegendText(*resolved.data);
			if (multiFile && resolved.file != nullptr)
			{
				label += L" · " + resolved.file->Title();
			}
			// 文本宽度按上限夹取，超出部分用省略号（与测量阶段保持一致）。
			const float maxTextWidth = kLegendMaxTextWidth * m_scale;
			const float fullTextWidth = UiTextWidth(g, label, m_fonts->uiSmall);
			const float textWidth = std::min(fullTextWidth, maxTextWidth);
			const std::wstring drawLabel =
			    (fullTextWidth > maxTextWidth) ? UiEllipsize(g, label, m_fonts->uiSmall, maxTextWidth) : label;
			const float itemWidth = kLegendSwatchSize * m_scale + 5.0f * m_scale + textWidth +
			                        kLegendItemGap * m_scale;
			if (drawnWidth + itemWidth > legendWidth + 0.5f)
			{
				break;
			}
			drawnWidth += itemWidth;

			const float itemLeft = cursorX;
			const float swatchSize = kLegendSwatchSize * m_scale;

			// 图例条目与被选中的信号保持一致的高亮反馈（与左侧列表选中态呼应）。
			const bool selected = (SelectedRef() == ref);
			const bool hovered = (ref == m_hoverSignal) || (ref == m_dragSignal);
			if (selected || hovered)
			{
				UiFillRoundRect(g, gd::RectF(itemLeft - 3.0f * m_scale, top - 1.0f * m_scale,
				                             itemWidth + 2.0f * m_scale, height + 2.0f * m_scale),
				                3.0f * m_scale, selected ? m_theme->selection : m_theme->hover);
			}

			UiDrawSwatch(g, gd::RectF(cursorX, top + (height - swatchSize) * 0.5f, swatchSize, swatchSize),
			             resolved.style->color, resolved.style->opacity, 1.5f * m_scale, m_scale);

			// 改名编辑态：在原位置绘制输入框。
			LegendHit hit;
			hit.ref = ref;
			hit.rect = gd::RectF(itemLeft - 3.0f * m_scale, top - 2.0f * m_scale,
			                     itemWidth + 2.0f * m_scale, height + 4.0f * m_scale);
			m_legendHits.push_back(hit);

			if (m_editTarget == PlotEditTarget::SIGNAL_NAME && m_editSignal == ref)
			{
				m_editFieldRect = hit.rect;
				UiDrawEditField(g, hit.rect, m_edit, m_fonts->uiSmall, m_scale);
				cursorX += itemWidth;
				++drawnCount;
				continue;
			}

			cursorX += swatchSize + 5.0f * m_scale;
			UiText(g, drawLabel, m_fonts->uiSmall,
			       gd::RectF(cursorX, top, std::max(8.0f, textWidth + 2.0f), height),
			       selected ? m_theme->textStrong : m_theme->text, TextAlign::LEFT);
			cursorX += textWidth + kLegendItemGap * m_scale;
			++drawnCount;
		}

		if (!anyVisible)
		{
			UiText(g, L"（无可见信号）", m_fonts->uiSmall,
			       gd::RectF(legendBand.X, top, lane.rect.Width, height), m_theme->textMuted,
			       TextAlign::LEFT);
		}
		else if (drawnCount < visibleCount)
		{
			// 图例空间不足时提示剩余信号数量，避免误认为信号丢失。
			const std::wstring moreText = L"+" + std::to_wstring(visibleCount - drawnCount);
			if (cursorX + 20.0f * m_scale <= maxX)
			{
				UiText(g, moreText, m_fonts->uiSmall, gd::RectF(cursorX, top, 24.0f * m_scale, height),
				       m_theme->textMuted, TextAlign::LEFT);
			}
		}
	}

	void PlotView::PaintLaneReadout(gd::Graphics& g, int laneIndex, const LaneVisual& lane, float visibleTop,
	                                float visibleBottom)
	{
		if (m_tab == nullptr || laneIndex < 0 || laneIndex >= static_cast<int>(m_tab->Lanes().size()))
		{
			return;
		}

		const double cursorTime = Tab().CursorTime();
		if (cursorTime < Tab().ViewMin() || cursorTime > Tab().ViewMax())
		{
			return;
		}

		struct ReadoutLine
		{
			std::wstring text;
		};

		std::vector<ReadoutLine> lines;
		const bool multiFile = LaneSpansMultipleFiles(laneIndex);
		for (const SignalRef& ref : m_tab->Lanes()[static_cast<std::size_t>(laneIndex)].signals)
		{
			const ResolvedSignal resolved = ResolveSignal(ref);
			if (resolved.data == nullptr || resolved.style == nullptr || resolved.file == nullptr ||
			    !resolved.visible)
			{
				continue;
			}

			const bool interpolate = (resolved.style->mode != DrawMode::SCATTER);
			double value = 0.0;
			if (!SampleFileAt(*resolved.file, *resolved.data, cursorTime, interpolate, value))
			{
				continue;
			}

