text: // 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_util.h"
  
  #include <stdint.h>
  
  #include <algorithm>
  #include <memory>
  
  #include "build/build_config.h"
  #include "skia/ext/image_operations.h"
  #include "third_party/skia/include/core/SkBitmap.h"
  #include "ui/gfx/codec/jpeg_codec.h"
  #include "ui/gfx/image/image.h"
  #include "ui/gfx/image/image_skia.h"
  #include "ui/gfx/image/resize_image_dimensions.h"
  
  namespace {
  
  // Returns whether column |x| of |bitmap| has any "visible pixels", where
  // "visible" is defined as having an opactiy greater than an arbitrary small
  // value.
  bool ColumnHasVisiblePixels(const SkBitmap& bitmap, int x) {
    const SkAlpha kMinimumVisibleOpacity = 12;
    for (int y = 0; y < bitmap.height(); ++y) {
      if (SkColorGetA(bitmap.getColor(x, y)) > kMinimumVisibleOpacity)
        return true;
    }
    return false;
  }
  
  }  // namespace
  
  namespace gfx {
  
  // The iOS implementations of the JPEG functions are in image_util_ios.mm.
  #if !defined(OS_IOS)
  
  Image ImageFrom1xJPEGEncodedData(const unsigned char* input,
                                   size_t input_size) {
    std::unique_ptr<SkBitmap> bitmap(gfx::JPEGCodec::Decode(input, input_size));
    if (bitmap.get())
      return Image::CreateFrom1xBitmap(*bitmap);
  
    return Image();
  }
  
  Image ResizedImageForSearchByImage(const Image& image) {
    return ResizedImageForSearchByImageSkiaRepresentation(image);
  }
  
  // The MacOS implementation of this function is in image_utils_mac.mm.
  #if !defined(OS_MACOSX)
  bool JPEG1xEncodedDataFromImage(const Image& image,
                                  int quality,
                                  std::vector<unsigned char>* dst) {
    return JPEG1xEncodedDataFromSkiaRepresentation(image, quality, dst);
  }
  #endif  // !defined(OS_MACOSX)
  
  bool JPEG1xEncodedDataFromSkiaRepresentation(const Image& image,
                                               int quality,
                                               std::vector<unsigned char>* dst) {
    const gfx::ImageSkiaRep& image_skia_rep =
        image.AsImageSkia().GetRepresentation(1.0f);
    if (image_skia_rep.scale() != 1.0f)
      return false;
  
    const SkBitmap& bitmap = image_skia_rep.GetBitmap();
    if (!bitmap.readyToDraw())
      return false;
  
    return gfx::JPEGCodec::Encode(bitmap, quality, dst);
  }
  
  Image ResizedImageForSearchByImageSkiaRepresentation(const Image& image) {
    const gfx::ImageSkiaRep& image_skia_rep =
        image.AsImageSkia().GetRepresentation(1.0f);
    if (image_skia_rep.scale() != 1.0f)
      return image;
  
    const SkBitmap& bitmap = image_skia_rep.GetBitmap();
    if (bitmap.height() * bitmap.width() > kSearchByImageMaxImageArea &&
        (bitmap.width() > kSearchByImageMaxImageWidth ||
         bitmap.height() > kSearchByImageMaxImageHeight)) {
      SkBitmap new_bitmap = skia::ImageOperations::Resize(
          bitmap, skia::ImageOperations::RESIZE_GOOD, kSearchByImageMaxImageWidth,
          kSearchByImageMaxImageHeight);
      return Image(ImageSkia(ImageSkiaRep(new_bitmap, 0.0f)));
    }
  
    return image;
  }
  #endif  // !defined(OS_IOS)
  
  void GetVisibleMargins(const ImageSkia& image, int* left, int* right) {
    *left = 0;
    *right = 0;
    if (!image.HasRepresentation(1.f))
      return;
    const SkBitmap& bitmap = image.GetRepresentation(1.f).GetBitmap();
    if (bitmap.drawsNothing() || bitmap.isOpaque())
      return;
  
    int x = 0;
    for (; x < bitmap.width(); ++x) {
      if (ColumnHasVisiblePixels(bitmap, x)) {
        *left = x;
        break;
      }
    }
  
    if (x == bitmap.width()) {
      // Image is fully transparent.  Divide the width in half, giving the leading
      // region the extra pixel for odd widths.
      *left = (bitmap.width() + 1) / 2;
      *right = bitmap.width() - *left;
      return;
    }
  
    // Since we already know column *left is non-transparent, we can avoid
    // rechecking that column; hence the '>' here.
    for (x = bitmap.width() - 1; x > *left; --x) {
      if (ColumnHasVisiblePixels(bitmap, x))
        break;
    }
    *right = bitmap.width() - 1 - x;
  }
  
  }  // namespace gfx
  