Vista - Applying a centered ScaleTransform via a Style

Hi,

I would like to apply a ScaleTransform to a control via a Style. This is
easy enough:

<Setter Property="RenderTransform">
<Setter.Value>
<ScaleTransform ScaleX="1.25"
ScaleY="1.25" />
</Setter.Value>
</Setter>

But I would like this ScaleTransform to be centered on the control. I
know the CenterX and CenterY properties exist for this purpose, but the
problem is that their value is dynamic (Control.Width/2,
Control.Height/2) and being in a Style declaration I do not know up
front the Width/Height of the control being styled.

Is there a way to specify an expression such as Width/2 declaratively in
XAML?

Thanks!

Pascal

There is no way to place an expression as an attribute value, and I do not
believe binding will solve this either, although you might be able to bind
the CenterX and CenterY properties to the control on which it is applied.
If that worked you could then create attached properties that are really
derived values using the expression you suggest. Probably an easier
approach would be to create a sub-type of ScaleTransform that computes
CenterX and CenterY dynamically.

Michael
Microsoft MVP (C# / WPF)

"Pascal Bourque" <bourquep@xceedsoft.com> wrote in message
news:upe58hrIGHA.3364@tk2msftngp13.phx.gbl...
> Hi,
>
> I would like to apply a ScaleTransform to a control via a Style. This is
> easy enough:
>
> <Setter Property="RenderTransform">
> <Setter.Value>
> <ScaleTransform ScaleX="1.25"
> ScaleY="1.25" />
> </Setter.Value>
> </Setter>
>
> But I would like this ScaleTransform to be centered on the control. I know
> the CenterX and CenterY properties exist for this purpose, but the problem
> is that their value is dynamic (Control.Width/2, Control.Height/2) and
> being in a Style declaration I do not know up front the Width/Height of
> the control being styled.
>
> Is there a way to specify an expression such as Width/2 declaratively in
> XAML?
>
> Thanks!
>
> Pascal

Thanks for the suggestions, Michael! I will try deriving form
ScaleTransform and post the results here!

Pascal

Michael Latta wrote:
> There is no way to place an expression as an attribute value, and I do not
> believe binding will solve this either, although you might be able to bind
> the CenterX and CenterY properties to the control on which it is applied.
> If that worked you could then create attached properties that are really
> derived values using the expression you suggest. Probably an easier
> approach would be to create a sub-type of ScaleTransform that computes
> CenterX and CenterY dynamically.
>
> Michael
> Microsoft MVP (C# / WPF)
>

Instead of setting the CenterX and CenterY properties of the ScaleTransform,
set the RenderTransformOrigin property of the object to 0.5,0.5. That will
center your ScaleTransform automatically. See
http://windowssdk.msdn.microsoft.com...formOrigin.asp
for more information about the RenderTransformOrigin property.

****
Mike Jacobs [MSFT]
This posting is provided "AS IS" with no warranties, and confers no rights.

****

"Pascal Bourque" <bourquep@xceedsoft.com> wrote in message
news:uYS6d7qJGHA.3856@TK2MSFTNGP12.phx.gbl...
> Thanks for the suggestions, Michael! I will try deriving form
> ScaleTransform and post the results here!
>
> Pascal
>
> Michael Latta wrote:
>> There is no way to place an expression as an attribute value, and I do
>> not believe binding will solve this either, although you might be able to
>> bind the CenterX and CenterY properties to the control on which it is
>> applied. If that worked you could then create attached properties that
>> are really derived values using the expression you suggest. Probably an
>> easier approach would be to create a sub-type of ScaleTransform that
>> computes CenterX and CenterY dynamically.
>>
>> Michael
>> Microsoft MVP (C# / WPF)
>>