			ReadoutLine line;
			line.text = resolved.data->Title();
			if (multiFile)
			{
				line.text += L" · " + resolved.file->Title();
			}
			line.text += L" = " + FormatValue(value);
			lines.push_back(std::move(line));
		}

		if (lines.empty())
		{
			return;
		}

		const float lineHeight = 17.0f * m_scale;
		const float maxLines =
		    std::max(1.0f, std::floor((lane.rect.Height - 12.0f * m_scale) / lineHeight));
		const std::size_t shown = std::min(lines.size(), static_cast<std::size_t>(maxLines));

		float boxWidth = 0.0f;
		for (std::size_t index = 0; index < shown; ++index)
		{
			boxWidth = std::max(boxWidth, UiTextWidth(g, lines[index].text, m_fonts->monoSmall));
		}
		boxWidth += 20.0f * m_scale;

		const float boxHeight = static_cast<float>(shown) * lineHeight + 8.0f * m_scale;
		const gd::RectF box(lane.rect.X + lane.rect.Width - kLanePadding * m_scale - boxWidth,
		                    lane.rect.Y + 4.0f * m_scale, boxWidth, boxHeight);

		// 读数框整体必须落在可见区内，否则文本会越过绘图区边界。
		if (!IsFullyVisible(box, visibleTop, visibleBottom))
		{
			return;
		}

		UiFillRoundRect(g, box, 4.0f * m_scale, WithAlpha(m_theme->readoutBg, 0xEE));
		UiDrawRoundRect(g, box, 4.0f * m_scale, m_theme->border, 1.0f);

		float textY = box.Y + 4.0f * m_scale;
		for (std::size_t index = 0; index < shown; ++index)
		{
			const gd::RectF lineRect(box.X + 10.0f * m_scale, textY, boxWidth - 14.0f * m_scale, lineHeight);
			UiText(g, lines[index].text, m_fonts->monoSmall, lineRect, m_theme->textStrong, TextAlign::LEFT);
			textY += lineHeight;
		}
	}

	bool PlotView::IsFullyVisible(const gd::RectF& rect, float visibleTop, float visibleBottom)
	{
		return (rect.Y >= visibleTop - 0.5f) && (rect.Y + rect.Height <= visibleBottom + 0.5f);
	}

	void PlotView::PaintTimeAxis(gd::Graphics& g, const std::vector<double>& timeTicks, double timeStep)
	{
		const float axisY = m_plotRect.Y + m_plotRect.Height;
		UiDrawLine(g, m_plotRect.X, axisY, m_plotRect.X + m_plotRect.Width, axisY, m_theme->axisLine, 1.0f);

		// 时间轴列名（取自首个可见信号所属文件），贴左侧绘制。
		std::wstring axisName = L"时间";
		if (m_dataSet != nullptr && m_tab != nullptr)
		{
			for (std::size_t fileIndex = 0; fileIndex < m_dataSet->FileCount(); ++fileIndex)
			{
				if (!m_tab->FileHasVisible(*m_dataSet, static_cast<int>(fileIndex)))
				{
					continue;
				}
				const DataFile* file = m_dataSet->FileAt(static_cast<int>(fileIndex));
				if (file != nullptr && !file->timeColumnName.empty())
				{
					axisName = file->timeColumnName;
					// CSV 中该列通常直接叫 "time"，这里补上时间单位秒便于阅读；
					// 若列名自带单位描述（以右括号结尾）则不重复追加。
					if (axisName.back() != L')')
					{
						axisName += L" (s)";
					}
				}
				break;
			}
		}

		const float nameWidth =
		    std::min(UiMeasureTextWidth(m_fonts->monoSmall, axisName) + 8.0f * m_scale,
		             m_plotRect.Width * 0.4f);
		const gd::RectF nameRect(m_plotRect.X + 2.0f * m_scale, axisY + 3.0f * m_scale, nameWidth,
		                         std::max(0.0f, m_timeAxisRect.Height - 5.0f * m_scale));
		UiText(g, UiEllipsize(g, axisName, m_fonts->monoSmall, nameWidth), m_fonts->monoSmall, nameRect,
		       m_theme->textMuted, TextAlign::LEFT);

		const float labelWidth = 96.0f * m_scale;
		for (const double tick : timeTicks)
		{
			const float x = TimeToX(tick);
			if (x < m_plotRect.X - 1.0f || x > m_plotRect.X + m_plotRect.Width + 1.0f)
			{
				continue;
			}

