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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#include "TouchActionHelper.h"
#include "mozilla/layers/IAPZCTreeManager.h"
#include "mozilla/PresShell.h"
#include "mozilla/TouchEvents.h"
#include "nsContainerFrame.h"
#include "nsIFrameInlines.h"
#include "nsIScrollableFrame.h"
#include "nsLayoutUtils.h"
namespace mozilla::layers {
static void UpdateAllowedBehavior(StyleTouchAction aTouchActionValue,
bool aConsiderPanning,
TouchBehaviorFlags& aOutBehavior) {
if (aTouchActionValue != StyleTouchAction::AUTO) {
// Double-tap-zooming need property value AUTO
aOutBehavior &= ~AllowedTouchBehavior::ANIMATING_ZOOM;
if (aTouchActionValue != StyleTouchAction::MANIPULATION &&
!(aTouchActionValue & StyleTouchAction::PINCH_ZOOM)) {
// Pinch-zooming needs value AUTO or MANIPULATION, or the PINCH_ZOOM bit
// set
aOutBehavior &= ~AllowedTouchBehavior::PINCH_ZOOM;
if (aConsiderPanning) {
if (aTouchActionValue == StyleTouchAction::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 & StyleTouchAction::PAN_X) &&
!(aTouchActionValue & StyleTouchAction::PAN_Y)) {
aOutBehavior &= ~AllowedTouchBehavior::VERTICAL_PAN;
} else if ((aTouchActionValue & StyleTouchAction::PAN_Y) &&
!(aTouchActionValue & StyleTouchAction::PAN_X)) {
aOutBehavior &= ~AllowedTouchBehavior::HORIZONTAL_PAN;
static TouchBehaviorFlags GetAllowedTouchBehaviorForPoint(
nsIWidget* aWidget, RelativeTo aRootFrame,
const LayoutDeviceIntPoint& aPoint) {
nsPoint relativePoint =
nsLayoutUtils::GetEventCoordinatesRelativeTo(aWidget, aPoint, aRootFrame);
nsIFrame* target = nsLayoutUtils::GetFrameForPoint(aRootFrame, relativePoint);
return TouchActionHelper::GetAllowedTouchBehaviorForFrame(target);
nsTArray<TouchBehaviorFlags> TouchActionHelper::GetAllowedTouchBehavior(
nsIWidget* aWidget, dom::Document* aDocument,
const WidgetTouchEvent& aEvent) {
nsTArray<TouchBehaviorFlags> flags;
if (!aWidget || !aDocument) {
return flags;
if (PresShell* presShell = aDocument->GetPresShell()) {
if (nsIFrame* rootFrame = presShell->GetRootFrame()) {
for (const auto& touch : aEvent.mTouches) {
aWidget, RelativeTo{rootFrame, ViewportType::Visual},
return flags;
TouchBehaviorFlags TouchActionHelper::GetAllowedTouchBehaviorForFrame(
nsIFrame* aFrame) {
TouchBehaviorFlags behavior = AllowedTouchBehavior::VERTICAL_PAN |
AllowedTouchBehavior::HORIZONTAL_PAN |
AllowedTouchBehavior::PINCH_ZOOM |
if (!aFrame) {
return behavior;
nsIScrollableFrame* nearestScrollableParent =
nsLayoutUtils::GetNearestScrollableFrame(aFrame, 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 = aFrame; frame && frame->GetContent() && behavior;
frame = frame->GetInFlowParent()) {
UpdateAllowedBehavior(frame->UsedTouchAction(), 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 mozilla::layers