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[dygraphs.git] / auto_tests / tests / CanvasAssertions.js

// Copyright (c) 2011 Google, Inc.
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// THE SOFTWARE.

/** 
 * @fileoverview Assertions and other code used to test a canvas proxy.
 *
 * @author konigsberg@google.com (Robert Konigsberg)
 */

var CanvasAssertions = {};

/**
 * Assert that a line is drawn between the two points
 *
 * This merely looks for one of these four possibilities:
 * moveTo(p1) -> lineTo(p2)
 * moveTo(p2) -> lineTo(p1)
 * lineTo(p1) -> lineTo(p2)
 * lineTo(p2) -> lineTo(p1)
 *
 * attrs is meant to be used when you want to track things like
 * color and stroke width.
 */
CanvasAssertions.assertLineDrawn = function(proxy, p1, p2, attrs) {
  // found = 1 when prior loop found p1.
  // found = 2 when prior loop found p2.
  var priorFound = 0;
  for (var i = 0; i < proxy.calls__.length; i++) {
    var call = proxy.calls__[i];

    // This disables lineTo -> moveTo pairs.
    if (call.name == "moveTo" && priorFound > 0) {
      priorFound = 0;
    }

    var found = 0;
    if (call.name == "moveTo" || call.name == "lineTo") {
      var matchp1 = CanvasAssertions.matchPixels(p1, call.args);
      var matchp2 = CanvasAssertions.matchPixels(p2, call.args);
      if (matchp1 || matchp2) {
        if (priorFound == 1 && matchp2) {
// TODO -- add property test here  CanvasAssertions.matchAttributes(attrs, call.properties)
          return;
        }
        if (priorFound == 2 && matchp1) {
       // TODO -- add property test here  CanvasAssertions.matchAttributes(attrs, call.properties)
          return;
        }
        found = matchp1 ? 1 : 2;
      }
    }
    priorFound = found;
  }

  var toString = function(x) {
    var s = "{";
    for (var prop in x) {
      if (x.hasOwnProperty(prop)) {
        if (s.length > 1) {
          s = s + ", ";
        }
        s = s + prop + ": " + x[prop];
      }
    }
    return s + "}";
  };
  fail("Can't find a line drawn between " + p1 +
      " and " + p2 + " with attributes " + toString(attrs));
}

CanvasAssertions.matchPixels = function(expected, actual) {
  // Expect array of two integers. Assuming the values are within one
  // integer unit of each other. This should be tightened down by someone
  // who knows what pixel a value of 5.8888 results in.
  return Math.abs(expected[0] - actual[0]) < 1 &&
      Math.abs(expected[1] - actual[1]) < 1;
}

CanvasAssertions.matchAttributes = function(expected, actual) {
  for (var attr in expected) {
    if (expected.hasOwnProperty(attr) && expected[attr] != actual[attr]) {
      return false;
    }
  }
  return true;
}