When performing offscreen rendering on windows, attempt to use a pbuffer context.

src/gpu/gl/win/SkNativeGLContext_win.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gl/SkNativeGLContext.h"
-#include "SkWGL.h"
 
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
 SkNativeGLContext::AutoContextRestore::AutoContextRestore() {
     fOldHGLRC = wglGetCurrentContext();
     fOldHDC = wglGetCurrentDC();
 }
 
 SkNativeGLContext::AutoContextRestore::~AutoContextRestore() {
     wglMakeCurrent(fOldHDC, fOldHGLRC);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 ATOM SkNativeGLContext::gWC = 0;
 
 SkNativeGLContext::SkNativeGLContext()
     : fWindow(NULL)
     , fDeviceContext(NULL)
-    , fGlRenderContext(0) {
+    , fGlRenderContext(0)
+    , fPbufferContext(NULL) {
 }
 
 SkNativeGLContext::~SkNativeGLContext() {
     this->destroyGLContext();
 }
 
 void SkNativeGLContext::destroyGLContext() {
+    SkSafeSetNull(fPbufferContext);
     if (fGlRenderContext) {
         wglDeleteContext(fGlRenderContext);
+        fGlRenderContext = 0;
     }
     if (fWindow && fDeviceContext) {
         ReleaseDC(fWindow, fDeviceContext);
+        fDeviceContext = 0;
     }
     if (fWindow) {
         DestroyWindow(fWindow);
+        fWindow = 0;
     }
 }
 
 const GrGLInterface* SkNativeGLContext::createGLContext(GrGLStandard forcedGpuAPI) {
     HINSTANCE hInstance = (HINSTANCE)GetModuleHandle(NULL);
 
     if (!gWC) {
         WNDCLASS wc;
         wc.cbClsExtra = 0;
         wc.cbWndExtra = 0;
@@ skipping 27 matching lines @@
         SkDebugf("Could not get device context.\n");
         this->destroyGLContext();
         return NULL;
     }
     // Requesting a Core profile would bar us from using NVPR. So we request
     // compatibility profile or GL ES.
     SkWGLContextRequest contextType =
         kGLES_GrGLStandard == forcedGpuAPI ?
         kGLES_SkWGLContextRequest : kGLPreferCompatibilityProfile_SkWGLContextRequest;
 
-    if (!(fGlRenderContext = SkCreateWGLContext(fDeviceContext, 0, contextType))) {
-        SkDebugf("Could not create rendering context.\n");
+    fPbufferContext = SkWGLPbufferContext::Create(fDeviceContext, 0, contextType);
+
+    HDC dc;
+    HGLRC glrc;
+
+    if (NULL == fPbufferContext) {
+        if (!(fGlRenderContext = SkCreateWGLContext(fDeviceContext, 0, contextType))) {
+            SkDebugf("Could not create rendering context.\n");
+            this->destroyGLContext();
+            return NULL;
+        }
+        dc = fDeviceContext;
+        glrc = fGlRenderContext;
+    } else {
+        ReleaseDC(fWindow, fDeviceContext);
+        fDeviceContext = 0;
+        DestroyWindow(fWindow);
+        fWindow = 0;
+
+        dc = fPbufferContext->getDC();
+        glrc = fPbufferContext->getGLRC();
+    }
+
+    if (!(wglMakeCurrent(dc, glrc))) {
+        SkDebugf("Could not set the context.\n");
         this->destroyGLContext();
         return NULL;
     }
 
-    if (!(wglMakeCurrent(fDeviceContext, fGlRenderContext))) {
-        SkDebugf("Could not set the context.\n");
-        this->destroyGLContext();
-        return NULL;
-    }
     const GrGLInterface* interface = GrGLCreateNativeInterface();
     if (NULL == interface) {
         SkDebugf("Could not create GL interface.\n");
         this->destroyGLContext();
         return NULL;
     }
 
     return interface;
 }
 
 void SkNativeGLContext::makeCurrent() const {
-    if (!wglMakeCurrent(fDeviceContext, fGlRenderContext)) {
+    HDC dc;
+    HGLRC glrc;
+
+    if (NULL == fPbufferContext) {
+        dc = fDeviceContext;
+        glrc = fGlRenderContext;
+    } else {
+        dc = fPbufferContext->getDC();
+        glrc = fPbufferContext->getGLRC();
+    }
+
+    if (!wglMakeCurrent(dc, glrc)) {
         SkDebugf("Could not create rendering context.\n");
     }
 }
 
 void SkNativeGLContext::swapBuffers() const {
-    if (!SwapBuffers(fDeviceContext)) {
+    HDC dc;
+
+    if (NULL == fPbufferContext) {
+        dc = fDeviceContext;
+    } else {
+        dc = fPbufferContext->getDC();
+    }
+    if (!SwapBuffers(dc)) {
         SkDebugf("Could not complete SwapBuffers.\n");
     }
 }