Use refs for non-null GraphicsContext, Scrollbar, etc. in scrollbar related code

third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacOverlayAPI.mm

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 22 matching lines @@
 
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 #include "platform/graphics/paint/DrawingRecorder.h"
 #include "platform/mac/LocalCurrentGraphicsContext.h"
 #include "platform/mac/NSScrollerImpDetails.h"
 #include "platform/scroll/ScrollbarThemeClient.h"
 #include "wtf/RetainPtr.h"
 
 @interface WebCoreScrollbarObserver : NSObject {
-    blink::ScrollbarThemeClient* _scrollbar;
+    blink::ScrollbarThemeClient& _scrollbar;
     RetainPtr<ScrollbarPainter> _scrollbarPainter;
     BOOL _visible;
 }
-- (id)initWithScrollbar:(blink::ScrollbarThemeClient*)scrollbar painter:(ScrollbarPainter)painter;
+- (id)initWithScrollbar:(blink::ScrollbarThemeClient&)scrollbar painter:(ScrollbarPainter)painter;
 @end
 
 @implementation WebCoreScrollbarObserver
 
-- (id)initWithScrollbar:(blink::ScrollbarThemeClient*)scrollbar painter:(ScrollbarPainter)painter
+- (id)initWithScrollbar:(blink::ScrollbarThemeClient&)scrollbar painter:(ScrollbarPainter)painter
 {
     if (!(self = [super init]))
         return nil;
     _scrollbar = scrollbar;
     _scrollbarPainter = painter;
 
     [_scrollbarPainter.get() addObserver:self forKeyPath:@"knobAlpha" options:0 context:nil];
     return self;
 }
 
@@ skipping 11 matching lines @@
 
 - (void)observeValueForKeyPath:(NSString*)keyPath
                       ofObject:(id)object
                         change:(NSDictionary*)change
                        context:(void*)context
 {
     if ([keyPath isEqualToString:@"knobAlpha"]) {
         BOOL visible = [_scrollbarPainter.get() knobAlpha] > 0;
         if (_visible != visible) {
             _visible = visible;
-            _scrollbar->visibilityChanged();
+            _scrollbar.visibilityChanged();
         }
     }
 }
 
 @end
 
 namespace blink {
 
-typedef HashMap<ScrollbarThemeClient*, RetainPtr<WebCoreScrollbarObserver> > ScrollbarPainterMap;
+typedef HashMap<ScrollbarThemeClient&, RetainPtr<WebCoreScrollbarObserver> > 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)
+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];
+    bool isHorizontal = scrollbar.orientation() == HorizontalScrollbar;
+    ScrollbarPainter scrollbarPainter = [NSClassFromString(@"NSScrollerImp") scrollerImpWithStyle:recommendedScrollerStyle() controlSize:(NSControlSize)scrollbar.controlSize() horizontal:isHorizontal replacingScrollerImp:nil];
     RetainPtr<WebCoreScrollbarObserver> observer = [[WebCoreScrollbarObserver alloc] initWithScrollbar:scrollbar painter:scrollbarPainter];
 
     scrollbarPainterMap()->add(scrollbar, observer);
     updateEnabledState(scrollbar);
     updateScrollbarOverlayStyle(scrollbar);
 }
 
-void ScrollbarThemeMacOverlayAPI::unregisterScrollbar(ScrollbarThemeClient* scrollbar)
+void ScrollbarThemeMacOverlayAPI::unregisterScrollbar(ScrollbarThemeClient& scrollbar)
 {
     scrollbarPainterMap()->remove(scrollbar);
 
     ScrollbarThemeMacCommon::unregisterScrollbar(scrollbar);
 }
 
-void ScrollbarThemeMacOverlayAPI::setNewPainterForScrollbar(ScrollbarThemeClient* scrollbar, ScrollbarPainter newPainter)
+void ScrollbarThemeMacOverlayAPI::setNewPainterForScrollbar(ScrollbarThemeClient& scrollbar, ScrollbarPainter newPainter)
 {
     RetainPtr<WebCoreScrollbarObserver> observer = [[WebCoreScrollbarObserver alloc] initWithScrollbar:scrollbar painter:newPainter];
     scrollbarPainterMap()->set(scrollbar, observer);
     updateEnabledState(scrollbar);
     updateScrollbarOverlayStyle(scrollbar);
 }
 
