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_THUMBNAILING_ALGORITHM_H_ 6 #define CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_ 7 8 #include "base/memory/ref_counted.h" 9 #include "chrome/browser/thumbnails/thumbnailing_context.h" 10 #include "ui/base/layout.h" 11 #include "ui/gfx/rect.h" 12 #include "ui/gfx/size.h" 13 14 class SkBitmap; 15 16 namespace thumbnails { 17 18 // An interface abstracting thumbnailing algorithms. Instances are intended to 19 // be created by ThumbnailService's implementations and used by 20 // ThumbnailTabHelper as consumers of captured source images. 21 class ThumbnailingAlgorithm 22 : public base::RefCountedThreadSafe<ThumbnailingAlgorithm> { 23 public: 24 typedef base::Callback<void(const ThumbnailingContext&, const SkBitmap&)> 25 ConsumerCallback; 26 // Provides information necessary to crop-and-resize image data from a source 27 // canvas of |source_size|. Auxiliary |scale_factor| helps compute the target 28 // thumbnail size. Parameters of the required copy operation are assigned to 29 // |clipping_rect| (cropping rectangle for the source canvas) and 30 // |target_size| (the size of the target bitmap). 31 // The return value indicates the type of clipping that will be done. 32 virtual ClipResult GetCanvasCopyInfo(const gfx::Size& source_size, 33 ui::ScaleFactor scale_factor, 34 gfx::Rect* clipping_rect, 35 gfx::Size* target_size) const = 0; 36 37 // Invoked to produce a thumbnail image from a |bitmap| extracted by the 38 // callee from source canvas according to instructions provided by a call 39 // to GetCanvasCopyInfo. 40 // Note that ProcessBitmap must be able to handle bitmaps which might have not 41 // been processed (scalled/cropped) as requested. |context| gives additional 42 // information on the source, including if and how it was clipped. 43 // The function shall invoke |callback| once done, passing in fully populated 44 // |context| along with resulting thumbnail bitmap. 45 virtual void ProcessBitmap(scoped_refptr<ThumbnailingContext> context, 46 const ConsumerCallback& callback, 47 const SkBitmap& bitmap) = 0; 48 49 protected: ~ThumbnailingAlgorithm()50 virtual ~ThumbnailingAlgorithm() {} 51 friend class base::RefCountedThreadSafe<ThumbnailingAlgorithm>; 52 }; 53 54 } 55 56 #endif // CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_ 57