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

third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacNonOverlayAPI.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 50 matching lines @@
 
 void ScrollbarThemeMacNonOverlayAPI::updateButtonPlacement(ScrollbarButtonsPlacement buttonPlacement)
 {
     gButtonPlacement = buttonPlacement;
 }
 
 // Override ScrollbarThemeMacCommon::paint() to add support for the following:
 //     - drawing using WebThemeEngine functions
 //     - drawing tickmarks
 //     - Skia specific changes
-bool ScrollbarThemeMacNonOverlayAPI::paint(const ScrollbarThemeClient* scrollbar, GraphicsContext* context, const CullRect& cullRect)
+bool ScrollbarThemeMacNonOverlayAPI::paint(const ScrollbarThemeClient& scrollbar, GraphicsContext& context, const CullRect& cullRect)
 {
-    DisplayItem::Type displayItemType = scrollbar->orientation() == HorizontalScrollbar ? DisplayItem::ScrollbarHorizontal : DisplayItem::ScrollbarVertical;
-    if (DrawingRecorder::useCachedDrawingIfPossible(*context, *scrollbar, displayItemType))
+    DisplayItem::Type displayItemType = scrollbar.orientation() == HorizontalScrollbar ? DisplayItem::ScrollbarHorizontal : DisplayItem::ScrollbarVertical;
+    if (DrawingRecorder::useCachedDrawingIfPossible(context, scrollbar, displayItemType))
         return true;
 
-    DrawingRecorder recorder(*context, *scrollbar, displayItemType, scrollbar->frameRect());
+    DrawingRecorder recorder(context, scrollbar, displayItemType, scrollbar.frameRect());
 
     // Get the tickmarks for the frameview.
     Vector<IntRect> tickmarks;
-    scrollbar->getTickmarks(tickmarks);
+    scrollbar.getTickmarks(tickmarks);
 
     HIThemeTrackDrawInfo trackInfo;
     trackInfo.version = 0;
-    trackInfo.kind = scrollbar->controlSize() == RegularScrollbar ? kThemeMediumScrollBar : kThemeSmallScrollBar;
-    trackInfo.bounds = scrollbar->frameRect();
+    trackInfo.kind = scrollbar.controlSize() == RegularScrollbar ? kThemeMediumScrollBar : kThemeSmallScrollBar;
+    trackInfo.bounds = scrollbar.frameRect();
     trackInfo.min = 0;
-    trackInfo.max = scrollbar->maximum();
-    trackInfo.value = scrollbar->currentPos();
-    trackInfo.trackInfo.scrollbar.viewsize = scrollbar->visibleSize();
+    trackInfo.max = scrollbar.maximum();
+    trackInfo.value = scrollbar.currentPos();
+    trackInfo.trackInfo.scrollbar.viewsize = scrollbar.visibleSize();
     trackInfo.attributes = hasThumb(scrollbar) ? kThemeTrackShowThumb : 0;
 
-    if (scrollbar->orientation() == HorizontalScrollbar)
+    if (scrollbar.orientation() == HorizontalScrollbar)
         trackInfo.attributes |= kThemeTrackHorizontal;
 
-    if (!scrollbar->enabled())
+    if (!scrollbar.enabled())
         trackInfo.enableState = kThemeTrackDisabled;
     else
-        trackInfo.enableState = scrollbar->isScrollableAreaActive() ? kThemeTrackActive : kThemeTrackInactive;
+        trackInfo.enableState = scrollbar.isScrollableAreaActive() ? kThemeTrackActive : kThemeTrackInactive;
 
     if (!hasButtons(scrollbar))
         trackInfo.enableState = kThemeTrackNothingToScroll;
-    trackInfo.trackInfo.scrollbar.pressState = scrollbarPartToHIPressedState(scrollbar->pressedPart());
+    trackInfo.trackInfo.scrollbar.pressState = scrollbarPartToHIPressedState(scrollbar.pressedPart());
 
-    SkCanvas* canvas = context->canvas();
+    SkCanvas* canvas = context.canvas();
     CGAffineTransform currentCTM = gfx::SkMatrixToCGAffineTransform(canvas->getTotalMatrix());
 
