OffscreenCanvas-clearRect-no-overdraw.html

<!DOCTYPE html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<canvas id="c" witdth="100" height="100"></canvas>
<script>

// This is a regression test for crbug.com/1054666
// Note: This test needs to use canvases that are attached to the DOM
// in order to be a valid repro case for bug 1054666

async_test(t =>{
  const c = document.getElementById("c");
  const offscreen_canvas = c.transferControlToOffscreen();
  const ctx_o = offscreen_canvas.getContext('2d');
  // Since it checks if content retaining |mode_| changes from frame to frame,
  // multiple calls to rAF are used to assure the creation of new frame.
  ctx_o.fillRect(50, 50, 50, 50);
  ctx_o.clearRect(0, 0, 100, 90);
  window.requestAnimationFrame(dt => {
    ctx_o.fillRect(0, 0, 15, 15);
    window.requestAnimationFrame(dt => {
      const reference_ctx = document.createElement("canvas").getContext("2d");
      reference_ctx.fillRect(0, 0, 15, 15);
      reference_ctx.fillRect(50, 90, 50, 10);
      const image_data = ctx_o.getImageData(0, 0, 100, 100);
      const expected_image_data = reference_ctx.getImageData(0, 0, 100, 100);
      t.step(() => {
        assert_array_equals(image_data.data, expected_image_data.data);
      });
      t.done();
    });
  });  
}, "First frame not fully overdrawn.");  

</script>
chromium/third_party/blink/web_tests/fast/canvas/OffscreenCanvas-clearRect-no-overdraw.html
