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 "GrContext.h"
10 #include "SDL.h"
11 #include "SkCanvas.h"
12 #include "SkRandom.h"
13 #include "SkSurface.h"
14
15 #include "gl/GrGLInterface.h"
16 #include "gl/GrGLUtil.h"
17
18 #if defined(SK_BUILD_FOR_ANDROID)
19 #include <GLES/gl.h>
20 #elif defined(SK_BUILD_FOR_UNIX)
21 #include <GL/gl.h>
22 #elif defined(SK_BUILD_FOR_MAC)
23 #include <OpenGL/gl.h>
24 #endif
25
26 /*
27 * This application is a simple example of how to combine SDL and Skia it demonstrates:
28 * how to setup gpu rendering to the main window
29 * how to perform cpu-side rendering and draw the result to the gpu-backed screen
30 * draw simple primitives (rectangles)
31 * draw more complex primitives (star)
32 */
33
34 struct ApplicationState {
ApplicationStateApplicationState35 ApplicationState() : fQuit(false) {}
36 // Storage for the user created rectangles. The last one may still be being edited.
37 SkTArray<SkRect> fRects;
38 bool fQuit;
39 };
40
handle_error()41 static void handle_error() {
42 const char* error = SDL_GetError();
43 SkDebugf("SDL Error: %s\n", error);
44 SDL_ClearError();
45 }
46
handle_events(ApplicationState * state,SkCanvas * canvas)47 static void handle_events(ApplicationState* state, SkCanvas* canvas) {
48 SDL_Event event;
49 while(SDL_PollEvent(&event)) {
50 switch (event.type) {
51 case SDL_MOUSEMOTION:
52 if (event.motion.state == SDL_PRESSED) {
53 SkRect& rect = state->fRects.back();
54 rect.fRight = event.motion.x;
55 rect.fBottom = event.motion.y;
56 }
57 break;
58 case SDL_MOUSEBUTTONDOWN:
59 if (event.button.state == SDL_PRESSED) {
60 state->fRects.push_back() = SkRect::MakeLTRB(SkIntToScalar(event.button.x),
61 SkIntToScalar(event.button.y),
62 SkIntToScalar(event.button.x),
63 SkIntToScalar(event.button.y));
64 }
65 break;
66 case SDL_KEYDOWN: {
67 SDL_Keycode key = event.key.keysym.sym;
68 if (key == SDLK_ESCAPE) {
69 state->fQuit = true;
70 }
71 break;
72 }
73 case SDL_QUIT:
74 state->fQuit = true;
75 break;
76 default:
77 break;
78 }
79 }
80 }
81
82 // Creates a star type shape using a SkPath
create_star()83 static SkPath create_star() {
84 static const int kNumPoints = 5;
85 SkPath concavePath;
86 SkPoint points[kNumPoints] = {{0, SkIntToScalar(-50)} };
87 SkMatrix rot;
88 rot.setRotate(SkIntToScalar(360) / kNumPoints);
89 for (int i = 1; i < kNumPoints; ++i) {
90 rot.mapPoints(points + i, points + i - 1, 1);
91 }
92 concavePath.moveTo(points[0]);
93 for (int i = 0; i < kNumPoints; ++i) {
94 concavePath.lineTo(points[(2 * i) % kNumPoints]);
95 }
96 concavePath.setFillType(SkPath::kEvenOdd_FillType);
97 SkASSERT(!concavePath.isConvex());
98 concavePath.close();
99 return concavePath;
100 }
101
102 #if defined(SK_BUILD_FOR_ANDROID)
SDL_main(int argc,char ** argv)103 int SDL_main(int argc, char** argv) {
104 #else
105 int main(int argc, char** argv) {
106 #endif
107 uint32_t windowFlags = 0;
108
109 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
110 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
111
112 SDL_GLContext glContext = nullptr;
113 #if defined(SK_BUILD_FOR_ANDROID)
114 // For Android we need to set up for OpenGL ES and we make the window hi res & full screen
115 SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
116 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE |
117 SDL_WINDOW_BORDERLESS | SDL_WINDOW_FULLSCREEN_DESKTOP |
118 SDL_WINDOW_ALLOW_HIGHDPI;
119 #else
120 // For all other clients we use the core profile and operate in a window
121 SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
122
123 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE;
124 #endif
125 static const int kStencilBits = 8; // Skia needs 8 stencil bits
126 SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
127 SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
128 SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
129 SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
130 SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
131 SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, kStencilBits);
132
133 SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
134
135 // If you want multisampling, uncomment the below lines and set a sample count
136 static const int kMsaaSampleCount = 0; //4;
137 // SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
138 // SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, kMsaaSampleCount);
139
140 /*
141 * In a real application you might want to initialize more subsystems
142 */
143 if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS) != 0) {
144 handle_error();
145 return 1;
146 }
147
148 // Setup window
149 // This code will create a window with the same resolution as the user's desktop.
