Bug 18300 – getComputedStyle() -> length values floored

• Component: DOM
• Status: RESOLVED INVALID

[Garrett Smith]

When getting the computed style, values are rounded. 

This sets the border width of the element in EM units, then gets the value of the computed border width in px, using getComputedStyle. The problem seems to be that the value is floored. The expected value would be: "11.8px"


borderWidth:
javascript:(function(){var c1 =document.getElementsByTagName("div")[0], style=c1.style; style.border ="1.18em solid"; style.fontSize = "10px"; var cs = getComputedStyle(c1, ""); alert([cs.borderTopWidth, cs.borderRightWidth, cs.borderBottomWidth, cs.borderLeftWidth]);})(); 

The actual value: "11px"

javascript:(function(){var c1 =document.getElementsByTagName("div")[0], style=c1.style; style.margin ="1.18em"; style.fontSize = "10px"; var cs = getComputedStyle(c1, ""); alert([cs.marginTop, cs.marginLeft, cs.marginBottom, cs.marginRight]);})(); 

This creates problems when attempting to measure the dimensions of an element, or find it's position.

[Garrett Smith]

updated URL

[Eric Seidel (no email)]

I've made a test case from the JS you posted.  Your test case was a URL to your local harddrive, which isn't accessible to me. ;)

[Eric Seidel (no email)]

Created attachment 28338 [details]
test case demonstrating that our behavior matches FF3

[Eric Seidel (no email)]

as far as I can tell, our behavior matches FF3, they also round.  Closing this bug as invalid.