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95 lines
2.6 KiB
95 lines
2.6 KiB
/**
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* This is the base class for components. The purpose is to abstract away several
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* common idioms to make derived components simpler.
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*
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* Usage:
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* function Component(gristDoc) {
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* Base.call(this, gristDoc);
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* ...
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* }
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* Base.setBaseFor(Component);
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*
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* To create an object:
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* var obj = Component.create(constructor_args...);
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*/
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/* global $ */
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var dispose = require('../lib/dispose');
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/**
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* gristDoc may be null when there is no active document.
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*/
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function Base(gristDoc) {
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this.gristDoc = gristDoc;
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this._debugName = this.constructor.name + '[' + Base._nextObjectId + ']';
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// TODO: devise a logging system that allows turning on/off different debug tags and levels.
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//console.log(this._debugName, "Base constructor");
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this._eventNamespace = '.Events_' + (Base._nextObjectId++);
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this._eventSources = [];
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this.autoDisposeCallback(this.clearEvents);
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}
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Base._nextObjectId = 1;
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/**
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* Sets ctor to inherit prototype methods from Base.
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* @param {function} ctor Constructor function which needs to inherit Base's prototype.
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*/
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Base.setBaseFor = function(ctor) {
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ctor.prototype = Object.create(Base.prototype, {
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constructor: {
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value: ctor,
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enumerable: false,
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writable: true,
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configurable: true
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}
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});
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dispose.makeDisposable(ctor);
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};
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/**
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* Subscribe to eventType on source, similarly to $(source).on(eventType, optSelector, method).
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* In fact, this uses JQuery internally. The convenience is that it allows unsubscribing in bulk.
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* Also, method is called with the context of `this`.
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*/
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Base.prototype.onEvent = function(source, eventType, optSelector, method) {
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if (typeof optSelector != 'string') {
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method = optSelector;
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optSelector = null;
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}
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if (this._eventSources.indexOf(source) === -1)
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this._eventSources.push(source);
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var self = this;
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$(source).on(eventType + this._eventNamespace, optSelector, function(event_args) {
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Array.prototype.unshift.call(arguments, this); // Unshift is generic enough for 'arguments'.
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if (self._eventSources)
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return method.apply(self, arguments);
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});
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};
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/**
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* Unsubscribes this object from eventType on source, similarly to $(source).off(eventType).
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*/
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Base.prototype.clearEvent = function(source, eventType) {
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$(source).off(eventType + this._eventNamespace);
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};
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/**
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* Unsubscribes this object from all events that it subscribed to via onEvent().
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*/
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Base.prototype.clearEvents = function() {
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var sources = this._eventSources;
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for (var i = 0; i < sources.length; i++) {
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$(sources[i]).off(this._eventNamespace);
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}
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this._eventSources.length = 0;
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};
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module.exports = Base;
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