150 SDL_DisplayMode dm;
151 if (SDL_GetDesktopDisplayMode(0, &dm) != 0) {
152 handle_error();
153 return 1;
154 }
155
156 SDL_Window* window = SDL_CreateWindow("SDL Window", SDL_WINDOWPOS_CENTERED,
157 SDL_WINDOWPOS_CENTERED, dm.w, dm.h, windowFlags);
158
159 if (!window) {
160 handle_error();
161 return 1;
162 }
163
164 // To go fullscreen
165 // SDL_SetWindowFullscreen(window, SDL_WINDOW_FULLSCREEN);
166
167 // try and setup a GL context
168 glContext = SDL_GL_CreateContext(window);
169 if (!glContext) {
170 handle_error();
171 return 1;
172 }
173
174 int success = SDL_GL_MakeCurrent(window, glContext);
175 if (success != 0) {
176 handle_error();
177 return success;
178 }
179
180 glViewport(0, 0, dm.w, dm.h);
181 glClearColor(1, 1, 1, 1);
182 glClearStencil(0);
183 glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
184
185 // setup GrContext
186 sk_sp<const GrGLInterface> interface(GrGLCreateNativeInterface());
187
188 // setup contexts
189 sk_sp<GrContext> grContext(GrContext::Create(kOpenGL_GrBackend,
190 (GrBackendContext)interface.get()));
191 SkASSERT(grContext);
192
193 // Wrap the frame buffer object attached to the screen in a Skia render target so Skia can
194 // render to it
195 GrBackendRenderTargetDesc desc;
196 desc.fWidth = dm.w;
197 desc.fHeight = dm.h;
198 desc.fConfig = kSkia8888_GrPixelConfig;
199 desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
200 desc.fSampleCnt = kMsaaSampleCount;
201 desc.fStencilBits = kStencilBits;
202 GrGLint buffer;
203 GR_GL_GetIntegerv(interface, GR_GL_FRAMEBUFFER_BINDING, &buffer);
204 desc.fRenderTargetHandle = buffer;
205
206 // setup SkSurface
207 // To use distance field text, use commented out SkSurfaceProps instead
208 // SkSurfaceProps props(SkSurfaceProps::kUseDeviceIndependentFonts_Flag,
209 // SkSurfaceProps::kLegacyFontHost_InitType);
210 SkSurfaceProps props(SkSurfaceProps::kLegacyFontHost_InitType);
211
212 sk_sp<SkSurface> surface(SkSurface::MakeFromBackendRenderTarget(grContext, desc, &props));
213
214 SkCanvas* canvas = surface->getCanvas();
215
216 ApplicationState state;
217
218 const char* helpMessage = "Click and drag to create rects. Press esc to quit.";
219
220 SkPaint paint;
221
222 // create a surface for CPU rasterization
223 sk_sp<SkSurface> cpuSurface(SkSurface::MakeRaster(canvas->imageInfo()));
224
225 SkCanvas* offscreen = cpuSurface->getCanvas();
226 offscreen->save();
227 offscreen->translate(50.0f, 50.0f);
228 offscreen->drawPath(create_star(), paint);
229 offscreen->restore();
230
231 sk_sp<SkImage> image = cpuSurface->makeImageSnapshot();
232
233 int rotation = 0;
234 while (!state.fQuit) { // Our application loop
235 SkRandom rand;
236 canvas->clear(SK_ColorWHITE);
237 handle_events(&state, canvas);
238
239 paint.setColor(SK_ColorBLACK);
240 canvas->drawText(helpMessage, strlen(helpMessage), SkIntToScalar(100),
241 SkIntToScalar(100), paint);
242 for (int i = 0; i < state.fRects.count(); i++) {
243 paint.setColor(rand.nextU() | 0x44808080);
244 canvas->drawRect(state.fRects[i], paint);
245 }
246
247 // draw offscreen canvas
248 canvas->save();
249 canvas->translate(dm.w / 2.0, dm.h / 2.0);
250 canvas->rotate(rotation++);
251 canvas->drawImage(image, -50.0f, -50.0f);
252 canvas->restore();
253
254 canvas->flush();
255 SDL_GL_SwapWindow(window);
256 }
257
258 if (glContext) {
259 SDL_GL_DeleteContext(glContext);
260 }
261
262 //Destroy window
263 SDL_DestroyWindow(window);
264
265 //Quit SDL subsystems
266 SDL_Quit();
267 return 0;
268 }
269