/// <summary>
/// Throws an exception if the value is invalid according to the currently set options
/// </summary>
/// <param name="Value"></param>
/// <returns></returns>
public void CheckAndThrow(ICssProperty Owner, CssValue Value)
{
if (Owner is null)
{
throw new ArgumentNullException(nameof(Owner));
}
if (Value is null)
{
throw new ArgumentNullException(nameof(Value));
}
Contract.EndContractBlock();
if (!Is_Valid_Value_Type(Value.Type))
{
throw new CssException($"The property({Name}) cannot be set to an {Enum.GetName(typeof(ECssValueTypes), Value.Type)}!");
}
switch (Value.Type)
{
case ECssValueTypes.KEYWORD:
{ // check this value against our keyword whitelist
if (KeywordWhitelist != null && KeywordWhitelist.Count > 0)
{
if (!KeywordWhitelist.Contains(Value.AsString()))
{
throw new CssException($"Property({Name}) does not accept '{Value.AsString()}' as a value!");
}
}
}
break;
}
}
/// <summary>
/// Throws an exception if the value is invalid according to the currently set options
/// </summary>
/// <param name="Value"></param>
/// <returns></returns>
public void CheckAndThrow(ICssProperty Owner, CssValue Value)
{
if (Owner is null)
{
throw new ArgumentNullException(nameof(Owner));
}
if (Value is null)
{
throw new ArgumentNullException(nameof(Value));
}
Contract.EndContractBlock();
if (!Is_Valid_Value_Type(Value.Type))
{
throw new CssException($"The property({Enum.GetName(typeof(EMediaFeatureName), Name.Value)}) cannot be set to an {Enum.GetName(typeof(ECssValueTypes), Value.Type)}!");
}
switch (Value.Type)
{
case ECssValueTypes.KEYWORD:
{ // check this value against our keyword whitelist
if (KeywordWhitelist is object && KeywordWhitelist.Count > 0)
{
//if (!Array.Exists(keywordWhitelist, x => x.Equals(Value.AsString(), StringComparison.InvariantCultureIgnoreCase)))
if (!KeywordWhitelist.Contains(Value.AsString()))
{
throw new CssException($"Property({Enum.GetName(typeof(EMediaFeatureName), Name.Value)}) does not accept '{Value.AsString()}' as a value!");
}
}
}
break;
}
}
static bool Compare(Document document, CssValue ValueA, CssValue ValueB, EMediaOperator Op)
{
/* An Excerpt:
* "If a media feature references a concept which does not exist on the device where the UA is running (for example, speech UAs do not have a concept of “width”), the media feature must always evaluate to false."
*/
double A, B;
/* First resolve these values to numbers we can compare */
if (ValueA.Type == ECssValueTypes.KEYWORD)
{
if (!Lookup.TryEnum(ValueA.AsString(), out EMediaFeatureName _))
{/* If we cant find this keyword then we treat it as if it were an unsupported feature */
return(false);
}
A = (double)Resolve_Media_Name_Value(document, ValueA.AsEnum <EMediaFeatureName>());
}
else
{
A = ValueA.AsDecimal();
}
if (ValueB.Type == ECssValueTypes.KEYWORD)
{
if (!Lookup.TryEnum(ValueB.AsString(), out EMediaFeatureName _))
{/* If we cant find this keyword then we treat it as if it were an unsupported feature */
return(false);
}
B = (double)Resolve_Media_Name_Value(document, ValueB.AsEnum <EMediaFeatureName>());
}
else
{
B = ValueB.AsDecimal();
}
/* Compare them and return the result */
switch (Op)
{
case EMediaOperator.EqualTo:
{
return(A == B);
}
case EMediaOperator.LessThan:
{
return(A < B);
}
case EMediaOperator.GreaterThan:
{
return(A > B);
}
case EMediaOperator.LessThanEq:
{
return(A < B || (A == B));
}
case EMediaOperator.GreaterThanEq:
{
return(A > B || (A == B));
}
}
return(false);
}
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);
}