Expose array of bitmaps contained by gfx::Image similar to NSImage

ui/gfx/image/image_skia.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.h"
+
+#include <limits>
+#include <cmath>
+
+#include "base/logging.h"
+#include "base/stl_util.h"
+
+namespace gfx {
+
+ImageSkia::ImageSkia(const SkBitmap* bitmap)
+    : size_(bitmap->width(), bitmap->height()),
+      mip_map_build_pending_(false) {
+  CHECK(bitmap);
+  // TODO(pkotwicz): Add a CHECK to ensure that !bitmap->isNull()
+  bitmaps_.push_back(bitmap);
+}
+
+ImageSkia::ImageSkia(const std::vector<const SkBitmap*>& bitmaps)
+    : bitmaps_(bitmaps),
+      mip_map_build_pending_(false) {
+  CHECK(!bitmaps_.empty());
+  // TODO(pkotwicz): Add a CHECK to ensure that !bitmap->isNull() for each
+  // vector element.
+  // Assume that the smallest bitmap represents 1x scale factor.
+  for (size_t i = 0; i < bitmaps_.size(); ++i) {
+    gfx::Size bitmap_size(bitmaps_[i]->width(), bitmaps_[i]->height());
+    if (size_.IsEmpty() || bitmap_size.GetArea() < size_.GetArea())
+      size_ = bitmap_size;
+  }
+}
+
+ImageSkia::~ImageSkia() {
+  STLDeleteElements(&bitmaps_);
+}
+
+void ImageSkia::BuildMipMap() {
+  mip_map_build_pending_ = true;
+}
+
+void ImageSkia::DrawToCanvasInt(gfx::Canvas* canvas, int x, int y) {
+  SkPaint p;
+  DrawToCanvasInt(canvas, x, y, p);
+}
+
+void ImageSkia::DrawToCanvasInt(gfx::Canvas* canvas,
+                                int x, int y,
+                                const SkPaint& paint) {
+
+  if (IsZeroSized())
+    return;
+
+  SkMatrix m = canvas->sk_canvas()->getTotalMatrix();
+  float scale_x = std::abs(SkScalarToFloat(m.getScaleX()));
+  float scale_y = std::abs(SkScalarToFloat(m.getScaleY()));
+
+  const SkBitmap* bitmap = GetBitmapForScale(scale_x, scale_y);
+
+  if (mip_map_build_pending_) {
+    const_cast<SkBitmap*>(bitmap)->buildMipMap();
+    mip_map_build_pending_ = false;
+  }
+
+  float bitmap_scale_x = static_cast<float>(bitmap->width()) / width();
+  float bitmap_scale_y = static_cast<float>(bitmap->height()) / height();
+
+  canvas->Save();
+  canvas->sk_canvas()->scale(1.0f / bitmap_scale_x,
+                             1.0f / bitmap_scale_y);
+  canvas->sk_canvas()->drawBitmap(*bitmap, SkFloatToScalar(x * bitmap_scale_x),
+                                  SkFloatToScalar(y * bitmap_scale_y));
+  canvas->Restore();
+}
+
+void ImageSkia::DrawToCanvasInt(gfx::Canvas* canvas,
+                                int src_x, int src_y, int src_w, int src_h,
+                                int dest_x, int dest_y, int dest_w, int dest_h,
+                                bool filter) {
+  SkPaint p;
+  DrawToCanvasInt(canvas, src_x, src_y, src_w, src_h, dest_x, dest_y,
+                  dest_w, dest_h, filter, p);
+}
+
+void ImageSkia::DrawToCanvasInt(gfx::Canvas* canvas,
+                                int src_x, int src_y, int src_w, int src_h,
+                                int dest_x, int dest_y, int dest_w, int dest_h,
+                                bool filter,
+                                const SkPaint& paint) {
+  if (IsZeroSized())
+    return;
+
+  SkMatrix m = canvas->sk_canvas()->getTotalMatrix();
+  float scale_x = std::abs(SkScalarToFloat(m.getScaleX()));
+  float scale_y = std::abs(SkScalarToFloat(m.getScaleY()));
+
+  const SkBitmap* bitmap = GetBitmapForScale(scale_x, scale_y);
+
+  if (mip_map_build_pending_) {
+    const_cast<SkBitmap*>(bitmap)->buildMipMap();
+    mip_map_build_pending_ = false;
+  }
+
+  float bitmap_scale_x = static_cast<float>(bitmap->width()) / width();
+  float bitmap_scale_y = static_cast<float>(bitmap->height()) / height();
+
+  canvas->Save();
+  canvas->sk_canvas()->scale(1.0f / bitmap_scale_x,
+                             1.0f / bitmap_scale_y);
+  canvas->DrawBitmapFloat(*bitmap,
+                        src_x * bitmap_scale_x, src_y * bitmap_scale_x,
+                        src_w * bitmap_scale_x, src_h * bitmap_scale_y,
+                        dest_x * bitmap_scale_x, dest_y * bitmap_scale_y,
+                        dest_w * bitmap_scale_x, dest_h * bitmap_scale_y,
+                        filter, paint);
+
+  canvas->Restore();
+}
+
+const SkBitmap* ImageSkia::GetBitmapForScale(float x_scale_factor,
+                                             float y_scale_factor) const {
+  // Get the desired bitmap width and height given |x_scale_factor|,
+  // |y_scale_factor| and |size_| at 1x density.
+  float desired_width = size_.width() * x_scale_factor;
+  float desired_height = size_.height() * y_scale_factor;
+
+  size_t closest_index = 0;
+  float smallest_diff = std::numeric_limits<float>::max();
+  for (size_t i = 0; i < bitmaps_.size(); ++i) {
+    if (bitmaps_[i]->isNull())
+      continue;
+
+    float diff = std::abs(bitmaps_[i]->width() - desired_width) +
+        std::abs(bitmaps_[i]->height() - desired_height);
+    if (diff < smallest_diff) {
+      closest_index = i;
+      smallest_diff = diff;
+    }
+  }
+  return bitmaps_[closest_index];
+}
+
+}  // namespace gfx