/** * This class provides access to a range of records in a {@link Ext.data.Store store}. * Instances of this class are not created directly but are rather returned by a store's * {@link Ext.data.AbstractStore#createActiveRange createActiveRange} method. * * This class is useful for buffered rendering where only a portion of the total set of * records are needed. By passing that information to a `Range`, the access to records * can be abstracted even across {@link Ext.data.virtual.Store virtual stores} where * only those records needed by views are fetched from the server. * @since 6.5.0 */Ext.define('Ext.data.Range', { requires: ['Ext.util.DelayedTask'], isDataRange: true, /** * @cfg {Number} begin * The first record index of interest. * * This property is set by the `goto` method and is stored on the instance for * readonly use. * @readonly */ begin: 0, /** * @cfg {Number} buffer * The buffer to execute server requests. */ buffer: 0, /** * @cfg {Number} end * The first record beyond the range of interest. This is to make "length" of the * range simply `end - begin`. * * This property is set by the `goto` method and is stored on the instance for * readonly use. */ end: 0, /** * @property (Number} length * The number of records in the range of `[begin, end)`. This is equal to the * difference `end - begin`. * * This property is maintained by the `goto` method and is stored on the instance for * readonly use. * @readonly */ length: 0, /** * @property {Ext.data.Model[]} records * The records corresponding to the `begin` and `end` of this range. For normal * stores this is the standard array of records. * * For a {@link Ext.data.virtual.Store virtual store} this is a sparse object of * available records bounded by the limits of this range. * * In all cases, this object is keyed by the record index and (except for the * `length` property) should be treated as an array. * @readonly */ /** * @cfg {Ext.data.AbstractStore} store * The associated store. This config must be supplied at construction and cannot * be changed after that time. * @readonly */ store: null, constructor: function (config) { var me = this, activeRanges, store; Ext.apply(me, config); store = me.store; if (!(activeRanges = store.activeRanges)) { store.activeRanges = activeRanges = []; } activeRanges.push(me); me.refresh(); if ('begin' in config) { me.begin = me.end = 0; // Applied on us above, so clear it me.goto(config.begin, config.end); } }, destroy: function () { var me = this, store = me.store, activeRanges = store && store.activeRanges; Ext.destroy(me.storeListeners); if (activeRanges) { Ext.Array.remove(activeRanges, me); } me.callParent(); }, goto: function (begin, end) { var me = this, buffer = me.buffer, task = me.task; me.begin = begin; me.end = end; me.length = end - begin; if (buffer > 0) { if (!task) { me.task = task = new Ext.util.DelayedTask(me.doGoto, me); } task.delay(buffer); } else { me.doGoto(); } }, privates: { lastBegin: 0, lastEnd: 0, doGoto: Ext.privateFn, refresh: function() { this.records = this.store.getData().items; } }});