WebKit/mac/WebView/WebDynamicScrollBarsView.mm - platform/external/webkit - Git at Google

 /*
  * Copyright (C) 2005, 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.
  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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.
  */

 #import "WebDynamicScrollBarsViewInternal.h"

 #import "WebDocument.h"
 #import "WebFrameInternal.h"
 #import "WebFrameView.h"
 #import "WebHTMLViewInternal.h"
 #import <WebCore/Frame.h>
 #import <WebCore/FrameView.h>
 #import <WebKitSystemInterface.h>

 using namespace WebCore;

 // FIXME: <rdar://problem/5898985> Mail expects a constant of this name to exist.
 const int WebCoreScrollbarAlwaysOn = ScrollbarAlwaysOn;

 @implementation WebDynamicScrollBarsView

 - (void)setAllowsHorizontalScrolling:(BOOL)flag
 {
     if (hScrollModeLocked)
         return;
     if (flag && hScroll == ScrollbarAlwaysOff)
         hScroll = ScrollbarAuto;
     else if (!flag && hScroll != ScrollbarAlwaysOff)
         hScroll = ScrollbarAlwaysOff;
     [self updateScrollers];
 }

 @end

 @implementation WebDynamicScrollBarsView (WebInternal)

 - (void)setSuppressLayout:(BOOL)flag;
 {
     suppressLayout = flag;
 }

 - (void)setScrollBarsSuppressed:(BOOL)suppressed repaintOnUnsuppress:(BOOL)repaint
 {
     suppressScrollers = suppressed;

     // This code was originally changes for a Leopard performance imporvement. We decided to
     // ifdef it to fix correctness issues on Tiger documented in <rdar://problem/5441823>.
 #ifndef BUILDING_ON_TIGER
     if (suppressed) {
         [[self verticalScroller] setNeedsDisplay:NO];
         [[self horizontalScroller] setNeedsDisplay:NO];
     }

     if (!suppressed && repaint)
         [super reflectScrolledClipView:[self contentView]];
 #else
     if (suppressed || repaint) {
         [[self verticalScroller] setNeedsDisplay: !suppressed];
         [[self horizontalScroller] setNeedsDisplay: !suppressed];
     }
 #endif
 }

 static const unsigned cMaxUpdateScrollbarsPass = 2;

 - (void)updateScrollers
 {
     NSView *documentView = [self documentView];

     // If we came in here with the view already needing a layout, then go ahead and do that
     // first.  (This will be the common case, e.g., when the page changes due to window resizing for example).
     // This layout will not re-enter updateScrollers and does not count towards our max layout pass total.
     if (!suppressLayout && !suppressScrollers && [documentView isKindOfClass:[WebHTMLView class]]) {
         WebHTMLView* htmlView = (WebHTMLView*)documentView;
         if ([htmlView _needsLayout]) {
             inUpdateScrollers = YES;
             [(id <WebDocumentView>)documentView layout];
             inUpdateScrollers = NO;
         }
     }

     BOOL hasHorizontalScroller = [self hasHorizontalScroller];
     BOOL hasVerticalScroller = [self hasVerticalScroller];

     BOOL newHasHorizontalScroller = hasHorizontalScroller;
     BOOL newHasVerticalScroller = hasVerticalScroller;

     if (!documentView) {
         newHasHorizontalScroller = NO;
         newHasVerticalScroller = NO;
     }

     if (hScroll != ScrollbarAuto)
         newHasHorizontalScroller = (hScroll == ScrollbarAlwaysOn);
     if (vScroll != ScrollbarAuto)
         newHasVerticalScroller = (vScroll == ScrollbarAlwaysOn);

     if (!documentView || suppressLayout || suppressScrollers || (hScroll != ScrollbarAuto && vScroll != ScrollbarAuto)) {
         inUpdateScrollers = YES;
         if (hasHorizontalScroller != newHasHorizontalScroller)
             [self setHasHorizontalScroller:newHasHorizontalScroller];
         if (hasVerticalScroller != newHasVerticalScroller)
             [self setHasVerticalScroller:newHasVerticalScroller];
         if (suppressScrollers) {
             [[self verticalScroller] setNeedsDisplay:NO];
             [[self horizontalScroller] setNeedsDisplay:NO];
         }
         inUpdateScrollers = NO;
         return;
     }

