Bug 1261299 - Update the selection cache on repaint to handle when a pre-existing selection becomes active aka the current selection. r=smaug

MozReview-Commit-ID: HrTQnHd12rg

--HG--
extra : rebase_source : bd727de70576a39da3cd3fab1754330c41add768

layout/generic/nsFrameSelection.h

@@ -373,7 +373,7 @@ public:
    *  specified by aSelectionType.
    * @param aSelectionType The selection type what you want to repaint.
    */
-  nsresult RepaintSelection(mozilla::SelectionType aSelectionType) const;
+  nsresult RepaintSelection(mozilla::SelectionType aSelectionType);
 
   /** GetFrameForNodeOffset given a node and its child offset, return the nsIFrame and
    *  the offset into that frame. 
@@ -681,6 +681,10 @@ private:
   // nsFrameSelection may get deleted when calling this,
   // so remember to use nsCOMPtr when needed.
   nsresult     NotifySelectionListeners(mozilla::SelectionType aSelectionType);
+  // Update the selection cache on repaint when the
+  // selection being repainted is not empty.
+  nsresult     UpdateSelectionCacheOnRepaintSelection(mozilla::dom::
+                                                      Selection* aSel);
 
   RefPtr<mozilla::dom::Selection>
     mDomSelections[mozilla::kPresentSelectionTypeCount];

layout/generic/nsSelection.cpp

@@ -1964,7 +1964,7 @@ nsFrameSelection::ScrollSelectionIntoView(SelectionType aSelectionType,
 }
 
 nsresult
-nsFrameSelection::RepaintSelection(SelectionType aSelectionType) const
+nsFrameSelection::RepaintSelection(SelectionType aSelectionType)
 {
   int8_t index = GetIndexFromSelectionType(aSelectionType);
   if (index < 0)
@@ -1972,6 +1972,14 @@ nsFrameSelection::RepaintSelection(SelectionType aSelectionType) const
   if (!mDomSelections[index])
     return NS_ERROR_NULL_POINTER;
   NS_ENSURE_STATE(mShell);
+
+// On macOS, update the selection cache to the new active selection
+// aka the current selection.
+#ifdef XP_MACOSX
+  if (aSelectionType == SelectionType::eNormal) {
+    UpdateSelectionCacheOnRepaintSelection(mDomSelections[index]);
+  }
+#endif
   return mDomSelections[index]->Repaint(mShell->GetPresContext());
 }
  
@@ -6512,6 +6520,44 @@ nsAutoCopyListener::NotifySelectionChanged(nsIDOMDocument *aDoc,
                                  mCachedClipboard, false);
 }
 
+/**
+ * See Bug 1288453.
+ *
+ * Update the selection cache on repaint to handle when a pre-existing
+ * selection becomes active aka the current selection.
+ *
+ * 1. Change the current selection by click n dragging another selection.
+ *   - Make a selection on content page. Make a selection in a text editor.
+ *   - You can click n drag the content selection to make it active again.
+ * 2. Change the current selection when switching to a tab with a selection.
+ *   - Make selection in tab.
+ *   - Switching tabs will make its respective selection active.
+ *
+ * Therefore, we only update the selection cache on a repaint
+ * if the current selection being repainted is not an empty selection.
+ *
+ * If the current selection is empty. The current selection cache
+ * would be cleared by nsAutoCopyListener::NotifySelectionChanged.
+ */
+nsresult
+nsFrameSelection::UpdateSelectionCacheOnRepaintSelection(Selection* aSel)
+{
+  nsIPresShell* ps = aSel->GetPresShell();
+  if (!ps) {
+    return NS_OK;
+  }
+  nsCOMPtr<nsIDocument> aDoc = ps->GetDocument();
+
+  bool collapsed;
+  if (aDoc && aSel &&
+      NS_SUCCEEDED(aSel->GetIsCollapsed(&collapsed)) && !collapsed) {
+    return nsCopySupport::HTMLCopy(aSel, aDoc,
+                                   nsIClipboard::kSelectionCache, false);
+  }
+
+  return NS_OK;
+}
+
 // SelectionChangeListener
 
 SelectionChangeListener::RawRangeData::RawRangeData(const nsRange* aRange)