42012 2010-07-09 17:47:51 -0700 Alpha value obtained by getComputedStyle is noticeably less than the actual value. 2012-07-15 20:39:54 -0700 1 1 1 Unclassified WebKit CSS 528+ (Nightly build) All All RESOLVED DUPLICATE 91355 P2 Normal --- 1 rniwa webkit-unassigned ap patrice simon.fraser oldest_to_newest 249394 0 61124 rniwa 2010-07-09 17:47:51 -0700 Created attachment 61124 demonstrates the bug When the background color is set to rgba(255, 255, 0.5), the computed style's background color indicates the actual alpha value to be 0.496094. Firefox returns 0.5 correctly. The bug is demonstrated in the attachment. 276858 1 patrice 2010-09-09 17:04:03 -0700 Also, sometimes, assigning the generated rgba color append to generate a new value : document.body.style.backgroundColor="rgba(0,0,0,0.3)"; "rgba(0,0,0,0.3)" document.body.style.backgroundColor = document.body.style.backgroundColor; "rgba(0, 0, 0, 0.296875)" document.body.style.backgroundColor = document.body.style.backgroundColor; "rgba(0, 0, 0, 0.292969)" document.body.style.backgroundColor = document.body.style.backgroundColor; "rgba(0, 0, 0, 0.292969)" 320988 2 76360 daniel.wagner 2010-12-13 01:44:08 -0800 Created attachment 76360 demonstrates issue with getComputedStyle for opacity Similarly, if an element's opacity is set to 0.7, getComputedStyle returns 0.699999988079071. 321231 3 simon.fraser 2010-12-13 10:37:47 -0800 I think this is a divide-by-255 vs. 256 issue. 321392 4 simon.fraser 2010-12-13 14:05:28 -0800 Internally rgba(255, 255, 0, 0.5) is stored as 0x7fffff00 (ARGB), and 127/255 is 0.49803921568627. (In reply to comment #2) > Created an attachment (id=76360) [details] > demonstrates issue with getComputedStyle for opacity > > Similarly, if an element's opacity is set to 0.7, getComputedStyle returns 0.699999988079071. This is just floating point rounding error. 670063 5 rniwa 2012-07-15 20:39:54 -0700 *** This bug has been marked as a duplicate of bug 91355 *** 61124 2010-07-09 17:47:51 -0700 2010-07-09 17:47:51 -0700 demonstrates the bug computedStyleTest.html text/html 276 rniwa PGh0bWw+Cjxib2R5Pgo8cD4KPHNwYW4gaWQ9InRlc3QiIHN0eWxlPSJiYWNrZ3JvdW5kLWNvbG9y OiByZ2JhKDI1NSwgMjU1LCAwLCAwLjUpOyI+aGVsbG8sIHdvcmxkPC9zcGFuPgo8L3A+CjxzY3Jp cHQgdHlwZT0idGV4dC9qYXZhc2NyaXB0Ij4KCnZhciBlID0gZG9jdW1lbnQuZ2V0RWxlbWVudEJ5 SWQoJ3Rlc3QnKTsKZG9jdW1lbnQud3JpdGUod2luZG93LmdldENvbXB1dGVkU3R5bGUoZSwgbnVs bCkuYmFja2dyb3VuZENvbG9yKTsKCjwvc2NyaXB0Pgo8L2JvZHk+CjwvaHRtbD4K 76360 2010-12-13 01:44:08 -0800 2010-12-13 01:44:08 -0800 demonstrates issue with getComputedStyle for opacity webkit_opacity.html text/html 651 daniel.wagner PCFET0NUWVBFIGh0bWwgUFVCTElDICItLy9XM0MvL0RURCBYSFRNTCAxLjEvL0VOIiAiaHR0cDov L3d3dy53My5vcmcvVFIveGh0bWwxMS9EVEQveGh0bWwxMS5kdGQiPgo8aHRtbCB4bWxucz0iaHR0 cDovL3d3dy53My5vcmcvMTk5OS94aHRtbCIgeG1sOmxhbmc9ImVuIj4KPGhlYWQ+CiAgPG1ldGEg aHR0cC1lcXVpdj0iQ29udGVudC1UeXBlIiBjb250ZW50PSJ0ZXh0L2h0bWw7IGNoYXJzZXQ9dXRm LTgiIC8+CiAgPHN0eWxlIHR5cGU9InRleHQvY3NzIj4KICAjdGVzdCB7CiAgICBiYWNrZ3JvdW5k LWNvbG9yOiBibGFjazsKICAgIGNvbG9yOiB3aGl0ZTsKICAgIG9wYWNpdHk6IDAuNzsKICB9CiAg PC9zdHlsZT4KICA8c2NyaXB0IHR5cGU9InRleHQvamF2YXNjcmlwdCI+CiAgd2luZG93Lm9ubG9h ZCA9IGZ1bmN0aW9uKCkKICB7CiAgICB2YXIgZWwgPSBkb2N1bWVudC5nZXRFbGVtZW50QnlJZCgi dGVzdCIpOwogICAgdmFyIGNvbXB1dGVkVmFsdWUgPSBkb2N1bWVudC5kZWZhdWx0Vmlldy5nZXRD b21wdXRlZFN0eWxlKGVsLCBudWxsKS5vcGFjaXR5OwogICAgZWwuaW5uZXJIVE1MID0gY29tcHV0 ZWRWYWx1ZTsKICB9OwogIDwvc2NyaXB0Pgo8L2hlYWQ+Cjxib2R5PgogIDxkaXYgaWQ9InRlc3Qi Pjwvb3V0Pgo8L2JvZHk+CjwvaHRtbD4K