VBufStorage and backends: ensure that a node and its descendants are …

…all re-rendered if a node has been given alternative text because the node had no useful descendants (E.g. an empty link).
michaelDCurran · Sep 25, 2018 · Aug 23, 2018 · Aug 27, 2018 · Aug 30, 2018 · Sep 3, 2018
commit b32201b5ab9168c0a434f124eebe13c1d3a6de30
@@ -922,20 +922,26 @@ VBufStorage_fieldNode_t* GeckoVBufBackend_t::fillVBuf(IAccessible2* pacc,
 				// If a link has no name, derive it from the URL.
 				buffer->addTextFieldNode(parentNode, NULL, getNameForURL(value));
 			}
+			// If any descendant is invalidated, this may change whether this node has no useful content.
+			parentNode->ensureDescendantsRequireParentUpdate();
 		}
 
 		if ((role == ROLE_SYSTEM_CELL || role == ROLE_SYSTEM_ROWHEADER || role == ROLE_SYSTEM_COLUMNHEADER||role==IA2_ROLE_UNKNOWN) && parentNode->getLength() == 0) {
 			// Always render a space for empty table cells and unknowns.
 			previousNode=buffer->addTextFieldNode(parentNode,previousNode,L" ");
 			if(previousNode&&!locale.empty()) previousNode->addAttribute(L"language",locale);
 			parentNode->isBlock=false;
+			// If any descendant is invalidated, this may change whether this node has no content. 
+			parentNode->ensureDescendantsRequireParentUpdate();
 		}
 
 		if ((isInteractive || role == ROLE_SYSTEM_SEPARATOR) && parentNode->getLength() == 0) {
 			// If the node is interactive or otherwise relevant even when empty
 			// and it still has no content, render a space so the user can access the node.
 			previousNode=buffer->addTextFieldNode(parentNode,previousNode,L" ");
 			if(previousNode&&!locale.empty()) previousNode->addAttribute(L"language",locale);
+			// If any descendant is invalidated, this may change whether this node has no useful content.
+			parentNode->ensureDescendantsRequireParentUpdate();
 		}
 	}
 

@@ -1244,6 +1244,8 @@ if(!(formatState&FORMATSTATE_INSERTED)&&nodeName.compare(L"INS")==0) {
 				previousNode=buffer->addTextFieldNode(parentNode,NULL,contentString);
 				fillTextFormattingForNode(pHTMLDOMNode,previousNode);
 			}
+			// If any descendant is invalidated, this may change whether this node has no useful content.
+			parentNode->ensureDescendantsRequireParentUpdate();
 		}
 	}
 
@@ -1278,12 +1280,16 @@ if(!(formatState&FORMATSTATE_INSERTED)&&nodeName.compare(L"INS")==0) {
 			if(parentNode->getLength()==0) {
 				isBlock=false;
 				buffer->addTextFieldNode(parentNode,previousNode,L" ");
+				// If any descendant is invalidated, this may change whether this node has no useful content.
+				parentNode->ensureDescendantsRequireParentUpdate();
 			}
 		}
 
 		//If a node is interactive, and still has no content, add a space
 		if(isInteractive&&parentNode->getLength()==0) {
 			buffer->addTextFieldNode(parentNode,previousNode,L" ");
+			// If any descendant is invalidated, this may change whether this node has no useful content.
+			parentNode->ensureDescendantsRequireParentUpdate();
 		}
 	}
 

@@ -47,11 +47,10 @@ void VBufBackend_t::initialize() {
 }
 
 void VBufBackend_t::forceUpdate() {
-	//this->cancelPendingUpdate();
-	//this->update();
+	this->cancelPendingUpdate();
+	this->update();
 }
 
