auto_tests/tests/CanvasAssertions.js

   1 // Copyright (c) 2011 Google, Inc.
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  20
  21 /**
  22  * @fileoverview Assertions and other code used to test a canvas proxy.
  23  *
  24  * @author konigsberg@google.com (Robert Konigsberg)
  25  */
  26
  27 var CanvasAssertions = {};
  28
  29 /**
  30  * Assert that a line is drawn between the two points
  31  *
  32  * This merely looks for one of these four possibilities:
  33  * moveTo(p1) -> lineTo(p2)
  34  * moveTo(p2) -> lineTo(p1)
  35  * lineTo(p1) -> lineTo(p2)
  36  * lineTo(p2) -> lineTo(p1)
  37  *
  38  * attrs is meant to be used when you want to track things like
  39  * color and stroke width.
  40  */
  41 CanvasAssertions.assertLineDrawn = function(proxy, p1, p2, attrs) {
  42   // found = 1 when prior loop found p1.
  43   // found = 2 when prior loop found p2.
  44   var priorFound = 0;
  45   for (var i = 0; i < proxy.calls__.length; i++) {
  46     var call = proxy.calls__[i];
  47
  48     // This disables lineTo -> moveTo pairs.
  49     if (call.name == "moveTo" && priorFound > 0) {
  50       priorFound = 0;
  51     }
  52
  53     var found = 0;
  54     if (call.name == "moveTo" || call.name == "lineTo") {
  55       var matchp1 = CanvasAssertions.matchPixels(p1, call.args);
  56       var matchp2 = CanvasAssertions.matchPixels(p2, call.args);
  57       if (matchp1 || matchp2) {
  58         if (priorFound == 1 && matchp2) {
  59 // TODO -- add property test here  CanvasAssertions.matchAttributes(attrs, call.properties)
  60           return;
  61         }
  62         if (priorFound == 2 && matchp1) {
  63        // TODO -- add property test here  CanvasAssertions.matchAttributes(attrs, call.properties)
  64           return;
  65         }
  66         found = matchp1 ? 1 : 2;
  67       }
  68     }
  69     priorFound = found;
  70   }
  71
  72   var toString = function(x) {
  73     var s = "{";
  74     for (var prop in x) {
  75       if (x.hasOwnProperty(prop)) {
  76         if (s.length > 1) {
  77           s = s + ", ";
  78         }
  79         s = s + prop + ": " + x[prop];
  80       }
  81     }
  82     return s + "}";
  83   };
  84   fail("Can't find a line drawn between " + p1 +
  85       " and " + p2 + " with attributes " + toString(attrs));
  86 }
  87
  88 /**
  89  * Checks how many lines of the given color have been drawn.
  90  * @return {Integer} The number of lines of the given color.
  91  */
  92 CanvasAssertions.numLinesDrawn = function(proxy, color) {
  93   var num_lines = 0;
  94   for (var i = 0; i < proxy.calls__.length; i++) {
  95     var call = proxy.calls__[i];
  96     if (call.name == "lineTo" && call.properties.strokeStyle == color) {
  97       num_lines++;
  98     }
  99   }
 100   return num_lines;
 101 }
 102
 103 CanvasAssertions.matchPixels = function(expected, actual) {
 104   // Expect array of two integers. Assuming the values are within one
 105   // integer unit of each other. This should be tightened down by someone
 106   // who knows what pixel a value of 5.8888 results in.
 107   return Math.abs(expected[0] - actual[0]) < 1 &&
 108       Math.abs(expected[1] - actual[1]) < 1;
 109 }
 110
 111 CanvasAssertions.matchAttributes = function(expected, actual) {
 112   for (var attr in expected) {
 113     if (expected.hasOwnProperty(attr) && expected[attr] != actual[attr]) {
 114       return false;
 115     }
 116   }
 117   return true;
 118 }