// 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_THUMBNAILING_ALGORITHM_H_
#define CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_
#include "base/memory/ref_counted.h"
#include "chrome/browser/thumbnails/thumbnailing_context.h"
#include "ui/gfx/rect.h"
#include "ui/gfx/size.h"
class SkBitmap;
namespace thumbnails {
// An interface abstracting thumbnailing algorithms. Instances are intended to
// be created by ThumbnailService's implementations and used by
// ThumbnailTabHelper as consumers of captured source images.
class ThumbnailingAlgorithm
: public base::RefCountedThreadSafe<ThumbnailingAlgorithm> {
public:
typedef base::Callback<void(const ThumbnailingContext&, const SkBitmap&)>
ConsumerCallback;
// Provides information necessary to crop-and-resize image data from a source
// canvas of |source_size|. Auxiliary |scale_factor| helps compute the target
// thumbnail size. Parameters of the required copy operation are assigned to
// |clipping_rect| (cropping rectangle for the source canvas) and
// |target_size| (the size of the target bitmap).
// The return value indicates the type of clipping that will be done.
virtual ClipResult GetCanvasCopyInfo(const gfx::Size& source_size,
ui::ScaleFactor scale_factor,
gfx::Rect* clipping_rect,
gfx::Size* target_size) const = 0;
// Invoked to produce a thumbnail image from a |bitmap| extracted by the
// callee from source canvas according to instructions provided by a call
// to GetCanvasCopyInfo.
// Note that ProcessBitmap must be able to handle bitmaps which might have not
// been processed (scalled/cropped) as requested. |context| gives additional
// information on the source, including if and how it was clipped.
// The function shall invoke |callback| once done, passing in fully populated
// |context| along with resulting thumbnail bitmap.
virtual void ProcessBitmap(scoped_refptr<ThumbnailingContext> context,
const ConsumerCallback& callback,
const SkBitmap& bitmap) = 0;
protected:
virtual ~ThumbnailingAlgorithm() {}
friend class base::RefCountedThreadSafe<ThumbnailingAlgorithm>;
};
}
#endif // CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_