fix(whiteboard): finish current stroke before changing pen color

[Amitesh-exp]

Anki.Droid.Issue.Fix.19236.mp4

Purpose / Description

When drawing, if the user tapped with another finger to change the brush color, the stroke would continue instead of ending. This caused unexpected merging of strokes with the wrong color.

Fixes

• Fixes [Whiteboard] While drawing, it’s possible to press the buttons. #19236

Approach

• Added handling for ACTION_POINTER_DOWN in onTouchEvent
• Now, whenever a second finger touches the screen while drawing, the current stroke is finalized (drawFinish()), isCurrentlyDrawing is reset, and the brush change is applied cleanly.
• This ensures multi-touch interactions stop the ongoing stroke before switching brush color.

How Has This Been Tested?

• Tested on Physical Device
• Drew with one finger, then tapped another finger to change color.
• Verified that the stroke ended before color switch.
• Confirmed new strokes started fresh with the new brush color.

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

Thanks! This fix is for the deprecated Whiteboard, the issue was logged against the Whiteboard in the new study screen: WhiteboardFragment.kt