     BOOL needsLayout = NO;

     NSSize documentSize = [documentView frame].size;
     NSSize visibleSize = [self documentVisibleRect].size;
     NSSize frameSize = [self frame].size;

     if (hScroll == ScrollbarAuto) {
         newHasHorizontalScroller = documentSize.width > visibleSize.width;
         if (newHasHorizontalScroller && !inUpdateScrollersLayoutPass && documentSize.height <= frameSize.height && documentSize.width <= frameSize.width)
             newHasHorizontalScroller = NO;
     }

     if (vScroll == ScrollbarAuto) {
         newHasVerticalScroller = documentSize.height > visibleSize.height;
         if (newHasVerticalScroller && !inUpdateScrollersLayoutPass && documentSize.height <= frameSize.height && documentSize.width <= frameSize.width)
             newHasVerticalScroller = NO;
     }

     // Unless in ScrollbarsAlwaysOn mode, if we ever turn one scrollbar off, always turn the other one off too.
     // Never ever try to both gain/lose a scrollbar in the same pass.
     if (!newHasHorizontalScroller && hasHorizontalScroller && vScroll != ScrollbarAlwaysOn)
         newHasVerticalScroller = NO;
     if (!newHasVerticalScroller && hasVerticalScroller && hScroll != ScrollbarAlwaysOn)
         newHasHorizontalScroller = NO;

     if (hasHorizontalScroller != newHasHorizontalScroller) {
         inUpdateScrollers = YES;
         [self setHasHorizontalScroller:newHasHorizontalScroller];
         inUpdateScrollers = NO;
         needsLayout = YES;
     }

     if (hasVerticalScroller != newHasVerticalScroller) {
         inUpdateScrollers = YES;
         [self setHasVerticalScroller:newHasVerticalScroller];
         inUpdateScrollers = NO;
         needsLayout = YES;
     }

     if (needsLayout && inUpdateScrollersLayoutPass < cMaxUpdateScrollbarsPass &&
         [documentView conformsToProtocol:@protocol(WebDocumentView)]) {
         inUpdateScrollersLayoutPass++;
         [(id <WebDocumentView>)documentView setNeedsLayout:YES];
         [(id <WebDocumentView>)documentView layout];
         NSSize newDocumentSize = [documentView frame].size;
         if (NSEqualSizes(documentSize, newDocumentSize)) {
             // The layout with the new scroll state had no impact on
             // the document's overall size, so updateScrollers didn't get called.
             // Recur manually.
             [self updateScrollers];
         }
         inUpdateScrollersLayoutPass--;
     }
 }

 // Make the horizontal and vertical scroll bars come and go as needed.
 - (void)reflectScrolledClipView:(NSClipView *)clipView
 {
     if (clipView == [self contentView]) {
         // FIXME: This hack here prevents infinite recursion that takes place when we
         // gyrate between having a vertical scroller and not having one. A reproducible
         // case is clicking on the "the Policy Routing text" link at
         // http://www.linuxpowered.com/archive/howto/Net-HOWTO-8.html.
         // The underlying cause is some problem in the NSText machinery, but I was not
         // able to pin it down.
         NSGraphicsContext *currentContext = [NSGraphicsContext currentContext];
         if (!inUpdateScrollers && (!currentContext || [currentContext isDrawingToScreen]))
             [self updateScrollers];
     }

