| Flutter Windows Embedder |

compositor_software.cc
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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/shell/platform/windows/compositor_software.h"
6
7 #include "flutter/shell/platform/windows/flutter_windows_engine.h"
8 #include "flutter/shell/platform/windows/flutter_windows_view.h"
9
10 namespace flutter {
11
12 constexpr int kOpaqueBlack = 0xff000000;
13
14 namespace {
15
16 /// Calculate the minimum and maximum x and y coordinates to enclose all layers.
17 FlutterRect CalculateBounds(const FlutterLayer** layers, size_t layers_count) {
18 double x_min = HUGE_VAL;
19 double x_max = -HUGE_VAL;
20 double y_min = HUGE_VAL;
21 double y_max = -HUGE_VAL;
22 for (const FlutterLayer** layer = layers; layer < layers + layers_count;
23 layer++) {
24 const FlutterPoint& offset = (*layer)->offset;
25 const FlutterSize& size = (*layer)->size;
26 x_min = std::min(x_min, offset.x);
27 y_min = std::min(y_min, offset.y);
28 x_max = std::max(x_max, offset.x + size.width);
29 y_max = std::max(y_max, offset.y + size.height);
30 }
31 return FlutterRect{x_min, y_min, x_max, y_max};
32 }
33
34 /// Blend layer in-place onto allocation, which already holds the previous
35 /// results of composition.
36 void BlendLayer(std::vector<uint32_t>& allocation,
37 const FlutterLayer& layer,
38 int x_min,
39 int y_min,
40 int width,
41 int height) {
42 FML_DCHECK(layer.type == kFlutterLayerContentTypeBackingStore);
43 auto& backing_store = *layer.backing_store;
44 FML_DCHECK(backing_store.type == kFlutterBackingStoreTypeSoftware);
45 auto src_data =
46 static_cast<const uint32_t*>(backing_store.software.allocation);
47 const FlutterPoint& offset = layer.offset;
48 const FlutterSize& size = layer.size;
49
50 // Bounds for iteration to prevent out-of-bounds destination coordinates.
51 int y_src_min = std::max(0., y_min - offset.y);
52 int y_src_max = std::min(size.height, height + y_min - offset.y);
53 int x_src_min = std::max(0., x_min - offset.x);
54 int x_src_max = std::min(size.width, width + x_min - offset.x);
55 for (int y_src = y_src_min; y_src < y_src_max; y_src++) {
56 int y_dst = y_src + offset.y - y_min;
57 for (int x_src = x_src_min; x_src < x_src_max; x_src++) {
58 int x_dst = x_src + offset.x + x_min;
59 size_t i_src = y_src * size.width + x_src;
60 size_t i_dst = y_dst * width + x_dst;
61 uint32_t src = src_data[i_src];
62 uint32_t dst = allocation[i_dst];
63
64 int r_src = (src >> 0) & 0xff;
65 int g_src = (src >> 8) & 0xff;
66 int b_src = (src >> 16) & 0xff;
67 int a_src = (src >> 24) & 0xff;
68
69 int r_dst = (dst >> 0) & 0xff;
70 int g_dst = (dst >> 8) & 0xff;
71 int b_dst = (dst >> 16) & 0xff;
72
73 int r = (r_dst * 255 + (r_src - r_dst) * a_src) / 255;
74 int g = (g_dst * 255 + (g_src - g_dst) * a_src) / 255;
75 int b = (b_dst * 255 + (b_src - b_dst) * a_src) / 255;
76
77 allocation[i_dst] = (r << 0) | (g << 8) | (b << 16) | (0xff << 24);
78 }
79 }
80 }
81
82 } // namespace
83
84 CompositorSoftware::CompositorSoftware() {}
85
86 bool CompositorSoftware::CreateBackingStore(
87 const FlutterBackingStoreConfig& config,
88 FlutterBackingStore* result) {
89 size_t size = config.size.width * config.size.height * 4;
90 void* allocation = std::calloc(size, sizeof(uint8_t));
91 if (!allocation) {
92 return false;
93 }
94
95 result->type = kFlutterBackingStoreTypeSoftware;
96 result->software.allocation = allocation;
97 result->software.height = config.size.height;
98 result->software.row_bytes = config.size.width * 4;
99 result->software.user_data = nullptr;
100 result->software.destruction_callback = [](void* user_data) {
101 // Backing store destroyed in `CompositorSoftware::CollectBackingStore`, set
102 // on FlutterCompositor.collect_backing_store_callback during engine start.
