/* -*- 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 http://mozilla.org/MPL/2.0/. */

#include "TouchActionHelper.h"

#include "mozilla/layers/IAPZCTreeManager.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