Allow objects without scrollbars to be scrollable

Source/core/platform/ScrollableArea.cpp

Index: Source/core/platform/ScrollableArea.cpp
diff --git a/Source/core/platform/ScrollableArea.cpp b/Source/core/platform/ScrollableArea.cpp
index 0f02cf04bc2b3ff3a325ea00e11de5e29b5a5752..00b262cc61007bbfce56467260d6412ed5d37929 100644
--- a/Source/core/platform/ScrollableArea.cpp
+++ b/Source/core/platform/ScrollableArea.cpp
@@ -52,6 +52,12 @@ struct SameSizeAsScrollableArea {
 
 COMPILE_ASSERT(sizeof(ScrollableArea) == sizeof(SameSizeAsScrollableArea), ScrollableArea_should_stay_small);
 
+int ScrollableArea::maxOverlapBetweenPages()
+{
+    static int maxOverlapBetweenPages = ScrollbarTheme::theme()->maxOverlapBetweenPages();
+    return maxOverlapBetweenPages;
+}
+
 ScrollableArea::ScrollableArea()
     : m_constrainsScrollingToContentEdge(true)
     , m_inLiveResize(false)
@@ -85,32 +91,30 @@ void ScrollableArea::setScrollOrigin(const IntPoint& origin)
 bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granularity, float multiplier)
 {
     ScrollbarOrientation orientation;
-    Scrollbar* scrollbar;
-    if (direction == ScrollUp || direction == ScrollDown) {
+
+    if (direction == ScrollUp || direction == ScrollDown)
         orientation = VerticalScrollbar;
-        scrollbar = verticalScrollbar();
-    } else {
+    else
         orientation = HorizontalScrollbar;
-        scrollbar = horizontalScrollbar();
-    }
 
-    if (!scrollbar)
+    if (!userInputScrollable(orientation))
         return false;
 
     float step = 0;
+

[aelias_OOO_until_Jul13, 2013/06/19 22:25:12]

nit: accidental newline

[bokan, 2013/06/19 23:50:58]

Done.

     switch (granularity) {
     case ScrollByLine:
-        step = scrollbar->lineStep();
+        step = lineStep(orientation);
         break;
     case ScrollByPage:
-        step = scrollbar->pageStep();
+        step = pageStep(orientation);
         break;
     case ScrollByDocument:
-        step = scrollbar->totalSize();
+        step = documentStep(orientation);
         break;
     case ScrollByPixel:
     case ScrollByPrecisePixel:
-        step = scrollbar->pixelStep();
+        step = pixelStep(orientation);
         break;
     }
 
@@ -364,13 +368,6 @@ void ScrollableArea::serviceScrollAnimations()
         scrollAnimator->serviceScrollAnimations();
 }
 
-IntPoint ScrollableArea::scrollPosition() const
-{
-    int x = horizontalScrollbar() ? horizontalScrollbar()->value() : 0;
-    int y = verticalScrollbar() ? verticalScrollbar()->value() : 0;
-    return IntPoint(x, y);
-}
-
 IntPoint ScrollableArea::minimumScrollPosition() const
 {
     return IntPoint();
@@ -410,4 +407,28 @@ void ScrollableArea::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
     info.addMember(m_scrollAnimator, "scrollAnimator");
 }
 
+int ScrollableArea::lineStep(ScrollbarOrientation) const
+{
+    return pixelsPerLineStep();
+}
+
+int ScrollableArea::pageStep(ScrollbarOrientation orientation) const

[aelias_OOO_until_Jul13, 2013/06/19 22:25:12]

This code appears specific to ScrollView so I suggest making it pure virtual and
moving the implementation to ScrollView.cpp.

[bokan, 2013/06/19 23:50:58]

Done.

+{
+    int length = (orientation == HorizontalScrollbar) ? visibleWidth() : visibleHeight();
+    int minPageStep = static_cast<float>(length) * minFractionToStepWhenPaging();
+    int pageStep = std::max(minPageStep, length - maxOverlapBetweenPages());
+
+    return std::max(pageStep, 1);
+}
+
+int ScrollableArea::documentStep(ScrollbarOrientation orientation) const
+{
+    return scrollSize(orientation);
+}
+
+float ScrollableArea::pixelStep(ScrollbarOrientation) const
+{
+    return 1.0f;
+}
+
 } // namespace WebCore