CustomControl and controlTemplate   

I want to write a custom control which has a (dependency ?) property which 
is an enum type, e.g. enum:.

    public enum LookKindOfMyCustomControl
    {
        TwoRectanglesAndALine,
        TwoEllipsesAndARectangle,
        ThreeEllipsesAndTwoRectangles
    }

(Just an example, the idea is that each of the items in the enumerator list 
represents composite shapes, GeometryGroups, PathGeometry or similar which 
is not easily represented as a parameterized "thing").

How can I best present this with a default style/template for the custom 
control ?
By setting a particular ControlTemplate based on change of the property ? 
How would the syntax be ?
Better done in code ? (but what about if an application wants to override 
the look of the control ?)

date: Tue, 25 Sep 2007 23:05:44 +0200   author:   Eager am

Re: CustomControl and controlTemplate   

Hi,

It's relatively easy to do if you use a Style trigger. For example (out 
of the top of my head)

<Control.Style>

     <Style TargetType="{x:Type Control}">

         <Setter Property="Template">
             <Setter.Value>
                 <!--Do something-->
             </Setter.Value>
         </Setter>

         <Style.Triggers>
             <DataTrigger Binding="{Binding MyLookAndFeel}"
                          Value="TwoRectanglesAndALine">
                 <Setter Property="Template">
                     <Setter.Value>
                         <!--Do something-->
                     </Setter.Value>
                 </Setter>
             </DataTrigger>
             <DataTrigger Binding="{Binding MyLookAndFeel}"
                          Value="TwoEllipsesAndARectangle">
                 <Setter Property="Template">
                     <Setter.Value>
                         <!--Do something-->
                     </Setter.Value>
                 </Setter>
             </DataTrigger>
             <DataTrigger Binding="{Binding MyLookAndFeel}"
                          Value="ThreeEllipsesAndTwoRectangles">
                 <Setter Property="Template">
                     <Setter.Value>
                         <!--Do something-->
                     </Setter.Value>
                 </Setter>
             </DataTrigger>
         </Style.Triggers>

     </Style>

</Control.Style>

To know if your property (which I named here MyLookAndFeel) must be a 
DependencyProperty, you must know if the value may change during 
runtime. If it's a DP, a change during runtime will be applied to the 
control. If it's a normal (CLR) property, the value will be loaded when 
the control is loaded, but subsequent changes will not be applied.

Greetings,
Laurent


Eager wrote:
> I want to write a custom control which has a (dependency ?) property 
> which is an enum type, e.g. enum:.
> 
>    public enum LookKindOfMyCustomControl
>    {
>        TwoRectanglesAndALine,
>        TwoEllipsesAndARectangle,
>        ThreeEllipsesAndTwoRectangles
>    }
> 
> (Just an example, the idea is that each of the items in the enumerator 
> list represents composite shapes, GeometryGroups, PathGeometry or 
> similar which is not easily represented as a parameterized "thing").
> 
> How can I best present this with a default style/template for the custom 
> control ?
> By setting a particular ControlTemplate based on change of the property 
> ? How would the syntax be ?
> Better done in code ? (but what about if an application wants to 
> override the look of the control ?)

-- 
Laurent Bugnion [MVP ASP.NET]
Software engineering, Blog: http://www.galasoft.ch
PhotoAlbum: http://www.galasoft.ch/pictures
Support children in Calcutta: http://www.calcutta-espoir.ch

date: Thu, 27 Sep 2007 11:36:59 +0200   author:   Laurent Bugnion, MVP

Re: CustomControl and controlTemplate   

Thanks a lot Laurent

I guess this means that XAML does not have something similar to a switch 
statement (C#), but only if statements which will all be executed (the 
trigger elements).


"Laurent Bugnion, MVP"  wrote in message 
news:usDj1nOAIHA.1204@TK2MSFTNGP03.phx.gbl...
> Hi,
>
> It's relatively easy to do if you use a Style trigger. For example (out of 
> the top of my head)
>
> <Control.Style>
>
>     <Style TargetType="{x:Type Control}">
>
>         <Setter Property="Template">
>             <Setter.Value>
>                 <!--Do something-->
>             </Setter.Value>
>         </Setter>
>
>         <Style.Triggers>
>             <DataTrigger Binding="{Binding MyLookAndFeel}"
>                          Value="TwoRectanglesAndALine">
>                 <Setter Property="Template">
>                     <Setter.Value>
>                         <!--Do something-->
>                     </Setter.Value>
>                 </Setter>
>             </DataTrigger>
>             <DataTrigger Binding="{Binding MyLookAndFeel}"
>                          Value="TwoEllipsesAndARectangle">
>                 <Setter Property="Template">
>                     <Setter.Value>
>                         <!--Do something-->
>                     </Setter.Value>
>                 </Setter>
>             </DataTrigger>
>             <DataTrigger Binding="{Binding MyLookAndFeel}"
>                          Value="ThreeEllipsesAndTwoRectangles">
>                 <Setter Property="Template">
>                     <Setter.Value>
>                         <!--Do something-->
>                     </Setter.Value>
>                 </Setter>
>             </DataTrigger>
>         </Style.Triggers>
>
>     </Style>
>
> </Control.Style>
>
> To know if your property (which I named here MyLookAndFeel) must be a 
> DependencyProperty, you must know if the value may change during runtime. 
> If it's a DP, a change during runtime will be applied to the control. If 
> it's a normal (CLR) property, the value will be loaded when the control is 
> loaded, but subsequent changes will not be applied.
>
> Greetings,
> Laurent
>
>
> Eager wrote:
>> I want to write a custom control which has a (dependency ?) property 
>> which is an enum type, e.g. enum:.
>>
>>    public enum LookKindOfMyCustomControl
>>    {
>>        TwoRectanglesAndALine,
>>        TwoEllipsesAndARectangle,
>>        ThreeEllipsesAndTwoRectangles
>>    }
>>
>> (Just an example, the idea is that each of the items in the enumerator 
>> list represents composite shapes, GeometryGroups, PathGeometry or similar 
>> which is not easily represented as a parameterized "thing").
>>
>> How can I best present this with a default style/template for the custom 
>> control ?
>> By setting a particular ControlTemplate based on change of the property ? 
>> How would the syntax be ?
>> Better done in code ? (but what about if an application wants to override 
>> the look of the control ?)
>
> -- 
> Laurent Bugnion [MVP ASP.NET]
> Software engineering, Blog: http://www.galasoft.ch
> PhotoAlbum: http://www.galasoft.ch/pictures
> Support children in Calcutta: http://www.calcutta-espoir.ch

date: Thu, 27 Sep 2007 17:12:30 +0200   author:   Eager am

Re: CustomControl and controlTemplate   

Hi,

Eager wrote:
> Thanks a lot Laurent
> 
> I guess this means that XAML does not have something similar to a switch 
> statement (C#), but only if statements which will all be executed (the 
> trigger elements).

:-) I think that if you try to compare XAML to C#, you're going to have 
long, sleepless nights. It's really a very different paradigm.

That said, you're right, in the sense that the triggers will all be 
evaluated, but in that particular case, only one will be applied.

Greetings!
Laurent
-- 
Laurent Bugnion [MVP ASP.NET]
Software engineering, Blog: http://www.galasoft.ch
PhotoAlbum: http://www.galasoft.ch/pictures
Support children in Calcutta: http://www.calcutta-espoir.ch

date: Fri, 28 Sep 2007 09:06:46 +0200   author:   Laurent Bugnion, MVP