b=202166 Edit actions place caret on invalid position

r=jfrancis sr=kin

editor/libeditor/base/nsEditor.cpp

@@ -3752,6 +3752,17 @@ nsEditor::IsContainer(nsIDOMNode *aNode)
   return mDTD->IsContainer(tagEnum);
 }
 
+PRBool
+nsEditor::IsTextInDirtyFrameVisible(nsIDOMNode *aNode)
+{
+  // virtual method
+  //
+  // If this is a simple non-html editor,
+  // the best we can do is to assume it's visible.
+
+  return PR_TRUE;
+}
+
 PRBool 
 nsEditor::IsEditable(nsIDOMNode *aNode)
 {
@@ -3778,7 +3789,14 @@ nsEditor::IsEditable(nsIDOMNode *aNode)
     nsFrameState fs;
     resultFrame->GetFrameState(&fs);
     if ((fs & NS_FRAME_IS_DIRTY)) // we can only trust width data for undirty frames
-      return PR_TRUE;  // assume all text nodes with dirty frames are editable
+    {
+      // In the past a comment said:
+      //   "assume all text nodes with dirty frames are editable"
+      // Nowadays we use a virtual function, that assumes TRUE
+      // in the simple editor world,
+      // and uses enhanced logic to find out in the HTML world.
+      return IsTextInDirtyFrameVisible(aNode);
+    }
     nsRect rect;
     resultFrame->GetRect(rect);
     if (rect.width > 0) 

editor/libeditor/base/nsEditor.h

@@ -474,6 +474,8 @@ public:
   /** returns PR_TRUE if aNode is an editable node */
   PRBool IsEditable(nsIDOMNode *aNode);
 
+  virtual PRBool IsTextInDirtyFrameVisible(nsIDOMNode *aNode);
+
   /** returns PR_TRUE if aNode is a MozEditorBogus node */
   PRBool IsMozEditorBogusNode(nsIDOMNode *aNode);
 

editor/libeditor/html/nsHTMLEditor.cpp

@@ -5412,6 +5412,21 @@ nsHTMLEditor::GetLastEditableLeaf( nsIDOMNode *aNode, nsCOMPtr<nsIDOMNode> *aOut
   return res;
 }
 
+PRBool
+nsHTMLEditor::IsTextInDirtyFrameVisible(nsIDOMNode *aNode)
+{
+  PRBool isEmptyTextNode;
+  nsresult res = IsVisTextNode(aNode, &isEmptyTextNode, PR_FALSE);
+  if (NS_FAILED(res))
+  {
+    // We are following the historical decision:
+    //   if we don't know, we say it's visible...
+
+    return PR_TRUE;
+  }
+
+  return !isEmptyTextNode;
+}
 
 
 ///////////////////////////////////////////////////////////////////////////

editor/libeditor/html/nsHTMLEditor.h

@@ -496,6 +496,8 @@ public:
   // aSelection is optional -- if null, we get current seletion
   nsresult CollapseSelectionToDeepestNonTableFirstChild(nsISelection *aSelection, nsIDOMNode *aNode);
 
+  virtual PRBool IsTextInDirtyFrameVisible(nsIDOMNode *aNode);
+
   nsresult IsVisTextNode( nsIDOMNode *aNode, 
                           PRBool *outIsEmptyNode, 
                           PRBool aSafeToAskFrames);