Source/platform/scroll/ScrollbarThemeMacOverlayAPI.mm

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#include "config.h"
#include "platform/scroll/ScrollbarThemeMacOverlayAPI.h"

#include "platform/graphics/GraphicsContext.h"
#include "platform/graphics/GraphicsContextStateSaver.h"
#include "platform/mac/LocalCurrentGraphicsContext.h"
#include "platform/mac/NSScrollerImpDetails.h"
#include "platform/scroll/ScrollbarThemeClient.h"

namespace blink {

typedef HashMap<ScrollbarThemeClient*, RetainPtr<ScrollbarPainter> > ScrollbarPainterMap;

static ScrollbarPainterMap* scrollbarPainterMap()
{
    static ScrollbarPainterMap* map = new ScrollbarPainterMap;
    return map;
}

static bool supportsExpandedScrollbars()
{
    // FIXME: This is temporary until all platforms that support ScrollbarPainter support this part of the API.
    static bool globalSupportsExpandedScrollbars = [NSClassFromString(@"NSScrollerImp") instancesRespondToSelector:@selector(setExpanded:)];
    return globalSupportsExpandedScrollbars;
}

void ScrollbarThemeMacOverlayAPI::registerScrollbar(ScrollbarThemeClient* scrollbar)
{
    ScrollbarThemeMacCommon::registerScrollbar(scrollbar);

    bool isHorizontal = scrollbar->orientation() == HorizontalScrollbar;
    ScrollbarPainter scrollbarPainter = [NSClassFromString(@"NSScrollerImp") scrollerImpWithStyle:recommendedScrollerStyle() controlSize:(NSControlSize)scrollbar->controlSize() horizontal:isHorizontal replacingScrollerImp:nil];
    scrollbarPainterMap()->add(scrollbar, scrollbarPainter);
    updateEnabledState(scrollbar);
    updateScrollbarOverlayStyle(scrollbar);
}

void ScrollbarThemeMacOverlayAPI::unregisterScrollbar(ScrollbarThemeClient* scrollbar)
{
    scrollbarPainterMap()->remove(scrollbar);

    ScrollbarThemeMacCommon::unregisterScrollbar(scrollbar);
}

void ScrollbarThemeMacOverlayAPI::setNewPainterForScrollbar(ScrollbarThemeClient* scrollbar, ScrollbarPainter newPainter)
{
    scrollbarPainterMap()->set(scrollbar, newPainter);
    updateEnabledState(scrollbar);
    updateScrollbarOverlayStyle(scrollbar);
}

ScrollbarPainter ScrollbarThemeMacOverlayAPI::painterForScrollbar(ScrollbarThemeClient* scrollbar)
{
    return scrollbarPainterMap()->get(scrollbar).get();
}

void ScrollbarThemeMacOverlayAPI::paintTrackBackground(GraphicsContext* context, ScrollbarThemeClient* scrollbar, const IntRect& rect) {
    ASSERT(isOverlayAPIAvailable());

    GraphicsContextStateSaver stateSaver(*context);
    context->translate(rect.x(), rect.y());
    LocalCurrentGraphicsContext localContext(context);

    CGRect frameRect = scrollbar->frameRect();
    ScrollbarPainter scrollbarPainter = painterForScrollbar(scrollbar);
    [scrollbarPainter setEnabled:scrollbar->enabled()];
    [scrollbarPainter setBoundsSize: NSSizeFromCGSize(frameRect.size)];

    NSRect trackRect = NSMakeRect(0, 0, frameRect.size.width, frameRect.size.height);
    [scrollbarPainter drawKnobSlotInRect:trackRect highlight:NO];
}

void ScrollbarThemeMacOverlayAPI::paintThumb(GraphicsContext* context, ScrollbarThemeClient* scrollbar, const IntRect& rect) {
    ASSERT(isOverlayAPIAvailable());

    GraphicsContextStateSaver stateSaver(*context);
    context->translate(rect.x(), rect.y());
    LocalCurrentGraphicsContext localContext(context);

