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Widget2.js
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Widget2.js
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import router from "./router.js";
import { eventCategory } from "yaem";
import htmlCanvas from "./htmlCanvas.js";
import jQuery from "jquery";
import { getCurrentWidget, withCurrentWidget } from "./currentWidget.js";
import { newId } from "./idGenerator.js";
/**
* Base for all widgets. A widget can keep state in variables, contain logic and
* render itself through `renderContentOn()`.
*
* @example
*
* class TitleWidget extends Widget {
* constructor({ title }) {
* this._title = title || "Hello World";
* }
*
* renderContentOn(html) {
* html.h1(this._title);
* }
*
* };
*
* let helloWorldWidget = new TitleWidget({ title: "Hello Widget!" });
*
* $(document).ready(() => {
* helloWorldWidget.appendTo("BODY");
* });
*
* Widgets can also be rendered on a HTML canvas (since widget
* implements `appendToBrush()`). Eg.
*
* html.div(helloWorldWidget)
*
* It is therefore easy to compose widgets from other widgets.
*
* @virtual
*
* @param {String} [spec.id] Unique id for widget. Also used for root
* element when attached/rendered to DOM.
* If not provided an ID will automatically
* be generated and assigned.
*/
export default class Widget2 {
constructor({ id } = {}) {
this._id = id || newId();
// When within an update transaction, do not update the widget
this._inUpdateTransaction = false;
// Keep track of the renderer subwidgets
this._children = [];
// Events for widget
this._events = eventCategory();
this.onAttach = this._events.createEvent();
this.onDetach = this._events.createEvent();
// Expose events
this.register = this._events.register;
this.registerOnce = this._events.registerOnce;
this.unregister = this._events.unregister;
this.trigger = this._events.trigger;
// Route / Controller extensions
this._router = router.getRouter();
this._linkTo = this._router.linkTo;
this._linkToPath = this._router.linkToPath;
this._linkToUrl = this._router.linkToUrl;
this._redirectTo = this._router.redirectTo;
this._redirectToPath = this._router.redirectToPath;
this._redirectToUrl = this._router.redirectToUrl;
this._redirectToLocationPath = this._router.redirectToLocationPath;
this._getParameters = this._router.getParameters;
this._getParameter = this._router.getParameter;
this._setParameters = this._router.setParameters;
}
//
// Public
//
/**
* Returns a unique id for the widget
*
* @returns {String}
*/
getId() {
return this._id;
}
/**
* Performance tasks need for freeing/releasing/cleaning-up
* resources used by widget.
*
* Should always be executed before a widget is
* disposed. Especially if the widget registers events to avoid
* memory leaks.
*
* Most widgets should override `_dispose` instead of overriding
* this function.
*
*/
dispose() {
this._children.forEach((child) => {
child.dispose();
});
this._dispose();
this._events.dispose();
}
/**
* Method to be performed when a root widget is detached from the
* DOM. The widget and all its children will call `_willDetach` in
* turn.
*/
willDetach() {
this._children.forEach((child) => {
child.willDetach();
});
this._willDetach();
this.onDetach.trigger();
}
/**
* Renders the widget on a JQuery / DOM
*
* @example
* widget.appendTo("BODY");
*
* @param aJQuery
*/
appendTo(aJQuery) {
this._withAttachHooks(() => {
this._renderBasicOn(htmlCanvas(aJQuery));
});
}
/**
* Does the same as `appendTo` except it first clears the elements
* matched by aJQuery
*
* @param aJQuery
*/
replace(aJQuery) {
this._withAttachHooks(() => {
let canvas = htmlCanvas(aJQuery);
canvas.root.asJQuery().empty();
this._renderBasicOn(canvas);
});
}
/**
* Answers a jQuery matching the root DOM element. By default
* by selecting an element that have the same ID as the widget.
*
* See "renderOn".
*/
asJQuery() {
return jQuery(`#${this.getId()}`);
}
/**
* Answers true if widget has rendered content in DOM
*
* @returns {boolean}
*/
isRendered() {
return this.asJQuery().length > 0;
}
/**
* Allows a widget to be appended to a brush. See "htmlCanvas".
*
* Basically it allows us to do:
* html.div(widget);
*/
appendToBrush(aTagBrush) {
this._withAttachHooks(() => {
this._renderBasicOn(htmlCanvas(aTagBrush.asJQuery()));
});
}
/**
* Trigger the `willAttach` event on the receiver and all
* rendered subwidgets.
*/
triggerWillAttach() {
this._willAttach();
this._children.forEach((widget) => {
widget.triggerWillAttach();
});
}
/**
* Trigger the `didAttach` hook on the receiver and all rendered
* subwidgets.
