<!DOCTYPE html>
<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->
<title>OffscreenCanvas test: 2d.text.drawing.style.wordSpacing.measure.relative</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/html/canvas/resources/canvas-tests.js"></script>

<h1>2d.text.drawing.style.wordSpacing.measure.relative</h1>
<p class="desc">Testing if word spacing is working properly with font-relative length</p>


<script>
var t = async_test("Testing if word spacing is working properly with font-relative length");
var t_pass = t.done.bind(t);
var t_fail = t.step_func(function(reason) {
    throw reason;
});
t.step(function() {

  var canvas = new OffscreenCanvas(100, 50);
  var ctx = canvas.getContext('2d');

  _assertSame(ctx.letterSpacing, '0px', "ctx.letterSpacing", "'0px'");
  _assertSame(ctx.wordSpacing, '0px', "ctx.wordSpacing", "'0px'");
  ctx.font = "10px monospace";
  var width_normal = ctx.measureText('Hello World, again').width;
  var ch_width = width_normal / 18;

  function test_word_spacing(value, difference_spacing, epsilon) {
    ctx.wordSpacing = value;
    _assertSame(ctx.letterSpacing, '0px', "ctx.letterSpacing", "'0px'");
    _assertSame(ctx.wordSpacing, value, "ctx.wordSpacing", "value");
    width_with_word_spacing = ctx.measureText('Hello World, again').width;
    assert_approx_equals(width_with_word_spacing, width_normal + difference_spacing, epsilon, "word spacing doesn't work.");
  }

  // The first value is the word Spacing to be set, the second value the
  // change in length of string 'Hello World', note that there are 2 words
  // in 'Hello World, again', so the length difference is always wordSpacing * 2.
  // and the third value is the acceptable differencee for the length change.
  test_cases = [['1em', 20, 0.1],
                ['-0.5em', -10, 0.1],
                ['1ch', 2 * ch_width, 0.1]]

  for (const test_case of test_cases) {
    test_word_spacing(test_case[0], test_case[1], test_case[2]);
  }
  t.done();

});
</script>