			UiDrawLine(g, x, axisY, x, axisY + 4.0f * m_scale, m_theme->axisLine, 1.0f);

			// 刻度标签夹在绘图区横向范围内，并与左侧列名互不重叠。
			float labelX = x - labelWidth * 0.5f;
			labelX = std::max(m_plotRect.X, std::min(labelX, m_plotRect.X + m_plotRect.Width - labelWidth));
			const gd::RectF labelRect(labelX, axisY + 4.0f * m_scale, labelWidth,
			                          std::max(0.0f, m_timeAxisRect.Height - 6.0f * m_scale));
			if (labelRect.X < nameRect.X + nameRect.Width)
			{
				continue;
			}
			UiText(g, FormatTick(tick, timeStep), m_fonts->monoSmall, labelRect, m_theme->textMuted,
			       TextAlign::CENTER);
		}
	}

	void PlotView::PaintCursor(gd::Graphics& g, const std::vector<LaneVisual>& lanes)
	{
		if (!Tab().CursorEnabled() || m_tab == nullptr)
		{
			return;
		}

		const double cursorTime = Tab().CursorTime();
		const float x = TimeToX(cursorTime);
		if (x < m_plotRect.X - 2.0f || x > m_plotRect.X + m_plotRect.Width + 2.0f)
		{
			return;
		}

		// 光标纵向贯穿全部网格，并延伸到时间轴底部，便于与刻度对齐读数。
		const float lineTop = m_plotRect.Y;
		const float lineBottom = m_timeAxisRect.Y + m_timeAxisRect.Height;
		const float lineWidth = (m_cursorHover || m_dragMode == PlotDragMode::CURSOR_MOVE) ? 2.0f : 1.2f;
		UiDrawLine(g, x, lineTop, x, lineBottom, m_theme->cursor, lineWidth * m_scale);

		// 顶部三角把手，提示该线可以被拖拽。
		{
			const float arm = 5.0f * m_scale;
			gd::PointF points[3];
			points[0] = gd::PointF(x - arm, lineTop);
			points[1] = gd::PointF(x + arm, lineTop);
			points[2] = gd::PointF(x, lineTop + arm * 1.4f);
			gd::SolidBrush handle(ToGdiColor(m_theme->cursor));
			g.FillPolygon(&handle, points, 3);
		}

		// 各网格上的取值标记（仅在网格可见范围内绘制）。
		for (std::size_t laneIndex = 0; laneIndex < lanes.size(); ++laneIndex)
		{
			const LaneVisual& lane = lanes[laneIndex];
			for (const SignalRef& ref : m_tab->Lanes()[laneIndex].signals)
			{
				const ResolvedSignal resolved = ResolveSignal(ref);
				if (resolved.data == nullptr || resolved.style == nullptr || resolved.file == nullptr ||
				    !resolved.visible)
				{
					continue;
				}

				double value = 0.0;
				if (!SampleFileAt(*resolved.file, *resolved.data, cursorTime,
				                  resolved.style->mode != DrawMode::SCATTER, value))
				{
					continue;
				}

				const float y = ValueToY(value, lane);
				if (y < std::max(lane.rect.Y, m_plotRect.Y) - 2.0f ||
				    y > std::min(lane.rect.Y + lane.rect.Height, m_plotRect.Y + m_plotRect.Height) + 2.0f)
				{
					continue;
				}

				const float radius = 3.4f * m_scale;
				gd::SolidBrush ring(ToGdiColor(m_theme->cardBg));
				gd::SolidBrush fill(ToGdiColor(StyleColor(*resolved.style)));
				g.FillEllipse(&ring, x - radius - 1.2f * m_scale, y - radius - 1.2f * m_scale,
				              (radius + 1.2f * m_scale) * 2.0f, (radius + 1.2f * m_scale) * 2.0f);
				g.FillEllipse(&fill, x - radius, y - radius, radius * 2.0f, radius * 2.0f);
			}
		}

		// 具体时间显示在绘图区顶部（不遮挡时间轴刻度），且仅在鼠标覆盖光标时出现。
		if (m_editTarget == PlotEditTarget::CURSOR_TIME)
		{
			PaintEditField(g);
			return;
		}
		if (!m_cursorHover)
		{
			return;
		}

		const gd::RectF labelRect = CursorLabelRect();
		if (labelRect.Width <= 0.0f)
		{
			return;
		}

