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Description
Bug Report
Prerequisites
- [/] Can you reproduce the problem in a MWE?
- [/] Are you running the latest version of AngleSharp.Css?
- [/] Did you check the FAQs to see if that helps you?
- [/] Are you reporting to the correct repository? (there are multiple AngleSharp libraries, e.g.,
AngleSharp.Css
for CSS support) - [/] Did you perform a search in the issues?
For more information, see the CONTRIBUTING
guide.
Description
Computed Styles do not translate em
units. This does not match the behavior of the javascript function window.getComputedStyles
. In the case of font-size
this becomes particularly problematic because the CssProperty
does not correctly set the IsInherited
property. This means that in the case of an element that has inherited an em
font-size
, there is no way to calculate what the "true" font-size is.
Edit: upon further review of the IsInherited
property, I now understand that to mean that it is indicated whether the property has a declaration of inherit
, in which case this is not the flag we would need to set to solve this problem. Either we may calculate the em
units properly or indicate that the css property returned does not originate on the element itself so that the value could be calculated.
Steps to Reproduce
var config = Configuration.Default.WithCss();
var context= BrowsingContext.New(config);
var source = "<p>This is <span>only</span> a test.</p>";
var cssSheet = "p { font-size: 1.5em }";
var document = await context.OpenAsync(req => req.Content(source));
var style = document.CreateElement<IHtmlStyleElement>();
style.TextContent = cssSheet;
document.Head.AppendChild(style);
var span = document.QuerySelector("span");
var fontSize = span.ComputeCurrentStyle().GetProperty("font-size");
fontSize.IsInherited.Dump();
fontSize.Value.Dump();
Expected behavior: Either IsInherited
== true
, or Value
== 24px
. Ideally both.
Actual behavior: IsInherited
== false
AND Value
== 1.5em
Environment details: Windows, .NET 6.0.14
Possible Solution
First, when a cssProperty is computed from the parent of the element in question, IsInherited
should be set to true
.
Ideally Length
units would utilize the ToPixels
method to translate relative units to pixels, as this is the behavior of the javascript method that is being mirrored.