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/image_filter_layer.h" |
6 | |
7 | namespace flutter { |
8 | |
9 | ImageFilterLayer::ImageFilterLayer(sk_sp<SkImageFilter> filter) |
10 | : filter_(std::move(filter)), |
11 | transformed_filter_(nullptr), |
12 | render_count_(1) {} |
13 | |
14 | void ImageFilterLayer::Preroll(PrerollContext* context, |
15 | const SkMatrix& matrix) { |
16 | TRACE_EVENT0("flutter" , "ImageFilterLayer::Preroll" ); |
17 | |
18 | Layer::AutoPrerollSaveLayerState save = |
19 | Layer::AutoPrerollSaveLayerState::Create(context); |
20 | |
21 | SkRect child_bounds = SkRect::MakeEmpty(); |
22 | PrerollChildren(context, matrix, &child_bounds); |
23 | if (filter_) { |
24 | const SkIRect filter_input_bounds = child_bounds.roundOut(); |
25 | SkIRect filter_output_bounds = |
26 | filter_->filterBounds(filter_input_bounds, SkMatrix::I(), |
27 | SkImageFilter::kForward_MapDirection); |
28 | child_bounds = SkRect::Make(filter_output_bounds); |
29 | } |
30 | set_paint_bounds(child_bounds); |
31 | |
32 | transformed_filter_ = nullptr; |
33 | if (render_count_ >= kMinimumRendersBeforeCachingFilterLayer) { |
34 | // We have rendered this same ImageFilterLayer object enough |
35 | // times to consider its properties and children to be stable |
36 | // from frame to frame so we try to cache the layer itself |
37 | // for maximum performance. |
38 | TryToPrepareRasterCache(context, this, matrix); |
39 | } else { |
40 | // This ImageFilterLayer is not yet considered stable so we |
41 | // increment the count to measure how many times it has been |
42 | // seen from frame to frame. |
43 | render_count_++; |
44 | |
45 | // Now we will try to pre-render the children into the cache. |
46 | // To apply the filter to pre-rendered children, we must first |
47 | // modify the filter to be aware of the transform under which |
48 | // the cached bitmap was produced. Some SkImageFilter |
49 | // instances can do this operation on some transforms and some |
50 | // (filters or transforms) cannot. We can only cache the children |
51 | // and apply the filter on the fly if this operation succeeds. |
52 | transformed_filter_ = filter_->makeWithLocalMatrix(matrix); |
53 | if (transformed_filter_) { |
54 | // With a modified SkImageFilter we can now try to cache the |
55 | // children to avoid their rendering costs if they remain |
56 | // stable between frames and also avoiding a rendering surface |
57 | // switch during the Paint phase even if they are not stable. |
58 | // This benefit is seen most during animations. |
59 | TryToPrepareRasterCache(context, GetCacheableChild(), matrix); |
60 | } |
61 | } |
62 | } |
63 | |
64 | void ImageFilterLayer::Paint(PaintContext& context) const { |
65 | TRACE_EVENT0("flutter" , "ImageFilterLayer::Paint" ); |
66 | FML_DCHECK(needs_painting()); |
67 | |
68 | if (context.raster_cache) { |
69 | if (context.raster_cache->Draw(this, *context.leaf_nodes_canvas)) { |
70 | return; |
71 | } |
72 | if (transformed_filter_) { |
73 | SkPaint paint; |
74 | paint.setImageFilter(transformed_filter_); |
75 | |
76 | if (context.raster_cache->Draw(GetCacheableChild(), |
77 | *context.leaf_nodes_canvas, &paint)) { |
78 | return; |
79 | } |
80 | } |
81 | } |
82 | |
83 | SkPaint paint; |
84 | paint.setImageFilter(filter_); |
85 | |
86 | // Normally a save_layer is sized to the current layer bounds, but in this |
87 | // case the bounds of the child may not be the same as the filtered version |
88 | // so we use the bounds of the child container which do not include any |
89 | // modifications that the filter might apply. |
90 | Layer::AutoSaveLayer save_layer = Layer::AutoSaveLayer::Create( |
91 | context, GetChildContainer()->paint_bounds(), &paint); |
92 | PaintChildren(context); |
93 | } |
94 | |
95 | } // namespace flutter |
96 | |