fix: add right-click interaction support to SelectionState

[MinCrohn]

No description provided.

[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 enhances the SelectionState by adding comprehensive support for right-click interactions. It provides a new onRightClick callback for custom event handling and automatically suppresses the browser's default context menu on the canvas. The underlying click event processing has also been refactored to accommodate these new features efficiently.

Highlights

• Right-Click Interaction: Introduced a new onRightClick callback function to the SelectionState configuration, allowing developers to define custom behavior for right-click events on the canvas.
• Context Menu Prevention: Implemented automatic prevention of the browser's default context menu when a right-click occurs within the canvas area, ensuring a cleaner user experience for custom right-click actions.
• Refactored Click Handling: Refactored the internal click processing logic within SelectionState by introducing a shared private method, #processClick, to handle common checks for onclick and the new rightclick events, improving code organization and maintainability.

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[gemini-code-assist]

Code Review

This pull request adds support for right-click interactions to SelectionState. The changes include updating the documentation, preventing the default context menu, and implementing the onRightClick callback. The implementation correctly refactors the existing onclick logic into a shared #processClick method to handle both left and right clicks, which is a good improvement for code reuse. However, I've found a bug in the onpointerdown handler for right-clicks that prevents movement detection from working correctly. My review includes a suggestion to fix this issue.

[gemini-code-assist]

In the onpointerdown handler, when a right-click is detected (e.button === 2), you are clearing the gesture state by calling #clear with gesture: true. This nullifies this.dragStartPoint immediately after it has been set.

This causes an issue in the new #processClick method, which is used by the rightclick handler. The isMoved() check inside #processClick relies on this.dragStartPoint to determine if the cursor has moved between pointerdown and pointerup. Because dragStartPoint is null, isMoved() will always return false, and every right-click will be treated as a non-drag click, even if the user moved the mouse.

To fix this, you should avoid clearing the gesture state here. You only need to set the interactionState to IDLE to prevent dragging from starting. The gesture state will be correctly cleared at the end of the rightclick event processing within #processClick.

Suggested change

	if (e.button === 2) {
	this.#clear({ state: true, selectionBox: true, gesture: true });
	}
	if (e.button === 2) {
	this.#clear({ state: true, selectionBox: true });
	}