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// Copyright (c) 2010 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 VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
#define VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
#pragma once
#include "views/events/event.h"
#include "views/view.h"
namespace views {
class ScrollBar;
/////////////////////////////////////////////////////////////////////////////
//
// ScrollBarController
//
// ScrollBarController defines the method that should be implemented to
// receive notification from a scrollbar
//
/////////////////////////////////////////////////////////////////////////////
class ScrollBarController {
public:
// Invoked by the scrollbar when the scrolling position changes
// This method typically implements the actual scrolling.
//
// The provided position is expressed in pixels. It is the new X or Y
// position which is in the GetMinPosition() / GetMaxPosition range.
virtual void ScrollToPosition(ScrollBar* source, int position) = 0;
// Returns the amount to scroll. The amount to scroll may be requested in
// two different amounts. If is_page is true the 'page scroll' amount is
// requested. The page scroll amount typically corresponds to the
// visual size of the view. If is_page is false, the 'line scroll' amount
// is being requested. The line scroll amount typically corresponds to the
// size of one row/column.
//
// The return value should always be positive. A value <= 0 results in
// scrolling by a fixed amount.
virtual int GetScrollIncrement(ScrollBar* source,
bool is_page,
bool is_positive) = 0;
};
/////////////////////////////////////////////////////////////////////////////
//
// ScrollBar
//
// A View subclass to wrap to implement a ScrollBar. Our current windows
// version simply wraps a native windows scrollbar.
//
// A scrollbar is either horizontal or vertical
//
/////////////////////////////////////////////////////////////////////////////
class ScrollBar : public View {
public:
virtual ~ScrollBar();
// Overridden from View:
virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
// Return whether this scrollbar is horizontal
bool IsHorizontal() const;
// Set / Get the controller
void SetController(ScrollBarController* controller);
ScrollBarController* GetController() const;
// Update the scrollbar appearance given a viewport size, content size and
// current position
virtual void Update(int viewport_size, int content_size, int current_pos);
// Return the max and min positions
int GetMaxPosition() const;
int GetMinPosition() const;
// Returns the position of the scrollbar.
virtual int GetPosition() const = 0;
// Get the width or height of this scrollbar, for use in layout calculations.
// For a vertical scrollbar, this is the width of the scrollbar, likewise it
// is the height for a horizontal scrollbar.
virtual int GetLayoutSize() const = 0;
protected:
// Create new scrollbar, either horizontal or vertical. These are protected
// since you need to be creating either a NativeScrollBar or a
// BitmapScrollBar.
ScrollBar(bool is_horiz);
private:
const bool is_horiz_;
// Current controller
ScrollBarController* controller_;
// properties
int max_pos_;
};
} // namespace views
#endif // VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
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