2d.text.drawing.style.letterSpacing.measure.html

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This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/text/2d.text.drawing.style.letterSpacing.measure.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->

<meta charset="UTF-8">

<title>OffscreenCanvas test: 2d.text.drawing.style.letterSpacing.measure</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.letterSpacing.measure</h1>

<p class="desc">Testing letter spacing with different length units</p>

<script>

var t = async_test("Testing letter spacing with different length units");

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'");

  var width_normal = ctx.measureText('Hello World').width;

  function test_letter_spacing(value, difference_spacing, epsilon) {

    ctx.letterSpacing = value;

    _assertSame(ctx.letterSpacing, value, "ctx.letterSpacing", "value");

    _assertSame(ctx.wordSpacing, '0px', "ctx.wordSpacing", "'0px'");

    width_with_letter_spacing = ctx.measureText('Hello World').width;

    assert_approx_equals(width_with_letter_spacing, width_normal + difference_spacing, epsilon, "letter spacing doesn't work.");

  // The first value is the letter Spacing to be set, the second value the

  // change in length of string 'Hello World', note that there are 11 letters

  // in 'hello world', so the length difference is always letterSpacing * 11.

  // and the third value is the acceptable differencee for the length change,

  // note that unit such as 1cm/1mm doesn't map to an exact pixel value.

  test_cases = [['3px', 33, 0.1],

               ['5px', 55, 0.1],

               ['-2px', -22, 0.1],

               ['1em', 110, 0.1],

               ['-0.1em', -11, 0.1],

               ['1in', 1056, 0.1],

               ['-0.1cm', -41.65, 0.2],

               ['-0.6mm', -24,95, 0.2]]

  for (const test_case of test_cases) {

    test_letter_spacing(test_case[0], test_case[1], test_case[2]);

  t.done();

});

</script>