Add OpenGL context to Viewer.

tools/viewer/sk_app/WindowContext.cpp

Index: tools/viewer/sk_app/WindowContext.cpp
diff --git a/tools/viewer/sk_app/WindowContext.cpp b/tools/viewer/sk_app/WindowContext.cpp
new file mode 100755
index 0000000000000000000000000000000000000000..41bbd14576b37f604c8f65d7001b8de076932553
--- /dev/null
+++ b/tools/viewer/sk_app/WindowContext.cpp
@@ -0,0 +1,74 @@
+
+/*
+ * 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 "GrContext.h"
+#include "SkSurface.h"
+#include "WindowContext.h"
+
+#include "gl/GrGLDefines.h"
+
+#include "gl/GrGLUtil.h"
+#include "GrRenderTarget.h"
+#include "GrContext.h"
+
+#include "SkCanvas.h"
+#include "SkImage_Base.h"
+
+namespace sk_app {
+
+sk_sp<SkSurface> WindowContext::createRenderSurface(sk_sp<GrRenderTarget> rt, int colorBits) {
+    auto flags = (fSurfaceProps.flags() & ~SkSurfaceProps::kGammaCorrect_Flag) |
+                 (GrPixelConfigIsSRGB(fPixelConfig) ? SkSurfaceProps::kGammaCorrect_Flag : 0);
+    SkSurfaceProps props(flags, fSurfaceProps.pixelGeometry());
+
+    if (!this->isGpuContext() || colorBits > 24 ||
+        kRGBA_F16_SkColorType == fDisplayParams.fColorType) {
+        // If we're rendering to F16, we need an off-screen surface - the current render
+        // target is most likely the wrong format.
+        //
+        // If we're rendering raster data or using a deep (10-bit or higher) surface, we probably
+        // need an off-screen surface. 10-bit, in particular, has strange gamma behavior.
+        SkImageInfo info = SkImageInfo::Make(fWidth, fHeight,
+                                             fDisplayParams.fColorType,
+                                             kUnknown_SkAlphaType,
+                                             fDisplayParams.fProfileType);
+        return SkSurface::MakeRenderTarget(fContext, SkBudgeted::kNo, info,
+                                           fDisplayParams.fMSAASampleCount, &props);
+    } else {
+        return SkSurface::MakeRenderTargetDirect(rt.get(), &props);
+    }
+}
+
+void WindowContext::presentRenderSurface(sk_sp<SkSurface> renderSurface, sk_sp<GrRenderTarget> rt,
+                                         int colorBits) {
+    if (!this->isGpuContext() || colorBits > 24 ||
+        kRGBA_F16_SkColorType == fDisplayParams.fColorType) {
+        // We made/have an off-screen surface. Get the contents as an SkImage:
+        SkImageInfo info = SkImageInfo::Make(fWidth, fHeight,
+                                             fDisplayParams.fColorType,
+                                             kUnknown_SkAlphaType,
+                                             fDisplayParams.fProfileType);
+        SkBitmap bm;
+        bm.allocPixels(info);
+        renderSurface->getCanvas()->readPixels(&bm, 0, 0);
+        SkPixmap pm;
+        bm.peekPixels(&pm);
+        sk_sp<SkImage> image(SkImage::MakeTextureFromPixmap(fContext, pm,
+                             SkBudgeted::kNo));
+        GrTexture* texture = as_IB(image)->peekTexture();
+        SkASSERT(texture);
+
+        // With ten-bit output, we need to manually apply the gamma of the output device
+        // (unless we're in non-gamma correct mode, in which case our data is already
+        // fake-sRGB, like we're expected to put in the 10-bit buffer):
+        bool doGamma = (colorBits == 30) && SkImageInfoIsGammaCorrect(info);
+        fContext->applyGamma(rt.get(), texture, doGamma ? 1.0f / 2.2f : 1.0f);
+    }
+}
+
+}   //namespace sk_app