Decouple ToolTips/ChartZoom/Cursor from PlotContent rendering pipeline by timmolter · Pull Request #942 · knowm/XChart

timmolter · 2026-05-22T06:46:41Z

Motivation

The Swing-interactive features (ToolTips, ChartZoom, Cursor) were tightly coupled into the core PlotContent_* rendering pipeline in two problematic ways:

Self-injection anti-pattern: ToolTips, ChartZoom, and Cursor constructors wrote themselves directly into chart.plot.plotContent via package-private field access. This caused NPEs when BitmapEncoder.saveBitmap() was called while these objects were still wired in (issue NPE on tooltips with BitmapEncoder.saveBitmap #862 root cause).
Styler pollution: Feature flags like isToolTipsEnabled, isZoomEnabled, and isCursorEnabled lived on Styler/AxesChartStyler/XYStyler -- chart visual style classes -- even though they control Swing panel behavior that is irrelevant during headless rendering.

Approach

Commit 1: Option C two-phase data collection (`PlotInteractionData`)

Introduces a plain data-transfer struct PlotInteractionData that PlotContent_* populates during rendering, replacing direct calls to toolTips.addData() and cursor.addData(). XChartPanel reads the struct after chart.paint() and drives all interaction painting.

New PlotInteractionData.java: holds ToolTipData list, CursorData list, and plotBounds
Chart.java: adds enableInteractionData() / getInteractionData() public methods
All 11 PlotContent_* subclasses: replace toolTips.addData() / cursor.addData() calls with interactionData.addToolTip() / interactionData.addCursorPoint()
PlotContent_.java: removes toolTips / chartZoom fields and the three nullable-field setters
ToolTips / Cursor: remove self-injection from constructors; add setData(PlotInteractionData) to consume the struct and replace all chart.plot.plotContent.getBounds() calls
ChartZoom: remove self-injection (one line)
XChartPanel: cursor and chartZoom become fields; calls enableInteractionData() in constructor; paintComponent() does two-phase render -> read -> paint interactions

Commit 2: Move interaction feature flags off Styler to XChartPanel

isToolTipsEnabled, isToolTipsAlwaysVisible, ToolTipType, isZoomEnabled, zoomSelectionColor, zoomResetByDoubleClick, zoomResetByButton, and isCursorEnabled are panel behaviors, not chart styles.

Removes all 8 flags from Styler, AxesChartStyler, XYStyler, OHLCStyler, Theme, and AbstractBaseTheme
ToolTipType promoted to a top-level public enum (org.knowm.xchart.ToolTipType) instead of a Styler inner type
XChartPanel gains 8 fields with fluent setters and a private rewireInteractions() method
PlotContent_* tooltip guards simplify from interactionData != null && styler.isToolTipsEnabled() to just interactionData != null
ChartZoom reads zoom config from xChartPanel getters instead of chart.getStyler()

New user API (breaking change)

Before:

chart.getStyler().setToolTipsEnabled(true);
chart.getStyler().setZoomEnabled(true);
// ((XYStyler) chart.getStyler()).setCursorEnabled(true);
XChartPanel<XYChart> panel = new XChartPanel<>(chart);

After:

XChartPanel<XYChart> panel = new XChartPanel<>(chart);
panel.setToolTipsEnabled(true)
     .setZoomEnabled(true)
     .setCursorEnabled(true)
     .setToolTipType(ToolTipType.yLabels);

Testing

All 44 existing tests pass. The BitmapEncoderTest was updated to reflect that interaction setup now belongs on the panel, not the chart styler.

