Smallest possible desktop application that uses Skia to render stuff.

experimental/SkiaExamples/BaseExample.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#include "BaseExample.h"
+
+#include "gl/GrGLInterface.h"
+#include "SkGpuDevice.h"
+
+BaseExample::BaseExample(void* hWnd, int argc, char** argv)
+    : INHERITED(hWnd)
+{
+    this->setConfig(SkBitmap::kARGB_8888_Config);
+    this->setVisibleP(true);
+    this->setClipToBounds(false);
+
+    // Software rendering by default
+    fType = kRaster_DeviceType;
+
+    setupBackend(fType);
+}
+
+BaseExample::~BaseExample() {
+    if (fType == kGPU_DeviceType) {
+        SkSafeUnref(fContext);
+        SkSafeUnref(fInterface);
+        SkSafeUnref(fRenderTarget);
+    }
+}
+
+void BaseExample::setupBackend(DeviceType type) {
+    fType = type;
+    if(type == kGPU_DeviceType) {
+        AttachmentInfo attachmentInfo;
+        bool result = attach(kNativeGL_BackEndType, 0 /*msaa*/, &attachmentInfo);
+
+        if (false == result) {
+            SkDebugf("Not possible to create GL backend. Defaulting to raster.");
+            fType = kRaster_DeviceType;
+            detach();
+            return;
+        }
+
+        const GrGLInterface* interface = GrGLCreateNativeInterface();
+        fInterface = const_cast<GrGLInterface*>(interface);
+        SkASSERT(NULL != interface);
+
+        fContext = GrContext::Create(kOpenGL_GrBackend, (GrBackendContext)interface);
+        SkASSERT(NULL != fContext);
+
+        GrBackendRenderTargetDesc desc;
+        desc.fWidth = SkScalarRound(width());
+        desc.fHeight = SkScalarRound(height());
+        desc.fConfig = kSkia8888_GrPixelConfig;
+        desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
+        desc.fSampleCnt = attachmentInfo.fSampleCount;
+        desc.fStencilBits = attachmentInfo.fStencilBits;
+
+        GrGLint buffer;
+        interface->fGetIntegerv(GL_FRAMEBUFFER_BINDING, &buffer);
+        desc.fRenderTargetHandle = buffer;
+
+        fRenderTarget = fContext->wrapBackendRenderTarget(desc);
+
+        fContext->setRenderTarget(fRenderTarget);
+    }
+}
+
+SkCanvas* BaseExample::createCanvas() {
+    if (fType == kGPU_DeviceType &&
+        NULL != fContext && NULL != fRenderTarget) {
+        SkAutoTUnref<SkDevice> device(new SkGpuDevice(fContext, fRenderTarget));
+        return new SkCanvas(device);
+    } else {
+        return INHERITED::createCanvas();
+    }
+}
+
+void BaseExample::draw(SkCanvas* canvas) {
+    if (getDeviceType() == kGPU_DeviceType) {
+        present();
+    }
+}
+