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// 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/opacity_layer.h"
#include "flutter/fml/trace_event.h"
#include "third_party/skia/include/core/SkPaint.h"
namespace flutter {
OpacityLayer::OpacityLayer(SkAlpha alpha, const SkPoint& offset)
: alpha_(alpha), offset_(offset), children_can_accept_opacity_(false) {
// We can always inhert opacity even if we cannot pass it along to
// our children as we can accumulate the inherited opacity into our
// own opacity value before we recurse.
set_layer_can_inherit_opacity(true);
}
void OpacityLayer::Diff(DiffContext* context, const Layer* old_layer) {
DiffContext::AutoSubtreeRestore subtree(context);
auto* prev = static_cast<const OpacityLayer*>(old_layer);
if (!context->IsSubtreeDirty()) {
FML_DCHECK(prev);
if (alpha_ != prev->alpha_ || offset_ != prev->offset_) {
context->MarkSubtreeDirty(context->GetOldLayerPaintRegion(old_layer));
}
}
context->PushTransform(SkMatrix::Translate(offset_.fX, offset_.fY));
#ifndef SUPPORT_FRACTIONAL_TRANSLATION
context->SetTransform(
RasterCache::GetIntegralTransCTM(context->GetTransform()));
#endif
DiffChildren(context, prev);
context->SetLayerPaintRegion(this, context->CurrentSubtreeRegion());
}
void OpacityLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
TRACE_EVENT0("flutter", "OpacityLayer::Preroll");
FML_DCHECK(!GetChildContainer()->layers().empty()); // We can't be a leaf.
SkMatrix child_matrix = matrix;
child_matrix.preTranslate(offset_.fX, offset_.fY);
// Similar to what's done in TransformLayer::Preroll, we have to apply the
// reverse transformation to the cull rect to properly cull child layers.
context->cull_rect = context->cull_rect.makeOffset(-offset_.fX, -offset_.fY);
context->mutators_stack.PushTransform(
SkMatrix::Translate(offset_.fX, offset_.fY));
context->mutators_stack.PushOpacity(alpha_);
Layer::AutoPrerollSaveLayerState save =
Layer::AutoPrerollSaveLayerState::Create(context);
ContainerLayer::Preroll(context, child_matrix);
context->mutators_stack.Pop();
context->mutators_stack.Pop();
set_children_can_accept_opacity(context->subtree_can_inherit_opacity);
set_paint_bounds(paint_bounds().makeOffset(offset_.fX, offset_.fY));
if (!children_can_accept_opacity()) {
#ifndef SUPPORT_FRACTIONAL_TRANSLATION
child_matrix = RasterCache::GetIntegralTransCTM(child_matrix);
#endif
TryToPrepareRasterCache(context, GetCacheableChild(), child_matrix);
}
// Restore cull_rect
context->cull_rect = context->cull_rect.makeOffset(offset_.fX, offset_.fY);
}
void OpacityLayer::Paint(PaintContext& context) const {
TRACE_EVENT0("flutter", "OpacityLayer::Paint");
FML_DCHECK(needs_painting(context));
SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
context.internal_nodes_canvas->translate(offset_.fX, offset_.fY);
#ifndef SUPPORT_FRACTIONAL_TRANSLATION
context.internal_nodes_canvas->setMatrix(RasterCache::GetIntegralTransCTM(
context.leaf_nodes_canvas->getTotalMatrix()));
#endif
SkScalar inherited_opacity = context.inherited_opacity;
SkScalar subtree_opacity = opacity() * inherited_opacity;
if (children_can_accept_opacity()) {
context.inherited_opacity = subtree_opacity;
PaintChildren(context);
context.inherited_opacity = inherited_opacity;
return;
}
SkPaint paint;
paint.setAlphaf(subtree_opacity);
if (context.raster_cache &&
context.raster_cache->Draw(GetCacheableChild(),
*context.leaf_nodes_canvas, &paint)) {
return;
}
// Skia may clip the content with saveLayerBounds (although it's not a
// guaranteed clip). So we have to provide a big enough saveLayerBounds. To do
// so, we first remove the offset from paint bounds since it's already in the
// matrix. Then we round out the bounds.
//
// Note that the following lines are only accessible when the raster cache is
// not available (e.g., when we're using the software backend in golden
// tests).
SkRect saveLayerBounds;
paint_bounds()
.makeOffset(-offset_.fX, -offset_.fY)
.roundOut(&saveLayerBounds);
Layer::AutoSaveLayer save_layer =
Layer::AutoSaveLayer::Create(context, saveLayerBounds, &paint);
PaintChildren(context);
}
} // namespace flutter