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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_AUTO_SCALER_H_
#define CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_AUTO_SCALER_H_
#include <optional>
#include "base/memory/raw_ref.h"
#include "content/common/content_export.h"
#include "media/capture/video/video_capture_feedback.h"
#include "ui/gfx/geometry/size.h"
namespace content {
class CONTENT_EXPORT WebContentsAutoScaler final {
public:
// Delegate used to get and set the device scale ratio override for the
// currently captured tab.
class CONTENT_EXPORT Delegate {
public:
Delegate();
virtual ~Delegate();
// Sets the capture scale override for the currently captured view.
virtual void SetCaptureScaleOverride(float new_value) = 0;
// Gets the current capture scale override for the currently captured view.
virtual float GetCaptureScaleOverride() const = 0;
};
WebContentsAutoScaler(Delegate& delegate, const gfx::Size& capture_size);
WebContentsAutoScaler(WebContentsAutoScaler&&) = delete;
WebContentsAutoScaler(const WebContentsAutoScaler&) = delete;
~WebContentsAutoScaler();
void SetCapturedContentSize(const gfx::Size& content_size);
// NOTE: the way this report gets applied in this class assumes that it is
// updated relatively infrequently (e.g. multiple seconds between reports). If
// we find that this is called more frequently the algorithm should be updated
// to weigh historic reports as well as the last received feedback.
void OnUtilizationReport(media::VideoCaptureFeedback feedback);
float GetDesiredCaptureScaleOverride() const;
int GetScaleOverrideChangeCount() const;
private:
// Sets the new capture scale override via `delegate_`.
void SetCaptureScaleOverride(float new_value);
// Determines the preferred DPI scaling factor based on the current content
// size of the video frame, meaning the populated pixels, and the unscaled
// current content size, meaning the original size of the frame before scaling
// was applied to fit the frame. These values are used to compare against
// the currently requested `capture_size_` set in
// `WillStartCapturingWebContents()`.
float CalculatePreferredScaleFactor(
const gfx::Size& current_content_size,
const gfx::Size& unscaled_current_content_size);
// Helper for applying the latest-received utilization feedback to throttle
// the capture scale override, if necessary.
float DetermineMaxScaleOverride();
// The maximum capture scale override.
static const float kMaxCaptureScaleOverride;
// Scale multiplier used for the captured content when HiDPI capture mode is
// active. A value of 1.0 means no override, using the original unmodified
// resolution. The scale override is a multiplier applied to both the X and Y
// dimensions, so a value of 2.0 means four times the pixel count. This value
// tracks the intended scale according to the heuristic. Whenever the value
// changes, the new scale is immediately applied to the RenderWidgetHostView
// via SetScaleOverrideForCapture. The value is also saved in this attribute
// so that it can be undone and/or re-applied when the RenderFrameHost
// changes.
//
// NOTE: the value provided to the captured content is the min of this
// property and `max_capture_scale_override_`.
float desired_capture_scale_override_ = 1.0f;
// Track the number of times the capture scale override mutates in a single
// session.
int scale_override_change_count_ = 0;
// The maximum capture scale override, based on the last received
// `capture_feedback_`.
float max_capture_scale_override_ = kMaxCaptureScaleOverride;
// Delegate for getting and setting the scale override.
raw_ref<Delegate> delegate_;
// The consumer-requested capture size.
const gfx::Size capture_size_;
// The last reported content size, if any.
std::optional<gfx::Size> content_size_;
// The last received video capture feedback, if any.
std::optional<media::VideoCaptureFeedback> capture_feedback_;
};
} // namespace content
#endif // CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_AUTO_SCALER_H_
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