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// Copyright (c) 2006-2008 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_COMMON_THUMBNAIL_SCORE_H__
#define CHROME_BROWSER_COMMON_THUMBNAIL_SCORE_H__
#include "base/time.h"
// A set of metadata about a Thumbnail.
struct ThumbnailScore {
// Initializes the ThumbnailScore to the absolute worst possible
// values except for time, which is set to Now().
ThumbnailScore();
// Builds a ThumbnailScore with the passed in values, and sets the
// thumbnail generation time to Now().
ThumbnailScore(double score, bool clipping, bool top);
// Builds a ThumbnailScore with the passed in values.
ThumbnailScore(double score, bool clipping, bool top,
const base::Time& time);
~ThumbnailScore();
// Tests for equivalence between two ThumbnailScore objects.
bool Equals(const ThumbnailScore& rhs) const;
// How "boring" a thumbnail is. The boring score is the 0,1 ranged
// percentage of pixels that are the most common luma. Higher boring
// scores indicate that a higher percentage of a bitmap are all the
// same brightness (most likely the same color).
double boring_score;
// Whether the thumbnail was taken with height greater then
// width. In cases where we don't have |good_clipping|, the
// thumbnails are either clipped from the horizontal center of the
// window, or are otherwise weirdly stretched.
bool good_clipping;
// Whether this thumbnail was taken while the renderer was
// displaying the top of the page. Most pages are more recognizable
// by their headers then by a set of random text half way down the
// page; i.e. most MediaWiki sites would be indistinguishable by
// thumbnails with |at_top| set to false.
bool at_top;
// Record the time when a thumbnail was taken. This is used to make
// sure thumbnails are kept fresh.
base::Time time_at_snapshot;
// How bad a thumbnail needs to be before we completely ignore it.
static const double kThumbnailMaximumBoringness;
// Time before we take a worse thumbnail (subject to
// kThumbnailMaximumBoringness) over what's currently in the database
// for freshness.
static const base::TimeDelta kUpdateThumbnailTime;
// Penalty of how much more boring a thumbnail should be per hour.
static const double kThumbnailDegradePerHour;
};
// Checks whether we should replace one thumbnail with another.
bool ShouldReplaceThumbnailWith(const ThumbnailScore& current,
const ThumbnailScore& replacement);
#endif // CHROME_BROWSER_COMMON_THUMBNAIL_SCORE_H__
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