flow/layers/clip_rect_layer.cc

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "flutter/flow/layers/clip_rect_layer.h"

namespace flow {

ClipRectLayer::ClipRectLayer(Clip clip_behavior)
    : clip_behavior_(clip_behavior) {
  FML_DCHECK(clip_behavior != Clip::none);
}

ClipRectLayer::~ClipRectLayer() = default;

void ClipRectLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
  SkRect previous_cull_rect = context->cull_rect;
  if (context->cull_rect.intersect(clip_rect_)) {
    SkRect child_paint_bounds = SkRect::MakeEmpty();
    PrerollChildren(context, matrix, &child_paint_bounds);

    if (child_paint_bounds.intersect(clip_rect_)) {
      set_paint_bounds(child_paint_bounds);
    }
  }
  context->cull_rect = previous_cull_rect;
}

#if defined(OS_FUCHSIA)

void ClipRectLayer::UpdateScene(SceneUpdateContext& context) {
  FML_DCHECK(needs_system_composite());

  scenic::Rectangle shape(context.session(),   // session
                          clip_rect_.width(),  //  width
                          clip_rect_.height()  //  height
  );

  // TODO(liyuqian): respect clip_behavior_
  SceneUpdateContext::Clip clip(context, shape, clip_rect_);
  UpdateSceneChildren(context);
}

#endif  // defined(OS_FUCHSIA)

void ClipRectLayer::Paint(PaintContext& context) const {
  TRACE_EVENT0("flutter", "ClipRectLayer::Paint");
  FML_DCHECK(needs_painting());

  SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
  context.internal_nodes_canvas->clipRect(clip_rect_,
                                          clip_behavior_ != Clip::hardEdge);
  if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
    context.internal_nodes_canvas->saveLayer(clip_rect_, nullptr);
  }
  PaintChildren(context);
  if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
    context.internal_nodes_canvas->restore();
  }
}

}  // namespace flow