blob: 17550f950178cae409a8edfec2d885f6f4aa6fe7 [file] [log] [blame]
// Copyright (c) 2011 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.
#pragma once
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "views/view.h"
#include "views/views_export.h"
namespace views {
class ScrollBar;
// ScrollBarController
// ScrollBarController defines the method that should be implemented to
// receive notification from a scrollbar
class VIEWS_EXPORT ScrollBarController {
// 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 VIEWS_EXPORT ScrollBar : public View {
virtual ~ScrollBar();
// Overridden from View:
virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
// Returns whether this scrollbar is horizontal.
bool IsHorizontal() const;
void set_controller(ScrollBarController* controller) {
controller_ = controller;
ScrollBarController* controller() const { return controller_; }
// 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);
// Returns 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;
// 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);
const bool is_horiz_;
ScrollBarController* controller_;
int max_pos_;
} // namespace views