<!DOCTYPE html>
<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->
<title>OffscreenCanvas test: 2d.filter.canvasFilterObject.componentTransfer.discrete.tentative</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/html/canvas/resources/canvas-tests.js"></script>

<h1>2d.filter.canvasFilterObject.componentTransfer.discrete.tentative</h1>
<p class="desc">Test pixels on CanvasFilter() componentTransfer with discrete type</p>


<script>
var t = async_test("Test pixels on CanvasFilter() componentTransfer with discrete type");
var t_pass = t.done.bind(t);
var t_fail = t.step_func(function(reason) {
    throw reason;
});
t.step(function() {

var canvas = new OffscreenCanvas(100, 50);
var ctx = canvas.getContext('2d');

// From https://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement
function getTransformedValue(C, V) {
    // Get the right interval
    const n = V.length;
    const k = C == 1 ? n - 1 : Math.floor(C * n);
    return V[k];
}

function getColor(inputColor, tableValues) {
    const result = [0, 0, 0];
    for (const i in inputColor) {
        const C = inputColor[i]/255;
        const Cprime = getTransformedValue(C, tableValues[i]);
        result[i] = Math.max(0, Math.min(1, Cprime)) * 255;
    }
    return result;
}

tableValuesR = [0, 0, 1, 1];
tableValuesG = [2, 0, 0.5, 3];
tableValuesB = [1, -1, 5, 0];
ctx.filter = new CanvasFilter({filter: "componentTransfer",
    funcR: {type: "discrete", tableValues: tableValuesR},
    funcG: {type: "discrete", tableValues: tableValuesG},
    funcB: {type: "discrete", tableValues: tableValuesB},
});

const inputColors = [
    [255, 255, 255],
    [0, 0, 0],
    [127, 0, 34],
    [252, 186, 3],
    [50, 68, 87],
];

for (const color of inputColors) {
    let outputColor = getColor(color, [tableValuesR, tableValuesG, tableValuesB]);
    ctx.fillStyle = `rgb(${color[0]}, ${color[1]}, ${color[2]})`;
    ctx.fillRect(0, 0, 10, 10);
    _assertPixelApprox(canvas, 5, 5, outputColor[0],outputColor[1],outputColor[2],255, "5,5", `${outputColor[0]},${outputColor[1]},${outputColor[2]}`, 2);
}
t.done();

});
</script>
