background-blend-mode-computed-multiple.html

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This WPT test may be referenced by the following Test IDs:
- /css/compositing/parsing/background-blend-mode-computed-multiple.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Compositing and Blending Level 1: getComputedStyle().backgroundBlendMode</title>

<link rel="help" href="https://drafts.fxtf.org/compositing-1/#propdef-background-blend-mode">

<meta name="assert" content="background-blend-mode computed value is as specified even when the number of images vary.">

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

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

<script src="/css/support/computed-testcommon.js"></script>

<style>

    #target {

        background-image: linear-gradient(green, green), linear-gradient(green, green), linear-gradient(green, green);

</style>

</head>

<body>

<div id="target"></div>

<script>

// This is testing the case with multiple background images

//

// see https://drafts.fxtf.org/compositing-1/#background-blend-mode

// and https://drafts.csswg.org/css-backgrounds-3/#layering

// > The lists are matched up from the first value: excess values at the end are not used.

// and

// > If a property doesn’t have enough comma-separated values

// > to match the number of layers, the UA must calculate its used value

// > by repeating the list of values until there are enough.

// but in https://drafts.csswg.org/css-values-4/#linked-properties

// it was decided that

// > The computed values of the coordinating list properties are not affected by such truncation or repetition.

//

// There is a distinction between specified values, used values, and computed values.

// if three images and one value, just send back the specified list.

test_computed_value("background-blend-mode", "normal");

test_computed_value("background-blend-mode", "multiply");

// if three images and two values, just send back the specified list.

test_computed_value("background-blend-mode", "normal, luminosity");

test_computed_value("background-blend-mode", "screen, overlay");

test_computed_value("background-blend-mode", "color, saturation");

// if three images and three values, just send back the specified list.

test_computed_value("background-blend-mode", "normal, luminosity, color");

test_computed_value("background-blend-mode", "screen, overlay, screen");

</script>

</body>

</html>