WPF Style Validation Trigger Command - wpf

I have some dynamic generated Textboxes with Validators. I want them to send a Command to VM, if a validation error occurs. This Behavior is placed in a style, so I don't need to write it into the xaml generation.
Here's the Code:
<behaviors:Triggers x:Key="validationTrigger" x:Shared="False">
<behaviors:ValidationErrorEventTrigger>
<cmd:EventToCommand Command="{Binding ValidationError,NotifyOnValidationError=True}"
PassEventArgsToCommand="True" />
</behaviors:ValidationErrorEventTrigger>
</behaviors:Triggers>
<Style x:Key="EditableTextBox" TargetType="{x:Type TextBox}">
<Setter Property="Background" Value="#DDFFDD" />
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<Border BorderBrush="Red" BorderThickness="2">
<AdornedElementPlaceholder />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="behaviors:OCCInteraction.Triggers" Value="{StaticResource ResourceKey=validationTrigger}" />
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="Background" Value="#FFDDDD"/>
</Trigger>
</Style.Triggers>
</Style>
The Problem I'm having now, is that the "Onvalidation" Event is called in the VlidationErrorEventTrigger class, but the Command isn't called in the Viewmodel.
I've tested it with a direct integration and not with a style and it works this way.
So maybe it has something to do with the Binding of the Command or so...
I hope this description is enough to solve the Problem. If not please tell me :)

I am not sure how you binding is done but assuming that DataContext of you `Control/Window has your ViewModel Instance andValidationError` is your command...
<behaviors:Triggers x:Key="validationTrigger" x:Shared="False">
<behaviors:ValidationErrorEventTrigger>
<cmd:EventToCommand Command="{Binding Path=DataContext.ValidationError,RelativeSource="{RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}",NotifyOnValidationError=True}"
PassEventArgsToCommand="True" />
</behaviors:ValidationErrorEventTrigger>
</behaviors:Triggers>
This is assuming that your trigger is not able to find the command required.

Related

Binding to last Validation Error

I have a style trigger for create a tooltip with a validation error:
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self},
Path=(Validation.Errors)[0].ErrorContent}"/>
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<DockPanel>
<Border BorderBrush="Red" BorderThickness="2" CornerRadius="2" Background="{x:Null}">
<AdornedElementPlaceholder/>
</Border>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Trigger>
I'm displaying first error (Validation.Errors)[0].ErrorContent), but I want to display the last one (the last is more prioritary, Framework textbox adds its validation errors at the end, for example strings not representing a date).
Thanks.
Well, for one thing you could change the Path to all errors and add a ValueConverter that returns only the last message.
A lot of people also move validation completely to the view-model and ditch the validation rules, that way you have a lot of control over what exactly you expose to the view.

Style trigger based on parent style property

I want to have buttons with little icons as content.
The icons are defined and stored in a ResourceDictionary like this:
<Path x:Key="BackIcon" Data="F1 M 57,42L 57,34L 32.25,34L 42.25,24L 31.75,24L 17... "/>
<Path x:Key="LoadFromFileIcon" Data="F1 M 48,39L 56,39L 56,49L 63.25,49L 52,60.2... "/>
<Path x:Key="SaveToFileIcon" Data="F1 M 48,60L 56,60L 56,50L 63.25,50L 52,38.75L... "/>
Since I also need to provide Path.Fill, Path.Stretch etc. properties, I decided to make my own IconButtonStyle so I won't have to repeat the same attribute in every Path in the icon dictionary and make buttons very easily like this:
<Button Style="{StaticResource IconButtonStyle}"
Content="{StaticResource ResetIcon}"/>
This is what I came up with:
<Style x:Key="IconButtonStyle" TargetType="Button">
<Style.Resources>
<Style TargetType="Path">
<Setter Property="Fill" Value="Black"/> <!-- Default path fill. -->
<Style.Triggers>
<!-- How can I set path fill to "Red" based on the parent Button IsEnabled property? -->
</Style.Triggers>
</Style>
</Style.Resources>
<Style.Triggers>
<Trigger Property="IsEnabled" Value="false">
<!-- ?? -->
</Trigger>
</Style.Triggers>
</Style>
My custom icon buttons have default path style defined via Style.Resources. Setting default path fill is easy but I can't figure out how to set a trigger that'll change path's fill to red when the owner button is disabled.
Is it even possible?
Okay... I guess you need to modify a few things before proceeding.
First in XAML you should use a code like this:
<Button Style="{DynamicResource IconButtonStyle}" IsEnabled="False" Content="{StaticResource _rect}">
</Button>
In this case I used a rectangle which I defined in Resources. this is the code for rectangle:
<Rectangle Width="10" Height="10" Style="{StaticResource ContentButtonPathStyle}" x:Key="_rect"></Rectangle>
you will obviously use your paths instead of rectangles...
You notice that the Style is set to ContentButtonPathStyle .
This is the code for that style:
<Style x:Key="ContentButtonPathStyle" TargetType="{x:Type Rectangle}">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource=
{RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}, Path=IsEnabled}" Value="False">
<Setter Property="Fill" Value="Red"/>
</DataTrigger>
<DataTrigger Binding="{Binding RelativeSource=
{RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}, Path=IsEnabled}" Value="True">
<Setter Property="Fill" Value="Black"/>
</DataTrigger>
</Style.Triggers>
</Style>
Note that you must define ContentButtonPathStyle before your rectangle (paths).
The last thing is that you don't even need to specify a Style for your button. unless you need it for other purposes.

