123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103 |
- // Copyright 2015 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 MEDIA_CAPTURE_CONTENT_CAPTURE_RESOLUTION_CHOOSER_H_
- #define MEDIA_CAPTURE_CONTENT_CAPTURE_RESOLUTION_CHOOSER_H_
- #include <vector>
- #include "media/capture/capture_export.h"
- #include "ui/gfx/geometry/size.h"
- namespace media {
- // Encapsulates the logic that determines the capture frame resolution based on:
- // 1. The configured minimum/maximum frame resolution.
- // 2. Whether the capture frame resolution must be of a fixed aspect ratio.
- // 3. Changes to resolution of the source content.
- // 4. Changes to the (externally-computed) target data volume, provided in
- // terms of the number of pixels in the frame.
- //
- // In variable-resolution use cases, the capture sizes are "snapped" to a small
- // (i.e., usually less than a dozen) set of possibilities. This is to prevent
- // the end-to-end system from having to deal with rapidly-changing video frame
- // resolutions that results from providing a fine-grained range of values. The
- // possibile snapped frame sizes are computed relative to the resolution of the
- // source content: They are the same or smaller in size, and are of the same
- // aspect ratio.
- class CAPTURE_EXPORT CaptureResolutionChooser {
- public:
- // Default constructor. Capture size is fixed at kDefaultCaptureSize until
- // SetConstraints() is called.
- CaptureResolutionChooser();
- ~CaptureResolutionChooser();
- // Returns the current capture frame resolution to use.
- const gfx::Size& capture_size() const { return capture_size_; }
- // Specifies a new range of acceptable capture resolutions and whether a fixed
- // aspect ratio is required. When |min_frame_size| is equal to
- // |max_frame_size|, capture resolution will be held constant. If a fixed
- // aspect ratio is required, the aspect ratio of |max_frame_size| is used.
- void SetConstraints(const gfx::Size& min_frame_size,
- const gfx::Size& max_frame_size,
- bool use_fixed_aspect_ratio);
- // Returns the currently-set source size.
- const gfx::Size& source_size() const { return source_size_; }
- // Updates the capture size based on a change in the resolution of the source
- // content.
- void SetSourceSize(const gfx::Size& source_size);
- // Updates the capture size to target the given frame area, in terms of
- // gfx::Size::GetArea(). The initial target frame area is the maximum int
- // (i.e., always target the source size).
- void SetTargetFrameArea(int area);
- // Search functions to, given a frame |area|, return the nearest snapped frame
- // size, or N size steps up/down. Snapped frame sizes are based on the
- // current source size.
- gfx::Size FindNearestFrameSize(int area) const;
- gfx::Size FindLargerFrameSize(int area, int num_steps_up) const;
- gfx::Size FindSmallerFrameSize(int area, int num_steps_down) const;
- // The default capture size, if SetConstraints() is never called.
- static constexpr gfx::Size kDefaultCaptureSize = gfx::Size(640, 360);
- private:
- // Called after any update that requires |capture_size_| be re-computed.
- void RecomputeCaptureSize();
- // Recomputes the |snapped_sizes_| cache.
- void UpdateSnappedFrameSizes();
- // Hard constraints.
- gfx::Size min_frame_size_;
- gfx::Size max_frame_size_;
- // If true, adjust the |source_size_| to match the aspect ratio of
- // |max_frame_size_| before computing the snapped frame sizes.
- bool apply_aspect_ratio_adjustment_;
- // Current source size.
- gfx::Size source_size_;
- // |capture_size_| will be computed such that its area is as close to this
- // value as possible.
- int target_area_;
- // The current computed capture frame resolution.
- gfx::Size capture_size_;
- // Cache of the set of possible values |capture_size_| can have, in order from
- // smallest to largest. This is recomputed whenever UpdateSnappedFrameSizes()
- // is called.
- std::vector<gfx::Size> snapped_sizes_;
- };
- } // namespace media
- #endif // MEDIA_CAPTURE_CONTENT_CAPTURE_RESOLUTION_CHOOSER_H_
|