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/*
* Copyright (C) 2014 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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.
*/
#include "config.h"
#include "AxisScrollSnapOffsets.h"
#include "HTMLCollection.h"
#include "HTMLElement.h"
#include "RenderBox.h"
#include "ScrollableArea.h"
#include "StyleScrollSnapPoints.h"
#if ENABLE(CSS_SCROLL_SNAP)
namespace WebCore {
static void appendChildSnapOffsets(HTMLElement& parent, bool shouldAddHorizontalChildOffsets, Vector<LayoutUnit>& horizontalSnapOffsetSubsequence, bool shouldAddVerticalChildOffsets, Vector<LayoutUnit>& verticalSnapOffsetSubsequence)
{
Element* child = parent.children()->collectionBegin();
// FIXME: Instead of traversing all children, register children with snap coordinates before appending to snapOffsetSubsequence.
while (child) {
if (RenderBox* box = child->renderBox()) {
LayoutUnit viewWidth = box->width();
LayoutUnit viewHeight = box->height();
#if PLATFORM(IOS)
// FIXME: Investigate why using localToContainerPoint gives the wrong offsets for iOS mainframe. Also, these offsets won't take transforms into account (make sure to test this!)
float left = child->offsetLeft();
float top = child->offsetTop();
#else
// FIXME: Check that localToContainerPoint works with CSS rotations.
FloatPoint position = box->localToContainerPoint(FloatPoint(), parent.renderBox());
float left = position.x();
float top = position.y();
#endif
for (auto& coordinate : box->style().scrollSnapCoordinates()) {
LayoutUnit lastPotentialSnapPositionX = LayoutUnit(left) + valueForLength(coordinate.width(), viewWidth);
if (shouldAddHorizontalChildOffsets && lastPotentialSnapPositionX > 0)
horizontalSnapOffsetSubsequence.append(lastPotentialSnapPositionX);
LayoutUnit lastPotentialSnapPositionY = LayoutUnit(top) + valueForLength(coordinate.height(), viewHeight);
if (shouldAddVerticalChildOffsets && lastPotentialSnapPositionY > 0)
verticalSnapOffsetSubsequence.append(lastPotentialSnapPositionY);
}
}
child = child->nextElementSibling();
}
}
static void updateFromStyle(Vector<LayoutUnit>& snapOffsets, const RenderStyle& style, ScrollEventAxis axis, LayoutUnit viewSize, LayoutUnit scrollSize, Vector<LayoutUnit>& snapOffsetSubsequence)
{
std::sort(snapOffsetSubsequence.begin(), snapOffsetSubsequence.end());
if (!snapOffsetSubsequence.size())
snapOffsetSubsequence.append(0);
bool isHorizontalAxis = axis == ScrollEventAxis::Horizontal;
auto& points = isHorizontalAxis ? style.scrollSnapPointsX() : style.scrollSnapPointsY();
auto& destination = style.scrollSnapDestination();
bool hasRepeat = points.hasRepeat;
LayoutUnit repeatOffset = valueForLength(points.repeatOffset, viewSize);
LayoutUnit destinationOffset = valueForLength(isHorizontalAxis ? destination.width() : destination.height(), viewSize);
LayoutUnit curSnapPositionShift = 0;
LayoutUnit maxScrollOffset = scrollSize - viewSize;
LayoutUnit lastSnapPosition = curSnapPositionShift;
snapOffsets.append(0);
do {
for (auto& snapPosition : snapOffsetSubsequence) {
LayoutUnit potentialSnapPosition = curSnapPositionShift + snapPosition - destinationOffset;
if (potentialSnapPosition <= 0)
continue;
if (potentialSnapPosition >= maxScrollOffset)
break;
snapOffsets.append(potentialSnapPosition);
lastSnapPosition = potentialSnapPosition + destinationOffset;
}
curSnapPositionShift = lastSnapPosition + repeatOffset;
} while (hasRepeat && curSnapPositionShift < maxScrollOffset);
// Always put a snap point on the maximum scroll offset.
