Bug 1241275 - Change the way -moz-window-dragging works. r=heycam,roc

This adds the value -moz-window-dragging: default as the initial value of the property,
and makes it a [reset] property. This allows us to change the way the window dragging
region is calculated: Elements with -moz-window-dragging: no-drag will now always be
undraggable, even if they are overlapped by -moz-window-dragging: drag elements. That
way we can keep the region calculation simple and don't have to add code to respect
z-ordering.

--HG--
extra : commitid : GX3ApAyzKi7
extra : rebase_source : 61cab4e535c6c5da75fe79eb1886b6c5b7d136ea
extra : amend_source : 0f461782b8f65eca1009c2f6c192b5b80b908233

layout/base/nsDisplayList.cpp

@@ -1181,6 +1181,13 @@ nsDisplayListBuilder::AdjustWindowDraggingRegion(nsIFrame* aFrame)
     return;
   }
 
+  const nsStyleUIReset* styleUI = aFrame->StyleUIReset();
+  if (styleUI->mWindowDragging == NS_STYLE_WINDOW_DRAGGING_DEFAULT) {
+    // This frame has the default value and doesn't influence the window
+    // dragging region.
+    return;
+  }
+
   LayoutDeviceToLayoutDeviceMatrix4x4 referenceFrameToRootReferenceFrame;
 
   // The const_cast is for nsLayoutUtils::GetTransformToAncestor.
@@ -1230,16 +1237,23 @@ nsDisplayListBuilder::AdjustWindowDraggingRegion(nsIFrame* aFrame)
     transformedDevPixelBorderBox.Round();
     LayoutDeviceIntRect transformedDevPixelBorderBoxInt;
     if (transformedDevPixelBorderBox.ToIntRect(&transformedDevPixelBorderBoxInt)) {
-      const nsStyleUserInterface* styleUI = aFrame->StyleUserInterface();
       if (styleUI->mWindowDragging == NS_STYLE_WINDOW_DRAGGING_DRAG) {
         mWindowDraggingRegion.OrWith(transformedDevPixelBorderBoxInt);
       } else {
-        mWindowDraggingRegion.SubOut(transformedDevPixelBorderBoxInt);
+        mWindowNoDraggingRegion.OrWith(transformedDevPixelBorderBoxInt);
       }
     }
   }
 }
 
+LayoutDeviceIntRegion
+nsDisplayListBuilder::GetWindowDraggingRegion() const
+{
+  LayoutDeviceIntRegion result;
+  result.Sub(mWindowDraggingRegion, mWindowNoDraggingRegion);;
+  return result;
+}
+
 const uint32_t gWillChangeAreaMultiplier = 3;
 static uint32_t GetWillChangeCost(const nsSize& aSize) {
   // There's significant overhead for each layer created from Gecko

layout/base/nsDisplayList.h

@@ -614,11 +614,12 @@ public:
    * Adjusts mWindowDraggingRegion to take into account aFrame. If aFrame's
    * -moz-window-dragging value is |drag|, its border box is added to the
    * collected dragging region; if the value is |no-drag|, the border box is
-   * subtracted from the region.
+   * subtracted from the region; if the value is |default|, that frame does
+   * not influence the window dragging region.
    */
   void AdjustWindowDraggingRegion(nsIFrame* aFrame);
 
-  const LayoutDeviceIntRegion& GetWindowDraggingRegion() { return mWindowDraggingRegion; }
+  LayoutDeviceIntRegion GetWindowDraggingRegion() const;
 