     // This code was originally changed for a Leopard performance imporvement. We decided to
     // ifdef it to fix correctness issues on Tiger documented in <rdar://problem/5441823>.
 #ifndef BUILDING_ON_TIGER
     // Update the scrollers if they're not being suppressed.
     if (!suppressScrollers)
         [super reflectScrolledClipView:clipView];
 #else
     [super reflectScrolledClipView:clipView];

     // Validate the scrollers if they're being suppressed.
     if (suppressScrollers) {
         [[self verticalScroller] setNeedsDisplay: NO];
         [[self horizontalScroller] setNeedsDisplay: NO];
     }
 #endif

 #if USE(ACCELERATED_COMPOSITING) && defined(BUILDING_ON_LEOPARD)
     NSView *documentView = [self documentView];
     if ([documentView isKindOfClass:[WebHTMLView class]]) {
         WebHTMLView *htmlView = (WebHTMLView *)documentView;
         if ([htmlView _isUsingAcceleratedCompositing])
             [htmlView _updateLayerHostingViewPosition];
     }
 #endif
 }

 - (BOOL)allowsHorizontalScrolling
 {
     return hScroll != ScrollbarAlwaysOff;
 }

 - (BOOL)allowsVerticalScrolling
 {
     return vScroll != ScrollbarAlwaysOff;
 }

 - (void)scrollingModes:(WebCore::ScrollbarMode*)hMode vertical:(WebCore::ScrollbarMode*)vMode
 {
     *hMode = static_cast<ScrollbarMode>(hScroll);
     *vMode = static_cast<ScrollbarMode>(vScroll);
 }

 - (ScrollbarMode)horizontalScrollingMode
 {
     return static_cast<ScrollbarMode>(hScroll);
 }

 - (ScrollbarMode)verticalScrollingMode
 {
     return static_cast<ScrollbarMode>(vScroll);
 }

 - (void)setHorizontalScrollingMode:(ScrollbarMode)horizontalMode andLock:(BOOL)lock
 {
     [self setScrollingModes:horizontalMode vertical:[self verticalScrollingMode] andLock:lock];
 }

 - (void)setVerticalScrollingMode:(ScrollbarMode)verticalMode andLock:(BOOL)lock
 {
     [self setScrollingModes:[self horizontalScrollingMode] vertical:verticalMode andLock:lock];
 }

 // Mail uses this method, so we cannot remove it.
 - (void)setVerticalScrollingMode:(ScrollbarMode)verticalMode
 {
     [self setScrollingModes:[self horizontalScrollingMode] vertical:verticalMode andLock:NO];
 }

 - (void)setScrollingModes:(ScrollbarMode)horizontalMode vertical:(ScrollbarMode)verticalMode andLock:(BOOL)lock
 {
     BOOL update = NO;
     if (verticalMode != vScroll && !vScrollModeLocked) {
         vScroll = verticalMode;
         update = YES;
     }

     if (horizontalMode != hScroll && !hScrollModeLocked) {
         hScroll = horizontalMode;
         update = YES;
     }

     if (lock)
         [self setScrollingModesLocked:YES];

     if (update)
         [self updateScrollers];
 }

 - (void)setHorizontalScrollingModeLocked:(BOOL)locked
 {
     hScrollModeLocked = locked;
 }

 - (void)setVerticalScrollingModeLocked:(BOOL)locked
 {
     vScrollModeLocked = locked;
 }

 - (void)setScrollingModesLocked:(BOOL)locked
 {
     hScrollModeLocked = vScrollModeLocked = locked;
 }

 - (BOOL)horizontalScrollingModeLocked
 {
     return hScrollModeLocked;
 }

 - (BOOL)verticalScrollingModeLocked
 {
     return vScrollModeLocked;
 }

 - (BOOL)autoforwardsScrollWheelEvents
 {
     return YES;
 }

 - (void)scrollWheel:(NSEvent *)event
 {
     float deltaX;
     float deltaY;
     BOOL isContinuous;
     WKGetWheelEventDeltas(event, &deltaX, &deltaY, &isContinuous);

