// Copyright (c) 2013 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. #ifndef CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_ #define CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_ #include <vector> #include "base/basictypes.h" #include "third_party/skia/include/core/SkColor.h" #include "ui/gfx/rect.h" #include "ui/gfx/size.h" class SkBitmap; namespace thumbnailing_utils { // Compute in-place gaussian gradient magnitude of |input_bitmap| with sigma // |kernel_sigma|. |input_bitmap| is requried to be of SkBitmap::kA8_Config // type. The routine computes first-order gaussian derivative on a // gaussian-smoothed image. Beware, this is fairly slow since kernel size is // 4 * kernel_sigma + 1. void ApplyGaussianGradientMagnitudeFilter(SkBitmap* input_bitmap, float kernel_sigma); // Accumulates vertical and horizontal sum of pixel values from a subsection of // |input_bitmap| defined by |image_area|. The image is required to be of // SkBitmap::kA8_Config type. // If non-empty |target_size| is given, the routine will use it to process the // profiles with closing operator sized to eliminate gaps which would be smaller // than 1 pixel after rescaling to |target_size|. // If |apply_log| is true, logarithm of counts are used for morhology (and // returned). void ExtractImageProfileInformation(const SkBitmap& input_bitmap, const gfx::Rect& image_area, const gfx::Size& target_size, bool apply_log, std::vector<float>* rows, std::vector<float>* columns); // Compute a threshold value separating background (low) from signal (high) // areas in the |input| profile. float AutoSegmentPeaks(const std::vector<float>& input); // Compute and return a workable (not too distorted, not bigger than the image) // target size for retargeting in ConstrainedProfileSegmentation. |target_size| // is the desired image size (defines aspect ratio and minimal image size) while // |computed_size| is the size of a result of unconstrained segmentation. // This routine makes very little sense outside ConstrainedProfileSegmentation // and is exposed only for unit tests (it is somehow complicated). gfx::Size AdjustClippingSizeToAspectRatio(const gfx::Size& target_size, const gfx::Size& image_size, const gfx::Size& computed_size); // Compute thresholding guides |included_rows| and |included_columns| by // segmenting 1-d profiles |row_profile| and |column_profile|. The routine will // attempt to keep the image which would result from using these guides as close // to the desired aspect ratio (given by |target_size|) as reasonable. void ConstrainedProfileSegmentation(const std::vector<float>& row_profile, const std::vector<float>& column_profile, const gfx::Size& target_size, std::vector<bool>* included_rows, std::vector<bool>* included_columns); // Shrinks the source |bitmap| by removing rows and columns where |rows| and // |columns| are false, respectively. The function returns a new bitmap if the // shrinking can be performed and an empty instance otherwise. SkBitmap ComputeDecimatedImage(const SkBitmap& bitmap, const std::vector<bool>& rows, const std::vector<bool>& columns); // Creates a new bitmap which contains only 'interesting' areas of // |source_bitmap|. The |target_size| is used to estimate some computation // parameters, but the resulting bitmap will not necessarily be of that size. // |kernel_sigma| defines the degree of image smoothing in gradient computation. // For a natural-sized (not shrunk) screenshot at 96 DPI and regular font size // 5.0 was determined to be a good value. SkBitmap CreateRetargetedThumbnailImage(const SkBitmap& source_bitmap, const gfx::Size& target_size, float kernel_sigma); } // namespace thumbnailing_utils #endif // CHROME_BROWSER_THUMBNAILS_CONTENT_ANALYSIS_H_