*/
triggerDidAttach() {
this._didAttach();
this._children.forEach((widget) => {
widget.triggerDidAttach();
});
this.onAttach.trigger();
}
/**
* Evaluate `fn`, calling `willAttach` before and `didAttach` after
* the evaluation.
*/
_withAttachHooks(fn) {
let inRenderingLoop = !!getCurrentWidget();
if (!inRenderingLoop) {
this.triggerWillAttach();
}
fn();
if (!inRenderingLoop) {
this.triggerDidAttach();
}
}
/**
* Create and expose an event named `name`.
*/
_createEvent(name) {
this[name] = this._events.createEvent();
}
/**
* Create and expose one event per string argument.
*/
_createEvents() {
let names = Array.prototype.slice.apply(arguments);
names.forEach((name) => this._createEvent(name));
}
//
// Protected
//
/**
* Exposes the internal ID generator. Generates new unique IDs to
* be used for sub-widgets, etc.
*
* @returns {String}
*/
_nextId() {
return newId();
}
/**
* Widget specific dispose.
*/
_dispose() {}
//
// Render
//
/**
* Private rendering function. This is the function
* internally called each time the widget is rendered, in
* `appendTo`, `replace` and `update`.
*
*/
_renderBasicOn(html) {
this._withChildrenRegistration(() => {
this.renderOn(html);
});
}
/**
* Main entry point for rendering. For convenience "renderOn" will wrap the content
* rendered by "renderContentOn" in a root element (renderRootOn) that will be matched
* by asJQuery.
*
* Usually concrete widgets override "renderContentOn" to render it content. Widgets
* can override "renderOn" but must then make sure that it can be matched by "asJQuery".
*
* One way to do that is to make sure to have only one root element and setting the ID of
* that element to the ID of the widget.
*
* @example
*
* renderOn(html) {
* html.ul({id: that.getId()}
* html.li("BMW"),
* html.li("Toyota")
* );
* };
*
*
* @param html
*/
renderOn(html) {
// Renders widget by wrapping `renderContentOn()` in a root element.
this._renderRootOn(html).render(this.renderContentOn.bind(this));
}
_withChildrenRegistration(fn) {
let parent = getCurrentWidget();
if (parent) {
parent.registerChild(this);
}
withCurrentWidget(() => {
this._children = [];
fn();
}, this);
}
registerChild(widget) {
this._children.push(widget);
}
/**
* Renders a wrapper element (by default a "widgetjs-widget" tag) and
* sets the element ID to the ID of the widget so that it can be found by
* "asJQuery" eg. when we re-render using "update".
*
* @param html
* @returns {htmlBrush}
*/
_renderRootOn(html) {
return html.tag("widgetjs-widget").id(this._id);
}
/**
* Overridden in concrete widgets to render widget to canvas/DOM.
*
* @example
*
* renderContentOn(html) {
* html.ul(
* html.li("BMW"),
* html.li("Toyota")
* );
* };
*
* @param {htmlCanvas} html
*/
renderContentOn(_html) {
throw new Error("Subclass responsibility");
}
/**
* Hook evaluated before the widget is attached (or reattached due
* to an update of rendering) to the DOM.
*/
_willAttach() {}
/**
* Hook evaluated each time the widget is attached (or
* reattached due to an update of rendering) to the DOM.
*/
_didAttach() {}
/**
* Hook evaluated when a widget is detached from the DOM.
*/
_willDetach() {}
/**
* Hook evaluated before widget update.
*/
_willUpdate() {}
/**
* Re-renders the widget and replace it in the DOM
*/
update() {
if (this._inUpdateTransaction || !this.isRendered()) {
return;
}
this.willDetach();
this._willUpdate();
this._withAttachHooks(() => {
// clear content of root
this.asJQuery().empty();
// re-render content on root
let html = htmlCanvas(this.asJQuery());
this._withChildrenRegistration(() => {
this.renderContentOn(html);
});
});
}
withinTransaction(fn, onDone) {
if (this._inUpdateTransaction) {
fn();
} else {
try {
this._inUpdateTransaction = true;
fn();
} finally {
this._inUpdateTransaction = false;
if (onDone) {
onDone();
}
}
}
}
/**
* Evaluate `fn`, ensuring that an update will be
* performed after evaluating the function. Nested calls
* to `withUpdate` or `update` will result in updating the
* widget only once.
*/
withUpdate(fn) {
this.withinTransaction(fn, this.update.bind(this));
}
withNoUpdate(fn) {
this.withinTransaction(fn);
}
}