     BOOL isLatchingEvent = WKIsLatchingWheelEvent(event);

     if (fabsf(deltaY) > fabsf(deltaX)) {
         if (![self allowsVerticalScrolling]) {
             [[self nextResponder] scrollWheel:event];
             return;
         }

         if (isLatchingEvent && !verticallyPinnedByPreviousWheelEvent) {
             double verticalPosition = [[self verticalScroller] doubleValue];
             if ((deltaY >= 0.0 && verticalPosition == 0.0) || (deltaY <= 0.0 && verticalPosition == 1.0))
                 return;
         }
     } else {
         if (![self allowsHorizontalScrolling]) {
             [[self nextResponder] scrollWheel:event];
             return;
         }

         if (isLatchingEvent && !horizontallyPinnedByPreviousWheelEvent) {
             double horizontalPosition = [[self horizontalScroller] doubleValue];
             if ((deltaX >= 0.0 && horizontalPosition == 0.0) || (deltaX <= 0.0 && horizontalPosition == 1.0))
                 return;
         }
     }

     // Calling super can release the last reference. <rdar://problem/7400263>
     // Hold a reference so the code following the super call will not crash.
     [self retain];

     [super scrollWheel:event];

     if (!isLatchingEvent) {
         double verticalPosition = [[self verticalScroller] doubleValue];
         double horizontalPosition = [[self horizontalScroller] doubleValue];

         verticallyPinnedByPreviousWheelEvent = (verticalPosition == 0.0 || verticalPosition == 1.0);
         horizontallyPinnedByPreviousWheelEvent = (horizontalPosition == 0.0 || horizontalPosition == 1.0);
     }

     [self release];
 }

 - (BOOL)accessibilityIsIgnored
 {
     id docView = [self documentView];
     if ([docView isKindOfClass:[WebFrameView class]] && ![(WebFrameView *)docView allowsScrolling])
         return YES;

     return [super accessibilityIsIgnored];
 }

 @end
	/*
	* Copyright (C) 2005, 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.
	* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
	* its contributors may be used to endorse or promote products derived
	* from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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.
	*/

	#import "WebDynamicScrollBarsViewInternal.h"

	#import "WebDocument.h"
	#import "WebFrameInternal.h"
	#import "WebFrameView.h"
	#import "WebHTMLViewInternal.h"
	#import <WebCore/Frame.h>
	#import <WebCore/FrameView.h>
	#import <WebKitSystemInterface.h>

	using namespace WebCore;

	// FIXME: <rdar://problem/5898985> Mail expects a constant of this name to exist.
	const int WebCoreScrollbarAlwaysOn = ScrollbarAlwaysOn;

	@implementation WebDynamicScrollBarsView

	- (void)setAllowsHorizontalScrolling:(BOOL)flag
	{
	if (hScrollModeLocked)
	return;
	if (flag && hScroll == ScrollbarAlwaysOff)
	hScroll = ScrollbarAuto;
	else if (!flag && hScroll != ScrollbarAlwaysOff)
	hScroll = ScrollbarAlwaysOff;
	[self updateScrollers];
	}

	@end

	@implementation WebDynamicScrollBarsView (WebInternal)

	- (void)setSuppressLayout:(BOOL)flag;
	{
	suppressLayout = flag;
	}

	- (void)setScrollBarsSuppressed:(BOOL)suppressed repaintOnUnsuppress:(BOOL)repaint
	{
	suppressScrollers = suppressed;

	// This code was originally changes for a Leopard performance imporvement. We decided to
	// ifdef it to fix correctness issues on Tiger documented in <rdar://problem/5441823>.
	#ifndef BUILDING_ON_TIGER
	if (suppressed) {
	[[self verticalScroller] setNeedsDisplay:NO];
	[[self horizontalScroller] setNeedsDisplay:NO];
	}

	if (!suppressed && repaint)
	[super reflectScrolledClipView:[self contentView]];
	#else
	if (suppressed \|\| repaint) {
	[[self verticalScroller] setNeedsDisplay: !suppressed];
	[[self horizontalScroller] setNeedsDisplay: !suppressed];
	}
	#endif
	}

	static const unsigned cMaxUpdateScrollbarsPass = 2;

