disconnected-canvas-lost-gpu-context.html

<html>
<head>
<script src="../../resources/js-test.js"></script>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
</head>
<body>
<script>
let ctx;
let lostEventHasFired = false;

function verifyContextLost(shouldBeLost) {
    // Verify context loss experimentally as well as isContextLost()
    ctx.fillStyle = '#0f0';
    ctx.fillRect(0, 0, 1, 1);
    contextLostTest = ctx.getImageData(0, 0, 1, 1).data[1] == 0;
    if (shouldBeLost) {
        assert_true(contextLostTest);
        assert_true(ctx.isContextLost());
    } else {
        assert_false(contextLostTest);
        assert_false(ctx.isContextLost());
    }
}

function contextLost() {
    assert_false(lostEventHasFired, 'Context lost event was dispatched more than once.');
    lostEventHasFired = true;
    verifyContextLost(true);
}

function contextRestored() {
    assert_true(lostEventHasFired, 'Context restored event was dispatched before a context lost event.');
    verifyContextLost(false);
}

async_test(function(t) {
    if (window.internals) {
        var canvas = document.createElement('canvas');
        canvas.addEventListener('contextlost', contextLost);
        canvas.addEventListener('contextrestored', contextRestored);
        ctx = canvas.getContext('2d', {willReadFrequently: true});

        ctx.fillRect(0, 0, 1, 1);
        // setTimeout creates a frame barrier that locks the canvas into gpu
        // acceleration mode when running under virtual/gpu
        setTimeout(t.step_func_done(() => {
            // Now it is safe to use verifyContextLost without fearing side-effects
            // because a rendering mode was fixed.
            verifyContextLost(false);

            internals.forceLoseCanvasContext(canvas, "2d");
            if (!ctx.isContextLost()) {
                assert_true(false, "canvas context is not lost properly. This is expected if canvas is not accelerated.");
            } else {
                verifyContextLost(true);
            }
        }, 0));
    } else {
        assert_true(false, 'This test requires window.internals.');
    }
}, "Test the behavior of disconneced canvas recovery after a gpu context loss");

</script>
</body>
</html>
chromium/third_party/blink/web_tests/fast/canvas/disconnected-canvas-lost-gpu-context.html
