public static CssValue Font_Size_Computed(ICssProperty Property)
{/* Docs: https://www.w3.org/TR/css-fonts-3/#font-size-prop */
if (Property == null)
{
throw new ArgumentNullException(nameof(Property));
}
Contract.EndContractBlock();
CssValue value = (Property as CssProperty).Specified;
if (value is null)
{
throw new CssException($"Unable to resolve absolute length for Computed \"{Property.CssName}\" value.");
}
Contract.EndContractBlock();
double Size = UserAgent.DEFAULT_FONT_SIZE; /* CssUIs' base font size */
double Scaling = 1.0; /* Scaling to apply to our base size, used if the specified value is a keyword */
if (value.HasValue)
{
if (value.IsDefinite)
{
Size = value.AsDecimal();
}
else
{
switch (value.Type)
{
case ECssValueTypes.DIMENSION:
{
Scaling = 1.0;
Size = value.Resolve(Property.Owner.ownerDocument.cssUnitResolver);
}
break;
case ECssValueTypes.KEYWORD:
{
var keyword = value.AsEnum <EFontSize>();
switch (keyword)
{
/* First off, if the value is an <absolute> size keyword we associate it with a scale and apply it to our base size */
case EFontSize.XXSmall:
case EFontSize.XSmall:
case EFontSize.Small:
case EFontSize.Medium:
case EFontSize.Large:
case EFontSize.XLarge:
case EFontSize.XXLarge:
Scaling = CssCommon.Get_Font_Size_Keyword_Scaling_Factor(keyword);
break;
/* Second, if the value is a <relative> size keyword we find the computed font size of our parent and increase/decrease it to get our value */
case EFontSize.Smaller:
{
double parentSize = Property.Owner.Style.Cascaded.FontSize.Computed.AsDecimal();
int scaleIndex = CssCommon.Get_Font_Scaling_Step_Index_From_Size(parentSize);
Scaling = CssCommon.Get_Font_Scaling_From_Step_Index(scaleIndex - 1);
}
break;
case EFontSize.Larger:
{
double parentSize = Property.Owner.Style.Cascaded.FontSize.Computed.AsDecimal();
int scaleIndex = CssCommon.Get_Font_Scaling_Step_Index_From_Size(parentSize);
Scaling = CssCommon.Get_Font_Scaling_From_Step_Index(scaleIndex + 1);
}
break;
}
}
break;
}
double finalSize = Size * Scaling;
return(CssValue.From(finalSize));
}
}
// Round the size up to the nearest whole pixel value
Size = CssCommon.SnapToPixel(Size);
return(CssValue.From(Size));
}
private bool Try_Match(Document document)
{
switch (Context)
{
case EMediaFeatureContext.Boolean:
{
/*
* ...the media feature is evaluated in a boolean context.
* If the feature would be true for any value other than the number 0, a <dimension> with the value 0, or the keyword none, the media feature evaluates to true.
* Otherwise, it evaluates to false.
*/
CssValue value = Values[0];
if (!Lookup.TryEnum(value.AsString(), out EMediaFeatureName nameLookup))
{ /* This feature is not supported (or maybe valid) so we need to treat it as if it simply doesnt match */
IsValid = false;
return(false);
}
// CssValue valueA = Values[0];
CssValue valueB = Values[1];
switch (valueB.Type)
{
case ECssValueTypes.KEYWORD:
{
return(Compare_Keyword(document, nameLookup, valueB.AsString()));
}
case ECssValueTypes.INTEGER:
case ECssValueTypes.NUMBER:
{
double A = (double)Resolve_Media_Name_Value(document, nameLookup);
double B = valueB.AsDecimal();
return(!(A == B));
}
case ECssValueTypes.DIMENSION:
case ECssValueTypes.RESOLUTION:
{
double A = (double)Resolve_Media_Name_Value(document, nameLookup);
double B = valueB.Resolve(document.cssUnitResolver);
return(!(A == B));
}
}
}
break;
case EMediaFeatureContext.Range:
{
/* Compare all value/operator pairs */
for (int i = 1; i < Operators.Length; i++)
{
CssValue A = Values[i - 1];
CssValue B = Values[i];
var op = Operators[i - 1];
if (!Compare(document, A, B, op))
{
return(false);
}
}
return(true);
}
}
return(false);
}