Make tab/tabstrip high density compatible

ui/gfx/image/image_skia_operations.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/image/image_skia_operations.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "skia/ext/platform_canvas.h"
+#include "ui/base/layout.h"
+#include "ui/base/ui_base_switches.h"
+#include "ui/gfx/image/image_skia.h"
+#include "ui/gfx/image/image_skia_rep.h"
+#include "ui/gfx/image/image_skia_source.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/size.h"
+#include "ui/gfx/skbitmap_operations.h"
+#include "ui/gfx/skia_util.h"
+
+namespace gfx {
+namespace {
+
+bool ScalingEnabled() {
+  static bool scale_images = !CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableScalingInImageSkiaOperations);
+  return scale_images;
+}
+
+// Creates 2x scaled image of the give |source|.
+ImageSkiaRep Create2XImageSkiaRep(const ImageSkiaRep& source) {
+  gfx::Size size(source.GetWidth() * 2.0f, source.GetHeight() * 2.0f);
+  skia::PlatformCanvas canvas(size.width(), size.height(), false);
+  SkRect resized_bounds = RectToSkRect(gfx::Rect(size));
+  canvas.drawBitmapRect(source.sk_bitmap(), NULL, resized_bounds);
+  SkBitmap resized_bitmap = canvas.getDevice()->accessBitmap(false);
+  return ImageSkiaRep(resized_bitmap, ui::SCALE_FACTOR_200P);
+}
+
+// A utility function to synchronize the scale factor of the two images.
+// When the command line option "--disable-scaling-in-image-skia-operation"
+// is provided, this function will fail if the scale factors of the two images
+// are different. This assumes that the platform only supports
+// 1x and 2x scale factors.
+// TODO(oshima): Remove and replace this with plain CHECK once
+// 2x images for all resources are provided.
+void MatchScale(ImageSkiaRep* first, ImageSkiaRep* second) {
+  if (first->scale_factor() != second->scale_factor()) {
+    CHECK(ScalingEnabled());
+    ImageSkiaRep* target = NULL;
+    if (first->scale_factor() == ui::SCALE_FACTOR_100P) {
+      target = first;
+    } else {
+      target = second;
+    }
+    *target = Create2XImageSkiaRep(*target);
+  }
+}
+
+class BlendingImageSource : public gfx::ImageSkiaSource {
+ public:
+  BlendingImageSource(const ImageSkia& first,
+                      const ImageSkia& second,
+                      double alpha)
+      : first_(first),
+        second_(second),
+        alpha_(alpha) {
+  }
+
+  // gfx::ImageSkiaSource overrides:
+  virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
+    ImageSkiaRep first_rep = first_.GetRepresentation(scale_factor);
+    ImageSkiaRep second_rep = second_.GetRepresentation(scale_factor);
+    MatchScale(&first_rep, &second_rep);
+    SkBitmap blended = SkBitmapOperations::CreateBlendedBitmap(
+        first_rep.sk_bitmap(), second_rep.sk_bitmap(), alpha_);
+    return ImageSkiaRep(blended, first_rep.scale_factor());
+  }
+
+ private:
+  const ImageSkia first_;
+  const ImageSkia second_;
+  double alpha_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlendingImageSource);
+};
+
+class MaskedImageSource : public gfx::ImageSkiaSource {
+ public:
+  MaskedImageSource(const ImageSkia& rgb, const ImageSkia& alpha)
+      : rgb_(rgb),
+        alpha_(alpha) {
+  }
+
+  // gfx::ImageSkiaSource overrides:
+  virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
+    ImageSkiaRep rgb_rep = rgb_.GetRepresentation(scale_factor);
+    ImageSkiaRep alpha_rep = alpha_.GetRepresentation(scale_factor);
+    MatchScale(&rgb_rep, &alpha_rep);
+    return ImageSkiaRep(SkBitmapOperations::CreateMaskedBitmap(
+        rgb_rep.sk_bitmap(), alpha_rep.sk_bitmap()),
+                        rgb_rep.scale_factor());
+  }
+
+ private:
+  const ImageSkia rgb_;
+  const ImageSkia alpha_;
+
+  DISALLOW_COPY_AND_ASSIGN(MaskedImageSource);
+};
+
+class TiledImageSource : public gfx::ImageSkiaSource {
+ public:
+  TiledImageSource(const ImageSkia& source,
+                   int src_x, int src_y,
+                   int dst_w, int dst_h)
+      : source_(source),
+        src_x_(src_x),
+        src_y_(src_y),
+        dst_w_(dst_w),
+        dst_h_(dst_h) {
+  }
+
+  // gfx::ImageSkiaSource overrides:
+  virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
+    ImageSkiaRep source_rep = source_.GetRepresentation(scale_factor);
+    float scale = ui::GetScaleFactorScale(source_rep.scale_factor());
+    return ImageSkiaRep(
+        SkBitmapOperations::CreateTiledBitmap(
+            source_rep.sk_bitmap(),
+            src_x_ * scale, src_y_ * scale, dst_w_ * scale, dst_h_ * scale),
+        source_rep.scale_factor());
+  }
+
+ private:
+  const ImageSkia& source_;
+  const int src_x_;
+  const int src_y_;
+  const int dst_w_;
+  const int dst_h_;
+
+  DISALLOW_COPY_AND_ASSIGN(TiledImageSource);
+};
+
+}  // namespace;
+
+// static
+ImageSkia ImageSkiaOperations::CreateBlendedImage(const ImageSkia& first,
+                                                  const ImageSkia& second,
+                                                  double alpha) {
+  return ImageSkia(new BlendingImageSource(first, second, alpha), first.size());
+}
+
+// static
+ImageSkia ImageSkiaOperations::CreateMaskedImage(const ImageSkia& rgb,
+                                                 const ImageSkia& alpha) {
+  return ImageSkia(new MaskedImageSource(rgb, alpha), rgb.size());
+}
+
+// static
+ImageSkia ImageSkiaOperations::CreateTiledImage(const ImageSkia& source,
+                                                int src_x, int src_y,
+                                                int dst_w, int dst_h) {
+  return ImageSkia(new TiledImageSource(source, src_x, src_y, dst_w, dst_h),
+                   gfx::Size(dst_w, dst_h));
+}
+
+}  // namespace gfx