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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "TouchActionHelper.h"
#include "mozilla/layers/APZCTreeManager.h"
#include "nsContainerFrame.h"
#include "nsIScrollableFrame.h"
#include "nsLayoutUtils.h"
namespace mozilla {
namespace layers {
void
TouchActionHelper::UpdateAllowedBehavior(uint32_t aTouchActionValue,
bool aConsiderPanning,
TouchBehaviorFlags& aOutBehavior)
{
if (aTouchActionValue != NS_STYLE_TOUCH_ACTION_AUTO) {
// Double-tap-zooming need property value AUTO
aOutBehavior &= ~AllowedTouchBehavior::DOUBLE_TAP_ZOOM;
if (aTouchActionValue != NS_STYLE_TOUCH_ACTION_MANIPULATION) {
// Pinch-zooming need value AUTO or MANIPULATION
aOutBehavior &= ~AllowedTouchBehavior::PINCH_ZOOM;
}
}
if (aConsiderPanning) {
if (aTouchActionValue == NS_STYLE_TOUCH_ACTION_NONE) {
aOutBehavior &= ~AllowedTouchBehavior::VERTICAL_PAN;
aOutBehavior &= ~AllowedTouchBehavior::HORIZONTAL_PAN;
}
// Values pan-x and pan-y set at the same time to the same element do not affect panning constraints.
// Therefore we need to check whether pan-x is set without pan-y and the same for pan-y.
if ((aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_X) && !(aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_Y)) {
aOutBehavior &= ~AllowedTouchBehavior::VERTICAL_PAN;
} else if ((aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_Y) && !(aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_X)) {
aOutBehavior &= ~AllowedTouchBehavior::HORIZONTAL_PAN;
}
}
}
TouchBehaviorFlags
TouchActionHelper::GetAllowedTouchBehavior(nsIWidget* aWidget,
nsIFrame* aRootFrame,
const LayoutDeviceIntPoint& aPoint)
{
TouchBehaviorFlags behavior = AllowedTouchBehavior::VERTICAL_PAN | AllowedTouchBehavior::HORIZONTAL_PAN |
AllowedTouchBehavior::PINCH_ZOOM | AllowedTouchBehavior::DOUBLE_TAP_ZOOM;
nsPoint relativePoint =
nsLayoutUtils::GetEventCoordinatesRelativeTo(aWidget, aPoint, aRootFrame);
nsIFrame *target = nsLayoutUtils::GetFrameForPoint(aRootFrame, relativePoint, nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME);
if (!target) {
return behavior;
}
nsIScrollableFrame *nearestScrollableParent = nsLayoutUtils::GetNearestScrollableFrame(target, 0);
nsIFrame* nearestScrollableFrame = do_QueryFrame(nearestScrollableParent);
// We're walking up the DOM tree until we meet the element with touch behavior and accumulating
// touch-action restrictions of all elements in this chain.
// The exact quote from the spec, that clarifies more:
// To determine the effect of a touch, find the nearest ancestor (starting from the element itself)
// that has a default touch behavior. Then examine the touch-action property of each element between
// the hit tested element and the element with the default touch behavior (including both the hit
// tested element and the element with the default touch behavior). If the touch-action property of
// any of those elements disallows the default touch behavior, do nothing. Otherwise allow the element
// to start considering the touch for the purposes of executing a default touch behavior.
// Currently we support only two touch behaviors: panning and zooming.
// For panning we walk up until we meet the first scrollable element (the element that supports panning)
// or root element.
// For zooming we walk up until the root element since Firefox currently supports only zooming of the
// root frame but not the subframes.
bool considerPanning = true;
for (nsIFrame *frame = target; frame && frame->GetContent() && behavior; frame = frame->GetParent()) {
UpdateAllowedBehavior(nsLayoutUtils::GetTouchActionFromFrame(frame), considerPanning, behavior);
if (frame == nearestScrollableFrame) {
// We met the scrollable element, after it we shouldn't consider touch-action
// values for the purpose of panning but only for zooming.
considerPanning = false;
}
}
return behavior;
}
} // namespace layers
} // namespace mozilla
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