1// Copyright (c) 2013 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_ 6#define CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_ 7 8#include <vector> 9 10#include "base/basictypes.h" 11#include "third_party/skia/include/core/SkColor.h" 12#include "ui/gfx/rect.h" 13#include "ui/gfx/size.h" 14 15class SkBitmap; 16 17namespace thumbnailing_utils { 18 19// Compute in-place gaussian gradient magnitude of |input_bitmap| with sigma 20// |kernel_sigma|. |input_bitmap| is requried to be of SkBitmap::kA8_Config 21// type. The routine computes first-order gaussian derivative on a 22// gaussian-smoothed image. Beware, this is fairly slow since kernel size is 23// 4 * kernel_sigma + 1. 24void ApplyGaussianGradientMagnitudeFilter(SkBitmap* input_bitmap, 25 float kernel_sigma); 26 27// Accumulates vertical and horizontal sum of pixel values from a subsection of 28// |input_bitmap| defined by |image_area|. The image is required to be of 29// SkBitmap::kA8_Config type. 30// If non-empty |target_size| is given, the routine will use it to process the 31// profiles with closing operator sized to eliminate gaps which would be smaller 32// than 1 pixel after rescaling to |target_size|. 33// If |apply_log| is true, logarithm of counts are used for morhology (and 34// returned). 35void ExtractImageProfileInformation(const SkBitmap& input_bitmap, 36 const gfx::Rect& image_area, 37 const gfx::Size& target_size, 38 bool apply_log, 39 std::vector<float>* rows, 40 std::vector<float>* columns); 41 42// Compute a threshold value separating background (low) from signal (high) 43// areas in the |input| profile. 44float AutoSegmentPeaks(const std::vector<float>& input); 45 46// Compute and return a workable (not too distorted, not bigger than the image) 47// target size for retargeting in ConstrainedProfileSegmentation. |target_size| 48// is the desired image size (defines aspect ratio and minimal image size) while 49// |computed_size| is the size of a result of unconstrained segmentation. 50// This routine makes very little sense outside ConstrainedProfileSegmentation 51// and is exposed only for unit tests (it is somehow complicated). 52gfx::Size AdjustClippingSizeToAspectRatio(const gfx::Size& target_size, 53 const gfx::Size& image_size, 54 const gfx::Size& computed_size); 55 56// Compute thresholding guides |included_rows| and |included_columns| by 57// segmenting 1-d profiles |row_profile| and |column_profile|. The routine will 58// attempt to keep the image which would result from using these guides as close 59// to the desired aspect ratio (given by |target_size|) as reasonable. 60void ConstrainedProfileSegmentation(const std::vector<float>& row_profile, 61 const std::vector<float>& column_profile, 62 const gfx::Size& target_size, 63 std::vector<bool>* included_rows, 64 std::vector<bool>* included_columns); 65 66// Shrinks the source |bitmap| by removing rows and columns where |rows| and 67// |columns| are false, respectively. The function returns a new bitmap if the 68// shrinking can be performed and an empty instance otherwise. 69SkBitmap ComputeDecimatedImage(const SkBitmap& bitmap, 70 const std::vector<bool>& rows, 71 const std::vector<bool>& columns); 72 73// Creates a new bitmap which contains only 'interesting' areas of 74// |source_bitmap|. The |target_size| is used to estimate some computation 75// parameters, but the resulting bitmap will not necessarily be of that size. 76// |kernel_sigma| defines the degree of image smoothing in gradient computation. 77// For a natural-sized (not shrunk) screenshot at 96 DPI and regular font size 78// 5.0 was determined to be a good value. 79SkBitmap CreateRetargetedThumbnailImage(const SkBitmap& source_bitmap, 80 const gfx::Size& target_size, 81 float kernel_sigma); 82 83} // namespace thumbnailing_utils 84 85#endif // CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_ 86