-
 LRESULT CALLBACK VBufBackend_t::destroy_callWndProcHook(int code, WPARAM wParam,LPARAM lParam) {
 	CWPSTRUCT* pcwp=(CWPSTRUCT*)lParam;
 	if((pcwp->message==WM_DESTROY)) {
@@ -181,12 +180,14 @@ bool VBufBackend_t::invalidateSubtree(VBufStorage_controlFieldNode_t* node) {
 	});
 	// Now mark this node as invalid.
 	pendingInvalidSubtreesList.push_back(node);
+	LOG_INFO(L"Invalidated node "<<node->getDebugInfo());
 	this->requestUpdate();
 	return true;
 }
 
 void VBufBackend_t::update() {
 	if(inUpdate) {
+		Beep(550,40);
 		return;
 	}
 	inUpdate=true;

@@ -104,7 +104,10 @@ static LRESULT CALLBACK destroy_callWndProcHook(int code, WPARAM wParam, LPARAM
  */
 	virtual void render(VBufStorage_buffer_t* buffer, int docHandle, int ID, VBufStorage_controlFieldNode_t* oldNode=NULL)=0;
 
-bool inUpdate {false};
+/**
+ * Tracks if the  backend is currently being updated, and if so does not allow update to become reentrant.
+  */
+	bool inUpdate {false};
 
 /**
  * Updates the content of the buffer. 

@@ -347,6 +347,18 @@ VBufStorage_controlFieldNode_t::VBufStorage_controlFieldNode_t(int docHandle, in
 	LOG_DEBUG(L"controlFieldNode initialization at "<<this<<L", with docHandle of "<<identifier.docHandle<<L" and ID of "<<identifier.ID); 
 }
 
+void VBufStorage_controlFieldNode_t::ensureDescendantsRequireParentUpdate() {
+	this->alwaysRerenderChildren=true;
+	for(auto child=this->getFirstChild();child!=nullptr;child=child->getNext()) {
+		auto childControlField=dynamic_cast<VBufStorage_controlFieldNode_t*>(child);
+		if(childControlField) {
+			childControlField->requiresParentUpdate=true;
+			LOG_INFO(L"making child controlField require parent update. childControlField "<<childControlField->getDebugInfo());
+			childControlField->ensureDescendantsRequireParentUpdate();
+		}
+	}
+}
+
 bool VBufStorage_controlFieldNode_t::getIdentifier(int* docHandle, int* ID) {
 	*docHandle=this->identifier.docHandle;
 	*ID=this->identifier.ID;
@@ -355,7 +367,7 @@ bool VBufStorage_controlFieldNode_t::getIdentifier(int* docHandle, int* ID) {
 
 std::wstring VBufStorage_controlFieldNode_t::getDebugInfo() const {
 	std::wostringstream s;
-	s<<L"control "<<this->VBufStorage_fieldNode_t::getDebugInfo()<<L", docHandle "<<identifier.docHandle<<L", ID is "<<identifier.ID;  
+	s<<L"control "<<this->VBufStorage_fieldNode_t::getDebugInfo()<<L", docHandle "<<identifier.docHandle<<L", ID is "<<identifier.ID<<L", requiresParentUpdate "<<requiresParentUpdate<<L", allowReuseInAncestorUpdate "<<allowReuseInAncestorUpdate<<L", denyReuseIfPreviousSiblingsChanged "<<denyReuseIfPreviousSiblingsChanged<<L", alwaysRerenderChildren "<<alwaysRerenderChildren;  
 	return s.str();
 }
 

@@ -357,6 +357,14 @@ class VBufStorage_controlFieldNode_t : public VBufStorage_fieldNode_t {
  */
 	bool alwaysRerenderChildren {false};
 
+/**
+ * Sets the requiresParentUpdate property to true on all descendants of this node, and sets alwaysRerenderChildren to true on this node and all descendants.
+ * This method is useful if some alternative text has been added to a node because its descendants don't seem to contain useful content (E.g. an empty link).
+ * This ensures that if a descendant is re-rendered, this node should also be re-rendered (as the alternative text may no longer be needed).
+ * It also ensures that if this node is re-rendered, none of its children are reused from here or somewhere else in the tree as the reused node may not have been makred as requiring a prent update. 
+ */
+	void ensureDescendantsRequireParentUpdate();
+
 /**
  * retreaves the node's doc handle and ID.
   * @param docHandle a memory location in which the doc handle will be placed.