1 /*
2  * Copyright 2011 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 #include "SkTypes.h"
8 #if defined(SK_BUILD_FOR_WIN)
9 
10 #include "SkLeanWindows.h"
11 
12 #include "gl/GrGLInterface.h"
13 #include "gl/GrGLAssembleInterface.h"
14 #include "gl/GrGLUtil.h"
15 
16 class AutoLibraryUnload {
17 public:
18     AutoLibraryUnload(const char* moduleName) {
19         fModule = LoadLibraryA(moduleName);
20     }
21     ~AutoLibraryUnload() {
22         if (fModule) {
23             FreeLibrary(fModule);
24         }
25     }
26     HMODULE get() const { return fModule; }
27 
28 private:
29     HMODULE fModule;
30 };
31 
32 class GLProcGetter {
33 public:
34     GLProcGetter() : fGLLib("opengl32.dll") {}
35 
36     bool isInitialized() const { return SkToBool(fGLLib.get()); }
37 
38     GrGLFuncPtr getProc(const char name[]) const {
39         GrGLFuncPtr proc;
40         if ((proc = (GrGLFuncPtr) GetProcAddress(fGLLib.get(), name))) {
41             return proc;
42         }
43         if ((proc = (GrGLFuncPtr) wglGetProcAddress(name))) {
44             return proc;
45         }
46         return nullptr;
47     }
48 
49 private:
50     AutoLibraryUnload fGLLib;
51 };
52 
53 static GrGLFuncPtr win_get_gl_proc(void* ctx, const char name[]) {
54     SkASSERT(ctx);
55     SkASSERT(wglGetCurrentContext());
56     const GLProcGetter* getter = (const GLProcGetter*) ctx;
57     return getter->getProc(name);
58 }
59 
60 /*
61  * Windows makes the GL funcs all be __stdcall instead of __cdecl :(
62  * This implementation will only work if GR_GL_FUNCTION_TYPE is __stdcall.
63  * Otherwise, a springboard would be needed that hides the calling convention.
64  */
65 sk_sp<const GrGLInterface> GrGLMakeNativeInterface() {
66     if (nullptr == wglGetCurrentContext()) {
67         return nullptr;
68     }
69 
70     GLProcGetter getter;
71     if (!getter.isInitialized()) {
72         return nullptr;
73     }
74 
75     GrGLGetStringProc getString = (GrGLGetStringProc)getter.getProc("glGetString");
76     if (nullptr == getString) {
77         return nullptr;
78     }
79     const char* verStr = reinterpret_cast<const char*>(getString(GR_GL_VERSION));
80     GrGLStandard standard = GrGLGetStandardInUseFromString(verStr);
81 
82     if (kGLES_GrGLStandard == standard) {
83         return GrGLMakeAssembledGLESInterface(&getter, win_get_gl_proc);
84     } else if (kGL_GrGLStandard == standard) {
85         return GrGLMakeAssembledGLInterface(&getter, win_get_gl_proc);
86     }
87     return nullptr;
88 }
89 
90 const GrGLInterface* GrGLCreateNativeInterface() { return GrGLMakeNativeInterface().release(); }
91 
92 #endif//defined(SK_BUILD_FOR_WIN)
93