paintOverflow method

void paintOverflow(PaintingContext context, Offset offset, EdgeInsets borderEdge, CSSBoxDecoration? decoration, PaintingContextCallback callback,)

Implementation

void paintOverflow(
  PaintingContext context,
  Offset offset,
  EdgeInsets borderEdge,
  CSSBoxDecoration? decoration,
  PaintingContextCallback callback
) {
  if (clipX == false && clipY == false) return callback(context, offset);

  final double paintOffsetX = _paintOffsetX;
  final double paintOffsetY = _paintOffsetY;
  final Offset paintOffset = Offset(paintOffsetX, paintOffsetY);
  // Overflow should not cover border.
  Rect clipRect = Offset(borderEdge.left, borderEdge.top) & Size(
    size.width - borderEdge.right - borderEdge.left,
    size.height - borderEdge.bottom - borderEdge.top,
  );
  if (_shouldClipAtPaintOffset(paintOffset, size)) {
    // ignore: prefer_function_declarations_over_variables
    PaintingContextCallback painter = (PaintingContext context, Offset offset) {
      callback(context, offset + paintOffset);
    };

    // If current or its descendants has a compositing layer caused by styles
    // (eg. transform, opacity, overflow...), then it needs to create a new layer
    // or else the clip in the older layer will not work.
    bool _needsCompositing = needsCompositing;

    if (decoration != null && decoration.hasBorderRadius) {
      BorderRadius radius = decoration.borderRadius!;
      Rect rect = Offset.zero & size;
      RRect borderRRect = radius.toRRect(rect);
      // A borderRadius can only be given for a uniform Border in Flutter.
      // https://github.com/flutter/flutter/issues/12583
      double? borderTop = renderStyle.borderTopWidth?.computedValue;
      // The content of overflow is trimmed to the padding edge curve.
      // https://www.w3.org/TR/css-backgrounds-3/#corner-clipping
      RRect clipRRect = borderTop != null
        ? borderRRect.deflate(borderTop)
        : borderRRect;

      // The content of replaced elements is trimmed to the content edge curve.
      if (this is RenderReplaced) {
        // @TODO: Currently only support clip uniform padding for replaced element.
        double paddingTop = renderStyle.paddingTop.computedValue;
        clipRRect = clipRRect.deflate(paddingTop);
      }
      _clipRRectLayer.layer = context.pushClipRRect(_needsCompositing, offset, clipRect, clipRRect, painter, oldLayer: _clipRRectLayer.layer);
    } else {
      _clipRectLayer.layer = context.pushClipRect(_needsCompositing, offset, clipRect, painter, oldLayer: _clipRectLayer.layer);
    }
  } else {
    _clipRectLayer.layer = null;
    _clipRRectLayer.layer = null;
    callback(context, offset);
  }
}