	- (void)updateScrollers
	{
	NSView *documentView = [self documentView];

	// If we came in here with the view already needing a layout, then go ahead and do that
	// first. (This will be the common case, e.g., when the page changes due to window resizing for example).
	// This layout will not re-enter updateScrollers and does not count towards our max layout pass total.
	if (!suppressLayout && !suppressScrollers && [documentView isKindOfClass:[WebHTMLView class]]) {
	WebHTMLView* htmlView = (WebHTMLView*)documentView;
	if ([htmlView _needsLayout]) {
	inUpdateScrollers = YES;
	[(id <WebDocumentView>)documentView layout];
	inUpdateScrollers = NO;
	}
	}

	BOOL hasHorizontalScroller = [self hasHorizontalScroller];
	BOOL hasVerticalScroller = [self hasVerticalScroller];

	BOOL newHasHorizontalScroller = hasHorizontalScroller;
	BOOL newHasVerticalScroller = hasVerticalScroller;

	if (!documentView) {
	newHasHorizontalScroller = NO;
	newHasVerticalScroller = NO;
	}

	if (hScroll != ScrollbarAuto)
	newHasHorizontalScroller = (hScroll == ScrollbarAlwaysOn);
	if (vScroll != ScrollbarAuto)
	newHasVerticalScroller = (vScroll == ScrollbarAlwaysOn);

	if (!documentView \|\| suppressLayout \|\| suppressScrollers \|\| (hScroll != ScrollbarAuto && vScroll != ScrollbarAuto)) {
	inUpdateScrollers = YES;
	if (hasHorizontalScroller != newHasHorizontalScroller)
	[self setHasHorizontalScroller:newHasHorizontalScroller];
	if (hasVerticalScroller != newHasVerticalScroller)
	[self setHasVerticalScroller:newHasVerticalScroller];
	if (suppressScrollers) {
	[[self verticalScroller] setNeedsDisplay:NO];
	[[self horizontalScroller] setNeedsDisplay:NO];
	}
	inUpdateScrollers = NO;
	return;
	}

	BOOL needsLayout = NO;

	NSSize documentSize = [documentView frame].size;
	NSSize visibleSize = [self documentVisibleRect].size;
	NSSize frameSize = [self frame].size;

	if (hScroll == ScrollbarAuto) {
	newHasHorizontalScroller = documentSize.width > visibleSize.width;
	if (newHasHorizontalScroller && !inUpdateScrollersLayoutPass && documentSize.height <= frameSize.height && documentSize.width <= frameSize.width)
	newHasHorizontalScroller = NO;
	}

	if (vScroll == ScrollbarAuto) {
	newHasVerticalScroller = documentSize.height > visibleSize.height;
	if (newHasVerticalScroller && !inUpdateScrollersLayoutPass && documentSize.height <= frameSize.height && documentSize.width <= frameSize.width)
	newHasVerticalScroller = NO;
	}

	// Unless in ScrollbarsAlwaysOn mode, if we ever turn one scrollbar off, always turn the other one off too.
	// Never ever try to both gain/lose a scrollbar in the same pass.
	if (!newHasHorizontalScroller && hasHorizontalScroller && vScroll != ScrollbarAlwaysOn)
	newHasVerticalScroller = NO;
	if (!newHasVerticalScroller && hasVerticalScroller && hScroll != ScrollbarAlwaysOn)
	newHasHorizontalScroller = NO;

	if (hasHorizontalScroller != newHasHorizontalScroller) {
	inUpdateScrollers = YES;
	[self setHasHorizontalScroller:newHasHorizontalScroller];
	inUpdateScrollers = NO;
	needsLayout = YES;
	}

