1// Copyright 2013 The Flutter Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "flutter/flow/layers/opacity_layer.h"
6
7#include "flutter/fml/trace_event.h"
8#include "third_party/skia/include/core/SkPaint.h"
9
10namespace flutter {
11
12OpacityLayer::OpacityLayer(SkAlpha alpha, const SkPoint& offset)
13 : alpha_(alpha), offset_(offset) {}
14
15void OpacityLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
16 TRACE_EVENT0("flutter", "OpacityLayer::Preroll");
17
18 ContainerLayer* container = GetChildContainer();
19 FML_DCHECK(!container->layers().empty()); // OpacityLayer can't be a leaf.
20
21 const bool parent_is_opaque = context->is_opaque;
22 SkMatrix child_matrix = matrix;
23 child_matrix.postTranslate(offset_.fX, offset_.fY);
24
25 // Similar to what's done in TransformLayer::Preroll, we have to apply the
26 // reverse transformation to the cull rect to properly cull child layers.
27 context->cull_rect = context->cull_rect.makeOffset(-offset_.fX, -offset_.fY);
28
29 context->is_opaque = parent_is_opaque && (alpha_ == SK_AlphaOPAQUE);
30 context->mutators_stack.PushTransform(
31 SkMatrix::Translate(offset_.fX, offset_.fY));
32 context->mutators_stack.PushOpacity(alpha_);
33 Layer::AutoPrerollSaveLayerState save =
34 Layer::AutoPrerollSaveLayerState::Create(context);
35 ContainerLayer::Preroll(context, child_matrix);
36 context->mutators_stack.Pop();
37 context->mutators_stack.Pop();
38 context->is_opaque = parent_is_opaque;
39
40 {
41 set_paint_bounds(paint_bounds().makeOffset(offset_.fX, offset_.fY));
42#ifndef SUPPORT_FRACTIONAL_TRANSLATION
43 child_matrix = RasterCache::GetIntegralTransCTM(child_matrix);
44#endif
45 TryToPrepareRasterCache(context, GetCacheableChild(), child_matrix);
46 }
47
48 // Restore cull_rect
49 context->cull_rect = context->cull_rect.makeOffset(offset_.fX, offset_.fY);
50}
51
52void OpacityLayer::Paint(PaintContext& context) const {
53 TRACE_EVENT0("flutter", "OpacityLayer::Paint");
54 FML_DCHECK(needs_painting());
55
56 SkPaint paint;
57 paint.setAlpha(alpha_);
58
59 SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
60 context.internal_nodes_canvas->translate(offset_.fX, offset_.fY);
61
62#ifndef SUPPORT_FRACTIONAL_TRANSLATION
63 context.internal_nodes_canvas->setMatrix(RasterCache::GetIntegralTransCTM(
64 context.leaf_nodes_canvas->getTotalMatrix()));
65#endif
66
67 if (context.raster_cache &&
68 context.raster_cache->Draw(GetCacheableChild(),
69 *context.leaf_nodes_canvas, &paint)) {
70 return;
71 }
72
73 // Skia may clip the content with saveLayerBounds (although it's not a
74 // guaranteed clip). So we have to provide a big enough saveLayerBounds. To do
75 // so, we first remove the offset from paint bounds since it's already in the
76 // matrix. Then we round out the bounds.
77 //
78 // Note that the following lines are only accessible when the raster cache is
79 // not available (e.g., when we're using the software backend in golden
80 // tests).
81 SkRect saveLayerBounds;
82 paint_bounds()
83 .makeOffset(-offset_.fX, -offset_.fY)
84 .roundOut(&saveLayerBounds);
85
86 Layer::AutoSaveLayer save_layer =
87 Layer::AutoSaveLayer::Create(context, saveLayerBounds, &paint);
88 PaintChildren(context);
89}
90
91#if defined(LEGACY_FUCHSIA_EMBEDDER)
92
93void OpacityLayer::UpdateScene(SceneUpdateContext& context) {
94 float saved_alpha = context.alphaf();
95 context.set_alphaf(context.alphaf() * (alpha_ / 255.f));
96 ContainerLayer::UpdateScene(context);
97 context.set_alphaf(saved_alpha);
98}
99
100#endif
101
102} // namespace flutter
103