src/src/TaskQueue.js

   1 /**
   2  * @private
   3  * Handle batch read / write of DOMs, currently used in SizeMonitor + PaintMonitor
   4  */
   5 Ext.define('Ext.TaskQueue', {
   6     requires: 'Ext.AnimationQueue',
   7
   8     singleton: true,
   9
  10     pending: false,
  11
  12     mode: true,
  13
  14     constructor: function() {
  15         this.readQueue = [];
  16         this.writeQueue = [];
  17
  18         this.run = Ext.Function.bind(this.run, this);
  19         this.watch = Ext.Function.bind(this.watch, this);
  20
  21         // iOS has a nasty bug which causes pending requestAnimationFrame to not release
  22         // the callback when the WebView is switched back and forth from / to being background process
  23         // We use a watchdog timer to workaround this, and restore the pending state correctly if this happens
  24         // This timer has to be set as an interval from the very beginning and we have to keep it running for
  25         // as long as the app lives, setting it later doesn't seem to work
  26         if (Ext.os.is.iOS) {
  27             setInterval(this.watch, 500);
  28         }
  29     },
  30
  31     requestRead: function(fn, scope, args) {
  32         this.request(true);
  33         this.readQueue.push(arguments);
  34     },
  35
  36     requestWrite: function(fn, scope, args) {
  37         this.request(false);
  38         this.writeQueue.push(arguments);
  39     },
  40
  41     request: function(mode) {
  42         if (!this.pending) {
  43             this.pendingTime = Date.now();
  44             this.pending = true;
  45             this.mode = mode;
  46             if (mode) {
  47                 setTimeout(this.run, 1);
  48             } else {
  49                 requestAnimationFrame(this.run);
  50             }
  51         }
  52     },
  53
  54     watch: function() {
  55         if (this.pending && Date.now() - this.pendingTime >= 500) {
  56             this.run();
  57         }
  58     },
  59
  60     run: function() {
  61         this.pending = false;
  62
  63         var readQueue = this.readQueue,
  64             writeQueue = this.writeQueue,
  65             request = null,
  66             queue;
  67
  68         if (this.mode) {
  69             queue = readQueue;
  70
  71             if (writeQueue.length > 0) {
  72                 request = false;
  73             }
  74         }
  75         else {
  76             queue = writeQueue;
  77
  78             if (readQueue.length > 0) {
  79                 request = true;
  80             }
  81         }
  82
  83         var tasks = queue.slice(),
  84             i, ln, task, fn, scope;
  85
  86         queue.length = 0;
  87
  88         for (i = 0, ln = tasks.length; i < ln; i++) {
  89             task = tasks[i];
  90             fn = task[0];
  91             scope = task[1];
  92
  93             if (typeof fn == 'string') {
  94                 fn = scope[fn];
  95             }
  96
  97             if (task.length > 2) {
  98                 fn.apply(scope, task[2]);
  99             }
 100             else {
 101                 fn.call(scope);
 102             }
 103         }
 104
 105         tasks.length = 0;
 106
 107         if (request !== null) {
 108             this.request(request);
 109         }
 110     }
 111 });