widget/ContentHelper.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "ContentHelper.h"
   7
   8 #include "nsContainerFrame.h"
   9 #include "nsIContent.h"
  10 #include "nsIScrollableFrame.h"
  11 #include "nsLayoutUtils.h"
  12 #include "nsStyleConsts.h"
  13 #include "nsView.h"
  14
  15 namespace mozilla {
  16 namespace widget {
  17
  18 uint32_t
  19 ContentHelper::GetTouchActionFromFrame(nsIFrame* aFrame)
  20 {
  21   // If aFrame is null then return default value
  22   if (!aFrame) {
  23     return NS_STYLE_TOUCH_ACTION_AUTO;
  24   }
  25
  26   // The touch-action CSS property applies to: all elements except:
  27   // non-replaced inline elements, table rows, row groups, table columns, and column groups
  28   bool isNonReplacedInlineElement = aFrame->IsFrameOfType(nsIFrame::eLineParticipant);
  29   if (isNonReplacedInlineElement) {
  30     return NS_STYLE_TOUCH_ACTION_AUTO;
  31   }
  32
  33   const nsStyleDisplay* disp = aFrame->StyleDisplay();
  34   bool isTableElement = disp->IsInnerTableStyle() &&
  35                         disp->mDisplay != NS_STYLE_DISPLAY_TABLE_CELL &&
  36                         disp->mDisplay != NS_STYLE_DISPLAY_TABLE_CAPTION;
  37   if (isTableElement) {
  38     return NS_STYLE_TOUCH_ACTION_AUTO;
  39   }
  40
  41   return disp->mTouchAction;
  42 }
  43
  44 void
  45 ContentHelper::UpdateAllowedBehavior(uint32_t aTouchActionValue, bool aConsiderPanning, TouchBehaviorFlags& aOutBehavior)
  46 {
  47   if (aTouchActionValue != NS_STYLE_TOUCH_ACTION_AUTO) {
  48     // Double-tap-zooming need property value AUTO
  49     aOutBehavior &= ~AllowedTouchBehavior::DOUBLE_TAP_ZOOM;
  50     if (aTouchActionValue != NS_STYLE_TOUCH_ACTION_MANIPULATION) {
  51       // Pinch-zooming need value AUTO or MANIPULATION
  52       aOutBehavior &= ~AllowedTouchBehavior::PINCH_ZOOM;
  53     }
  54   }
  55
  56   if (aConsiderPanning) {
  57     if (aTouchActionValue == NS_STYLE_TOUCH_ACTION_NONE) {
  58       aOutBehavior &= ~AllowedTouchBehavior::VERTICAL_PAN;
  59       aOutBehavior &= ~AllowedTouchBehavior::HORIZONTAL_PAN;
  60     }
  61
  62     // Values pan-x and pan-y set at the same time to the same element do not affect panning constraints.
  63     // Therefore we need to check whether pan-x is set without pan-y and the same for pan-y.
  64     if ((aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_X) && !(aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_Y)) {
  65       aOutBehavior &= ~AllowedTouchBehavior::VERTICAL_PAN;
  66     } else if ((aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_Y) && !(aTouchActionValue & NS_STYLE_TOUCH_ACTION_PAN_X)) {
  67       aOutBehavior &= ~AllowedTouchBehavior::HORIZONTAL_PAN;
  68     }
  69   }
  70 }
  71
  72 ContentHelper::TouchBehaviorFlags
  73 ContentHelper::GetAllowedTouchBehavior(nsIWidget* aWidget, const nsIntPoint& aPoint)
  74 {
  75   nsView *view = nsView::GetViewFor(aWidget);
  76   nsIFrame *viewFrame = view->GetFrame();
  77
  78   nsPoint relativePoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(aWidget, aPoint, viewFrame);
  79
  80   nsIFrame *target = nsLayoutUtils::GetFrameForPoint(viewFrame, relativePoint, nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME);
  81   nsIScrollableFrame *nearestScrollableParent = nsLayoutUtils::GetNearestScrollableFrame(target, 0);
  82   nsIFrame* nearestScrollableFrame = do_QueryFrame(nearestScrollableParent);
  83
  84   // We're walking up the DOM tree until we meet the element with touch behavior and accumulating
  85   // touch-action restrictions of all elements in this chain.
  86   // The exact quote from the spec, that clarifies more:
  87   // To determine the effect of a touch, find the nearest ancestor (starting from the element itself)
  88   // that has a default touch behavior. Then examine the touch-action property of each element between
  89   // the hit tested element and the element with the default touch behavior (including both the hit
  90   // tested element and the element with the default touch behavior). If the touch-action property of
  91   // any of those elements disallows the default touch behavior, do nothing. Otherwise allow the element
  92   // to start considering the touch for the purposes of executing a default touch behavior.
  93
  94   // Currently we support only two touch behaviors: panning and zooming.
  95   // For panning we walk up until we meet the first scrollable element (the element that supports panning)
  96   // or root element.
  97   // For zooming we walk up until the root element since Firefox currently supports only zooming of the
  98   // root frame but not the subframes.
  99
 100   bool considerPanning = true;
 101   TouchBehaviorFlags behavior = AllowedTouchBehavior::VERTICAL_PAN | AllowedTouchBehavior::HORIZONTAL_PAN |
 102                                 AllowedTouchBehavior::PINCH_ZOOM | AllowedTouchBehavior::DOUBLE_TAP_ZOOM;
 103
 104   for (nsIFrame *frame = target; frame && frame->GetContent() && behavior; frame = frame->GetParent()) {
 105     UpdateAllowedBehavior(GetTouchActionFromFrame(frame), considerPanning, behavior);
 106
 107     if (frame == nearestScrollableFrame) {
 108       // We met the scrollable element, after it we shouldn't consider touch-action
 109       // values for the purpose of panning but only for zooming.
 110       considerPanning = false;
 111     }
 112   }
 113
 114   return behavior;
 115 }
 116
 117 }
 118 }