Bug 977003 - Make async got/lostpointercapture events. r=smaug

content/base/public/Element.h

@@ -682,11 +682,16 @@ public:
       aError.Throw(NS_ERROR_DOM_INVALID_POINTER_ERR);
       return;
     }
-
-    // Ignoring ReleasePointerCapture call on incorrect element (on element
-    // that didn't have capture before).
-    if (nsIPresShell::GetPointerCapturingContent(aPointerId) == this) {
-      nsIPresShell::ReleasePointerCapturingContent(aPointerId, this);
+    nsIPresShell::PointerCaptureInfo* pointerCaptureInfo = nullptr;
+    if (nsIPresShell::gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo) && pointerCaptureInfo) {
+      // Call ReleasePointerCapture only on correct element
+      // (on element that have status pointer capture override
+      // or on element that have status pending pointer capture)
+      if (pointerCaptureInfo->mOverrideContent == this) {
+        nsIPresShell::ReleasePointerCapturingContent(aPointerId, this);
+      } else if (pointerCaptureInfo->mPendingContent == this) {
+        nsIPresShell::ReleasePointerCapturingContent(aPointerId, this);
+      }
     }
   }
   void SetCapture(bool aRetargetToElement)

layout/base/nsIPresShell.h

@@ -27,6 +27,7 @@
 #include "nsTHashtable.h"
 #include "nsHashKeys.h"
 #include "nsISupports.h"
+#include "nsIContent.h"
 #include "nsQueryFrame.h"
 #include "nsCoord.h"
 #include "nsColor.h"
@@ -43,7 +44,6 @@
 #include "nsMargin.h"
 #include "nsFrameState.h"
 
-class nsIContent;
 class nsDocShell;
 class nsIDocument;
 class nsIFrame;
@@ -1213,10 +1213,32 @@ public:
   static nsRefPtrHashtable<nsUint32HashKey, mozilla::dom::Touch>* gCaptureTouchList;
   static bool gPreventMouseEvents;
 
+  struct PointerCaptureInfo
+  {
+    nsCOMPtr<nsIContent> mPendingContent;
+    nsCOMPtr<nsIContent> mOverrideContent;
+    bool                 mReleaseContent;
+    
+    PointerCaptureInfo(nsIContent* aPendingContent) :
+      mPendingContent(aPendingContent), mReleaseContent(false)
+    {
+      MOZ_COUNT_CTOR(PointerCaptureInfo);
+    }
+    ~PointerCaptureInfo()
+    {
+      MOZ_COUNT_DTOR(PointerCaptureInfo);
+    }
+
+    bool Empty()
+    {
+      return !(mPendingContent || mOverrideContent);
+    }
+  };
+
   // Keeps a map between pointerId and element that currently capturing pointer
   // with such pointerId. If pointerId is absent in this map then nobody is
-  // capturing it.
-  static nsRefPtrHashtable<nsUint32HashKey, nsIContent>* gPointerCaptureList;
+  // capturing it. Additionally keep information about pending capturing content.
+  static nsClassHashtable<nsUint32HashKey, PointerCaptureInfo>* gPointerCaptureList;
 
   struct PointerInfo
   {
@@ -1229,11 +1251,12 @@ public:
   static nsClassHashtable<nsUint32HashKey, PointerInfo>* gActivePointersIds;
 
   static void DispatchGotOrLostPointerCaptureEvent(bool aIsGotCapture,
-                                                    uint32_t aPointerId,
-                                                    nsIContent* aCaptureTarget);
+                                                   uint32_t aPointerId,
+                                                   nsIContent* aCaptureTarget);
   static void SetPointerCapturingContent(uint32_t aPointerId, nsIContent* aContent);
   static void ReleasePointerCapturingContent(uint32_t aPointerId, nsIContent* aContent);
   static nsIContent* GetPointerCapturingContent(uint32_t aPointerId);
+  static void CheckPointerCaptureState(uint32_t aPointerId);
 