     // The Aqua scrollbar is buggy when rotated and scaled.  We will just draw into a bitmap if we detect a scale or rotation.
     bool canDrawDirectly = currentCTM.a == 1.0f && currentCTM.b == 0.0f && currentCTM.c == 0.0f && (currentCTM.d == 1.0f || currentCTM.d == -1.0f);
     OwnPtr<ImageBuffer> imageBuffer;
     SkCanvas* drawingCanvas;
     if (!canDrawDirectly) {
-        trackInfo.bounds = IntRect(IntPoint(), scrollbar->frameRect().size());
+        trackInfo.bounds = IntRect(IntPoint(), scrollbar.frameRect().size());
 
-        IntRect bufferRect(scrollbar->frameRect());
+        IntRect bufferRect(scrollbar.frameRect());
         bufferRect.intersect(cullRect.m_rect);
-        bufferRect.move(-scrollbar->frameRect().x(), -scrollbar->frameRect().y());
+        bufferRect.move(-scrollbar.frameRect().x(), -scrollbar.frameRect().y());
 
         imageBuffer = ImageBuffer::create(bufferRect.size());
         if (!imageBuffer)
             return true;
 
         drawingCanvas = imageBuffer->canvas();
     } else {
         drawingCanvas = canvas;
     }
 
     // Draw the track and its thumb.
     gfx::SkiaBitLocker bitLocker(
         drawingCanvas,
-        ThemeMac::inflateRectForAA(scrollbar->frameRect()),
-        canDrawDirectly ? context->deviceScaleFactor() : 1.0f);
+        ThemeMac::inflateRectForAA(scrollbar.frameRect()),
+        canDrawDirectly ? context.deviceScaleFactor() : 1.0f);
     CGContextRef cgContext = bitLocker.cgContext();
     HIThemeDrawTrack(&trackInfo, 0, cgContext, kHIThemeOrientationNormal);
 
     IntRect tickmarkTrackRect = trackRect(scrollbar, false);
     if (!canDrawDirectly) {
         tickmarkTrackRect.setX(0);
         tickmarkTrackRect.setY(0);
     }
     // The ends are rounded and the thumb doesn't go there.
     tickmarkTrackRect.inflateY(-tickmarkTrackRect.width());
     // Inset a bit.
     tickmarkTrackRect.setX(tickmarkTrackRect.x() + 2);
     tickmarkTrackRect.setWidth(tickmarkTrackRect.width() - 5);
     paintGivenTickmarks(drawingCanvas, scrollbar, tickmarkTrackRect, tickmarks);
 
     if (!canDrawDirectly) {
         ASSERT(imageBuffer);
-        if (!context->contextDisabled()) {
-            imageBuffer->draw(context, FloatRect(scrollbar->frameRect().location(), FloatSize(imageBuffer->size())),
+        if (!context.contextDisabled()) {
+            imageBuffer->draw(&context, FloatRect(scrollbar.frameRect().location(), FloatSize(imageBuffer->size())),
                 nullptr, SkXfermode::kSrcOver_Mode);
         }
     }
 
     return true;
 }
 
 int ScrollbarThemeMacNonOverlayAPI::scrollbarThickness(ScrollbarControlSize controlSize)
 {
     return cScrollbarThickness[controlSize];
 }
 
 ScrollbarButtonsPlacement ScrollbarThemeMacNonOverlayAPI::buttonsPlacement() const
 {
     return gButtonPlacement;
 }
 
-bool ScrollbarThemeMacNonOverlayAPI::hasButtons(const ScrollbarThemeClient* scrollbar)
+bool ScrollbarThemeMacNonOverlayAPI::hasButtons(const ScrollbarThemeClient& scrollbar)
 {
-    return scrollbar->enabled() && buttonsPlacement() != ScrollbarButtonsPlacementNone
-             && (scrollbar->orientation() == HorizontalScrollbar
-             ? scrollbar->width()
-             : scrollbar->height()) >= 2 * (cRealButtonLength[scrollbar->controlSize()] - cButtonHitInset[scrollbar->controlSize()]);
+    return scrollbar.enabled() && buttonsPlacement() != ScrollbarButtonsPlacementNone
+             && (scrollbar.orientation() == HorizontalScrollbar
+             ? scrollbar.width()
+             : scrollbar.height()) >= 2 * (cRealButtonLength[scrollbar.controlSize()] - cButtonHitInset[scrollbar.controlSize()]);
 }
 
