renderChild method

@protected void renderChild(Canvas canvas, Component child)

Renders a single child component onto canvas.

Override this method (instead of renderTree) when you need to intercept per-child rendering — for example, to accumulate draw calls for batching. The default implementation propagates the parent's render contexts into the child before delegating to the child's Component.renderTree, and cleans them up afterwards.

Implementation

@protected
void renderChild(Canvas canvas, Component child) {
  int? originalLength;
  final hasContext = _renderContexts.isNotEmpty;
  if (hasContext) {
    originalLength = child._renderContexts.length;
    child._renderContexts.addAll(_renderContexts);
  }
  child.renderTree(canvas);
  if (hasContext) {
    child._renderContexts.removeRange(
      originalLength!,
      child._renderContexts.length,
    );
  }
}