// Not a part of the spec, but necessary to prevent unreachable content when snapping.
if (snapOffsets.last() != maxScrollOffset)
snapOffsets.append(maxScrollOffset);
}
void updateSnapOffsetsForScrollableArea(ScrollableArea& scrollableArea, HTMLElement& scrollingElement, const RenderBox& scrollingElementBox, const RenderStyle& scrollingElementStyle)
{
if (scrollingElementStyle.scrollSnapType() == ScrollSnapType::None) {
scrollableArea.clearHorizontalSnapOffsets();
scrollableArea.clearVerticalSnapOffsets();
return;
}
LayoutUnit viewWidth = scrollingElementBox.width();
LayoutUnit viewHeight = scrollingElementBox.height();
LayoutUnit scrollWidth = scrollingElementBox.scrollWidth();
LayoutUnit scrollHeight = scrollingElementBox.scrollHeight();
bool canComputeHorizontalOffsets = scrollWidth > 0 && viewWidth > 0 && viewWidth < scrollWidth;
bool canComputeVerticalOffsets = scrollHeight > 0 && viewHeight > 0 && viewHeight < scrollHeight;
if (!canComputeHorizontalOffsets)
scrollableArea.clearHorizontalSnapOffsets();
if (!canComputeVerticalOffsets)
scrollableArea.clearVerticalSnapOffsets();
if (!canComputeHorizontalOffsets && !canComputeVerticalOffsets)
return;
Vector<LayoutUnit> horizontalSnapOffsetSubsequence;
Vector<LayoutUnit> verticalSnapOffsetSubsequence;
if (scrollingElementStyle.scrollSnapPointsX().usesElements || scrollingElementStyle.scrollSnapPointsY().usesElements) {
bool shouldAddHorizontalChildOffsets = scrollingElementStyle.scrollSnapPointsX().usesElements && canComputeHorizontalOffsets;
bool shouldAddVerticalChildOffsets = scrollingElementStyle.scrollSnapPointsY().usesElements && canComputeVerticalOffsets;
appendChildSnapOffsets(scrollingElement, shouldAddHorizontalChildOffsets, horizontalSnapOffsetSubsequence, shouldAddVerticalChildOffsets, verticalSnapOffsetSubsequence);
}
if (!scrollingElementStyle.scrollSnapPointsX().usesElements && canComputeHorizontalOffsets) {
for (auto& snapLength : scrollingElementStyle.scrollSnapPointsX().offsets)
horizontalSnapOffsetSubsequence.append(valueForLength(snapLength, viewWidth));
}
if (!scrollingElementStyle.scrollSnapPointsY().usesElements && canComputeVerticalOffsets) {
for (auto& snapLength : scrollingElementStyle.scrollSnapPointsY().offsets)
verticalSnapOffsetSubsequence.append(valueForLength(snapLength, viewHeight));
}
if (canComputeHorizontalOffsets) {
auto horizontalSnapOffsets = std::make_unique<Vector<LayoutUnit>>();
updateFromStyle(*horizontalSnapOffsets, scrollingElementStyle, ScrollEventAxis::Horizontal, viewWidth, scrollWidth, horizontalSnapOffsetSubsequence);
scrollableArea.setHorizontalSnapOffsets(WTF::move(horizontalSnapOffsets));
}
if (canComputeVerticalOffsets) {
auto verticalSnapOffsets = std::make_unique<Vector<LayoutUnit>>();
updateFromStyle(*verticalSnapOffsets, scrollingElementStyle, ScrollEventAxis::Vertical, viewHeight, scrollHeight, verticalSnapOffsetSubsequence);
scrollableArea.setVerticalSnapOffsets(WTF::move(verticalSnapOffsets));
}
}
} // namespace WebCore
#endif // CSS_SCROLL_SNAP
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