-bool ScrollbarThemeMacNonOverlayAPI::hasThumb(const ScrollbarThemeClient* scrollbar)
+bool ScrollbarThemeMacNonOverlayAPI::hasThumb(const ScrollbarThemeClient& scrollbar)
 {
-    int minLengthForThumb = 2 * cButtonInset[scrollbar->controlSize()] + cThumbMinLength[scrollbar->controlSize()] + 1;
-    return scrollbar->enabled() && (scrollbar->orientation() == HorizontalScrollbar ?
-             scrollbar->width() :
-             scrollbar->height()) >= minLengthForThumb;
+    int minLengthForThumb = 2 * cButtonInset[scrollbar.controlSize()] + cThumbMinLength[scrollbar.controlSize()] + 1;
+    return scrollbar.enabled() && (scrollbar.orientation() == HorizontalScrollbar ?
+             scrollbar.width() :
+             scrollbar.height()) >= minLengthForThumb;
 }
 
 static IntRect buttonRepaintRect(const IntRect& buttonRect, ScrollbarOrientation orientation, ScrollbarControlSize controlSize, bool start)
 {
     ASSERT(gButtonPlacement != ScrollbarButtonsPlacementNone);
 
     IntRect paintRect(buttonRect);
     if (orientation == HorizontalScrollbar) {
         paintRect.setWidth(cRealButtonLength[controlSize]);
         if (!start)
             paintRect.setX(buttonRect.x() - (cRealButtonLength[controlSize] - buttonRect.width()));
     } else {
         paintRect.setHeight(cRealButtonLength[controlSize]);
         if (!start)
             paintRect.setY(buttonRect.y() - (cRealButtonLength[controlSize] - buttonRect.height()));
     }
 
     return paintRect;
 }
 
-IntRect ScrollbarThemeMacNonOverlayAPI::backButtonRect(const ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
+IntRect ScrollbarThemeMacNonOverlayAPI::backButtonRect(const ScrollbarThemeClient& scrollbar, ScrollbarPart part, bool painting)
 {
     IntRect result;
 
     if (part == BackButtonStartPart && (buttonsPlacement() == ScrollbarButtonsPlacementNone || buttonsPlacement() == ScrollbarButtonsPlacementDoubleEnd))
         return result;
 
     if (part == BackButtonEndPart && (buttonsPlacement() == ScrollbarButtonsPlacementNone || buttonsPlacement() == ScrollbarButtonsPlacementDoubleStart || buttonsPlacement() == ScrollbarButtonsPlacementSingle))
         return result;
 
-    int thickness = scrollbarThickness(scrollbar->controlSize());
+    int thickness = scrollbarThickness(scrollbar.controlSize());
     bool outerButton = part == BackButtonStartPart && (buttonsPlacement() == ScrollbarButtonsPlacementDoubleStart || buttonsPlacement() == ScrollbarButtonsPlacementDoubleBoth);
     if (outerButton) {
-        if (scrollbar->orientation() == HorizontalScrollbar)
-            result = IntRect(scrollbar->x(), scrollbar->y(), cOuterButtonLength[scrollbar->controlSize()] + (painting ? cOuterButtonOverlap : 0), thickness);
+        if (scrollbar.orientation() == HorizontalScrollbar)
+            result = IntRect(scrollbar.x(), scrollbar.y(), cOuterButtonLength[scrollbar.controlSize()] + (painting ? cOuterButtonOverlap : 0), thickness);
         else
-            result = IntRect(scrollbar->x(), scrollbar->y(), thickness, cOuterButtonLength[scrollbar->controlSize()] + (painting ? cOuterButtonOverlap : 0));
+            result = IntRect(scrollbar.x(), scrollbar.y(), thickness, cOuterButtonLength[scrollbar.controlSize()] + (painting ? cOuterButtonOverlap : 0));
         return result;
     }
 
