auto_tests/tests/fast_canvas_proxy.js

   1 /**
   2  * @fileoverview Tests for fastCanvasProxy, which drops superfluous segments.
   3  *
   4  * @author danvdk@gmail.com (Dan Vanderkam)
   5  */
   6 describe("fast-canvas-proxy", function() {
   7
   8 beforeEach(function() {
   9 });
  10
  11 afterEach(function() {
  12 });
  13
  14 var fakeCanvasContext = {
  15   moveTo: function() {},
  16   lineTo: function() {},
  17   beginPath: function() {},
  18   closePath: function() {},
  19   fill: function() {},
  20   stroke: function() {}
  21 }
  22
  23 function extractMoveToAndLineToCalls(proxy) {
  24   var calls = proxy.calls__;
  25   var out = [];
  26   for (var i = 0; i < calls.length; i++) {
  27     var c = calls[i];
  28     if (c.name == 'moveTo' || c.name == 'lineTo') {
  29       out.push([c.name, c.args[0], c.args[1]]);
  30     }
  31   }
  32   return out;
  33 }
  34
  35 it('testExtraMoveTosElided', function() {
  36   var htx = new Proxy(fakeCanvasContext);
  37   var fastProxy = DygraphCanvasRenderer._fastCanvasProxy(htx);
  38
  39   fastProxy.moveTo(1, 1);
  40   fastProxy.lineTo(2, 1);
  41   fastProxy.moveTo(2, 1);
  42   fastProxy.lineTo(3, 1);
  43   fastProxy.moveTo(3, 1);
  44   fastProxy.stroke();
  45
  46   assert.deepEqual([['moveTo', 1, 1],
  47                 ['lineTo', 2, 1],
  48                 ['lineTo', 3, 1]], extractMoveToAndLineToCalls(htx));
  49 });
  50
  51 it('testConsecutiveMoveTosElided', function() {
  52   var htx = new Proxy(fakeCanvasContext);
  53   var fastProxy = DygraphCanvasRenderer._fastCanvasProxy(htx);
  54
  55   fastProxy.moveTo(1, 1);
  56   fastProxy.lineTo(2, 1);
  57   fastProxy.moveTo(3, 1);
  58   fastProxy.moveTo(3.1, 2);
  59   fastProxy.moveTo(3.2, 3);
  60   fastProxy.stroke();
  61
  62   assert.deepEqual([['moveTo', 1, 1],
  63                 ['lineTo', 2, 1],
  64                 ['moveTo', 3.2, 3]], extractMoveToAndLineToCalls(htx));
  65 });
  66
  67 it('testSuperfluousSegmentsElided', function() {
  68   var htx = new Proxy(fakeCanvasContext);
  69   var fastProxy = DygraphCanvasRenderer._fastCanvasProxy(htx);
  70
  71   fastProxy.moveTo(0.6, 1);
  72   fastProxy.lineTo(0.7, 2);
  73   fastProxy.lineTo(0.8, 3);
  74   fastProxy.lineTo(0.9, 4);
  75   fastProxy.lineTo(1.0, 5);  // max for Math.round(x) == 1
  76   fastProxy.lineTo(1.1, 3);
  77   fastProxy.lineTo(1.2, 0);  // min for Math.round(x) == 1
  78   fastProxy.lineTo(1.3, 1);
  79   fastProxy.lineTo(1.4, 2);
  80   fastProxy.moveTo(1.4, 2);
  81   fastProxy.lineTo(1.5, 2);  // rounding up to 2
  82   fastProxy.moveTo(1.5, 2);
  83   fastProxy.lineTo(1.6, 3);
  84   fastProxy.moveTo(1.6, 3);
  85   fastProxy.lineTo(1.7, 30);  // max for Math.round(x) == 2
  86   fastProxy.moveTo(1.7, 30);
  87   fastProxy.lineTo(1.8, -30);  // min for Math.round(x) == 2
  88   fastProxy.moveTo(1.8, -30);
  89   fastProxy.lineTo(1.9, 0);
  90   fastProxy.moveTo(3, 0);  // dodge the "don't touch the last pixel" rule.
  91   fastProxy.stroke();
  92
  93   assert.deepEqual([['moveTo', 0.6, 1],
  94                 ['lineTo', 1.0, 5],
  95                 ['lineTo', 1.2, 0],
  96                 ['lineTo', 1.7, 30],
  97                 ['lineTo', 1.8, -30],
  98                 ['moveTo', 3, 0]], extractMoveToAndLineToCalls(htx));
  99 });
 100
 101
 102 // For a more visual version of this test, see
 103 // https://gist.github.com/danvk/e98dbb24253c9b153696
 104 // The drawing commands in the following two tests are taken from there.
 105 it('should handle gaps on the left', function() {
 106   var htx = new Proxy(fakeCanvasContext);
 107   var fastProxy = DygraphCanvasRenderer._fastCanvasProxy(htx);
 108
 109   fastProxy.moveTo(0, 320);
 110   fastProxy.lineTo(0, 320);
 111   fastProxy.lineTo(53.21, 187);
 112   fastProxy.lineTo(53.23, 29);
 113   fastProxy.lineTo(53.41, 320);
 114   fastProxy.lineTo(54.15, 320);
 115   fastProxy.lineTo(475, 320);
 116   fastProxy.lineTo(475, 320);
 117   fastProxy.fill();
 118
 119   assert.deepEqual([
 120     ['moveTo', 0, 320],
 121     ['lineTo', 0, 320],
 122     ['lineTo', 53.21, 187],
 123     ['lineTo', 53.23, 29],
 124     ['lineTo', 53.41, 320],
 125     ['lineTo', 54.15, 320],
 126     ['lineTo', 475, 320],
 127     ['lineTo', 475, 320]
 128   ], extractMoveToAndLineToCalls(htx));
 129 });
 130
 131 it('should handle gaps on the right', function() {
 132   var htx = new Proxy(fakeCanvasContext);
 133   var fastProxy = DygraphCanvasRenderer._fastCanvasProxy(htx);
 134   fastProxy.moveTo(240.2, 320);
 135   fastProxy.lineTo(240.2, 320);
 136   fastProxy.lineTo(240.2, 174);
 137   fastProxy.lineTo(240.7, 145);
 138   fastProxy.lineTo(240.8, 320);
 139   fastProxy.lineTo(241.3, 29);
 140   fastProxy.lineTo(241.4, 320);
 141   fastProxy.lineTo(715.9, 320);
 142   fastProxy.lineTo(715.9, 320);
 143   fastProxy.fill();
 144
 145   assert.deepEqual([
 146     ['moveTo', 240.2, 320],
 147     ['lineTo', 240.2, 320],
 148     ['lineTo', 240.2, 174],
 149     ['lineTo', 240.7, 145],
 150     ['lineTo', 240.8, 320],
 151     ['lineTo', 241.3, 29],
 152     ['lineTo', 241.4, 320],
 153     ['lineTo', 715.9, 320],
 154     ['lineTo', 715.9, 320]
 155   ], extractMoveToAndLineToCalls(htx));
 156 });
 157
 158 });