feat: add Paint Selection feature to SelectionState

[MinCrohn]

Users can now perform "Paint Selection" by brushing over objects with the mouse, offering a more flexible and intuitive alternative to standard box selection. This feature includes built-in path interpolation to ensure accurate detection of all objects along the movement path, even during rapid mouse gestures.

Usage

// Activate Paint Selection mode
patchmap.stateManager.setState('selection', {
  draggable: true,      // Enables drag (painting) functionality
  paintSelection: true, // Enables Paint Selection mode (default: false)
  selectUnit: 'entity', // Sets the selection unit
  
  // Real-time feedback during selection
  onDrag: (selected) => {
    console.log('Currently painted objects:', selected);
  },
  
  // Callback fired when selection ends
  onDragEnd: (selected) => {
    console.log('Selection complete:', selected.map(el => el.id));
    if (patchmap.transformer) {
      patchmap.transformer.elements = selected;
    }
  }
});

[gemini-code-assist]

Summary of Changes

Hello @MinCrohn, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the user interaction model by introducing a "Paint Selection" feature. This new mode allows for a more fluid and intuitive object selection experience, where users can simply brush over elements to select them, moving beyond the traditional rectangular box selection. The implementation includes robust path interpolation to maintain selection accuracy even with fast mouse gestures, making the selection process more reliable and user-friendly.

Highlights

• New "Paint Selection" Feature: Introduced a new 'paint' drag mode in SelectionState allowing users to select objects by brushing over them, offering a more flexible alternative to standard box selection.
• Path Interpolation for Accurate Selection: The paint selection feature includes built-in path interpolation, ensuring accurate detection of all objects along the mouse movement path, even during rapid gestures.
• New Intersection Utilities: Added intersectSegment and findIntersectObjectsBySegment functions to efficiently detect objects that intersect with a given line segment, forming the core logic for paint selection.
• Duplicate Link Prevention in Relations: Enhanced the Relations component to prevent the addition of duplicate links when merging changes, improving data integrity and consistency.
• Explicit Merge Strategy for Viewport Drawing: The draw function now explicitly sets mergeStrategy: 'replace' when applying canvas children to the viewport, ensuring consistent and predictable rendering behavior.

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[gemini-code-assist]

Code Review

This pull request introduces a great new "Paint Selection" feature. The implementation looks solid and follows existing patterns in the codebase. I've identified a couple of areas for improvement and one bug, which I've detailed in the comments. The most significant concern is the lack of tests for this new feature. Given that this is a new user-facing interaction, it would be highly beneficial to add tests covering the paint selection functionality to ensure it is robust and to prevent future regressions. This would include verifying that dragMode: 'paint' enables the feature, testing that objects are correctly selected during a paint gesture, and ensuring that onDrag and onDragEnd callbacks are fired with the correct set of selected objects.

[MinCrohn]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces an excellent new "Paint Selection" feature, providing a more intuitive way for users to select objects. The implementation, which includes path interpolation for accuracy during rapid mouse movements, is well-thought-out. My main concern is the absence of tests for this new functionality. Adding unit or integration tests is crucial to ensure the feature's stability and prevent future regressions. I've also included a couple of review comments: one to prevent a potential side effect by avoiding mutation of an input object in Relations.js, and another with a suggestion to improve code conciseness in SelectionState.js.

[MinCrohn]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new 'Paint Selection' feature, allowing users to select objects by brushing over them. The implementation is well-structured, adding new states and intersection logic. The documentation and tests are also updated to reflect these changes. I have one suggestion to improve the consistency of the onDrag callback's behavior in the new paint selection mode.