media/capture/capture_resolution_chooser.h

   1 // Copyright 2015 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 MEDIA_CAPTURE_CAPTURE_RESOLUTION_CHOOSER_H_
   6 #define MEDIA_CAPTURE_CAPTURE_RESOLUTION_CHOOSER_H_
   7
   8 #include "media/base/media_export.h"
   9 #include "media/base/video_capture_types.h"
  10 #include "ui/gfx/geometry/size.h"
  11
  12 namespace media {
  13
  14 // Encapsulates the logic that determines the capture frame resolution based on:
  15 //   1. The configured maximum frame resolution and resolution change policy.
  16 //   2. The resolution of the source content.
  17 //   3. The current capabilities of the end-to-end system, in terms of the
  18 //      maximum number of pixels per frame.
  19 class MEDIA_EXPORT CaptureResolutionChooser {
  20  public:
  21   // media::ResolutionChangePolicy determines whether the variable frame
  22   // resolutions being computed must adhere to a fixed aspect ratio or not, or
  23   // that there must only be a single fixed resolution.
  24   CaptureResolutionChooser(
  25       const gfx::Size& max_frame_size,
  26       ResolutionChangePolicy resolution_change_policy);
  27   ~CaptureResolutionChooser();
  28
  29   // Returns the current capture frame resolution to use.
  30   gfx::Size capture_size() const {
  31     return capture_size_;
  32   }
  33
  34   // Updates the capture size based on a change in the resolution of the source
  35   // content.
  36   void SetSourceSize(const gfx::Size& source_size);
  37
  38  private:
  39   // Called after any update that requires |capture_size_| be re-computed.
  40   void RecomputeCaptureSize();
  41
  42   // Hard constraints.
  43   const gfx::Size max_frame_size_;
  44   const gfx::Size min_frame_size_;  // Computed from the ctor arguments.
  45
  46   // Specifies the set of heuristics to use.
  47   const ResolutionChangePolicy resolution_change_policy_;
  48
  49   // The capture frame resolution to use, ignoring the limitations imposed by
  50   // the capability metric.
  51   gfx::Size constrained_size_;
  52
  53   // The current computed capture frame resolution.
  54   gfx::Size capture_size_;
  55 };
  56
  57 }  // namespace media
  58
  59 #endif  // MEDIA_CAPTURE_RESOLUTION_CHOOSER_H_