Add OpenGL context to Viewer.

tools/viewer/sk_app/win/GLWindowContext_win.cpp

Index: tools/viewer/sk_app/win/GLWindowContext_win.cpp
diff --git a/tools/viewer/sk_app/win/GLWindowContext_win.cpp b/tools/viewer/sk_app/win/GLWindowContext_win.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..0694db308ff59736be165d38b6184f0418ebd96a
--- /dev/null
+++ b/tools/viewer/sk_app/win/GLWindowContext_win.cpp
@@ -0,0 +1,110 @@
+
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GLWindowContext_win.h"
+
+#include <GL/gl.h>
+
+ // windows stuff
+#include "win/SkWGL.h"
+#include "Window_win.h"
+
+namespace sk_app {
+
+// platform-dependent create
+GLWindowContext* GLWindowContext::Create(void* platformData, const DisplayParams& params) {
+    GLWindowContext_win* ctx = new GLWindowContext_win(platformData, params);
+    if (!ctx->isValid()) {
+        delete ctx;
+        return nullptr;
+    }
+    return ctx;
+}
+
+GLWindowContext_win::GLWindowContext_win(void* platformData, const DisplayParams& params)
+    : GLWindowContext(platformData, params)
+    , fHWND(0)
+    , fHGLRC(NULL) {
+
+    // any config code here (particularly for msaa)?
+
+    this->initializeContext(platformData, params);
+}
+
+GLWindowContext_win::~GLWindowContext_win() {
+    this->destroyContext();
+}
+
+void GLWindowContext_win::onInitializeContext(void* platformData, const DisplayParams& params) {
+
+    ContextPlatformData_win* winPlatformData =
+        reinterpret_cast<ContextPlatformData_win*>(platformData);
+
+    if (winPlatformData) {
+        fHWND = winPlatformData->fHWnd;
+    }
+    HDC dc = GetDC(fHWND);
+
+    fHGLRC = SkCreateWGLContext(dc, params.fMSAASampleCount, params.fDeepColor,
+                                kGLPreferCompatibilityProfile_SkWGLContextRequest);
+    if (NULL == fHGLRC) {
+        return;
+    }
+
+    if (wglMakeCurrent(dc, fHGLRC)) {
+        glClearStencil(0);
+        glClearColor(0, 0, 0, 0);
+        glStencilMask(0xffffffff);
+        glClear(GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
+
+        // use DescribePixelFormat to get the stencil and color bit depth.
+        int pixelFormat = GetPixelFormat(dc);
+        PIXELFORMATDESCRIPTOR pfd;
+        DescribePixelFormat(dc, pixelFormat, sizeof(pfd), &pfd);
+        fStencilBits = pfd.cStencilBits;
+        // pfd.cColorBits includes alpha, so it will be 32 in 8/8/8/8 and 10/10/10/2
+        fColorBits = pfd.cRedBits + pfd.cGreenBits + pfd.cBlueBits;
+
+        // Get sample count if the MSAA WGL extension is present
+        SkWGLExtensions extensions;
+        if (extensions.hasExtension(dc, "WGL_ARB_multisample")) {
+            static const int kSampleCountAttr = SK_WGL_SAMPLES;
+            extensions.getPixelFormatAttribiv(dc,
+                                              pixelFormat,
+                                              0,
+                                              1,
+                                              &kSampleCountAttr,
+                                              &fSampleCount);
+        } else {
+            fSampleCount = 0;
+        }
+
+        RECT rect;
+        GetClientRect(fHWND, &rect);
+        fWidth = rect.right - rect.left;
+        fHeight = rect.bottom - rect.top;
+        glViewport(0, 0, fWidth, fHeight);
+    }
+}
+
+
+void GLWindowContext_win::onDestroyContext() {
+    wglMakeCurrent(wglGetCurrentDC(), NULL);
+    wglDeleteContext(fHGLRC);
+    fHGLRC = NULL;
+}
+
+
+void GLWindowContext_win::onSwapBuffers() {
+    HDC dc = GetDC((HWND)fHWND);
+    SwapBuffers(dc);
+    ReleaseDC((HWND)fHWND, dc);
+}
+
+
+}   //namespace sk_app