use SkSurface behind gfx::Canvas

ui/gfx/canvas.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/canvas.h"
 
 #include <cmath>
 #include <limits>
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/geometry/insets_f.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/safe_integer_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/scoped_canvas.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/transform.h"
 
 namespace gfx {
 
+namespace {
+
+sk_sp<SkSurface> CreateSurface(const Size& size, bool is_opaque) {
+  // SkSurface cannot be zero-sized, but clients of Canvas sometimes request
+  // that (and then later resize).
+  int width = std::max(size.width(), 1);
+  int height = std::max(size.height(), 1);
+  SkAlphaType alpha = is_opaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
+  SkImageInfo info = SkImageInfo::MakeN32(width, height, alpha);
+  return SkSurface::MakeRaster(info);
+}
+
+}  // namespace
+
 Canvas::Canvas(const Size& size, float image_scale, bool is_opaque)
     : image_scale_(image_scale) {
   Size pixel_size = ScaleToCeiledSize(size, image_scale);
-  canvas_owner_ = skia::CreatePlatformCanvas(pixel_size.width(),
-                                             pixel_size.height(), is_opaque);
-  canvas_ = canvas_owner_.get();
+  surface_ = CreateSurface(pixel_size, is_opaque);
+  canvas_ = surface_->getCanvas();
 
 #if !defined(USE_CAIRO)
   // skia::PlatformCanvas instances are initialized to 0 by Cairo, but
   // uninitialized on other platforms.
   if (!is_opaque)
     canvas_->clear(SkColorSetARGB(0, 0, 0, 0));
 #endif
 
   SkScalar scale_scalar = SkFloatToScalar(image_scale);
   canvas_->scale(scale_scalar, scale_scalar);
 }
 
 Canvas::Canvas()
     : image_scale_(1.f),
-      canvas_owner_(skia::CreatePlatformCanvas(0, 0, false)),
-      canvas_(canvas_owner_.get()) {}
+      surface_(CreateSurface({0, 0}, false)),
+      canvas_(surface_->getCanvas()) {}
 
 Canvas::Canvas(SkCanvas* canvas, float image_scale)
     : image_scale_(image_scale), canvas_(canvas) {
   DCHECK(canvas_);
 }
 
 Canvas::~Canvas() {
 }
 
 void Canvas::RecreateBackingCanvas(const Size& size,
                                    float image_scale,
                                    bool is_opaque) {
   image_scale_ = image_scale;
   Size pixel_size = ScaleToFlooredSize(size, image_scale);
-  canvas_owner_ = skia::CreatePlatformCanvas(pixel_size.width(),
-                                             pixel_size.height(), is_opaque);
-  canvas_ = canvas_owner_.get();
+  surface_ = CreateSurface(pixel_size, is_opaque);
+  canvas_ = surface_->getCanvas();
 
   SkScalar scale_scalar = SkFloatToScalar(image_scale);
   canvas_->scale(scale_scalar, scale_scalar);
 }
 
 // static
 void Canvas::SizeStringInt(const base::string16& text,
                            const FontList& font_list,
                            int* width,
                            int* height,
@@ skipping 501 matching lines @@
   p.setFilterQuality(filter ? kLow_SkFilterQuality : kNone_SkFilterQuality);
   p.setShader(CreateImageRepShaderForScale(
       image_rep, SkShader::kRepeat_TileMode, shader_scale,
       remove_image_scale ? image_rep.scale() : 1.f));
 
   // The rect will be filled by the bitmap.
   canvas_->drawRect(dest_rect, p);
 }
 
 }  // namespace gfx