tools/perf/page_sets/tough_canvas_cases/many_images/sprites.js

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 var sprites = (function() {
   6   var objs;
   7   var width;
   8   var height;
   9   var SPRITE_SPEED = 2;
  10
  11   var sprites = {};
  12   sprites.init = function(w, h) {
  13     objs = [];
  14     width = w;
  15     height = h;
  16   };
  17   sprites.add = function(img) {
  18     var obj = { img: img,
  19                   x: Math.random() * (width - img.width),
  20                   y: Math.random() * (height - img.height),
  21                  dx: SPRITE_SPEED * (Math.random() < .5 ? -1 : 1),
  22                  dy: SPRITE_SPEED * (Math.random() < .5 ? -1 : 1) };
  23     objs.push(obj);
  24   };
  25   sprites.draw = function(context) {
  26     for (var i = 0, len = objs.length; i < len; ++i) {
  27       var obj = objs[i];
  28
  29       obj.x += obj.dx;
  30       if ((obj.x > (width - obj.img.width)) || (obj.x < 0))
  31         obj.dx *= -1;
  32
  33       obj.y += obj.dy;
  34       if ((obj.y > (height - obj.img.height)) || (obj.y < 0))
  35         obj.dy *= -1;
  36
  37       context.drawImage(obj.img, obj.x, obj.y);
  38   };
  39   };
  40   return sprites;
  41 })();