third_party/WebKit/Source/platform/scroll/ScrollbarTheme.h

/*
 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ScrollbarTheme_h
#define ScrollbarTheme_h

#include "platform/PlatformExport.h"
#include "platform/geometry/IntRect.h"
#include "platform/graphics/paint/DisplayItem.h"
#include "platform/scroll/ScrollTypes.h"
#include "platform/scroll/Scrollbar.h"
#include "public/platform/WebScrollbarButtonsPlacement.h"

namespace blink {

class CullRect;
class GraphicsContext;
class PlatformMouseEvent;
class ScrollbarThemePaintParams;

class PLATFORM_EXPORT ScrollbarTheme {
    WTF_MAKE_NONCOPYABLE(ScrollbarTheme); USING_FAST_MALLOC(ScrollbarTheme);
public:
    ScrollbarTheme() { }
    virtual ~ScrollbarTheme() { }

    // If true, then scrollbars with this theme will be painted every time
    // Scrollbar::setNeedsPaintInvalidation is called. If false, then only parts
    // which are explicitly invalidated will be repainted.
    virtual bool shouldRepaintAllPartsOnInvalidation() const { return true; }

    virtual void updateEnabledState(const ScrollbarThemeClient&) { }

    virtual bool paint(const Scrollbar&, GraphicsContext&, const CullRect&);

    virtual ScrollbarPart hitTest(const ScrollbarThemeClient&, const IntPoint&);

    virtual int scrollbarThickness(ScrollbarControlSize = RegularScrollbar) { return 0; }
    virtual int scrollbarMargin() const { return 0; }

    virtual WebScrollbarButtonsPlacement buttonsPlacement() const { return WebScrollbarButtonsPlacementSingle; }

    virtual bool supportsControlTints() const { return false; }
    virtual bool usesOverlayScrollbars() const { return false; }
    virtual void updateScrollbarOverlayStyle(const ScrollbarThemeClient&) { }

    virtual bool invalidateOnMouseEnterExit() { return false; }
    virtual bool invalidateOnWindowActiveChange() const { return false; }

    // Returns parts of the scrollbar which must be repainted following a change
    // in the thumb position, given scroll positions before and after.
    virtual ScrollbarPart invalidateOnThumbPositionChange(
        const ScrollbarThemeClient&, float oldPosition, float newPosition) const
    {
        return AllParts;
    }

    virtual void paintScrollCorner(GraphicsContext&, const DisplayItemClient&, const IntRect& cornerRect);
    virtual void paintTickmarks(GraphicsContext&, const Scrollbar&, const IntRect&) { }

    virtual bool shouldCenterOnThumb(const ScrollbarThemeClient&, const PlatformMouseEvent&);
    virtual bool shouldSnapBackToDragOrigin(const ScrollbarThemeClient&, const PlatformMouseEvent&);
    virtual bool shouldDragDocumentInsteadOfThumb(const ScrollbarThemeClient&, const PlatformMouseEvent&) { return false; }

    // The position of the thumb relative to the track.
    int thumbPosition(const ScrollbarThemeClient& scrollbar) { return thumbPosition(scrollbar, scrollbar.currentPos()); }
    // The position the thumb would have, relative to the track, at the specified scroll position.
    virtual int thumbPosition(const ScrollbarThemeClient&, float scrollPosition);
    // The length of the thumb along the axis of the scrollbar.
    virtual int thumbLength(const ScrollbarThemeClient&);
    // The position of the track relative to the scrollbar.
    virtual int trackPosition(const ScrollbarThemeClient&);
    // The length of the track along the axis of the scrollbar.
    virtual int trackLength(const ScrollbarThemeClient&);
    // The opacity to be applied to the thumb.
    virtual float thumbOpacity(const ScrollbarThemeClient&) const { return 1.0f; }

    virtual bool hasButtons(const ScrollbarThemeClient&) = 0;
    virtual bool hasThumb(const ScrollbarThemeClient&) = 0;

    virtual IntRect backButtonRect(const ScrollbarThemeClient&, ScrollbarPart, bool painting = false) = 0;
    virtual IntRect forwardButtonRect(const ScrollbarThemeClient&, ScrollbarPart, bool painting = false) = 0;
    virtual IntRect trackRect(const ScrollbarThemeClient&, bool painting = false) = 0;
    virtual IntRect thumbRect(const ScrollbarThemeClient&);
    virtual int thumbThickness(const ScrollbarThemeClient&);

    virtual int minimumThumbLength(const ScrollbarThemeClient&);

    virtual void splitTrack(const ScrollbarThemeClient&, const IntRect& track, IntRect& startTrack, IntRect& thumb, IntRect& endTrack);

    virtual void paintScrollbarBackground(GraphicsContext&, const Scrollbar&) { }
    virtual void paintTrackBackground(GraphicsContext&, const Scrollbar&, const IntRect&) { }
    virtual void paintTrackPiece(GraphicsContext&, const Scrollbar&, const IntRect&, ScrollbarPart) { }
    virtual void paintButton(GraphicsContext&, const Scrollbar&, const IntRect&, ScrollbarPart) { }
    virtual void paintThumb(GraphicsContext&, const Scrollbar&, const IntRect&) { }

    virtual int maxOverlapBetweenPages() { return std::numeric_limits<int>::max(); }

    virtual double initialAutoscrollTimerDelay() { return 0.25; }
    virtual double autoscrollTimerDelay() { return 0.05; }

    virtual IntRect constrainTrackRectToTrackPieces(const ScrollbarThemeClient&, const IntRect& rect) { return rect; }

    virtual void registerScrollbar(ScrollbarThemeClient&) { }
    virtual void unregisterScrollbar(ScrollbarThemeClient&) { }

    virtual bool isMockTheme() const { return false; }

    static ScrollbarTheme& theme();

    static void setMockScrollbarsEnabled(bool flag);
    static bool mockScrollbarsEnabled();

protected:
    static DisplayItem::Type buttonPartToDisplayItemType(ScrollbarPart);
    static DisplayItem::Type trackPiecePartToDisplayItemType(ScrollbarPart);

private:
    static ScrollbarTheme& nativeTheme(); // Must be implemented to return the correct theme subclass.
    static bool gMockScrollbarsEnabled;
};

} // namespace blink
#endif