Commit 50f5bff4 authored by Nick Lebedev's avatar Nick Lebedev
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Bug 795567 - Part 2: Introduce ContentHelper class that will be responsible... 

Bug 795567 - Part 2: Introduce ContentHelper class that will be responsible for retrieving touch-action info from content and setting it to widget. r=kats
parent 8f48b7bb

widget/xpwidgets/ContentHelper.cpp

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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 "ContentHelper.h"

#include "nsQueryFrame.h"

#include "nsIContent.h"

#include "nsIScrollableFrame.h"

#include "nsLayoutUtils.h"

#include "nsStyleConsts.h"

#include "nsView.h"



namespace mozilla {

namespace widget {



uint32_t

ContentHelper::GetTouchActionFromFrame(nsIFrame* aFrame)

{

  if (!aFrame || !aFrame->GetContent() || !aFrame->GetContent()->GetPrimaryFrame()) {

    // If frame is invalid or null then return default value.

    return NS_STYLE_TOUCH_ACTION_AUTO;

  }



  if (!aFrame->IsFrameOfType(nsIFrame::eSVG) && !aFrame->IsFrameOfType(nsIFrame::eBlockFrame)) {

    // Since touch-action property can be applied to only svg and block-level

    // elements we ignore frames of other types.

    return NS_STYLE_TOUCH_ACTION_AUTO;

  }



  return (aFrame->GetContent()->GetPrimaryFrame()->StyleDisplay()->mTouchAction);

}



void

ContentHelper::UpdateAllowedBehavior(uint32_t aTouchActionValue, bool aConsiderPanning, TouchBehaviorFlags& aOutBehavior)

{

  if (aTouchActionValue != NS_STYLE_TOUCH_ACTION_AUTO) {

    // Dropping zoom flag since zooming requires touch-action values of all touches

    // to be AUTO.

    aOutBehavior &= ~AllowedTouchBehavior::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;

    }

  }

}



ContentHelper::TouchBehaviorFlags

ContentHelper::GetAllowedTouchBehavior(nsIWidget* aWidget, const nsIntPoint& aPoint)

{

  nsView *view = nsView::GetViewFor(aWidget);

  nsIFrame *viewFrame = view->GetFrame();



  nsPoint relativePoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(aWidget, aPoint, viewFrame);



  nsIFrame *target = nsLayoutUtils::GetFrameForPoint(viewFrame, relativePoint, nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME);

  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;

  TouchBehaviorFlags behavior = AllowedTouchBehavior::VERTICAL_PAN | AllowedTouchBehavior::HORIZONTAL_PAN |

                                AllowedTouchBehavior::ZOOM;



  for (nsIFrame *frame = target; frame && frame->GetContent() && behavior; frame = frame->GetParent()) {

    UpdateAllowedBehavior(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;

}



}

}
 
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widget/xpwidgets/ContentHelper.h

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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/. */



#ifndef __mozilla_widget_ContentHelper_h__

#define __mozilla_widget_ContentHelper_h__



#include "nsIFrame.h"

#include "nsIWidget.h"

#include "mozilla/layers/APZCTreeManager.h"



namespace mozilla {

namespace widget {



/*

 * Allow different platform widgets to access Content/DOM stuff.

 */

class ContentHelper

{

  typedef mozilla::layers::AllowedTouchBehavior AllowedTouchBehavior;

  typedef uint32_t TouchBehaviorFlags;



private:

  static uint32_t GetTouchActionFromFrame(nsIFrame* aFrame);

  static void UpdateAllowedBehavior(uint32_t aTouchActionValue, bool aConsiderPanning, TouchBehaviorFlags& aOutBehavior);



public:

  /*

   * Performs hit testing on content, finds frame that corresponds to the aPoint and retrieves

   * touch-action css property value from it according the rules specified in the spec:

   * http://www.w3.org/TR/pointerevents/#the-touch-action-css-property.

   */

  static TouchBehaviorFlags GetAllowedTouchBehavior(nsIWidget* aWidget, const nsIntPoint& aPoint);

};



}

}



#endif /*__mozilla_widget_ContentHelper_h__ */
 
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widget/xpwidgets/moz.build

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Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 


EXPORTS += [

    'APZCCallbackHelper.h',

    'ContentHelper.h',

    'GfxDriverInfo.h',

    'GfxInfoBase.h',

    'GfxInfoCollector.h',
@@ -13,6 +14,7 @@ EXPORTS += [ 


UNIFIED_SOURCES += [

    'APZCCallbackHelper.cpp',

    'ContentHelper.cpp',

    'GfxDriverInfo.cpp',

    'GfxInfoBase.cpp',

    'GfxInfoCollector.cpp',