1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/reftests/css-blending/background-blending-alpha-ref.html Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,62 @@
1.4 +<!--
1.5 + Any copyright is dedicated to the Public Domain.
1.6 + http://creativecommons.org/publicdomain/zero/1.0/
1.7 +-->
1.8 +<html>
1.9 +<style>
1.10 +.reftest {
1.11 + background-color: rgba(0, 255, 0, 0.5);
1.12 +}
1.13 +
1.14 +.child {
1.15 + width: 100px;
1.16 + height: 100px;
1.17 + opacity: 0.5;
1.18 + background-color: rgb(0, 127, 0);
1.19 +}
1.20 +
1.21 +.topleft {
1.22 + float:left;
1.23 +
1.24 + width: 100px;
1.25 + height: 100px;
1.26 +
1.27 + /*First blend black rect with green in place*/
1.28 + /* Cs = (1 - αb) x Cs + αb x B(Cb, Cs)*/
1.29 + /* B(Cb, Cs) = | Cb - Cs | = (0, 0, 0) */
1.30 + /* 0.5 * (0, 255, 0) + 0.5 * (0, 0, 0) = (0, 127.5, 0)*/
1.31 +
1.32 + /* Now, composite the resulting color with src-over; the alpha is the original alpha for the top layer
1.33 + while the color is the blending result*/
1.34 + /* co = αs x Fa x Cs + αb x Fb x Cb - this is premultiplied */
1.35 + /* αo = αs + αb x (1 – αs) */
1.36 + /* Source over: Fa = 1; Fb = 1 – αs */
1.37 + /*co = 0.5 * 1 * (0, 127.5, 0) + 0.5 * 0.5 * (0, 255, 0) = (0, 63.5, 0) + 0.25 * (0, 255, 0) = (0, 127.5, 0)*/
1.38 + /*ao = 0.5 + 0.5 * 0.5 = 0.75*/
1.39 + /* Co = co/ao = (0, 127.5, 0) / 0.75*/
1.40 +
1.41 + /* Now alpha composite on white background */
1.42 + /*co = 0.75 * 1 * (0, 127.5, 0) / 0.75 + 1 * 0.25 * (255, 255, 255) = (0, 127.5, 0) + (63.75, 63.75, 63.75) = (63.75, 159, 63.75) = (64, 191, 64) */
1.43 +
1.44 + background-color: rgb(64, 191, 64);
1.45 +}
1.46 +
1.47 +.topright {
1.48 + float:left;
1.49 + width: 100px;
1.50 + height: 100px;
1.51 +}
1.52 +
1.53 +.bottom {
1.54 + width:200px;
1.55 + height: 100px;
1.56 + clear:both;
1.57 +}
1.58 +
1.59 +</style>
1.60 +
1.61 +<div class="topleft"></div>
1.62 +<div class="reftest topright"></div>
1.63 +<div class="reftest bottom"></div>
1.64 +
1.65 +</html>