     // Our repaint rect is slightly larger, since we are a button that is adjacent to the track.
-    if (scrollbar->orientation() == HorizontalScrollbar) {
-        int start = part == BackButtonStartPart ? scrollbar->x() : scrollbar->x() + scrollbar->width() - cOuterButtonLength[scrollbar->controlSize()] - cButtonLength[scrollbar->controlSize()];
-        result = IntRect(start, scrollbar->y(), cButtonLength[scrollbar->controlSize()], thickness);
+    if (scrollbar.orientation() == HorizontalScrollbar) {
+        int start = part == BackButtonStartPart ? scrollbar.x() : scrollbar.x() + scrollbar.width() - cOuterButtonLength[scrollbar.controlSize()] - cButtonLength[scrollbar.controlSize()];
+        result = IntRect(start, scrollbar.y(), cButtonLength[scrollbar.controlSize()], thickness);
     } else {
-        int start = part == BackButtonStartPart ? scrollbar->y() : scrollbar->y() + scrollbar->height() - cOuterButtonLength[scrollbar->controlSize()] - cButtonLength[scrollbar->controlSize()];
-        result = IntRect(scrollbar->x(), start, thickness, cButtonLength[scrollbar->controlSize()]);
+        int start = part == BackButtonStartPart ? scrollbar.y() : scrollbar.y() + scrollbar.height() - cOuterButtonLength[scrollbar.controlSize()] - cButtonLength[scrollbar.controlSize()];
+        result = IntRect(scrollbar.x(), start, thickness, cButtonLength[scrollbar.controlSize()]);
     }
 
     if (painting)
-        return buttonRepaintRect(result, scrollbar->orientation(), scrollbar->controlSize(), part == BackButtonStartPart);
+        return buttonRepaintRect(result, scrollbar.orientation(), scrollbar.controlSize(), part == BackButtonStartPart);
     return result;
 }
 
-IntRect ScrollbarThemeMacNonOverlayAPI::forwardButtonRect(const ScrollbarThemeClient* scrollbar, ScrollbarPart part, bool painting)
+IntRect ScrollbarThemeMacNonOverlayAPI::forwardButtonRect(const ScrollbarThemeClient& scrollbar, ScrollbarPart part, bool painting)
 {
     IntRect result;
 
     if (part == ForwardButtonEndPart && (buttonsPlacement() == ScrollbarButtonsPlacementNone || buttonsPlacement() == ScrollbarButtonsPlacementDoubleStart))
         return result;
 
     if (part == ForwardButtonStartPart && (buttonsPlacement() == ScrollbarButtonsPlacementNone || buttonsPlacement() == ScrollbarButtonsPlacementDoubleEnd || buttonsPlacement() == ScrollbarButtonsPlacementSingle))
         return result;
 
-    int thickness = scrollbarThickness(scrollbar->controlSize());
-    int outerButtonLength = cOuterButtonLength[scrollbar->controlSize()];
-    int buttonLength = cButtonLength[scrollbar->controlSize()];
+    int thickness = scrollbarThickness(scrollbar.controlSize());
+    int outerButtonLength = cOuterButtonLength[scrollbar.controlSize()];
+    int buttonLength = cButtonLength[scrollbar.controlSize()];
 
     bool outerButton = part == ForwardButtonEndPart && (buttonsPlacement() == ScrollbarButtonsPlacementDoubleEnd || buttonsPlacement() == ScrollbarButtonsPlacementDoubleBoth);
     if (outerButton) {
-        if (scrollbar->orientation() == HorizontalScrollbar) {
-            result = IntRect(scrollbar->x() + scrollbar->width() - outerButtonLength, scrollbar->y(), outerButtonLength, thickness);
+        if (scrollbar.orientation() == HorizontalScrollbar) {
+            result = IntRect(scrollbar.x() + scrollbar.width() - outerButtonLength, scrollbar.y(), outerButtonLength, thickness);
             if (painting)
                 result.inflateX(cOuterButtonOverlap);
         } else {
-            result = IntRect(scrollbar->x(), scrollbar->y() + scrollbar->height() - outerButtonLength, thickness, outerButtonLength);
+            result = IntRect(scrollbar.x(), scrollbar.y() + scrollbar.height() - outerButtonLength, thickness, outerButtonLength);
             if (painting)
                 result.inflateY(cOuterButtonOverlap);
         }
         return result;
     }
 
