wpf禁用不透明度级别

Question

I need to change the opacity of controls within a container (grid/dockpanel/etc) when they are disabled, so they appear brighter, or less dimmed.

When the container is disabled, nested controls appear to be reduced to about 0.5 (say) opacity. If I try to adjust the opacity of the container when disabled, the max is always limited to 0.5, no matter what I set it to. The method of assigning the opacity doesn't matter either, I have tried directly in code and with styles/triggers.

I am guessing this is implemented in the container by masking with a rectangle (or other window type) and setting the opacity. Then, from MSDN it says :

Opacity is applied from parent elements on down the element tree to child elements, but the visible effects of the nested opacity settings aren't indicated in the property value of individual child elements. For instance, if a list has a 50% (0.5) opacity and one of its list items has its own opacity set to 20% (0.2), the net visible opacity for that list item will be rendered as if it were 10% (0.1), but the property value of the list item Opacity property would still be 0.2 when queried.

So I understand why I am seeing this behaviour, I am just hoping there is a way to override it?

If not, the only alternative I can think of is to roll my own disabled behaviour with my own rectangle, and I can then set the opacity level I need. Just sounds like unnecessary hassle to me, unless I am missing something?

Note that I was interested in this question , but setting the opacity from code in this manner doesn't do anything different, the disabled controls appear unaffected.

Answer 1

Normally disabled state in WPF controls is rendered by using different Background and Foreground brushes which are set using a trigger in the control's template rather than changing opacity. Eg for a TextBox it has this trigger:

<ControlTemplate.Triggers>
    <Trigger Property="IsEnabled" Value="false">
        <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
    </Trigger>
</ControlTemplate.Triggers>

The opacity is unchanged. If you have a GroupBox with IsEnabled="False" then all child controls will inherit the IsEnabled state.

If you want to change the disabled appearance in some way then create your own template style or modify the default one.