		UiFillRoundRect(g, labelRect, 3.0f * m_scale, m_theme->cursor);
		UiText(g, FormatValue(cursorTime), m_fonts->monoSmall, labelRect, m_theme->textOnAccent,
		       TextAlign::CENTER);
	}

	void PlotView::PaintEditField(gd::Graphics& g)
	{
		const gd::RectF fieldRect = EditFieldRect();
		if (fieldRect.Width <= 0.0f || fieldRect.Height <= 0.0f)
		{
			return;
		}

		// 编辑态：强调色外框 + 选区高亮 + 插入符，首次键入即整体替换（与常规输入框一致）。
		UiDrawEditField(g, fieldRect, m_edit, m_fonts->monoSmall, m_scale);
	}

	void PlotView::PaintSignalInteraction(gd::Graphics& g)
	{
		if (m_tab == nullptr || m_dataSet == nullptr || m_lanes.empty())
		{
			return;
		}

		// 拖拽中：虚影跟随鼠标纵向位移，同时在目标网格内高亮落点。
		if (m_dragMode == PlotDragMode::MOVE_SIGNAL && m_dragSignal.IsValid())
		{
			const ResolvedSignal resolved = ResolveSignal(m_dragSignal);
			const int sourceLane = m_tab->LaneOfSignal(m_dragSignal);
			if (resolved.data == nullptr || resolved.style == nullptr || sourceLane < 0 ||
			    sourceLane >= static_cast<int>(m_lanes.size()))
			{
				return;
			}

			// 虚影：以源网格的幅值映射构建波形，再按鼠标位移整体平移。
			// 第一帧位移为 0，因此虚影必然精确落在鼠标下方（曲线形态与抓住时完全一致）；
			// 之后纵向与横向均自由跟随，形成“拖着曲线走”的观感。
			const LaneVisual& sourceVisual = m_lanes[static_cast<std::size_t>(sourceLane)];
			const float offsetX = static_cast<float>(m_dragMouseX - m_dragStartX);
			const float offsetY = static_cast<float>(m_dragMouseY - m_dragStartY);

			{
				const int saveState = g.Save();
				g.SetClip(gd::RectF(m_plotRect.X, m_plotRect.Y, m_plotRect.Width, m_plotRect.Height),
				          gd::CombineModeIntersect);

				std::vector<gd::PointF> points;
				std::vector<std::size_t> breaks;
				BuildPolyline(resolved, sourceVisual, points, breaks);

				for (gd::PointF& point : points)
				{
					point.X += offsetX;
					point.Y += offsetY;
				}

				const DrawMode mode = resolved.style->mode;
				const bool drawLine = (mode != DrawMode::SCATTER);
				const bool drawScatter = (mode == DrawMode::SCATTER || mode == DrawMode::LINE_SCATTER);

				// 虚影保持原信号的颜色与样式（不再是虚线），仅以轻微透明区分“尚未落地”。
				const std::uint32_t ghostColor = WithAlpha(resolved.style->color,
				                                           static_cast<unsigned int>(
				                                               std::max(0.35, static_cast<double>(resolved.style->opacity)) *
				                                               255.0 + 0.5));

				if (drawLine && !breaks.empty())
				{
					gd::Pen ghost(ToGdiColor(ghostColor),
					              std::max(1.0f, resolved.style->lineWidth) * m_scale);
					ghost.SetLineJoin(gd::LineJoinRound);
					ghost.SetStartCap(gd::LineCapRound);
					ghost.SetEndCap(gd::LineCapRound);
					for (std::size_t k = 0; k < breaks.size(); ++k)
					{
						const std::size_t start = breaks[k];
						const std::size_t stop = (k + 1 < breaks.size()) ? breaks[k + 1] : points.size();
						if (stop <= start + 1)
						{
							continue;
						}
						g.DrawLines(&ghost, points.data() + start, static_cast<INT>(stop - start));
					}
				}

				if (drawScatter && !points.empty())
				{
					const float radius = static_cast<float>(
					    ClampDouble(static_cast<double>(resolved.style->lineWidth) * kScatterRadiusScale,
					                kMinScatterRadius, kMaxScatterRadius) *
					    m_scale);
					const std::size_t scatterStride =
					    std::max<std::size_t>(1, points.size() / kMaxScatterPoints);
					gd::SolidBrush brush(ToGdiColor(ghostColor));
					for (std::size_t k = 0; k < points.size(); k += scatterStride)
					{
						g.FillEllipse(&brush, points[k].X - radius, points[k].Y - radius, radius * 2.0f,
						              radius * 2.0f);
					}
				}