   // GetPointerInfo returns true if pointer with aPointerId is situated in device, false otherwise.
   // aActiveState is additional information, which shows state of pointer like button state for mouse.

layout/base/nsPresShell.cpp

@@ -201,7 +201,7 @@ CapturingContentInfo nsIPresShell::gCaptureInfo =
     false /* mPreventDrag */, nullptr /* mContent */ };
 nsIContent* nsIPresShell::gKeyDownTarget;
 nsRefPtrHashtable<nsUint32HashKey, dom::Touch>* nsIPresShell::gCaptureTouchList;
-nsRefPtrHashtable<nsUint32HashKey, nsIContent>* nsIPresShell::gPointerCaptureList;
+nsClassHashtable<nsUint32HashKey, nsIPresShell::PointerCaptureInfo>* nsIPresShell::gPointerCaptureList;
 nsClassHashtable<nsUint32HashKey, nsIPresShell::PointerInfo>* nsIPresShell::gActivePointersIds;
 bool nsIPresShell::gPreventMouseEvents = false;
 
@@ -6274,10 +6274,27 @@ nsIPresShell::SetCapturingContent(nsIContent* aContent, uint8_t aFlags)
   }
 }
 
+class AsyncCheckPointerCaptureStateCaller : public nsRunnable
+{
+public:
+  AsyncCheckPointerCaptureStateCaller(int32_t aPointerId) : mPointerId(aPointerId) {}
+
+  NS_IMETHOD Run()
+  {
+    nsIPresShell::CheckPointerCaptureState(mPointerId);
+    return NS_OK;
+  }
+
+private:
+  int32_t mPointerId;
+};
+
 /* static */ void
 nsIPresShell::SetPointerCapturingContent(uint32_t aPointerId, nsIContent* aContent)
 {
-  nsIContent* content = GetPointerCapturingContent(aPointerId);
+  PointerCaptureInfo* pointerCaptureInfo = nullptr;
+  gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo);
+  nsIContent* content = pointerCaptureInfo ? pointerCaptureInfo->mOverrideContent : nullptr;
 
   PointerInfo* pointerInfo = nullptr;
   if (!content && gActivePointersIds->Get(aPointerId, &pointerInfo) &&
@@ -6286,19 +6303,11 @@ nsIPresShell::SetPointerCapturingContent(uint32_t aPointerId, nsIContent* aConte
     SetCapturingContent(aContent, CAPTURE_PREVENTDRAG);
   }
 
-  if (content) {
-    // Releasing capture for given pointer.
-    gPointerCaptureList->Remove(aPointerId);
-    DispatchGotOrLostPointerCaptureEvent(false, aPointerId, content);
-    // Need to check the state because a lostpointercapture listener
-    // may have called SetPointerCapture
-    if (GetPointerCapturingContent(aPointerId)) {
-      return;
-    }
+  if (pointerCaptureInfo) {
+    pointerCaptureInfo->mPendingContent = aContent;
+  } else {
+    gPointerCaptureList->Put(aPointerId, new PointerCaptureInfo(aContent));
   }
-
-  gPointerCaptureList->Put(aPointerId, aContent);
-  DispatchGotOrLostPointerCaptureEvent(true, aPointerId, aContent);
 }
 
 /* static */ void
@@ -6308,16 +6317,61 @@ nsIPresShell::ReleasePointerCapturingContent(uint32_t aPointerId, nsIContent* aC
     SetCapturingContent(nullptr, CAPTURE_PREVENTDRAG);
   }
 
-  // Releasing capture for given pointer.
-  gPointerCaptureList->Remove(aPointerId);
-
-  DispatchGotOrLostPointerCaptureEvent(false, aPointerId, aContent);
+  PointerCaptureInfo* pointerCaptureInfo = nullptr;
+  if (gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo) && pointerCaptureInfo) {
+    // Set flag to asyncronously release capture for given pointer.
+    pointerCaptureInfo->mReleaseContent = true;
+    nsRefPtr<AsyncCheckPointerCaptureStateCaller> asyncCaller =
+      new AsyncCheckPointerCaptureStateCaller(aPointerId);
+    NS_DispatchToCurrentThread(asyncCaller);
+  }
 }
 