    ScrollbarPainter scrollbarPainter = painterForScrollbar(scrollbar);
    [scrollbarPainter setEnabled:scrollbar->enabled()];
    [scrollbarPainter setBoundsSize:NSSizeFromCGSize(rect.size())];
    [scrollbarPainter setDoubleValue:0];
    [scrollbarPainter setKnobProportion:1];
    if (scrollbar->enabled())
        [scrollbarPainter drawKnob];

    // If this state is not set, then moving the cursor over the scrollbar area will only cause the
    // scrollbar to engorge when moved over the top of the scrollbar area.
    [scrollbarPainter setBoundsSize: NSSizeFromCGSize(scrollbar->frameRect().size())];
}

int ScrollbarThemeMacOverlayAPI::scrollbarThickness(ScrollbarControlSize controlSize)
{
    ScrollbarPainter scrollbarPainter = [NSClassFromString(@"NSScrollerImp") scrollerImpWithStyle:recommendedScrollerStyle() controlSize:controlSize horizontal:NO replacingScrollerImp:nil];
    if (supportsExpandedScrollbars())
        [scrollbarPainter setExpanded:YES];
    return [scrollbarPainter trackBoxWidth];
}

bool ScrollbarThemeMacOverlayAPI::usesOverlayScrollbars() const
{
    return recommendedScrollerStyle() == NSScrollerStyleOverlay;
}

void ScrollbarThemeMacOverlayAPI::updateScrollbarOverlayStyle(ScrollbarThemeClient* scrollbar)
{
    ScrollbarPainter painter = painterForScrollbar(scrollbar);
    switch (scrollbar->scrollbarOverlayStyle()) {
    case ScrollbarOverlayStyleDefault:
        [painter setKnobStyle:NSScrollerKnobStyleDefault];
        break;
    case ScrollbarOverlayStyleDark:
        [painter setKnobStyle:NSScrollerKnobStyleDark];
        break;
    case ScrollbarOverlayStyleLight:
        [painter setKnobStyle:NSScrollerKnobStyleLight];
        break;
    }
}

ScrollbarButtonsPlacement ScrollbarThemeMacOverlayAPI::buttonsPlacement() const
{
    return ScrollbarButtonsNone;
}

bool ScrollbarThemeMacOverlayAPI::hasThumb(ScrollbarThemeClient* scrollbar)
{
    ScrollbarPainter painter = painterForScrollbar(scrollbar);
    int minLengthForThumb = [painter knobMinLength] + [painter trackOverlapEndInset] + [painter knobOverlapEndInset]
        + 2 * ([painter trackEndInset] + [painter knobEndInset]);
    return scrollbar->enabled() && (scrollbar->orientation() == HorizontalScrollbar ?
             scrollbar->width() :
             scrollbar->height()) >= minLengthForThumb;
}

IntRect ScrollbarThemeMacOverlayAPI::backButtonRect(ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
{
    ASSERT(buttonsPlacement() == ScrollbarButtonsNone);
    return IntRect();
}

IntRect ScrollbarThemeMacOverlayAPI::forwardButtonRect(ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
{
    ASSERT(buttonsPlacement() == ScrollbarButtonsNone);
    return IntRect();
}

IntRect ScrollbarThemeMacOverlayAPI::trackRect(ScrollbarThemeClient* scrollbar, bool painting)
{
    ASSERT(!hasButtons(scrollbar));
    return scrollbar->frameRect();
}

int ScrollbarThemeMacOverlayAPI::minimumThumbLength(ScrollbarThemeClient* scrollbar)
{
    return [painterForScrollbar(scrollbar) knobMinLength];
}

void ScrollbarThemeMacOverlayAPI::updateEnabledState(ScrollbarThemeClient* scrollbar)
{
    [painterForScrollbar(scrollbar) setEnabled:scrollbar->enabled()];
}

} // namespace blink