-ScrollbarPainter ScrollbarThemeMacOverlayAPI::painterForScrollbar(const ScrollbarThemeClient* scrollbar) const
+ScrollbarPainter ScrollbarThemeMacOverlayAPI::painterForScrollbar(const ScrollbarThemeClient& scrollbar) const
 {
-    return [scrollbarPainterMap()->get(const_cast<ScrollbarThemeClient*>(scrollbar)).get() painter];
+    return [scrollbarPainterMap()->get(const_cast<ScrollbarThemeClient&>(scrollbar)).get() painter];
 }
 
-void ScrollbarThemeMacOverlayAPI::paintTrackBackground(GraphicsContext* context, const ScrollbarThemeClient* scrollbar, const IntRect& rect) {
-    if (DrawingRecorder::useCachedDrawingIfPossible(*context, *scrollbar, DisplayItem::ScrollbarTrackBackground))
+void ScrollbarThemeMacOverlayAPI::paintTrackBackground(GraphicsContext& context, const ScrollbarThemeClient& scrollbar, const IntRect& rect) {
+    if (DrawingRecorder::useCachedDrawingIfPossible(context, scrollbar, DisplayItem::ScrollbarTrackBackground))
         return;
 
-    DrawingRecorder recorder(*context, *scrollbar, DisplayItem::ScrollbarTrackBackground, rect);
+    DrawingRecorder recorder(context, scrollbar, DisplayItem::ScrollbarTrackBackground, rect);
 
     ASSERT(isOverlayAPIAvailable());
 
-    GraphicsContextStateSaver stateSaver(*context);
+    GraphicsContextStateSaver stateSaver(context);
     context->translate(rect.x(), rect.y());
     LocalCurrentGraphicsContext localContext(context, IntRect(IntPoint(), rect.size()));
 
-    CGRect frameRect = scrollbar->frameRect();
+    CGRect frameRect = scrollbar.frameRect();
     ScrollbarPainter scrollbarPainter = painterForScrollbar(scrollbar);
-    [scrollbarPainter setEnabled:scrollbar->enabled()];
+    [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, const ScrollbarThemeClient* scrollbar, const IntRect& rect) {
-    if (DrawingRecorder::useCachedDrawingIfPossible(*context, *scrollbar, DisplayItem::ScrollbarThumb))
+void ScrollbarThemeMacOverlayAPI::paintThumb(GraphicsContext& context, const ScrollbarThemeClient& scrollbar, const IntRect& rect) {
+    if (DrawingRecorder::useCachedDrawingIfPossible(context, scrollbar, DisplayItem::ScrollbarThumb))
         return;
 
     // Expand dirty rect to allow for scroll thumb anti-aliasing in minimum thumb size case.
     IntRect dirtyRect = IntRect(rect);
     dirtyRect.inflate(1);
-    DrawingRecorder recorder(*context, *scrollbar, DisplayItem::ScrollbarThumb, dirtyRect);
+    DrawingRecorder recorder(context, scrollbar, DisplayItem::ScrollbarThumb, dirtyRect);
 
     ASSERT(isOverlayAPIAvailable());
 
-    GraphicsContextStateSaver stateSaver(*context);
+    GraphicsContextStateSaver stateSaver(context);
     context->translate(rect.x(), rect.y());
     LocalCurrentGraphicsContext localContext(context, IntRect(IntPoint(), rect.size()));
 
     ScrollbarPainter scrollbarPainter = painterForScrollbar(scrollbar);
-    [scrollbarPainter setEnabled:scrollbar->enabled()];
+    [scrollbarPainter setEnabled:scrollbar.enabled()];
     [scrollbarPainter setBoundsSize:NSSizeFromCGSize(rect.size())];
     [scrollbarPainter setDoubleValue:0];
     [scrollbarPainter setKnobProportion:1];
 
     CGFloat oldKnobAlpha = [scrollbarPainter knobAlpha];
     [scrollbarPainter setKnobAlpha:1];
 
