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 34struct ApplicationState { 35 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 41static void handle_error() { 42 const char* error = SDL_GetError(); 43 SkDebugf("SDL Error: %s\n", error); 44 SDL_ClearError(); 45} 46 47static 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 83static 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) 103int SDL_main(int argc, char** argv) { 104#else 105int 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