fix: incomplete path not included on saving

[ian-wd]

Fix Sketch Canvas Save Functionality - Incomplete Strokes Now Preserved

Description

Fixed a critical issue where incomplete drawing strokes were not included in saved images, causing user work to be lost when save operations were called before stroke completion.

Issue Analysis

The original implementation had a fundamental design flaw where the save functionality only captured completed paths from _frozenImage but ignored incomplete strokes in _currentPath. This created a timing-dependent failure where:

1. Visual Inconsistency: Users could see strokes on screen that wouldn't appear in saved images
2. Data Loss: Incomplete strokes were lost during save operations
3. Poor UX: "What you see is what you get" principle was violated

Root Cause: The code assumed every drawing gesture would complete normally via onPanResponderRelease, but real-world scenarios (system interruptions, app switching, gesture conflicts) could prevent this from happening.

Solution

Enhanced the createImageWithTransparentBackground method to include incomplete paths in saved images:

// Before: Only completed paths were saved
CGContextDrawImage(context, targetRect, _frozenImage);
CGContextDrawImage(context, targetRect, _translucentFrozenImage);

// After: Include both completed and incomplete paths
CGContextDrawImage(context, targetRect, _frozenImage);
CGContextDrawImage(context, targetRect, _translucentFrozenImage);

// Include current incomplete path in saved image
if (_currentPath) {
    [_currentPath drawInContext:context];
}

Key Benefits:

• Minimal Changes: Only 6 lines added across two code paths
• No Breaking Changes: All existing functionality preserved
• Backward Compatible: Works with existing API
• No New Functions: Uses only existing native methods

Testing

Tested Scenarios:

1. Normal Operation: Completed strokes save correctly (existing behavior)
2. Timing Issues: Incomplete strokes now included in saves
3. System Interruptions: Strokes preserved even when endPath is delayed
4. Gesture Conflicts: Incomplete strokes saved when gesture is interrupted

Test Cases:

• Draw complete stroke → Save → Stroke appears in image
• Start drawing → Save before lifting finger → Incomplete stroke appears in image
• Draw multiple strokes → Save during drawing → All visible strokes appear in image
• App interruption during drawing → Save → Partial stroke preserved

Before/After

Before: Incomplete strokes visible on screen but missing from saved images
After: All visible strokes (complete and incomplete) are preserved in saved images

Checklist

• Code follows the project's style guidelines
• Self-review of code has been completed
• Code has been tested locally
• No new warnings or errors introduced
• Changes are backward compatible

Related Issues

• Fixes timing-dependent save failures
• Addresses user experience inconsistency
• Resolves data loss during interrupted drawing sessions