This adds helper functions to get specific types of content editors (if
possible) through the nsIEditor interface, as opposed to doing manual
casting and the ad hoc `GetHTMLEditor()` function.
Helper functions are spread out over multiple headers due to the
circular dependency issues that would be triggered otherwise.
At first, HTMLEditor::GetActiveEditingHost might return null in this situation, we should check whether nullptr is returned. At second, SplitNodeDeep returns error since curent is design mode and selection node has no parent. So we should check error.
Ref: Bug 1350772
In a lot of places, edit action handlers and their helper methods return nsresult and aHandled and aCanceled with out params. However, the out params cause the code complicated since:
* it's not unclear if the method will overwrite aHandled and aCanceled value.
* callers need to create temporary variable event if some of them are not necessary.
This patch rewrites the helper methods of HTMLEditRules::WillDeleteSelection() with it.
Tag #1563
When selection is collapsed and JoinBlocks() doesn't handle nor cancel the action, WillDeleteSelection() should move selection to the start/end of leftmost/rightmost editable leaf node and retry to handle the action again.
For avoiding infinite loop, it checks if selected node is changed actually before calling itself again.
Tag #1563
When HTMLEditRules::WillDeleteSelection() tries to remove something from the end/start of a block to its last/first text node but it's contained by block elements, it tries to join the container and the block. However, JoinBlocks() always fails to join them since it's impossible operation. In this case, HTMLEditRules::WillDeleteSelection() should retry to remove something in the leaf, however, it's impossible for now because JoinBlocks() and its helper methods don't return if it handles the action actually.
This patch renames |JoinBlocks()| to |TryToJoinBlocks()| for representing what it is. And this patch adds |bool* aHandled| to the helper methods. Then, *aHandled and *aCancel are now always returns the result of each method. Therefore, for merging the result of multiple helper methods, callers need to receive the result with temporary variables and merge them by themselves.
Note that when they modify DOM node actually or the action should do nothing (for example, selection is across tables), aHandled is set to true.
Tag #1563
Moonchild
FranklinDM
Gaming4JC
Matt A. Tobin
wolfbeast
roytam1