WIP RasterCanvasLayerAllocator experiment 2

src/core/SkRasterCanvasLayerAllocator.cpp

+/*
+ * 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 "SkRasterCanvasLayerAllocator.h"
+
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkManagedBitmapDevice.h"
+
+SkRasterCanvasLayerAllocator::SkRasterCanvasLayerAllocator() { }
+
+SkRasterCanvasLayerAllocator::~SkRasterCanvasLayerAllocator() { }
+
+sk_sp<SkCanvas> SkRasterCanvasLayerAllocator::createCanvas(const SkImageInfo& info,
+                                                           const SkSurfaceProps& props,
+                                                           void* initialData) {
+    SkBaseDevice* device = makeDevice(info, props, initialData);
+    if (!device) {
+        return nullptr;
+    }
+    return sk_make_sp<SkCanvas>(device, this);
+}
+
+
+SkBaseDevice* SkRasterCanvasLayerAllocator::makeDevice(
+        const SkImageInfo& info,
+        const SkSurfaceProps& props,
+        void* initialData) {
+    SkBitmap bitmap;
+    size_t rowBytes;
+    void (*deallocator)(void*) = nullptr;
+    void* payload = nullptr;
+    void* pixels = this->allocateLayer(info, &rowBytes,
+                                       &deallocator, &payload,
+                                       initialData);
+    if (!pixels) {
+        return nullptr;
+    }
+    if (!bitmap.installPixels(info, pixels, rowBytes)) {
+        deallocator(payload);
+        return nullptr;
+    };
+
+    return new SkManagedBitmapDevice(bitmap, props, deallocator, payload);
+}
+