1 /*
2 * Copyright 2015 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 *
7 */
8
9 #include "GrBackendSurface.h"
10 #include "GrContext.h"
11 #include "SDL.h"
12 #include "SkCanvas.h"
13 #include "SkRandom.h"
14 #include "SkSurface.h"
15
16 #include "gl/GrGLInterface.h"
17 #include "gl/GrGLUtil.h"
18
19 #if defined(SK_BUILD_FOR_ANDROID)
20 #include <GLES/gl.h>
21 #elif defined(SK_BUILD_FOR_UNIX)
22 #include <GL/gl.h>
23 #elif defined(SK_BUILD_FOR_MAC)
24 #include <OpenGL/gl.h>
25 #elif defined(SK_BUILD_FOR_IOS)
26 #include <OpenGLES/ES2/gl.h>
27 #endif
28
29 /*
30 * This application is a simple example of how to combine SDL and Skia it demonstrates:
31 * how to setup gpu rendering to the main window
32 * how to perform cpu-side rendering and draw the result to the gpu-backed screen
33 * draw simple primitives (rectangles)
34 * draw more complex primitives (star)
35 */
36
37 struct ApplicationState {
ApplicationStateApplicationState38 ApplicationState() : fQuit(false) {}
39 // Storage for the user created rectangles. The last one may still be being edited.
40 SkTArray<SkRect> fRects;
41 bool fQuit;
42 };
43
handle_error()44 static void handle_error() {
45 const char* error = SDL_GetError();
46 SkDebugf("SDL Error: %s\n", error);
47 SDL_ClearError();
48 }
49
handle_events(ApplicationState * state,SkCanvas * canvas)50 static void handle_events(ApplicationState* state, SkCanvas* canvas) {
51 SDL_Event event;
52 while(SDL_PollEvent(&event)) {
53 switch (event.type) {
54 case SDL_MOUSEMOTION:
55 if (event.motion.state == SDL_PRESSED) {
56 SkRect& rect = state->fRects.back();
57 rect.fRight = event.motion.x;
58 rect.fBottom = event.motion.y;
59 }
60 break;
61 case SDL_MOUSEBUTTONDOWN:
62 if (event.button.state == SDL_PRESSED) {
63 state->fRects.push_back() = SkRect::MakeLTRB(SkIntToScalar(event.button.x),
64 SkIntToScalar(event.button.y),
65 SkIntToScalar(event.button.x),
66 SkIntToScalar(event.button.y));
67 }
68 break;
69 case SDL_KEYDOWN: {
70 SDL_Keycode key = event.key.keysym.sym;
71 if (key == SDLK_ESCAPE) {
72 state->fQuit = true;
73 }
74 break;
75 }
76 case SDL_QUIT:
77 state->fQuit = true;
78 break;
79 default:
80 break;
81 }
82 }
83 }
84
85 // Creates a star type shape using a SkPath
create_star()86 static SkPath create_star() {
87 static const int kNumPoints = 5;
88 SkPath concavePath;
89 SkPoint points[kNumPoints] = {{0, SkIntToScalar(-50)} };
90 SkMatrix rot;
91 rot.setRotate(SkIntToScalar(360) / kNumPoints);
92 for (int i = 1; i < kNumPoints; ++i) {
93 rot.mapPoints(points + i, points + i - 1, 1);
94 }
95 concavePath.moveTo(points[0]);
96 for (int i = 0; i < kNumPoints; ++i) {
97 concavePath.lineTo(points[(2 * i) % kNumPoints]);
98 }
99 concavePath.setFillType(SkPath::kEvenOdd_FillType);
100 SkASSERT(!concavePath.isConvex());
101 concavePath.close();
102 return concavePath;
103 }
104
105 #if defined(SK_BUILD_FOR_ANDROID)
SDL_main(int argc,char ** argv)106 int SDL_main(int argc, char** argv) {
107 #else
108 int main(int argc, char** argv) {
109 #endif
110 uint32_t windowFlags = 0;
111
112 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
113 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
114
115 SDL_GLContext glContext = nullptr;
116 #if defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_IOS)
117 // For Android/iOS we need to set up for OpenGL ES and we make the window hi res & full screen
118 SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
119 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE |
120 SDL_WINDOW_BORDERLESS | SDL_WINDOW_FULLSCREEN_DESKTOP |
121 SDL_WINDOW_ALLOW_HIGHDPI;
122 #else
123 // For all other clients we use the core profile and operate in a window
124 SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
125
126 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE;
127 #endif
128 static const int kStencilBits = 8; // Skia needs 8 stencil bits
129 SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
130 SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
131 SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
132 SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
133 SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
134 SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, kStencilBits);
135
136 SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
137
138 // If you want multisampling, uncomment the below lines and set a sample count
139 static const int kMsaaSampleCount = 0; //4;
140 // SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
141 // SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, kMsaaSampleCount);
142
143 /*
144 * In a real application you might want to initialize more subsystems
145 */
146 if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS) != 0) {
147 handle_error();
148 return 1;
149 }
150
151 // Setup window
152 // This code will create a window with the same resolution as the user's desktop.