   /**
    * Allocate memory in our arena. It will only be freed when this display list
@@ -1227,6 +1228,7 @@ private:
   nsRegion                       mWindowExcludeGlassRegion;
   nsRegion                       mWindowOpaqueRegion;
   LayoutDeviceIntRegion          mWindowDraggingRegion;
+  LayoutDeviceIntRegion          mWindowNoDraggingRegion;
   // The display item for the Windows window glass background, if any
   nsDisplayItem*                 mGlassDisplayItem;
   // When encountering inactive layers, we need to hoist scroll info items

layout/style/nsCSSPropList.h

@@ -3674,7 +3674,7 @@ CSS_PROP_POSITION(
     kWidthKTable,
     offsetof(nsStylePosition, mWidth),
     eStyleAnimType_Coord)
-CSS_PROP_USERINTERFACE(
+CSS_PROP_UIRESET(
     -moz-window-dragging,
     _moz_window_dragging,
     CSS_PROP_DOMPROP_PREFIXED(WindowDragging),

layout/style/nsCSSProps.cpp

@@ -2116,6 +2116,7 @@ const KTableEntry nsCSSProps::kWidthKTable[] = {
 };
 
 const KTableEntry nsCSSProps::kWindowDraggingKTable[] = {
+  { eCSSKeyword_default, NS_STYLE_WINDOW_DRAGGING_DEFAULT },
   { eCSSKeyword_drag, NS_STYLE_WINDOW_DRAGGING_DRAG },
   { eCSSKeyword_no_drag, NS_STYLE_WINDOW_DRAGGING_NO_DRAG },
   { eCSSKeyword_UNKNOWN, -1 }

layout/style/nsComputedDOMStyle.cpp

@@ -3844,7 +3844,7 @@ nsComputedDOMStyle::DoGetWindowDragging()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
   val->SetIdent(
-    nsCSSProps::ValueToKeywordEnum(StyleUserInterface()->mWindowDragging,
+    nsCSSProps::ValueToKeywordEnum(StyleUIReset()->mWindowDragging,
                                    nsCSSProps::kWindowDraggingKTable));
   return val.forget();
 }

layout/style/nsRuleNode.cpp

@@ -4863,13 +4863,6 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
               parentUI->mUserFocus,
               NS_STYLE_USER_FOCUS_NONE, 0, 0, 0, 0);
 
-  // -moz-window-dragging: enum, inherit, initial
-  SetDiscrete(*aRuleData->ValueForWindowDragging(),
-              ui->mWindowDragging, conditions,
-              SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
-              parentUI->mWindowDragging,
-              NS_STYLE_WINDOW_DRAGGING_NO_DRAG, 0, 0, 0, 0);
-
   COMPUTE_END_INHERITED(UserInterface, ui)
 }
 
@@ -4905,6 +4898,13 @@ nsRuleNode::ComputeUIResetData(void* aStartStruct,
               parentUI->mForceBrokenImageIcon,
               0, 0, 0, 0, 0);
 
+  // -moz-window-dragging: enum, inherit, initial
+  SetDiscrete(*aRuleData->ValueForWindowDragging(),
+              ui->mWindowDragging, conditions,
+              SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
+              parentUI->mWindowDragging,
+              NS_STYLE_WINDOW_DRAGGING_DEFAULT, 0, 0, 0, 0);
+
   // -moz-window-shadow: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWindowShadow(),
               ui->mWindowShadow, conditions,

layout/style/nsStyleConsts.h

@@ -120,8 +120,9 @@ enum class StyleBoxSizing : uint8_t {
 #define NS_STYLE_USER_MODIFY_WRITE_ONLY  2
 
 // -moz-window-dragging
-#define NS_STYLE_WINDOW_DRAGGING_DRAG    0
-#define NS_STYLE_WINDOW_DRAGGING_NO_DRAG 1
+#define NS_STYLE_WINDOW_DRAGGING_DEFAULT 0
+#define NS_STYLE_WINDOW_DRAGGING_DRAG    1
+#define NS_STYLE_WINDOW_DRAGGING_NO_DRAG 2
 
