diff --git a/core/modules/widgets/element.js b/core/modules/widgets/element.js index b76e37b00..41ed4ebd1 100755 --- a/core/modules/widgets/element.js +++ b/core/modules/widgets/element.js @@ -29,45 +29,47 @@ Render this widget into the DOM ElementWidget.prototype.render = function(parent,nextSibling) { this.parentDomNode = parent; this.computeAttributes(); - this.execute(); // Neuter blacklisted elements - var tag = this.parseTreeNode.tag; - if($tw.config.htmlUnsafeElements.indexOf(tag) !== -1) { - tag = "safe-" + tag; + this.tag = this.parseTreeNode.tag; + if($tw.config.htmlUnsafeElements.indexOf(this.tag) !== -1) { + this.tag = "safe-" + this.tag; } // Adjust headings by the current base level - var headingLevel = ["h1","h2","h3","h4","h5","h6"].indexOf(tag); + var headingLevel = ["h1","h2","h3","h4","h5","h6"].indexOf(this.tag); if(headingLevel !== -1) { var baseLevel = parseInt(this.getVariable("tv-adjust-heading-level","0"),10) || 0; headingLevel = Math.min(Math.max(headingLevel + 1 + baseLevel,1),6); - tag = "h" + headingLevel; + this.tag = "h" + headingLevel; } - // Create the DOM node - var domNode = this.document.createElementNS(this.namespace,tag); - this.assignAttributes(domNode,{excludeEventAttributes: true}); - parent.insertBefore(domNode,nextSibling); - this.renderChildren(domNode,null); - this.domNodes.push(domNode); -}; - -/* -Compute the internal state of the widget -*/ -ElementWidget.prototype.execute = function() { // Select the namespace for the tag var tagNamespaces = { svg: "http://www.w3.org/2000/svg", math: "http://www.w3.org/1998/Math/MathML", body: "http://www.w3.org/1999/xhtml" }; - this.namespace = tagNamespaces[this.parseTreeNode.tag]; + this.namespace = tagNamespaces[this.tag]; if(this.namespace) { this.setVariable("namespace",this.namespace); } else { this.namespace = this.getVariable("namespace",{defaultValue: "http://www.w3.org/1999/xhtml"}); } + // Invoke the th-rendering-element hook + var parseTreeNodes = $tw.hooks.invokeHook("th-rendering-element",null,this); + this.isReplaced = !!parseTreeNodes; + if(parseTreeNodes) { + // Use the parse tree nodes provided by the hook + this.makeChildWidgets(parseTreeNodes); + this.renderChildren(this.parentDomNode,null); + return; + } // Make the child widgets this.makeChildWidgets(); + // Create the DOM node and render children + var domNode = this.document.createElementNS(this.namespace,this.tag); + this.assignAttributes(domNode,{excludeEventAttributes: true}); + parent.insertBefore(domNode,nextSibling); + this.renderChildren(domNode,null); + this.domNodes.push(domNode); }; /* @@ -77,8 +79,13 @@ ElementWidget.prototype.refresh = function(changedTiddlers) { var changedAttributes = this.computeAttributes(), hasChangedAttributes = $tw.utils.count(changedAttributes) > 0; if(hasChangedAttributes) { - // Update our attributes - this.assignAttributes(this.domNodes[0],{excludeEventAttributes: true}); + if(!this.isReplaced) { + // Update our attributes + this.assignAttributes(this.domNodes[0],{excludeEventAttributes: true}); + } else { + // If we were replaced then completely refresh ourselves + return this.refreshSelf(); + } } return this.refreshChildren(changedTiddlers) || hasChangedAttributes; }; diff --git a/editions/dev/tiddlers/new/Hook__th-rendering-element.tid b/editions/dev/tiddlers/new/Hook__th-rendering-element.tid new file mode 100644 index 000000000..3aba8d7be --- /dev/null +++ b/editions/dev/tiddlers/new/Hook__th-rendering-element.tid @@ -0,0 +1,35 @@ +created: 20200630121235997 +modified: 20200630121235997 +tags: HookMechanism +title: Hook: th-rendering-element + +This hook provides a notification that a DOM element is about to be rendered by the "element" widget. The hook can optionally provide an alternate parse tree that will be rendered in place of the intended element. + +Note the element widget only renders those HTML elements that were parsed as plain HTML elements within wikitext (i.e. using the `` syntax). This means that this hook is not invoked for elements created by other widgets. + +Hook function parameters: + +* ''newParseTreeNodes'': optional parse tree nodes provided by a previously called hook +* ''widget'': instance of the element widget invoking the hook + +Return value: + +* ''newParseTreeNodes'': optionally new parse tree nodes to replace the intended element, or a falsey value to leave the element untouched + +Here is an example of a handler for this hook: + +```js +$tw.hooks.addHook("th-rendering-element",function(parseTreeNodes,widget) { + // Return the previous mapping if there is one + if(parseTreeNodes) { + return parseTreeNodes; + } + // Detect the elements we're interested in + if(someCondition()) { + // Replace them with a parse tree + return generateParseTreeNodes(); + } + // Otherwise do nothing + return null; +}); +```