cc/pinch_zoom_viewport.h

// Copyright 2013 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 CC_PINCH_ZOOM_VIEWPORT_H_
#define CC_PINCH_ZOOM_VIEWPORT_H_

#include "cc/cc_export.h"
#include "ui/gfx/rect.h"
#include "ui/gfx/transform.h"

namespace cc {

// PinchZoomViewport models the bounds and offset of the viewport that is used
// during a pinch-zoom operation. It tracks the layout-space dimensions of the
// viewport before any applied scale, and then tracks the layout-space
// coordinates of the viewport respecting the pinch settings.
class CC_EXPORT PinchZoomViewport {
 public:
  PinchZoomViewport();

  float total_page_scale_factor() const {
    return page_scale_factor_ * page_scale_delta_;
  }

  void set_page_scale_factor(float factor) { page_scale_factor_ = factor; }
  float page_scale_factor() const { return page_scale_factor_; }

  void set_page_scale_delta(float delta);
  float page_scale_delta() const  { return page_scale_delta_; }

  float min_page_scale_factor() const { return min_page_scale_factor_; }
  float max_page_scale_factor() const { return max_page_scale_factor_; }

  void set_sent_page_scale_delta(float delta) {
    sent_page_scale_delta_ = delta;
  }

  float sent_page_scale_delta() const { return sent_page_scale_delta_; }

  void set_device_scale_factor(float factor) { device_scale_factor_ = factor; }
  float device_scale_factor() const { return device_scale_factor_; }

  // Returns true if the passed parameters were different from those previously
  // cached.
  bool SetPageScaleFactorAndLimits(float page_scale_factor,
                                   float min_page_scale_factor,
                                   float max_page_scale_factor);

  // Returns the bounds and offset of the scaled and translated viewport to use
  // for pinch-zoom.
  gfx::RectF Bounds() const;

  const gfx::Vector2dF& zoomed_viewport_offset() const {
    return zoomed_viewport_offset_;
  }

  void set_layout_viewport_size(const gfx::SizeF& size) {
    layout_viewport_size_ = size;
  }

  // Apply the scroll offset in layout space to the offset of the pinch-zoom
  // viewport. The viewport cannot be scrolled outside of the layout viewport
  // bounds. Returns the component of the scroll that is un-applied due to this
  // constraint.
  gfx::Vector2dF ApplyScroll(const gfx::Vector2dF);

  // The implTransform goes from the origin of the unzoomedDeviceViewport to the
  // origin of the zoomedDeviceViewport.
  //
  // implTransform = S[pageScale] * Tr[-zoomedDeviceViewportOffset]
  gfx::Transform ImplTransform(bool page_scale_pinch_zoom_enabled) const;

 private:
  float page_scale_factor_;
  float page_scale_delta_;
  float sent_page_scale_delta_;
  float max_page_scale_factor_;
  float min_page_scale_factor_;
  float device_scale_factor_;

  gfx::Vector2dF zoomed_viewport_offset_;
  gfx::SizeF layout_viewport_size_;
};

}  // namespace cc

#endif  // CC_PINCH_ZOOM_VIEWPORT_H_