How to set an event function via a style?
Martin,
you can assign an event handler directly from a style using an EventSetter:
<Style TargetType="{x:Type Button}">
<EventSetter Event="Click" Handler="SomeAction"/>
</Style>
@ColinE:
I am not sure that using a style to perform event wire-up is a good idea. Styles, by definition, define the visual appearance of controls.
Unfortunately, this seems to be a common and widespread misconception about WPF styles: Although their name suggests they are, like what you say, merely meant to define the visual appearance, they are actually much more: It is helpful to view styles more generally as a shortcut for assigning a set of properties to a control.
Comments
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Martin Hennings almost 2 years
I have several GUI control elements of which some are supposed to generate the same action (code-behind function call) on mouse interaction (MouseEnter, MouseLeave).
[edit] I am performing some non style related functionality in my event handlers.
Right now I'm using event attributes in each control:<Button Name="Button" Content="Button 1" MouseEnter="GeneralMouseEnter" MouseLeave="GeneralMouseLeave" PreviewMouseDown="Button1_PreviewMouseDown" PreviewMouseUp="Button1_PreviewMouseUp" /> <Button Name="NotInteractingButton" Content="Button 2" /><!-- this button has no MouseOver-effects --> <ToggleButton Content="ToggleButton" MouseEnter="GeneralMouseEnter" MouseLeave="GeneralMouseLeave" /> <!-- needs to use IsMouseDirectlyOver on the slider knob... --> <Slider Name="HorizontalSlider" MouseEnter="GeneralMouseEnter" MouseLeave="GeneralMouseLeave" ValueChanged="Slider_ValueChanged" /> <Slider Name="VerticalSlider" Orientation="Vertical" MouseEnter="GeneralMouseEnter" MouseLeave="GeneralMouseLeave" ValueChanged="Slider_ValueChanged" />
Since many controls in this example are calling the same two functions "GeneralMouseEnter" and "GeneralMouseLeave", I'd like to be able to define a style or something similar to encapsulate that behavior.
[edit - clarification]
This is supposed to become a kind of plugin later on.
(Include code and XAML files to any GUI program and set a style on each interactive control element...)From what I found on the web, I can use
EventTriggers
like in this example:<Style.Triggers> <EventTrigger RoutedEvent="Click"> <EventTrigger.Actions> <BeginAction TargetName="SomeAction" /> </EventTrigger.Actions> </EventTrigger> </Style.Triggers>
I don't know though if and how to call functions within an action.
- Is it possible to get this functionality by creating a style with action + trigger to be applied to each control? How to do that?
- How do I assign multiple styles (for multiple interaction events) to one control?
- Is there maybe even a cleaner way to achieve this behavior?
- [edit]
What if I want to, let's say, have mouse interaction on all sliders in my GUI?
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Martin Hennings over 13 yearsGreat, that's exactly what I was searching for - especially in combination with
BasedOn="..."
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luka over 5 yearsThis works only if you use the style tag under the class. If you use this in a separate dictionary this error was thrown: 'ResourceDictionary' root element requires a x:Class attribute to support event handlers in the XAML file. Either remove the event handler for the Click event, or add a x:Class attribute to the root element. obviously the X:Class attribute in dictionary can't used, if the dictionary is a merged dictionary in class.
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Brains almost 4 yearsThe event inside
EventSetter
must be aRoutedEvent
(not works withTargetUpdated
) -
Brains almost 4 years