103 };
104 return true;
105 }
106
107 bool CompositorSoftware::CollectBackingStore(const FlutterBackingStore* store) {
108 std::free(const_cast<void*>(store->software.allocation));
109 return true;
110 }
111
112 bool CompositorSoftware::Present(FlutterWindowsView* view,
113 const FlutterLayer** layers,
114 size_t layers_count) {
115 FML_DCHECK(view != nullptr);
116
117 // Clear the view if there are no layers to present.
118 if (layers_count == 0) {
119 return view->ClearSoftwareBitmap();
120 }
121
122 // Bypass composition logic if there is only one layer.
123 if (layers_count == 1) {
124 const FlutterLayer* layer = layers[0];
125 FML_DCHECK(layer != nullptr);
126 if (layer->type == kFlutterLayerContentTypeBackingStore &&
127 layer->offset.x == 0 && layer->offset.y == 0) {
128 auto& backing_store = *layer->backing_store;
129 FML_DCHECK(backing_store.type == kFlutterBackingStoreTypeSoftware);
130 auto& software = backing_store.software;
131 return view->PresentSoftwareBitmap(software.allocation,
132 software.row_bytes, software.height);
133 }
134 }
135
136 // Composite many layers.
137 FlutterRect bounds = CalculateBounds(layers, layers_count);
138 // Truncate from double to integer to represent whole pixels.
139 int x_min = static_cast<int>(bounds.left);
140 int x_max = static_cast<int>(bounds.right);
141 int y_min = static_cast<int>(bounds.top);
142 int y_max = static_cast<int>(bounds.bottom);
143
144 int width = x_max - x_min;
145 int height = y_max - y_min;
146 std::vector<uint32_t> allocation(width * height, kOpaqueBlack);
147
148 for (const FlutterLayer** layer = layers; layer < layers + layers_count;
149 layer++) {
150 // TODO(schectman): handle platform view type layers.
151 // https://github.com/flutter/flutter/issues/143375
152 if ((*layer)->type == kFlutterLayerContentTypeBackingStore) {
153 BlendLayer(allocation, **layer, x_min, y_min, width, height);
154 } else {
155 FML_UNREACHABLE();
156 return false;
157 }
158 }
159
160 return view->PresentSoftwareBitmap(static_cast<void*>(allocation.data()),
161 width * sizeof(uint32_t), height);
162 }
163
164 } // namespace flutter
flutter::FlutterWindowsView
Definition: flutter_windows_view.h:34
flutter::CompositorSoftware::Present
bool Present(FlutterWindowsView *view, const FlutterLayer **layers, size_t layers_count) override
|Compositor|
Definition: compositor_software.cc:112
user_data
void * user_data
Definition: flutter_windows_view_unittests.cc:53
flutter::CompositorSoftware::CreateBackingStore
bool CreateBackingStore(const FlutterBackingStoreConfig &config, FlutterBackingStore *result) override
|Compositor|
Definition: compositor_software.cc:86
flutter_windows_view.h
flutter
Definition: accessibility_bridge_windows.cc:11
compositor_software.h
flutter::FlutterWindowsView::PresentSoftwareBitmap
virtual bool PresentSoftwareBitmap(const void *allocation, size_t row_bytes, size_t height)
Definition: flutter_windows_view.cc:682
flutter_windows_engine.h
flutter::FlutterWindowsView::ClearSoftwareBitmap
virtual bool ClearSoftwareBitmap()
Definition: flutter_windows_view.cc:678
flutter::CompositorSoftware::CompositorSoftware
CompositorSoftware()
Definition: compositor_software.cc:84
flutter::CompositorSoftware::CollectBackingStore
bool CollectBackingStore(const FlutterBackingStore *store) override
|Compositor|
Definition: compositor_software.cc:107
flutter::kOpaqueBlack
constexpr int kOpaqueBlack
Definition: compositor_software.cc:12