Remove ToolTips, ChartZoom, and Cursor from PlotContent_* pipeline. PlotContent_* now populates PlotInteractionData during doPaint(). XChartPanel reads interactionData after chart.paint() to drive all interaction painting. - Add PlotInteractionData struct with ToolTipData and CursorData - PlotContent_.java: replace toolTips/chartZoom fields with interactionData - PlotContent_XY/Category_Bar/HorizontalBar/Bubble/OHLC/Box/HeatMap/Pie/Dial/Radar: replace toolTips.addData() -> interactionData.addToolTip(), cursor refs removed - Chart.java: add enableInteractionData() and getInteractionData() - ToolTips.java: remove self-injection, add plotBounds field and setData() - ChartZoom.java: remove self-injection - Cursor.java: remove self-injection, add plotBounds and setData(), remove addData/clearDataPoints - XChartPanel.java: add cursor/chartZoom fields, call enableInteractionData(), update componentResized, rewrite paintComponent() for two-phase painting Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

isToolTipsEnabled, isToolTipsAlwaysVisible, ToolTipType, isZoomEnabled, zoomSelectionColor, zoomResetByDoubleClick, zoomResetByButton, and isCursorEnabled are Swing-panel behaviors, not chart visual styles. - Remove from Styler / AxesChartStyler / XYStyler / OHLCStyler - Remove from Theme interface and AbstractBaseTheme - Add fields + fluent setters to XChartPanel - Extract ToolTipType as top-level enum in org.knowm.xchart - Simplify PlotContent_* guards to interactionData != null - Refactor XChartPanel constructor wiring into rewireInteractions() Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Move setToolTipsEnabled, setToolTipsAlwaysVisible, setToolTipType, setZoomEnabled, setZoomResetByDoubleClick, setZoomResetByButton, and setCursorEnabled calls from chart Styler to XChartPanel in all 37 affected demo files. Also fix SwingWrapper.displayChartMatrix() to use invokeAndWait (was invokeLater) so getXChartPanel(i) is safe to call immediately after display. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace the generic placeholder chart with the exact chart from the original bug report: logarithmic Y-axis, x in [-3, 3], y = 10^x, LegendPosition.InsideNW, XAxisLabelRotation 45, red tooltip border. The Javadoc is also updated to describe the real fix — the two-phase PlotInteractionData architecture — rather than the interim null-guard approach documented previously. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

toolTipsAlwaysVisible and toolTipType are rendering/visual properties that control data-label output — they belong on the Styler, not on XChartPanel. Moving them ensures BitmapEncoder output includes the rendered labels when isToolTipsAlwaysVisible() is true, restoring the behavior present before the interaction-decoupling refactor. Changes: - Styler: add toolTipsAlwaysVisible (default false) and toolTipType (default xAndYLabels) fields with getters/setters - Chart: add paintAlwaysVisibleToolTips(Graphics2D) protected helper that creates a ToolTips in always-visible mode and renders all data-point labels - All 10 chart paint() methods: call enableInteractionData() when isToolTipsAlwaysVisible(), then call paintAlwaysVisibleToolTips() at end - XChartPanel: remove toolTipsAlwaysVisible field/setter; remove toolTipType field/setter; hover ToolTips always created with alwaysVisible=false and toolTipType read from chart.getStyler() - TestForIssue862: setToolTipsAlwaysVisible/setToolTipType moved to getChart() on the styler so the saved PNG now contains rendered tooltip labels - BarChart07, TestForIssue106, TestForIssue370, TestForIssue545: migrate setToolTipsAlwaysVisible/setToolTipType calls from XChartPanel to styler Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Tool Tips: distinguish hover (XChartPanel.setToolTipsEnabled) from always-visible labels (styler.setToolTipsAlwaysVisible); note that always-visible labels appear in BitmapEncoder/headless output too; fix Styler.ToolTipType -> ToolTipType top-level enum reference - Zoom: move example from chart.getStyler() to XChartPanel setters - Cursor: move setCursorEnabled to XChartPanel; keep visual properties on styler - BoxChart example: move setToolTipsEnabled to XChartPanel Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Each demo chart that configures interaction features (toolTips, zoom, cursor) in its main() method now also overrides customizePanel() so those features work when the chart is displayed inside XChartDemo. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

timmolter · 2026-05-22T10:19:19Z

When componentResized fires (e.g. after setBottomComponent in JSplitPane), rewireInteractions() creates a new ToolTips instance with an empty toolTipList. If paintComponent() ran before that event, the new ToolTips never gets setData() called on it. The user's mouse moves find an empty list, no repaint is triggered, and tooltips never appear. Fix: call repaint() after wiring interactions so paintComponent() always runs (and calls setData()) after any rewiring. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR refactors XChart’s Swing interaction features (ToolTips, ChartZoom, Cursor) to be decoupled from the core PlotContent_* rendering pipeline, preventing headless rendering (e.g., BitmapEncoder) from depending on Swing-wired state and addressing the root cause of issue #862. It also moves interaction enablement/configuration from stylers to XChartPanel, while keeping “always-visible” data labels as a rendering concern.

