<!DOCTYPE html>
<head>
    <link rel="match" href="canvas-filter-object-convolve-matrix-expected.html">
    <style type="text/css">
      canvas {
        margin: 5px;
      }
    </style>
</head>
<body>
</body>
<script>
function makeConvolveFilter(options) {
  const KERNEL_MATRIX = [
    [3, 0, 0],
    [0, 0, 0],
    [0, 0, -3],
  ];

  options = Object.assign(options, {
    kernelMatrix: KERNEL_MATRIX, filter: "convolveMatrix"});
  return new CanvasFilter(options);
}

const test_cases = [
  {},
  {preserveAlpha: true},
  {targetX: 2, targetY: 2},
  {divisor: 3},
  {bias: 0.5},
  {edgeMode: "wrap"}
];

function draw(ctx) {
  ctx.fillRect(0, 20, 120, 100);

  ctx.beginPath();
  ctx.arc(150, 70, 50, 0, 2*Math.PI);
  ctx.fill();

  ctx.beginPath();
  ctx.moveTo(220, 20);
  ctx.lineTo(170, 120);
  ctx.lineTo(270, 120);
  ctx.lineTo(220, 20);
  ctx.fill();
}

for (tc of test_cases) {
  const canvas = document.createElement("canvas");
  document.body.prepend(canvas);
  const ctx = canvas.getContext("2d");
  ctx.filter = "blur(0px)";
  ctx.fillStyle = "rgba(0,255,0,0.5)";
  draw(ctx);
  ctx.fillStyle = "rgba(255,0,255,0.5)";
  ctx.filter = makeConvolveFilter(tc);
  draw(ctx);
}
</script>
