I'd like to show an icon instead of a value in a listview. Basically, the ListView is bind to ModelView-Class (Observable-Collection as a property in that) and has a column called "status". Depending on status value, I'd like to show a different image. What would be the best way to do it. I read about DataTemplate, but I don't know where to hook in the code to switch the image.
MV-Class constructor looks like:
public TaskViewModel()
{
this.TaskCollection = ac.GetAllTasks();
}
Many thanks in advance,
Adam
I'd use a DataTrigger. Here's an example:
<Style TargetType="{x:Type ListViewItem}">
<Setter Property="Template" Value="{StaticResource DisabledImageTemplate}" />
<Style.Triggers>
<DataTrigger Binding="{Binding Status}" Value="Active">
<Setter Property="Template" Value="{StaticResource ActiveImageTemplate}" />
</DataTrigger>
</Style.Triggers>
</Style>
If your images path/name dictated by code behind (this is bad but sometimes happens), you could implement IValueConverter and name it like StatusToIconConverter. See here on MSDN with a simple example.
Regarding Data Templates See at the DataTemplateSelector class. Here is also a very simple example.
The key point is to define simple class which just analizes a passed in value and returns an appropriate data template, obviously you have to declare one data template per image.
Related
I have a very basic custom control consisting of a Label and a Textbox. I've used my control for sometime without any issues.
I've now come to styling my application and have my style inside a XAML file containing just a ResourceDictionary. I have the following for my UserControl:
<Style TargetType="local:LabelEdit">
<Setter Property="Background" Value="{StaticResource BackgroundBrush}" />
<Setter Property="Foreground" Value="{StaticResource ForegroundBrush}" />
<Setter Property="BorderBrush" Value="{StaticResource BorderBrush}" />
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<StackPanel>
<AdornedElementPlaceholder />
<Image Source="/AJSoft.Controls;component/Resources/Icons/cross.ico" />
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="Foreground" Value="{StaticResource ErrorForegroundBrush}" />
<Setter Property="Background" Value="{StaticResource ErrorBackgroundBrush}" />
<Setter Property="BorderBrush" Value="{StaticResource ErrorBorderBrush}" />
</Trigger>
</Style.Triggers>
</Style>
Everything works absolutely fine if I comment out the Setter for Validation.ErrorTemplate. If the ErrorTemplate is left intact, the cross shows (I haven't sorted out placement yet, but that can come later...), but the Textbox component of my UserControl does not show the caret or accept keyboard input. The rest of the controls in my Window work as expected.
Here are some screenies where I've deliberately put in some erroneous text to show how it looks.
The same problem happens even if I change that huge image to be a textblock with a small red "!" - the image is just for effect for now.
What am I doing that's causing the problem? I'm new to Validation in WPF...
EDIT: The image shown (big red cross) is just one example of what I've done. Even if I use a small image shown alongside the UserControl, I still get the same effect.
If you were to look at how error templates usually work, you'd see they apply to a single control.
Part of the issue you have here is you've got a label and textbox in one parent user control.
If you then apply an error template at the usercontrol level, it's on everything in that. Label, textbox, everything in your usercontrol.
The next thing to consider is how your error template ends up visible on top of everything. This happens because your error template generates UI in the adorner layer. That's top of everything ( in the window ).
Add these together and you got a big image on top of the content of your usercontrol.
At risk of over simplifying:
You put a top on your box and you can't now get at what's in that box.
There are several ways you could "fix" this but they all involve some design change or compromise.
Maybe a big X on top of your input control isn't a good idea.
You could kind of make it work.
You could make your image IsHitTestVisible="False".
It'll be visually in the way but you can then likely click on the textbox and type.
Just maybe not see everything.
Probably not ideal.
You could show your cross next to the textbox using a datatrigger rather than error template.
Add an image to your usercontrol so you have label, textbox, CrossImage.
Add a style to that with a setter makes it visible collapsed by default.
Use a trigger in that style to show the CrossImage when the control has errors.
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter ... />
</Trigger>
</Style.Triggers>
You may well find it simplest to use the tag on the usercontrol and set that to visible/collapsed. Bind visibility of the image to that.
I have a custom component that should change your alignment as a property of the window changes and getting the value of another property of itself. The property of the window is changing correctly, however, the alignment of the component is not changing. The converter that returns the alignment is also working correctly (it returns Left, Right or Center, depending on the other property of the component). So where is the error? Here is the code of the DataTrigger:
<myComponent.Resources>
<lib:HorizontalAlignmentConverter x:Key="HorizontalAlignmentConverter"/>
<Style TargetType="{x:Type myComponent}" x:Key="HorizontalAligner">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=MainWindow1, Path=myWindowResizedProperty}" Value="True">
<Setter Property="HorizontalAlignment" Value="{Binding Path=myOtherProperty, RelativeSource={RelativeSource Self}, Converter={StaticResource HorizontalAlignmentConverter}}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</myComponent.Resources>
Thanks in advance!
Another question: Is there any way I can reference, in the expression of DataTrigger Binding, the Window object, without using his name? This way would be more generic.
Thanks again!
The subject is that I've defined a customized control bound to a DataContext. And I wished to change the control template dynamically according to the DataContext's specific property values.
There're 2 ways I've thought of,but I have no idea about which way is better.
1.Do not use the control template in a ResourceDictionary and all details of the control are defined in C# code.Use the DependencyProperty CallBack method to render the control when DataContext's property values change.
2.Define control template in the ResourceDictionary and use DataTrigger to change the 'Control.Template' property.
