(WPF) How to set value of a sys:Double to SystemFonts.MessageFontSize from ResourceDictionary?
Scenario:
I want to use 3 standard font size for my WPF application : BigFontSize
, NormalFontSize
, and SmallFontSize
. These are double values and they are defined in resource dictionary as (where sys
is appropriately defined):
<sys:Double x:Key="BigFontSize">18</sys:Double>
<sys:Double x:Key="NormalFontSize">14</sys:Double>
<sys:Double x:Key="SmallFontSize">12</sys:Double>
This works well. But i have randomly selected 14 as a normal size. What i want is to get a system defined font size for NormalFontSize
. (If that's done, I can use a converter as described here to get BigFontSize
and SmallFontSize
relative to NormalFontSize
)
I found from the documentation that default font size is stored in a static property (double) SystemFonts.MessageFontSize
. But what should I do to retrieve that value to resource dictionary? (I know Binding
or DynamicResource
cannot be applied. But hey, this is a static value, so how can I apply StaticResource
or x:Static
or whatever?)
I have tried
<sys:Double x:Key="XXXFontSize">
<StaticResource ResourceKey="SystemFonts.MessageFontSize" />
</sys:Double>
and
<sys:Double x:Key="XXXFontSize">
<x:Static ResourceKey="SystemFonts.MessageFontSize" />
</sys:Double>
Both of which doesn't seem to work (as expected). I get an error saying Cannot add content to object of type 'System.Double'.
Note:
- I don't want to do this from code, e.g from App(). (Is it possible to have a code-behind for ResourceDictionary?)
I don't want to encapsulate this in generalized style from which other styles can be derived (using
That is, I cannot useBasedOn
) because I have several Resource Dictionaries, and it'll not be possible to useDynamicResource
withBasedOn
<Style x:Key="BigFont" TargetType="{x:Type Control}"}> <Setter Property="Control.FontSize" Value="{Binding Source={x:Static SystemFonts.MessageFontSize}, Converter={ . . . }" /> </Style>
Because, if I have a style in other ResourceDictionary, say
HeaderTextBlockStyle
, then I would have to useBasedOn={DynamicResource BigFont}
which is not possible (I think)
Any help would be greatly appreciated.
Thank you.TAGS : WPF SystemFonts.MessageFontSize ResourceDictionary FontSize BasedOn DynamicResource
I've done like this...
public partial class GlobalResources : ResourceDictionary
{
public GlobalResources()
{
this.Add("GiantFontSize", SystemFonts.MessageFontSize * 2.5);
this.Add("BigFontSize", SystemFonts.MessageFontSize * 1.5);
this.Add("MediumFontSize", SystemFonts.MessageFontSize * 1.25);
this.Add("NormalFontSize", SystemFonts.MessageFontSize);
this.Add("SmallFontSize", SystemFonts.MessageFontSize * 0.85);
}
}
... and it's working like like a miracle!!! I can use these resources in the same (partial) resource dictionary or from other resource dictionaries like this...
<Style ...>
<Setter Property="FontSize"
Value="{DynamicResource MediumFontSize}" />
...
</Style>
I don't know if it is a "good practice" or not (please comment on this), I only know that it works..!!!
Check out this article: Override default styles It may have what you are looking for.
精彩评论