ui/views/controls/resize_area.h

// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_VIEWS_CONTROLS_RESIZE_AREA_H_
#define UI_VIEWS_CONTROLS_RESIZE_AREA_H_

#include "base/memory/raw_ptr.h"
#include "ui/views/view.h"

namespace views {

class ResizeAreaDelegate;

// An invisible area that acts like a horizontal/vertical resizer.
class VIEWS_EXPORT ResizeArea : public View {
  METADATA_HEADER(ResizeArea, View)

 public:
  enum class Axis {
    kHorizontal,  // Resizes left/right
    kVertical,    // Resizes up/down
  };

  explicit ResizeArea(ResizeAreaDelegate* delegate);

  ResizeArea(const ResizeArea&) = delete;
  ResizeArea& operator=(const ResizeArea&) = delete;

  ~ResizeArea() override;

  // views::View:
  ui::Cursor GetCursor(const ui::MouseEvent& event) override;
  void OnGestureEvent(ui::GestureEvent* event) override;
  bool OnMousePressed(const ui::MouseEvent& event) override;
  bool OnMouseDragged(const ui::MouseEvent& event) override;
  void OnMouseReleased(const ui::MouseEvent& event) override;
  void OnMouseCaptureLost() override;

  // Returns true if a resize has been reported to the delegate but the
  // |last_update| resize has not yet been reported. For example, if a mouse
  // drag has happened but the mouse has not yet been released.
  bool is_resizing() { return is_resizing_; }

  Axis axis() const { return axis_; }
  void set_axis(Axis axis) { axis_ = axis; }

 private:
  // Report the amount the user resized by to the delegate, accounting for
  // directionality.
  void ReportResizeAmount(int resize_amount, bool last_update);

  // Converts |event_position| to screen coordinates and sets
  // |initial_position_| to this value.
  void SetInitialPosition(int event_position);

  // The delegate to notify when we have updates.
  raw_ptr<ResizeAreaDelegate> delegate_;

  bool is_resizing_ = false;

  // The event's position in the resize axis at the start of the resize
  // operation. The resize area will move while being dragged, so
  // |initial_position_| is represented in screen coordinates so that we don't
  // lose our bearings.
  int initial_position_ = 0;

  Axis axis_ = Axis::kHorizontal;
};

}  // namespace views

#endif  // UI_VIEWS_CONTROLS_RESIZE_AREA_H_