153 SDL_DisplayMode dm;
154 if (SDL_GetDesktopDisplayMode(0, &dm) != 0) {
155 handle_error();
156 return 1;
157 }
158
159 SDL_Window* window = SDL_CreateWindow("SDL Window", SDL_WINDOWPOS_CENTERED,
160 SDL_WINDOWPOS_CENTERED, dm.w, dm.h, windowFlags);
161
162 if (!window) {
163 handle_error();
164 return 1;
165 }
166
167 // To go fullscreen
168 // SDL_SetWindowFullscreen(window, SDL_WINDOW_FULLSCREEN);
169
170 // try and setup a GL context
171 glContext = SDL_GL_CreateContext(window);
172 if (!glContext) {
173 handle_error();
174 return 1;
175 }
176
177 int success = SDL_GL_MakeCurrent(window, glContext);
178 if (success != 0) {
179 handle_error();
180 return success;
181 }
182
183 uint32_t windowFormat = SDL_GetWindowPixelFormat(window);
184 int contextType;
185 SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &contextType);
186
187
188 int dw, dh;
189 SDL_GL_GetDrawableSize(window, &dw, &dh);
190
191 glViewport(0, 0, dw, dh);
192 glClearColor(1, 1, 1, 1);
193 glClearStencil(0);
194 glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
195
196 // setup GrContext
197 auto interface = GrGLMakeNativeInterface();
198
199 // setup contexts
200 sk_sp<GrContext> grContext(GrContext::MakeGL(interface));
201 SkASSERT(grContext);
202
203 // Wrap the frame buffer object attached to the screen in a Skia render target so Skia can
204 // render to it
205 GrGLint buffer;
206 GR_GL_GetIntegerv(interface.get(), GR_GL_FRAMEBUFFER_BINDING, &buffer);
207 GrGLFramebufferInfo info;
208 info.fFBOID = (GrGLuint) buffer;
209 SkColorType colorType;
210
211 if (SDL_PIXELFORMAT_RGBA8888 == windowFormat) {
212 info.fFormat = GR_GL_RGBA8;
213 colorType = kRGBA_8888_SkColorType;
214 } else {
215 SkASSERT(SDL_PIXELFORMAT_BGRA8888);
216 colorType = kBGRA_8888_SkColorType;
217 if (SDL_GL_CONTEXT_PROFILE_ES == contextType) {
218 info.fFormat = GR_GL_BGRA8;
219 } else {
220 // We assume the internal format is RGBA8 on desktop GL
221 info.fFormat = GR_GL_RGBA8;
222 }
223 }
224
225 GrBackendRenderTarget target(dw, dh, kMsaaSampleCount, kStencilBits, info);
226
227 // setup SkSurface
228 // To use distance field text, use commented out SkSurfaceProps instead
229 // SkSurfaceProps props(SkSurfaceProps::kUseDeviceIndependentFonts_Flag,
230 // SkSurfaceProps::kLegacyFontHost_InitType);
231 SkSurfaceProps props(SkSurfaceProps::kLegacyFontHost_InitType);
232
233 sk_sp<SkSurface> surface(SkSurface::MakeFromBackendRenderTarget(grContext.get(), target,
234 kBottomLeft_GrSurfaceOrigin,
235 colorType, nullptr, &props));
236
237 SkCanvas* canvas = surface->getCanvas();
238 canvas->scale((float)dw/dm.w, (float)dh/dm.h);
239
240 ApplicationState state;
241
242 const char* helpMessage = "Click and drag to create rects. Press esc to quit.";
243
244 SkPaint paint;
245
246 // create a surface for CPU rasterization
247 sk_sp<SkSurface> cpuSurface(SkSurface::MakeRaster(canvas->imageInfo()));
248
249 SkCanvas* offscreen = cpuSurface->getCanvas();
250 offscreen->save();
251 offscreen->translate(50.0f, 50.0f);
252 offscreen->drawPath(create_star(), paint);
253 offscreen->restore();
254
255 sk_sp<SkImage> image = cpuSurface->makeImageSnapshot();
256
257 int rotation = 0;
258 while (!state.fQuit) { // Our application loop
259 SkRandom rand;
260 canvas->clear(SK_ColorWHITE);
261 handle_events(&state, canvas);
262
263 paint.setColor(SK_ColorBLACK);
264 canvas->drawText(helpMessage, strlen(helpMessage), SkIntToScalar(100),
265 SkIntToScalar(100), paint);
266 for (int i = 0; i < state.fRects.count(); i++) {
267 paint.setColor(rand.nextU() | 0x44808080);
268 canvas->drawRect(state.fRects[i], paint);
269 }
270
271 // draw offscreen canvas
272 canvas->save();
273 canvas->translate(dm.w / 2.0, dm.h / 2.0);
274 canvas->rotate(rotation++);
275 canvas->drawImage(image, -50.0f, -50.0f);
276 canvas->restore();
277
278 canvas->flush();
279 SDL_GL_SwapWindow(window);
280 }
281
282 if (glContext) {
283 SDL_GL_DeleteContext(glContext);
284 }
285
286 //Destroy window
287 SDL_DestroyWindow(window);
288
289 //Quit SDL subsystems
290 SDL_Quit();
291 return 0;
292 }
293