 // box-align
 #define NS_STYLE_BOX_ALIGN_STRETCH     0

layout/style/nsStyleStruct.cpp

@@ -3789,7 +3789,6 @@ nsStyleUserInterface::nsStyleUserInterface(void)
   mUserInput = NS_STYLE_USER_INPUT_AUTO;
   mUserModify = NS_STYLE_USER_MODIFY_READ_ONLY;
   mUserFocus = NS_STYLE_USER_FOCUS_NONE;
-  mWindowDragging = NS_STYLE_WINDOW_DRAGGING_NO_DRAG;
 
   mCursor = NS_STYLE_CURSOR_AUTO; // fix for bugzilla bug 51113
 
@@ -3801,7 +3800,6 @@ nsStyleUserInterface::nsStyleUserInterface(const nsStyleUserInterface& aSource)
   mUserInput(aSource.mUserInput),
   mUserModify(aSource.mUserModify),
   mUserFocus(aSource.mUserFocus),
-  mWindowDragging(aSource.mWindowDragging),
   mCursor(aSource.mCursor)
 { 
   MOZ_COUNT_CTOR(nsStyleUserInterface);
@@ -3841,10 +3839,6 @@ nsChangeHint nsStyleUserInterface::CalcDifference(const nsStyleUserInterface& aO
     NS_UpdateHint(hint, nsChangeHint_NeutralChange);
   }
 
-  if (mWindowDragging != aOther.mWindowDragging) {
-    NS_UpdateHint(hint, nsChangeHint_SchedulePaint);
-  }
-
   return hint;
 }
 
@@ -3873,6 +3867,7 @@ nsStyleUIReset::nsStyleUIReset(void)
   mUserSelect = NS_STYLE_USER_SELECT_AUTO;
   mForceBrokenImageIcon = 0;
   mIMEMode = NS_STYLE_IME_MODE_AUTO;
+  mWindowDragging = NS_STYLE_WINDOW_DRAGGING_DEFAULT;
   mWindowShadow = NS_STYLE_WINDOW_SHADOW_DEFAULT;
 }
 
@@ -3882,6 +3877,7 @@ nsStyleUIReset::nsStyleUIReset(const nsStyleUIReset& aSource)
   mUserSelect = aSource.mUserSelect;
   mForceBrokenImageIcon = aSource.mForceBrokenImageIcon;
   mIMEMode = aSource.mIMEMode;
+  mWindowDragging = aSource.mWindowDragging;
   mWindowShadow = aSource.mWindowShadow;
 }
 
@@ -3903,6 +3899,11 @@ nsChangeHint nsStyleUIReset::CalcDifference(const nsStyleUIReset& aOther) const
   }
   if (mUserSelect != aOther.mUserSelect)
     return NS_STYLE_HINT_VISUAL;
+
+  if (mWindowDragging != aOther.mWindowDragging) {
+    return nsChangeHint_SchedulePaint;
+  }
+
   return NS_STYLE_HINT_NONE;
 }
 

layout/style/nsStyleStruct.h

@@ -2951,6 +2951,7 @@ struct nsStyleUIReset
   uint8_t   mUserSelect;      // [reset] (selection-style)
   uint8_t   mForceBrokenImageIcon; // [reset]  (0 if not forcing, otherwise forcing)
   uint8_t   mIMEMode;         // [reset]
+  uint8_t   mWindowDragging;  // [reset]
   uint8_t   mWindowShadow;    // [reset]
 };
 
@@ -3017,7 +3018,6 @@ struct nsStyleUserInterface
   uint8_t   mUserInput;       // [inherited]
   uint8_t   mUserModify;      // [inherited] (modify-content)
   uint8_t   mUserFocus;       // [inherited] (auto-select)
-  uint8_t   mWindowDragging;  // [inherited]
 
   uint8_t   mCursor;          // [inherited] See nsStyleConsts.h
 

layout/style/test/property_database.js

@@ -4434,10 +4434,10 @@ var gCSSProperties = {
   },
   "-moz-window-dragging": {
     domProp: "MozWindowDragging",
-    inherited: true,
+    inherited: false,
     type: CSS_TYPE_LONGHAND,
-    initial_values: [ "no-drag" ],
-    other_values: [ "drag" ],
+    initial_values: [ "default" ],
+    other_values: [ "drag", "no-drag" ],
     invalid_values: [ "none" ]
   },
   "align-content": {