 /* static */ nsIContent*
 nsIPresShell::GetPointerCapturingContent(uint32_t aPointerId)
 {
-  return gPointerCaptureList->GetWeak(aPointerId);
+  PointerCaptureInfo* pointerCaptureInfo = nullptr;
+  if (gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo) && pointerCaptureInfo) {
+    return pointerCaptureInfo->mOverrideContent;
+  }
+  return nullptr;
+}
+
+/* static */ void
+nsIPresShell::CheckPointerCaptureState(uint32_t aPointerId)
+{
+  PointerCaptureInfo* pointerCaptureInfo = nullptr;
+  if (gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo) && pointerCaptureInfo) {
+    // If pendingContent exist or anybody calls element.releasePointerCapture
+    // we should dispatch lostpointercapture event to overrideContent if it exist
+    if (pointerCaptureInfo->mPendingContent || pointerCaptureInfo->mReleaseContent) {
+      if (pointerCaptureInfo->mOverrideContent) {
+        nsCOMPtr<nsIContent> content;
+        pointerCaptureInfo->mOverrideContent.swap(content);
+        if (pointerCaptureInfo->mReleaseContent) {
+          pointerCaptureInfo->mPendingContent = nullptr;
+        }
+        if (pointerCaptureInfo->Empty()) {
+          gPointerCaptureList->Remove(aPointerId);
+        }
+        DispatchGotOrLostPointerCaptureEvent(false, aPointerId, content);
+      } else if (pointerCaptureInfo->mPendingContent && pointerCaptureInfo->mReleaseContent) {
+        // If anybody calls element.releasePointerCapture
+        // We should clear overrideContent and pendingContent
+        pointerCaptureInfo->mPendingContent = nullptr;
+        pointerCaptureInfo->mReleaseContent = false;
+      }
+    }
+  }
+  if (gPointerCaptureList->Get(aPointerId, &pointerCaptureInfo) && pointerCaptureInfo) {
+    // If pendingContent exist we should dispatch gotpointercapture event to it
+    if (pointerCaptureInfo && pointerCaptureInfo->mPendingContent) {
+      pointerCaptureInfo->mOverrideContent = pointerCaptureInfo->mPendingContent;
+      pointerCaptureInfo->mPendingContent = nullptr;
+      pointerCaptureInfo->mReleaseContent = false;
+      DispatchGotOrLostPointerCaptureEvent(true, aPointerId, pointerCaptureInfo->mOverrideContent);
+    }
+  }
 }
 
 /* static */ bool
@@ -7188,6 +7242,14 @@ PresShell::HandleEvent(nsIFrame* aFrame,
       }
     }
 
+    if (aEvent->mClass == ePointerEventClass) {
+      if (WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent()) {
+        // Before any pointer events, we should check state of pointer capture,
+        // Thus got/lostpointercapture events emulate asynchronous behavior.
+        CheckPointerCaptureState(pointerEvent->pointerId);
+      }
+    }
+
     if (aEvent->mClass == ePointerEventClass &&
         aEvent->message != NS_POINTER_DOWN) {
       if (WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent()) {
@@ -10345,7 +10407,7 @@ void nsIPresShell::InitializeStatics()
 {
   NS_ASSERTION(!gCaptureTouchList, "InitializeStatics called multiple times!");
   gCaptureTouchList = new nsRefPtrHashtable<nsUint32HashKey, dom::Touch>;
-  gPointerCaptureList = new nsRefPtrHashtable<nsUint32HashKey, nsIContent>;
+  gPointerCaptureList = new nsClassHashtable<nsUint32HashKey, PointerCaptureInfo>;
   gActivePointersIds = new nsClassHashtable<nsUint32HashKey, PointerInfo>;
 }