chromium/third_party/blink/web_tests/resize-observer/device-pixel-notification.html

<!doctype HTML>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<script src="./resources/resizeTestHelper.js"></script>
<body></body>

<script>
'use strict';

// allow uncaught exception because ResizeObserver posts exceptions
// to window error handler when limit is exceeded.
setup({allow_uncaught_exception: true});

function test() {
  let t = document.createElement("div");
  document.body.appendChild(t);
  t.style.height = "25.25px";
  t.style.width = "55.5px";
  document.body.style.zoom = 1;
  let helper = new ResizeTestHelper(
    "An observation is fired when device-pixel-content-box is being " +
    "observed and sub pixel values are used",
  [
    {
      setup: observer => {
        observer.observe(t, {box: "device-pixel-content-box"});
      },
      notify: entries => {
        assert_equals(entries.length, 1, "1 pending notification");
        assert_equals(entries[0].target, t, "target is t");
        assert_equals(entries[0].contentRect.width, 55.5, "target width");
        assert_equals(entries[0].contentRect.height, 25.25, "target height");
        assert_equals(entries[0].contentBoxSize[0].inlineSize, 55.5,
                      "target content-box inline size");
        assert_equals(entries[0].contentBoxSize[0].blockSize, 25.25,
                      "target content-box block size");
        assert_equals(entries[0].borderBoxSize[0].inlineSize, 55.5,
                      "target border-box inline size");
        assert_equals(entries[0].borderBoxSize[0].blockSize, 25.25,
                      "target border-box block size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].inlineSize, 56,
                      "target device-pixel-content-box inline size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].blockSize, 25,
                      "target device-pixel-content-box block size");
      }
    },
    {
      setup: observer => {
        t.style.marginLeft = "10.5px"
      },
      notify: entries => {
        assert_equals(entries.length, 1, "1 pending notification");
        assert_equals(entries[0].target, t, "target is t");
        assert_equals(entries[0].contentRect.width, 55.5, "target width");
        assert_equals(entries[0].contentRect.height, 25.25, "target height");
        assert_equals(entries[0].contentBoxSize[0].inlineSize, 55.5,
                      "target content-box inline size");
        assert_equals(entries[0].contentBoxSize[0].blockSize, 25.25,
                      "target content-box block size");
        assert_equals(entries[0].borderBoxSize[0].inlineSize, 55.5,
                      "target border-box inline size");
        assert_equals(entries[0].borderBoxSize[0].blockSize, 25.25,
                      "target border-box block size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].inlineSize, 55,
                      "target device-pixel-content-box inline size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].blockSize, 25,
                      "target device-pixel-content-box block size");
      }
    },
    {
      setup: observer => {
        document.body.style.zoom = 3;
      },
      notify: entries => {
        assert_equals(entries.length, 1, "1 pending notification");
        assert_equals(entries[0].target, t, "target is t");
        assert_equals(entries[0].contentRect.width, 55.5, "target width");
        assert_equals(entries[0].contentRect.height, 25.25, "target height");
        assert_equals(entries[0].contentBoxSize[0].inlineSize, 55.5,
                      "target content-box inline size");
        assert_equals(entries[0].contentBoxSize[0].blockSize, 25.25,
                      "target content-box block size");
        assert_equals(entries[0].borderBoxSize[0].inlineSize, 55.5,
                      "target content-box inline size");
        assert_equals(entries[0].borderBoxSize[0].blockSize, 25.25,
                      "target content-box block size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].inlineSize, 166,
                      "target content-box inline size");
        assert_equals(entries[0].devicePixelContentBoxSize[0].blockSize, 76,
                      "target content-box block size");
      }
    }
  ]);

  return helper.start(() => t.remove());
}

function test2() {
  // Ensure a resize observer callback that triggers only layout does not crash
  // the browser

  let c = document.createElement('canvas');
  let a = document.createElement('div');
  a.style.height = '10px';
  a.style.width = '20px';
  c.width = "500";
  c.height = "500";
  document.body.appendChild(c);
  document.body.appendChild(a);

  let helper = new ResizeTestHelper(
    "Resize observer callback triggers layout without style change",
  [
    {
      setup: observer => {
        observer.observe(a, { box: "border-box" });
      },
      notify: entries => {

      }
    },
    {
      setup: observer => {
        a.style.width = '50px';
      },
      notify: entries => {
        c.height = "100";
        assert_equals(entries.length, 1, "1 pending notification");
        assert_equals(entries[0].target, a, "target is t");
        assert_equals(entries[0].contentRect.width, 50, "target width");
        assert_equals(entries[0].contentRect.height, 10, "target height");
        assert_equals(entries[0].borderBoxSize[0].inlineSize, 50,
                      "target border-box inline size");
        assert_equals(entries[0].borderBoxSize[0].blockSize, 10,
                      "target border-box block size");
      }
    },
  ]);
  return helper.start(() => assert_equals(c.height, 100,
                      "canvas height"));
}

test();
test2();

</script>