In my application,thousands of instances in this type would be created,so it's really unacceptable if the ControlTemplate changging is not effective.
Could you please give me some advices or better solutions?
Using any standard WPF technique might not be effective if it would involve a thousands of instances of complex controls. See http://msdn.microsoft.com/en-us/magazine/dd483292.aspx.
I would go with MultiBinding + IMultiValueConverter to Control.Template dependency property, since Template would depend on multiple DataContext properties and would, perhaps, involve complex logic.
Perhaps you could used a ContentPresenter in your ControlTemplate to customize parts of your control. You could provide DataTemplates for those customizable parts which are automatically applied.
I would use a style with the data triggers to control which template is displayed. Like this example:
<Style x:Key="Die1Face" TargetType="{x:Type Button}">
<Setter Property="Template" Value="{StaticResource dieNone}" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=ThrowDie1[0]}" Value="1" >
<Setter Property="Template" Value="{StaticResource dieOneA}" />
</DataTrigger>
<DataTrigger Binding="{Binding Path=ThrowDie1[0]}" Value="2" >
<Setter Property="Template" Value="{StaticResource dieTwoA}" />
</DataTrigger>
</Style.Triggers>
</Style>
This would give the flexibility you need.
As title, is it possible?
I have seen in TreeView you can defines different HierarchicalDataTemplate for different datatype using DataType attribute, it doens't even need DataTemplateSelector.
So I wonder if is possible to choose a template according to a binded value without using DataTemplateSelector?
In my condition, is very simple, if the data object's Property = 1, then display template1, 2 then template2.
Is it possible to do it without DataTemplateSelector?
Yes, you can use a DataTrigger
<Style TargetType="{x:Type ListBoxItem}">
<Setter Property="Template" Value="{StaticResource DefaultTemplate}" />
<Style.Triggers>
<DataTrigger Binding="{Binding SomeProperty}" Value="2">
<Setter Property="Template" Value="{StaticResource Template2}" />
</DataTrigger>
</Style.Triggers>
</Style>
I actually prefer DataTriggers to a DataTemplateSelector because they respond to PropertyChange notifications, and I prefer to see my UI logic in my UI code.
I'd like to create a simple custom panel to layout children in a business form fashion. Ideally I'd like my markup to look like this:
<Panels:FormPanel>
<TextBlock Text="Name:"/>
<TextBox />
<TextBlock Text="Address"/>
<TextBlock Text="Unknown"/>
<TextBlock Text="City"/>
<TextBox HorizontalAlignment="Stretch"/>
<TextBlock Text="State"/>
<ComboBox/>
<TextBlock Text="Country"/>
<StackPanel>...</StackPanel>
</Panels:FormPanel>
The panel will layout controls in two columns labels on the left side and values on the right.
I have no problem laying out my controls. The problem is that I also need to alternate background for the rows to create stripes for easier reading.
Any ideas how can this be done?
This doesn't directly answer your question, but you could consider this as another solution to the underlying problem.
Take a look at http://wpg.codeplex.com/. I used a similar property-grid-like control in Windows Forms that was modified to understand custom attributes on my business objects.
Now, in WPF, I would think something similar would work really well if you follow the MVVM pattern and you decorate your ViewModel with attributes that such a property grid understands. Then you don't need to explicitly define the fields like you show above.
You could have a ViewModel:
class PersonViewModel
{
[DisplayName("Name")] // The property Grid uses this the Textblock text
[IsRequired] // The property grid could do validation on the field
[Visible]
public string Name { get; set; }
public long InvisibleSystemField { get; set; } // Not shown
}
And then you'd only have Views (Xaml files) like this:
<myCommon:PropertyGrid DataContext={Binding}/>
It could simply use it's DataContext as the starting point for reflection.
OK I'll stop there for now :)
I'm working on a WPF powered LOB application and I'll possibly build something like this in future.
Implementing a custom panel is not actually that difficult. You have to override two methods, Measure and Arrange. Google for "wpf custom panel" to get some articles about that.
What I would suggest you do to get the behavior exactly as you required in the question is extend Windows.Controls.Grid. Your custom grid could then have two columns by default that you initialize in the constructor and you can programmatically set the Grid.Column and Grid.Row properties on the child controls.
Also worth looking at could be the ItemsControl. It does have support for alternatively colored rows. This example (from MSDN) shows how to use it:
<Grid>
<Grid.Resources>
<Style x:Key="alternatingWithTriggers" TargetType="{x:Type ListBoxItem}">
<Setter Property="Background" Value="Blue"/>
<Setter Property="Foreground" Value="White"/>
<Style.Triggers>
<Trigger Property="ListBox.AlternationIndex" Value="1">
<Setter Property="Background" Value="CornflowerBlue"/>
<Setter Property="Foreground" Value="Black"/>
</Trigger>
<Trigger Property="ListBox.AlternationIndex" Value="2">
<Setter Property="Background" Value="LightBlue"/>
<Setter Property="Foreground" Value="Navy"/>
</Trigger>
</Style.Triggers>
</Style>
</Grid.Resources>
<ListBox AlternationCount="3" ItemsSource="{StaticResource data}"
ItemContainerStyle="{StaticResource alternatingWithTriggers}">
</ListBox>
</Grid>
You could then specify a template for the items that includes a Label and a TextBox, but getting this to work could be fiddly.
Here's one final thing I'll suggest:
XAML Powertoys include features that allow you to generate business forms from ViewModels, ViewModels from Models and much more. You might need to modify the source to get alternating row colors though.
Good luck!