	if (hasVerticalScroller != newHasVerticalScroller) {
	inUpdateScrollers = YES;
	[self setHasVerticalScroller:newHasVerticalScroller];
	inUpdateScrollers = NO;
	needsLayout = YES;
	}

	if (needsLayout && inUpdateScrollersLayoutPass < cMaxUpdateScrollbarsPass &&
	[documentView conformsToProtocol:@protocol(WebDocumentView)]) {
	inUpdateScrollersLayoutPass++;
	[(id <WebDocumentView>)documentView setNeedsLayout:YES];
	[(id <WebDocumentView>)documentView layout];
	NSSize newDocumentSize = [documentView frame].size;
	if (NSEqualSizes(documentSize, newDocumentSize)) {
	// The layout with the new scroll state had no impact on
	// the document's overall size, so updateScrollers didn't get called.
	// Recur manually.
	[self updateScrollers];
	}
	inUpdateScrollersLayoutPass--;
	}
	}

	// Make the horizontal and vertical scroll bars come and go as needed.
	- (void)reflectScrolledClipView:(NSClipView *)clipView
	{
	if (clipView == [self contentView]) {
	// FIXME: This hack here prevents infinite recursion that takes place when we
	// gyrate between having a vertical scroller and not having one. A reproducible
	// case is clicking on the "the Policy Routing text" link at
	// http://www.linuxpowered.com/archive/howto/Net-HOWTO-8.html.
	// The underlying cause is some problem in the NSText machinery, but I was not
	// able to pin it down.
	NSGraphicsContext *currentContext = [NSGraphicsContext currentContext];
	if (!inUpdateScrollers && (!currentContext \|\| [currentContext isDrawingToScreen]))
	[self updateScrollers];
	}

	// This code was originally changed for a Leopard performance imporvement. We decided to
	// ifdef it to fix correctness issues on Tiger documented in <rdar://problem/5441823>.
	#ifndef BUILDING_ON_TIGER
	// Update the scrollers if they're not being suppressed.
	if (!suppressScrollers)
	[super reflectScrolledClipView:clipView];
	#else
	[super reflectScrolledClipView:clipView];

	// Validate the scrollers if they're being suppressed.
	if (suppressScrollers) {
	[[self verticalScroller] setNeedsDisplay: NO];
	[[self horizontalScroller] setNeedsDisplay: NO];
	}
	#endif

	#if USE(ACCELERATED_COMPOSITING) && defined(BUILDING_ON_LEOPARD)
	NSView *documentView = [self documentView];
	if ([documentView isKindOfClass:[WebHTMLView class]]) {
	WebHTMLView htmlView = (WebHTMLView )documentView;
	if ([htmlView _isUsingAcceleratedCompositing])
	[htmlView _updateLayerHostingViewPosition];
	}
	#endif
	}

	- (BOOL)allowsHorizontalScrolling
	{
	return hScroll != ScrollbarAlwaysOff;
	}

	- (BOOL)allowsVerticalScrolling
	{
	return vScroll != ScrollbarAlwaysOff;
	}

	- (void)scrollingModes:(WebCore::ScrollbarMode)hMode vertical:(WebCore::ScrollbarMode)vMode
	{
	*hMode = static_cast<ScrollbarMode>(hScroll);
	*vMode = static_cast<ScrollbarMode>(vScroll);
	}

	- (ScrollbarMode)horizontalScrollingMode
	{
	return static_cast<ScrollbarMode>(hScroll);
	}

	- (ScrollbarMode)verticalScrollingMode
	{
	return static_cast<ScrollbarMode>(vScroll);
	}

	- (void)setHorizontalScrollingMode:(ScrollbarMode)horizontalMode andLock:(BOOL)lock
	{
	[self setScrollingModes:horizontalMode vertical:[self verticalScrollingMode] andLock:lock];
	}