-    if (scrollbar->orientation() == HorizontalScrollbar) {
-        int start = part == ForwardButtonEndPart ? scrollbar->x() + scrollbar->width() - buttonLength : scrollbar->x() + outerButtonLength;
-        result = IntRect(start, scrollbar->y(), buttonLength, thickness);
+    if (scrollbar.orientation() == HorizontalScrollbar) {
+        int start = part == ForwardButtonEndPart ? scrollbar.x() + scrollbar.width() - buttonLength : scrollbar.x() + outerButtonLength;
+        result = IntRect(start, scrollbar.y(), buttonLength, thickness);
     } else {
-        int start = part == ForwardButtonEndPart ? scrollbar->y() + scrollbar->height() - buttonLength : scrollbar->y() + outerButtonLength;
-        result = IntRect(scrollbar->x(), start, thickness, buttonLength);
+        int start = part == ForwardButtonEndPart ? scrollbar.y() + scrollbar.height() - buttonLength : scrollbar.y() + outerButtonLength;
+        result = IntRect(scrollbar.x(), start, thickness, buttonLength);
     }
     if (painting)
-        return buttonRepaintRect(result, scrollbar->orientation(), scrollbar->controlSize(), part == ForwardButtonStartPart);
+        return buttonRepaintRect(result, scrollbar.orientation(), scrollbar.controlSize(), part == ForwardButtonStartPart);
     return result;
 }
 
-IntRect ScrollbarThemeMacNonOverlayAPI::trackRect(const ScrollbarThemeClient* scrollbar, bool painting)
+IntRect ScrollbarThemeMacNonOverlayAPI::trackRect(const ScrollbarThemeClient& scrollbar, bool painting)
 {
     if (painting || !hasButtons(scrollbar))
-        return scrollbar->frameRect();
+        return scrollbar.frameRect();
 
     IntRect result;
-    int thickness = scrollbarThickness(scrollbar->controlSize());
+    int thickness = scrollbarThickness(scrollbar.controlSize());
     int startWidth = 0;
     int endWidth = 0;
-    int outerButtonLength = cOuterButtonLength[scrollbar->controlSize()];
-    int buttonLength = cButtonLength[scrollbar->controlSize()];
+    int outerButtonLength = cOuterButtonLength[scrollbar.controlSize()];
+    int buttonLength = cButtonLength[scrollbar.controlSize()];
     int doubleButtonLength = outerButtonLength + buttonLength;
     switch (buttonsPlacement()) {
         case ScrollbarButtonsPlacementSingle:
             startWidth = buttonLength;
             endWidth = buttonLength;
             break;
         case ScrollbarButtonsPlacementDoubleStart:
             startWidth = doubleButtonLength;
             break;
         case ScrollbarButtonsPlacementDoubleEnd:
             endWidth = doubleButtonLength;
             break;
         case ScrollbarButtonsPlacementDoubleBoth:
             startWidth = doubleButtonLength;
             endWidth = doubleButtonLength;
             break;
         default:
             break;
     }
 
     int totalWidth = startWidth + endWidth;
-    if (scrollbar->orientation() == HorizontalScrollbar)
-        return IntRect(scrollbar->x() + startWidth, scrollbar->y(), scrollbar->width() - totalWidth, thickness);
-    return IntRect(scrollbar->x(), scrollbar->y() + startWidth, thickness, scrollbar->height() - totalWidth);
+    if (scrollbar.orientation() == HorizontalScrollbar)
+        return IntRect(scrollbar.x() + startWidth, scrollbar.y(), scrollbar.width() - totalWidth, thickness);
+    return IntRect(scrollbar.x(), scrollbar.y() + startWidth, thickness, scrollbar.height() - totalWidth);
 }
 
-int ScrollbarThemeMacNonOverlayAPI::minimumThumbLength(const ScrollbarThemeClient* scrollbar)
+int ScrollbarThemeMacNonOverlayAPI::minimumThumbLength(const ScrollbarThemeClient& scrollbar)
 {
-    return cThumbMinLength[scrollbar->controlSize()];
+    return cThumbMinLength[scrollbar.controlSize()];
 }
 
 }