chrome/browser/ui/lens/lens_overlay_blur_layer_delegate.h

// 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 CHROME_BROWSER_UI_LENS_LENS_OVERLAY_BLUR_LAYER_DELEGATE_H_
#define CHROME_BROWSER_UI_LENS_LENS_OVERLAY_BLUR_LAYER_DELEGATE_H_

#include "base/memory/weak_ptr.h"
#include "base/timer/timer.h"
#include "content/public/browser/render_widget_host_view.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/compositor/layer.h"
#include "ui/compositor/layer_delegate.h"
#include "ui/compositor/paint_context.h"

namespace lens {

// LayerDelegate for controlling the background blur behind the overlay. This
// class is only a LayerDelegate to control the layer painting and does not own
// the layer.
class LensOverlayBlurLayerDelegate : public ui::LayerDelegate {
 public:
  // Starts painting to the given layer with a blurring background image using
  // the given render view as the background.
  // TODO(b/364902039): Starting blurring is not optimal, since we might be
  // doing work for a layer the user can't even see yet. Instead, we should
  // start blurring once the user can actually see the blur.
  LensOverlayBlurLayerDelegate(ui::Layer* layer,
                               content::RenderWidgetHostView* background_view);
  ~LensOverlayBlurLayerDelegate() override;

 private:
  // ui::LayerDelegate:
  void OnPaintLayer(const ui::PaintContext& context) override;
  void OnDeviceScaleFactorChanged(float old_device_scale_factor,
                                  float new_device_scale_factor) override;

  // Fetches a new background screenshot to use for blurring.
  void FetchBackgroundImage();

  // Updates background_screenshot_ to the new bitmap and rerenders IFF bitmap
  // is visually different than background_screenshot_.
  void UpdateBackgroundImage(const SkBitmap& bitmap);

  // The latest screenshot being used to render the background.
  SkBitmap background_screenshot_;

  // A timer to periodically take screenshots of the underlying page.
  base::RepeatingTimer screenshot_timer_;

  // Pointer to the layer we are adding the blur to. Belongs to a child of the
  // LensOverlayController so guaranteed to outlive this class.
  raw_ptr<ui::Layer> layer_;

  // Pointer to the RenderWidgetHostView to get the contents which we are
  // blurring. Owned by the live page web contents, so is possible to become
  // null.
  raw_ptr<content::RenderWidgetHostView> background_view_;

  // Must be the last member.
  base::WeakPtrFactory<LensOverlayBlurLayerDelegate> weak_factory_{this};
};

}  // namespace lens

#endif  // CHROME_BROWSER_UI_LENS_LENS_OVERLAY_BLUR_LAYER_DELEGATE_H_