	- (void)setVerticalScrollingMode:(ScrollbarMode)verticalMode andLock:(BOOL)lock
	{
	[self setScrollingModes:[self horizontalScrollingMode] vertical:verticalMode andLock:lock];
	}

	// Mail uses this method, so we cannot remove it.
	- (void)setVerticalScrollingMode:(ScrollbarMode)verticalMode
	{
	[self setScrollingModes:[self horizontalScrollingMode] vertical:verticalMode andLock:NO];
	}

	- (void)setScrollingModes:(ScrollbarMode)horizontalMode vertical:(ScrollbarMode)verticalMode andLock:(BOOL)lock
	{
	BOOL update = NO;
	if (verticalMode != vScroll && !vScrollModeLocked) {
	vScroll = verticalMode;
	update = YES;
	}

	if (horizontalMode != hScroll && !hScrollModeLocked) {
	hScroll = horizontalMode;
	update = YES;
	}

	if (lock)
	[self setScrollingModesLocked:YES];

	if (update)
	[self updateScrollers];
	}

	- (void)setHorizontalScrollingModeLocked:(BOOL)locked
	{
	hScrollModeLocked = locked;
	}

	- (void)setVerticalScrollingModeLocked:(BOOL)locked
	{
	vScrollModeLocked = locked;
	}

	- (void)setScrollingModesLocked:(BOOL)locked
	{
	hScrollModeLocked = vScrollModeLocked = locked;
	}

	- (BOOL)horizontalScrollingModeLocked
	{
	return hScrollModeLocked;
	}

	- (BOOL)verticalScrollingModeLocked
	{
	return vScrollModeLocked;
	}

	- (BOOL)autoforwardsScrollWheelEvents
	{
	return YES;
	}

	- (void)scrollWheel:(NSEvent *)event
	{
	float deltaX;
	float deltaY;
	BOOL isContinuous;
	WKGetWheelEventDeltas(event, &deltaX, &deltaY, &isContinuous);

	BOOL isLatchingEvent = WKIsLatchingWheelEvent(event);

	if (fabsf(deltaY) > fabsf(deltaX)) {
	if (![self allowsVerticalScrolling]) {
	[[self nextResponder] scrollWheel:event];
	return;
	}

	if (isLatchingEvent && !verticallyPinnedByPreviousWheelEvent) {
	double verticalPosition = [[self verticalScroller] doubleValue];
	if ((deltaY >= 0.0 && verticalPosition == 0.0) \|\| (deltaY <= 0.0 && verticalPosition == 1.0))
	return;
	}
	} else {
	if (![self allowsHorizontalScrolling]) {
	[[self nextResponder] scrollWheel:event];
	return;
	}

	if (isLatchingEvent && !horizontallyPinnedByPreviousWheelEvent) {
	double horizontalPosition = [[self horizontalScroller] doubleValue];
	if ((deltaX >= 0.0 && horizontalPosition == 0.0) \|\| (deltaX <= 0.0 && horizontalPosition == 1.0))
	return;
	}
	}

	// Calling super can release the last reference. <rdar://problem/7400263>
	// Hold a reference so the code following the super call will not crash.
	[self retain];

	[super scrollWheel:event];

	if (!isLatchingEvent) {
	double verticalPosition = [[self verticalScroller] doubleValue];
	double horizontalPosition = [[self horizontalScroller] doubleValue];

	verticallyPinnedByPreviousWheelEvent = (verticalPosition == 0.0 \|\| verticalPosition == 1.0);
	horizontallyPinnedByPreviousWheelEvent = (horizontalPosition == 0.0 \|\| horizontalPosition == 1.0);
	}

	[self release];
	}

	- (BOOL)accessibilityIsIgnored
	{
	id docView = [self documentView];
	if ([docView isKindOfClass:[WebFrameView class]] && ![(WebFrameView *)docView allowsScrolling])
	return YES;

	return [super accessibilityIsIgnored];
	}

	@end