Add RasterWindowContext_mac

tools/viewer/sk_app/mac/RasterWindowContext_mac.cpp

Index: tools/viewer/sk_app/mac/RasterWindowContext_mac.cpp
diff --git a/tools/viewer/sk_app/mac/RasterWindowContext_mac.cpp b/tools/viewer/sk_app/mac/RasterWindowContext_mac.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..47f349b2eb8e1ba6234f384511c5f713a01a1a0f
--- /dev/null
+++ b/tools/viewer/sk_app/mac/RasterWindowContext_mac.cpp
@@ -0,0 +1,153 @@
+
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "../GLWindowContext.h"
+#include "SkCanvas.h"
+#include "SkGammaColorFilter.h"
+#include "WindowContextFactory_mac.h"
+
+#include "SDL.h"
+
+#include <OpenGL/gl.h>
+
+using sk_app::DisplayParams;
+using sk_app::window_context_factory::MacWindowInfo;
+using sk_app::GLWindowContext;
+
+namespace {
+
+// We use SDL to support Mac windowing mainly for convenience's sake. However, it
+// does not allow us to support a purely raster backend because we have no hooks into
+// the NSWindow's drawRect: method. Hence we use GL to handle the update. Should we
+// want to avoid this, we will probably need to write our own windowing backend.
+
+class RasterWindowContext_mac : public GLWindowContext {
+public:
+    RasterWindowContext_mac(const MacWindowInfo&, const DisplayParams&);
+
+    ~RasterWindowContext_mac() override;
+
+    sk_sp<SkSurface> getBackbufferSurface() override;
+
+    void onSwapBuffers() override;
+
+    void onInitializeContext() override;
+    void onDestroyContext() override;
+
+private:
+    SDL_Window*   fWindow;
+    SDL_GLContext fGLContext;
+    sk_sp<SkSurface> fBackbufferSurface;
+
+    typedef GLWindowContext INHERITED;
+};
+
+RasterWindowContext_mac::RasterWindowContext_mac(const MacWindowInfo& info,
+                                                 const DisplayParams& params)
+    : INHERITED(params)
+    , fWindow(info.fWindow)
+    , fGLContext(nullptr) {
+
+    // any config code here (particularly for msaa)?
+
+    this->initializeContext();
+}
+
+RasterWindowContext_mac::~RasterWindowContext_mac() {
+    this->destroyContext();
+}
+
+void RasterWindowContext_mac::onInitializeContext() {
+    SkASSERT(fWindow);
+
+    fGLContext = SDL_GL_CreateContext(fWindow);
+    if (!fGLContext) {
+        SkDebugf("%s\n", SDL_GetError());
+        return;
+    }
+
+    if (0 == SDL_GL_MakeCurrent(fWindow, fGLContext)) {
+        glClearStencil(0);
+        glClearColor(0, 0, 0, 0);
+        glStencilMask(0xffffffff);
+        glClear(GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
+
+        int redBits, greenBits, blueBits;
+        SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &redBits);
+        SDL_GL_GetAttribute(SDL_GL_GREEN_SIZE, &greenBits);
+        SDL_GL_GetAttribute(SDL_GL_BLUE_SIZE, &blueBits);
+        fColorBits = redBits + greenBits + blueBits;
+
+        SDL_GL_GetAttribute(SDL_GL_STENCIL_SIZE, &fStencilBits);
+        SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &fSampleCount);
+
+        SDL_GetWindowSize(fWindow, &fWidth, &fHeight);
+        glViewport(0, 0, fWidth, fHeight);
+    } else {
+        SkDebugf("MakeCurrent failed: %s\n", SDL_GetError());
+    }
+
+    // make the offscreen image
+    SkImageInfo info = SkImageInfo::Make(fWidth, fHeight, fDisplayParams.fColorType,
+                                         kPremul_SkAlphaType, fDisplayParams.fColorSpace);
+    fBackbufferSurface = SkSurface::MakeRaster(info);
+}
+
+void RasterWindowContext_mac::onDestroyContext() {
+    if (!fWindow || !fGLContext) {
+        return;
+    }
+    fBackbufferSurface.reset(nullptr);
+    SDL_GL_DeleteContext(fGLContext);
+    fGLContext = nullptr;
+}
+
+sk_sp<SkSurface> RasterWindowContext_mac::getBackbufferSurface() { return fBackbufferSurface; }
+
+void RasterWindowContext_mac::onSwapBuffers() {
+    if (fWindow && fGLContext) {
+        // We made/have an off-screen surface. Get the contents as an SkImage:
+        sk_sp<SkImage> snapshot = fBackbufferSurface->makeImageSnapshot();
+        
+        // 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 = (fActualColorBits == 30) &&
+                       (fDisplayParams.fColorSpace != nullptr ||
+                        kRGBA_F16_SkColorType == fDisplayParams.fColorType);
+        SkPaint gammaPaint;
+        gammaPaint.setXfermodeMode(SkXfermode::kSrc_Mode);
+        if (doGamma) {
+            gammaPaint.setColorFilter(SkGammaColorFilter::Make(1.0f / 2.2f));
+        }
+
+        sk_sp<SkSurface> gpuSurface = INHERITED::getBackbufferSurface();
+        SkCanvas* gpuCanvas = gpuSurface->getCanvas();
+        gpuCanvas->drawImage(snapshot, 0, 0, &gammaPaint);
+        gpuCanvas->flush();
+
+        SDL_GL_SwapWindow(fWindow);
+    }
+}
+
+}  // anonymous namespace
+
+namespace sk_app {
+namespace window_context_factory {
+
+WindowContext* NewRasterForMac(const MacWindowInfo& info, const DisplayParams& params) {
+    WindowContext* ctx = new RasterWindowContext_mac(info, params);
+    if (!ctx->isValid()) {
+        delete ctx;
+        return nullptr;
+    }
+    return ctx;
+}
+
+}  // namespace window_context_factory
+}  // namespace sk_app