image.smoothing.html

Enable keyboard shortcuts

This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/manual/image-smoothing/image.smoothing.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>OffscreenCanvasRenderingContext2D imageSmoothingEnabled test</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<link rel="help" href="https://html.spec.whatwg.org/#the-offscreen-2d-rendering-context">

<script>

function createTestImage() {

  var image = new OffscreenCanvas(100, 50);

  var imgctx = image.getContext('2d');

  imgctx.fillStyle = "#F00";

  imgctx.fillRect(0, 0, 2, 2);

  imgctx.fillStyle = "#0F0";

  imgctx.fillRect(0, 0, 1, 1);

  return image;

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  assert_true(ctx.imageSmoothingEnabled);

}, "When the context is created, imageSmoothingEnabled must be set to true.");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  ctx.imageSmoothingEnabled = false;

  assert_false(ctx.imageSmoothingEnabled);

}, "On getting imageSmoothingEnabled, the user agent must return the last value it was set to.");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  var image = createTestImage();

  ctx.scale(10, 10);

  ctx.drawImage(image, 0, 0);

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_not_equals(pixels[0], 0);

  assert_not_equals(pixels[1], 255);

}, "Test that image smoothing is actually on by default.");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  ctx.imageSmoothingEnabled = true;

  var image = createTestImage();

  ctx.scale(10, 10);

  ctx.drawImage(image, 0, 0);

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_not_equals(pixels[0], 0);

  assert_not_equals(pixels[1], 255);

}, "Test that image smoothing works when imageSmoothingEnabled is set to true");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  var image = createTestImage();

  ctx.imageSmoothingEnabled = false;

  ctx.scale(10, 10);

  ctx.drawImage(image, 0, 0);

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_array_equals(pixels, [0, 255, 0, 255]);

}, "Test that imageSmoothingEnabled = false (nearest-neighbor interpolation) works with drawImage().");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  var image = createTestImage();

  ctx.imageSmoothingEnabled = false;

  ctx.scale(10, 10);

  ctx.fillStyle = ctx.createPattern(image, 'repeat');

  ctx.fillRect(0, 0, 10, 10);

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_array_equals(pixels, [0, 255, 0, 255]);

}, "Test that imageSmoothingEnabled = false (nearest-neighbor interpolation) works with fillRect and createPattern().");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  var image = createTestImage();

  ctx.imageSmoothingEnabled = false;

  ctx.fillStyle = ctx.createPattern(image, 'repeat');

  ctx.scale(10, 10);

  ctx.rect(0, 0, 10, 10);

  ctx.fill();

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_array_equals(pixels, [0, 255, 0, 255]);

}, "Test that imageSmoothingEnabled = false (nearest-neighbor interpolation) works with fill() and createPattern().");

test(function() {

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  var image = createTestImage();

  ctx.strokeStyle = ctx.createPattern(image, 'repeat');

  ctx.lineWidth = 5;

  ctx.imageSmoothingEnabled = false;

  ctx.scale(10, 10);

  ctx.beginPath();

  ctx.moveTo(0, 0);

  ctx.lineTo(10, 10);

  ctx.stroke();

  var pixels = ctx.getImageData(9, 9, 1, 1).data;

  assert_array_equals(pixels, [0, 255, 0, 255]);

}, "Test that imageSmoothingEnabled = false (nearest-neighbor interpolation) works with stroke() and createPattern().");

test(function() {

  var repaints = 5;

  var offscreenCanvas = new OffscreenCanvas(100, 50);

  var ctx = offscreenCanvas.getContext('2d');

  function draw() {

    ctx.clearRect(0, 0, 10, 10);

    ctx.setTransform(1, 0, 0, 1, 0, 0);

    var image = createTestImage();

    ctx.imageSmoothingEnabled = false;

    ctx.scale(10, 10);

    ctx.drawImage(image, 0, 0);

    var pixels = ctx.getImageData(9, 9, 1, 1).data;

    assert_array_equals(pixels, [0, 255, 0, 255]);

  while (repaints > 0) {

    draw();

    repaints = repaints - 1;

}, "Test that imageSmoothingEnabled = false (nearest-neighbor interpolation) still works after repaints.");

</script>