				g.Restore(saveState);
			}

			// 落点提示：高亮鼠标所在网格并给出文字说明。
			const int target = (m_dragTargetLane >= 0) ? m_dragTargetLane : sourceLane;
			if (target >= 0 && target < static_cast<int>(m_lanes.size()))
			{
				const gd::RectF& targetRect = m_lanes[static_cast<std::size_t>(target)].rect;
				const float visibleTop = std::max(targetRect.Y, m_plotRect.Y);
				const float visibleBottom = std::min(targetRect.Y + targetRect.Height,
				                                     m_plotRect.Y + m_plotRect.Height);
				if (visibleBottom > visibleTop)
				{
					gd::Pen frame(ToGdiColor(m_theme->accent), 2.0f);
					g.DrawRectangle(&frame, targetRect.X, visibleTop, targetRect.Width,
					                visibleBottom - visibleTop);

					const std::wstring hint = (target == sourceLane)
					                              ? std::wstring(L"松开左键放回本网格")
					                              : (L"移动到网格 " + std::to_wstring(target + 1) +
					                                 L"：松开左键确认");
					const float textWidth = UiTextWidth(g, hint, m_fonts->uiSmall) + 16.0f * m_scale;
					const float height = 20.0f * m_scale;
					float left = targetRect.X + (targetRect.Width - textWidth) * 0.5f;
					left = std::max(m_plotRect.X, std::min(left, m_plotRect.X + m_plotRect.Width - textWidth));
					const gd::RectF pill(left, visibleTop + 4.0f * m_scale, textWidth, height);
					UiFillRoundRect(g, pill, 3.0f * m_scale, m_theme->accent);
					UiText(g, hint, m_fonts->uiSmall, pill, m_theme->textOnAccent, TextAlign::CENTER);
				}
			}
			return;
		}

		// 悬停提示：光标贴近曲线时给出可拖拽说明（与时间光标的提示方式一致）。
		if (!m_hoverSignal.IsValid())
		{
			return;
		}
		const int laneIndex = m_tab->LaneOfSignal(m_hoverSignal);
		if (laneIndex < 0 || laneIndex >= static_cast<int>(m_lanes.size()))
		{
			return;
		}
		const ResolvedSignal resolved = ResolveSignal(m_hoverSignal);
		if (resolved.data == nullptr)
		{
			return;
		}

		const LaneVisual& lane = m_lanes[static_cast<std::size_t>(laneIndex)];
		const std::wstring text = resolved.data->Title() + L" · 按住拖拽可移入其它网格";

		const float textWidth = UiTextWidth(g, text, m_fonts->uiSmall) + 16.0f * m_scale;
		const float height = 20.0f * m_scale;
		float left = m_mouseX + 12.0f * m_scale;
		if (left + textWidth > m_plotRect.X + m_plotRect.Width)
		{
			left = m_plotRect.X + m_plotRect.Width - textWidth;
		}
		left = std::max(m_plotRect.X, left);

		float top = m_mouseY + 14.0f * m_scale;
		top = std::min(top, m_plotRect.Y + m_plotRect.Height - height - 2.0f * m_scale);
		top = std::max(top, lane.rect.Y + 2.0f * m_scale);

		const gd::RectF pill(left, top, textWidth, height);
		UiFillRoundRect(g, pill, 3.0f * m_scale, WithAlpha(m_theme->readoutBg, 0xF2));
		UiDrawRoundRect(g, pill, 3.0f * m_scale, m_theme->accent, 1.0f);
		UiText(g, text, m_fonts->uiSmall, pill, m_theme->textStrong, TextAlign::CENTER);
	}

	void PlotView::PaintScrollBar(gd::Graphics& g)
	{
		if (!m_scrollBarVisible || m_laneContentHeight <= m_plotRect.Height)
		{
			return;
		}

		UiFillRoundRect(g, m_scrollBarRect, kScrollBarThickness * m_scale * 0.5f, m_theme->gridWeak);

		const float ratio = std::min(1.0f, m_plotRect.Height / m_laneContentHeight);
		const float thumbHeight = std::max(24.0f * m_scale, m_scrollBarRect.Height * ratio);
		const float maxScroll = m_laneContentHeight - m_plotRect.Height;
		const float progress = (maxScroll > 0.0f) ? (Tab().LaneScroll() / maxScroll) : 0.0f;
		const float thumbY = m_scrollBarRect.Y + progress * (m_scrollBarRect.Height - thumbHeight);

		const gd::RectF thumb(m_scrollBarRect.X, thumbY, m_scrollBarRect.Width, thumbHeight);
		UiFillRoundRect(g, thumb, kScrollBarThickness * m_scale * 0.5f, m_theme->borderStrong);
	}

} // namespace jdi