Changes:

Introduces PlotInteractionData as a two-phase “collect during chart render → consume in panel paint” mechanism.
Removes tooltip/zoom/cursor self-injection into plot content and rewires interactions to be owned by XChartPanel.
Updates demos/docs to configure hover interactions via XChartPanel, and adds support for always-visible labels in headless rendering.

Reviewed changes

Copilot reviewed 76 out of 76 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
xchart/src/test/java/org/knowm/xchart/BitmapEncoderTest.java	Updates regression tests for #862 (though current assertions no longer exercise tooltip/zoom-enabled scenarios).
xchart/src/main/java/org/knowm/xchart/XYChart.java	Enables interaction-data collection when always-visible labels are enabled; paints always-visible labels post-render.
xchart/src/main/java/org/knowm/xchart/XChartPanel.java	Owns ToolTips/Cursor/ChartZoom; rewires listeners and paints interactions using `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/ToolTipType.java	Promotes tooltip label type to a top-level public enum.
xchart/src/main/java/org/knowm/xchart/SwingWrapper.java	Changes chart display creation to be synchronous (invokeAndWait) to allow immediate panel access.
xchart/src/main/java/org/knowm/xchart/style/XYStyler.java	Removes cursor/zoom enablement flags from styler; keeps cursor appearance settings.
xchart/src/main/java/org/knowm/xchart/style/theme/Theme.java	Removes interaction enablement defaults from Theme (tooltips/zoom/cursor).
xchart/src/main/java/org/knowm/xchart/style/theme/AbstractBaseTheme.java	Drops cursor-enabled override since enablement moved off Theme.
xchart/src/main/java/org/knowm/xchart/style/Styler.java	Removes hover-tooltip enablement; keeps always-visible labels as a rendering option and uses new `ToolTipType`.
xchart/src/main/java/org/knowm/xchart/style/OHLCStyler.java	Removes zoom enablement covariant overrides (zoom now panel-owned).
xchart/src/main/java/org/knowm/xchart/style/AxesChartStyler.java	Removes zoom enablement/configuration state from axes stylers.
xchart/src/main/java/org/knowm/xchart/RadarChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/PieChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/OHLCChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/ToolTips.java	Removes self-injection; consumes `PlotInteractionData` via `setData()` and uses plot bounds from the struct.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotInteractionData.java	New interaction DTO for tooltips + cursor points + plot bounds.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_XY.java	Switches tooltip/cursor collection to `PlotInteractionData` (no direct interaction painting).
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Radar.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Pie.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_OHLC.java	Switches tooltip collection to `PlotInteractionData` (including composite hit areas).
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_HorizontalBar.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_HeatMap.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Dial.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Category_Bar.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Bubble.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Box.java	Switches tooltip collection to `PlotInteractionData`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_.java	Removes embedded ToolTips/ChartZoom plumbing; clears and populates `PlotInteractionData` bounds per paint.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/Cursor.java	Removes self-injection; consumes `PlotInteractionData` via `setData()` and uses plot bounds from the struct.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/ChartZoom.java	Removes self-injection; reads zoom config from `XChartPanel`.
xchart/src/main/java/org/knowm/xchart/internal/chartpart/Chart.java	Adds public `enableInteractionData()` / `getInteractionData()` and a shared `paintAlwaysVisibleToolTips()` helper.
xchart/src/main/java/org/knowm/xchart/HorizontalBarChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/HeatMapChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/DialChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/CategoryChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/BubbleChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart/src/main/java/org/knowm/xchart/BoxChart.java	Adds always-visible tooltip label rendering path via interaction-data enablement.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue862.java	Updates standalone repro to demonstrate headless rendering safety + panel-owned hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue770.java	Moves zoom enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue593.java	Moves cursor enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue545.java	Moves hover tooltip enablement to panel after display; keeps always-visible labels on styler.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue54_2.java	Moves hover tooltip enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue54_1.java	Moves hover tooltip enablement to panels created by matrix wrapper.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue530.java	Moves hover tooltip enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue410.java	Moves hover tooltip enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue370.java	Moves hover tooltip enablement to panels created by matrix wrapper; keeps always-visible labels on styler.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue349.java	Moves zoom enablement to panel.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue335.java	Moves hover tooltip enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue291.java	Moves hover tooltip enablement to panel after display.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue244.java	Moves hover tooltip enablement to panels created by matrix wrapper.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue210.java	Moves hover tooltip enablement to panels created by matrix wrapper.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue189_1.java	Moves hover tooltip enablement to a specific panel in matrix wrapper.
xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue106.java	Updates tooltip type enum usage and moves hover enablement to panels created by matrix wrapper.
xchart-demo/src/main/java/org/knowm/xchart/demo/XChartDemo.java	Adds `ExampleChart.customizePanel()` hook to configure panel interactions when switching examples.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/theme/ThemeChart03.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/radar/RadarChart02.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/radar/RadarChart01.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/pie/PieChart02.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/ohlc/OHLCChart03.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/ohlc/OHLCChart02.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/ohlc/OHLCChart01.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/line/LineChart09.java	Implements `customizePanel()` to enable cursor.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/line/LineChart05.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/horizontalbar/HorizontalBarChart04.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/heatmap/HeatMapChart05.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/heatmap/HeatMapChart04.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/heatmap/HeatMapChart03.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/ExampleChart.java	Adds `customizePanel()` extension point for panel-owned interactions.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/dial/DialChart02.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/dial/DialChart01.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/date/DateChart09.java	Implements `customizePanel()` to enable cursor.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/date/DateChart01.java	Implements `customizePanel()` to enable zoom.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/bubble/BubbleChart01.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/box/BoxChart03.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/box/BoxChart02.java	Implements `customizePanel()` to enable hover tooltips.
xchart-demo/src/main/java/org/knowm/xchart/demo/charts/bar/BarChart07.java	Updates tooltip type enum usage and implements `customizePanel()` to enable hover tooltips.
README.md	Updates public docs for panel-owned hover interactions and styler-owned always-visible labels/appearance.