-    if (scrollbar->enabled())
+    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())];
+    [scrollbarPainter setBoundsSize: NSSizeFromCGSize(scrollbar.frameRect().size())];
     [scrollbarPainter setKnobAlpha:oldKnobAlpha];
 }
 
 int ScrollbarThemeMacOverlayAPI::scrollbarThickness(ScrollbarControlSize controlSize)
 {
     NSControlSize nsControlSize = static_cast<NSControlSize>(controlSize);
     ScrollbarPainter scrollbarPainter = [NSClassFromString(@"NSScrollerImp") scrollerImpWithStyle:recommendedScrollerStyle() controlSize:nsControlSize horizontal:NO replacingScrollerImp:nil];
     BOOL wasExpanded = NO;
     if (supportsExpandedScrollbars()) {
         wasExpanded = [scrollbarPainter isExpanded];
         [scrollbarPainter setExpanded:YES];
     }
     int thickness = [scrollbarPainter trackBoxWidth];
     if (supportsExpandedScrollbars())
         [scrollbarPainter setExpanded:wasExpanded];
     return thickness;
 }
 
 bool ScrollbarThemeMacOverlayAPI::usesOverlayScrollbars() const
 {
     return recommendedScrollerStyle() == NSScrollerStyleOverlay;
 }
 
-void ScrollbarThemeMacOverlayAPI::updateScrollbarOverlayStyle(const ScrollbarThemeClient* scrollbar)
+void ScrollbarThemeMacOverlayAPI::updateScrollbarOverlayStyle(const ScrollbarThemeClient& scrollbar)
 {
     ScrollbarPainter painter = painterForScrollbar(scrollbar);
-    switch (scrollbar->scrollbarOverlayStyle()) {
+    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 ScrollbarButtonsPlacementNone;
 }
 
-bool ScrollbarThemeMacOverlayAPI::hasThumb(const ScrollbarThemeClient* scrollbar)
+bool ScrollbarThemeMacOverlayAPI::hasThumb(const 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;
+    return scrollbar.enabled() && (scrollbar.orientation() == HorizontalScrollbar ?
+             scrollbar.width() :
+             scrollbar.height()) >= minLengthForThumb;
 }
 
-IntRect ScrollbarThemeMacOverlayAPI::backButtonRect(const ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
+IntRect ScrollbarThemeMacOverlayAPI::backButtonRect(const ScrollbarThemeClient& scrollbar, ScrollbarPart part, bool painting)
 {
     ASSERT(buttonsPlacement() == ScrollbarButtonsPlacementNone);
     return IntRect();
 }
 
-IntRect ScrollbarThemeMacOverlayAPI::forwardButtonRect(const ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
+IntRect ScrollbarThemeMacOverlayAPI::forwardButtonRect(const ScrollbarThemeClient& scrollbar, ScrollbarPart part, bool painting)
 {
     ASSERT(buttonsPlacement() == ScrollbarButtonsPlacementNone);
     return IntRect();
 }
 
-IntRect ScrollbarThemeMacOverlayAPI::trackRect(const ScrollbarThemeClient* scrollbar, bool painting)
+IntRect ScrollbarThemeMacOverlayAPI::trackRect(const ScrollbarThemeClient& scrollbar, bool painting)
 {
     ASSERT(!hasButtons(scrollbar));
-    return scrollbar->frameRect();
+    return scrollbar.frameRect();
 }
 
-int ScrollbarThemeMacOverlayAPI::minimumThumbLength(const ScrollbarThemeClient* scrollbar)
+int ScrollbarThemeMacOverlayAPI::minimumThumbLength(const ScrollbarThemeClient& scrollbar)
 {
     return [painterForScrollbar(scrollbar) knobMinLength];
 }
 
-void ScrollbarThemeMacOverlayAPI::updateEnabledState(const ScrollbarThemeClient* scrollbar)
+void ScrollbarThemeMacOverlayAPI::updateEnabledState(const ScrollbarThemeClient& scrollbar)
 {
-    [painterForScrollbar(scrollbar) setEnabled:scrollbar->enabled()];
+    [painterForScrollbar(scrollbar) setEnabled:scrollbar.enabled()];
 }
 
-float ScrollbarThemeMacOverlayAPI::thumbOpacity(const ScrollbarThemeClient* scrollbar) const {
+float ScrollbarThemeMacOverlayAPI::thumbOpacity(const ScrollbarThemeClient& scrollbar) const {
     ScrollbarPainter scrollbarPainter = painterForScrollbar(scrollbar);
     return [scrollbarPainter knobAlpha];
 }
 
 } // namespace blink