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      1 
      2 /*
      3  * Copyright 2011 Google Inc.
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 #include "gl/GrGLInterface.h"
     10 #include "gl/GrGLAssembleInterface.h"
     11 #define WIN32_LEAN_AND_MEAN
     12 #include <windows.h>
     13 
     14 class AutoLibraryUnload {
     15 public:
     16     AutoLibraryUnload(const char* moduleName) {
     17         fModule = LoadLibrary(moduleName);
     18     }
     19     ~AutoLibraryUnload() {
     20         if (NULL != fModule) {
     21             FreeLibrary(fModule);
     22         }
     23     }
     24     HMODULE get() const { return fModule; }
     25 
     26 private:
     27     HMODULE fModule;
     28 };
     29 
     30 class GLProcGetter {
     31 public:
     32     GLProcGetter() : fGLLib("opengl32.dll") {}
     33 
     34     bool isInitialized() const { return NULL != fGLLib.get(); }
     35 
     36     GrGLFuncPtr getProc(const char name[]) const {
     37         GrGLFuncPtr proc;
     38         if (NULL != (proc = (GrGLFuncPtr) GetProcAddress(fGLLib.get(), name))) {
     39             return proc;
     40         }
     41         if (NULL != (proc = (GrGLFuncPtr) wglGetProcAddress(name))) {
     42             return proc;
     43         }
     44         return NULL;
     45     }
     46 
     47 private:
     48     AutoLibraryUnload fGLLib;
     49 };
     50 
     51 static GrGLFuncPtr win_get_gl_proc(void* ctx, const char name[]) {
     52     SkASSERT(NULL != ctx);
     53     SkASSERT(NULL != wglGetCurrentContext());
     54     const GLProcGetter* getter = (const GLProcGetter*) ctx;
     55     return getter->getProc(name);
     56 }
     57 
     58 /*
     59  * Windows makes the GL funcs all be __stdcall instead of __cdecl :(
     60  * This implementation will only work if GR_GL_FUNCTION_TYPE is __stdcall.
     61  * Otherwise, a springboard would be needed that hides the calling convention.
     62  */
     63 const GrGLInterface* GrGLCreateNativeInterface() {
     64     if (NULL == wglGetCurrentContext()) {
     65         return NULL;
     66     }
     67 
     68     GLProcGetter getter;
     69     if (!getter.isInitialized()) {
     70         return NULL;
     71     }
     72 
     73     return GrGLAssembleGLInterface(&getter, win_get_gl_proc);
     74 }
     75