- PlotInteractionData: remove public modifier (now package-private) - Chart.getInteractionData(): remove public modifier (now package-private) - Chart: add public consumeInteractionData(Graphics2D, ToolTips, Cursor) bridge so XChartPanel never imports PlotInteractionData - XChartPanel: remove unused ToolTipType and PlotInteractionData imports; use consumeInteractionData(); only enable interaction data when tooltips or cursor are active (not for zoom-only) - SwingWrapper: add EDT guard (isEventDispatchThread check) for both displayChart() and displayChartMatrix(); restore interrupt flag on InterruptedException - BitmapEncoderTest: rename/update tests to actually exercise the #862 regression (setToolTipsAlwaysVisible) and clarify headless no-NPE test Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

timmolter and others added 7 commits May 22, 2026 01:52

timmolter requested a review from Copilot May 22, 2026 10:43

Copilot started reviewing on behalf of timmolter May 22, 2026 10:43 View session

Copilot AI reviewed May 22, 2026

View reviewed changes

timmolter merged commit ab019d3 into develop May 22, 2026
1 check passed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Decouple ToolTips/ChartZoom/Cursor from PlotContent rendering pipeline#942

Decouple ToolTips/ChartZoom/Cursor from PlotContent rendering pipeline#942
timmolter merged 9 commits into
developfrom
timmolter/tooltips-zoom-architecture-investigation

timmolter commented May 22, 2026

Uh oh!

timmolter commented May 22, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

timmolter commented May 22, 2026

Motivation

Approach

Commit 1: Option C two-phase data collection (PlotInteractionData)

Commit 2: Move interaction feature flags off Styler to XChartPanel

New user API (breaking change)

Testing

Uh oh!

timmolter commented May 22, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Commit 1: Option C two-phase data collection (`PlotInteractionData`)