1 files changed, 22 insertions, 0 deletions
diff --git a/testing/web-platform/tests/resize-observer/create-pattern-data-url.js b/testing/web-platform/tests/resize-observer/create-pattern-data-url.js
new file mode 100644
index 0000000000..d3634dc424
--- /dev/null
+++ b/testing/web-platform/tests/resize-observer/create-pattern-data-url.js
@@ -0,0 +1,22 @@
+const patternSize = 4;
+
+export default function createPatternDataURL() {
+  const ctx = document.createElement('canvas').getContext('2d');
+  ctx.canvas.width = patternSize;
+  ctx.canvas.height = patternSize;
+
+  const b = [0, 0, 0, 255];
+  const t = [0, 0, 0, 0];
+  const r = [255, 0, 0, 255];
+  const g = [0, 255, 0, 255];
+
+  const imageData = new ImageData(patternSize, patternSize);
+  imageData.data.set([
+    b, t, t, r,
+    t, b, g, t,
+    t, r, b, t,
+    g, t, t, b,
+  ].flat());
+  ctx.putImageData(imageData, 0, 0);
+  return {patternSize, dataURL: ctx.canvas.toDataURL()};
+}