Diagnosing and fixing CustomPainter jank
WHAT IT TESTS: optimizing custom canvas rendering. OUTLINE: avoid work in paint, gate repaints with shouldRepaint, isolate with RepaintBoundary, cache static layers. RED FLAG: blaming the device or repainting everything every frame.
WHAT IT TESTS: whether you can find and remove redundant painting work. ANSWER OUTLINE: common causes are heavy computation inside paint, returning true from shouldRepaint unconditionally, painting on every frame for static content, expensive operations like saveLayer or path rebuilds each frame, and overdraw. Fixes include precomputing paths and Paint objects, implementing shouldRepaint correctly, wrapping the painter in a RepaintBoundary so it gets its own layer, and caching static layers as a Picture or image.
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- #flutter
- #custompainter
- #performance
- #repaintboundary
- #rendering
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