WPF ComboBox selected item text

I made a custom combobox where I have a TextBlock (named mySelectedContent) to display the selected item and a TextBox for editing in "IsEditable" mode. I have a MultiDataTrigger that is being shot correctly, however, I am unable to "catch" the text of the selected item and put it into the TextBlock. How should be mounted the correct expression in place of "???". Thanks a lot!
Here is the code of the trigger (I'm showing mainly the part of the trigger because it's just in it the problem):
<ComboBox.Resources>
<Style x:Key="myComboBox" TargetType="{x:Type ComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton>
...
</ToggleButton>
<TextBlock
Name="mySelectedContent"
.../>
<TextBox x:Name="myEditableTextBox"
.../>
<Popup>
...
</Popup>
</Grid>
<ControlTemplate.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
...
</MultiDataTrigger.Conditions>
<MultiDataTrigger.Setters>
<Setter TargetName="myEditableTextBox" Property="Visibility" Value="Hidden"/>
<Setter TargetName="mySelectedContent" Property="Visibility" Value="Visible"/>
<Setter TargetName="mySelectedContent" Property="Text" Value="???"/>
</MultiDataTrigger.Setters>
</MultiDataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ComboBox.Resources>
It was solved with cYounes first suggestion. I used:
Value={Binding ElementName=MyEditableTextBox Path=Text}
and it works as expected!
Thanks!
That's way too much work when you simply could have used the Tag property to get the value easily with 2 lines:
in XAML:
<ComboBoxItem Content="This Value" Tag="This Value"/>
Then:
GetValue=ComboBoxName.SelectedItem.Tag.ToString()
will give you "This Value" and not
"System.Windows.Controls.ComboBoxItem: This Value"
Much simpler, faster and less time consuming.

Binding Path Fill to Button Foreground in ContentPresenter

I have a Button Style with a Template containing a ContentPresenter, in which I am attempting to bind the Fill of a Path to the Foreground of a button:
<!-- This is inside the template of a button style -->
<ContentPresenter>
<ContentPresenter.Resources>
<Style TargetType="{x:Type Path}">
<Setter Property="Fill" Value="{Binding Path=Foreground, RelativeSource={RelativeSource AncestorType=Button}}"/>
</Style>
</ContentPresenter.Resources>
</ContentPresenter>
I also have a Path with no Fill set, that I can reference in the button as the content, like so:
<Button Style="{DynamicResource MyButtonStyle}" Content="{DynamicResource PathIcon}" Foreground="Blue"/>
I would expect the Path inside the button to be blue, but it isn't... it doesn't grab the foreground from the button.
How can I get the Path to bind to the color of the button?
Thank you!
P.S.:
If I put a hardcoded color in the Value (i.e. Value="Red"), the Path inside the button is red... so I know that works...
<ContentPresenter>
<ContentPresenter.Resources>
<Style TargetType="{x:Type Path}">
<Setter Property="Fill" Value="Red"/>
</Style>
</ContentPresenter.Resources>
</ContentPresenter>
Edit:
Here is the complete Style and ControlTemplate:
<Style x:Key="Button_Style" TargetType="{x:Type Button}">
<Setter Property="Foreground" Value="{StaticResource White_Brush}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid x:Name="grid" Background="Transparent">
<ContentPresenter>
<ContentPresenter.Resources>
<Style TargetType="{x:Type Path}">
<Setter Property="Fill" Value="{Binding Path=Foreground, RelativeSource={RelativeSource AncestorType=Button}}"/>
</Style>
</ContentPresenter.Resources>
</ContentPresenter>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<!-- Should affect Text as well as Paths in the Content property of the button! -->
<Setter Property="Foreground" Value="{StaticResource Black_Brush}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Okay, let's order:
it doesn't grab the foreground from the button.
In styles this construction:
RelativeSource={RelativeSource AncestorType=Button}
will not work, because the Style is just the collection of setters, he does not know about control, are there, specifically about the content of the visual tree. Because RelativeSource should refer to the items above in the visual tree. For this purpose, usually using DataTemplate or ControlTemplate.
If I put a hardcoded color in the Value (i.e. Value="Red")
Yes, in this case, will be working, and always better to create the design of the form:
<SolidColorBrush x:Key="MyButtonColor" Color="Blue" />
And use it for control, like Button:
<Button Background="{StaticResource MyButtonColor}" ... />
and in Style or elsewhere:
<Setter Property="Fill" Value="{StaticResource MyButtonColor}" />
That is, it is better not to depend on the element parameters (background color, etc.) located in a visual tree, because it can:
May move to another panel (Grid, StackPanel) or UserControl
May leave from the project
And brushes in the as resources will always be in one place, changing them in this place, all the elements of their pick up. Also colors can be stored in a special data model that does not depend on the specific technical implementations (resources, variables) in which the data can come from an external source, such as the project/config settings.
If possible, it is better to avoid the use of dynamic resources due to unnecessary use of system perfomance (and in some cases memory leaks), in your cases they are not needed.
Dynamic resources are usually explicitly defined for SolidColorBrush and another species brushes, because by default they are frozen, and they not recommended changed because of the above mentioned reasons (memory leaks). More information can be found here:
Freezable Objects Overview on MSDN
Edit
As I understand it, you want to make universal Style for Button to make the contents of Path or Text (in the case of simultaneous use will be easier). As I have already mentioned above, RelativeSource should be around ControlTemplate, therefore, the Path will be in the Grid with the ContentPresenter.
To style knew, which is provided for the text or for the path, to the Tag (optional property) indicates two properties: OnlyText or OnlyPath.
To set the data for the Path, I've created a attached dependency property, and prescribed it in the ControlTemplate.
Below is a complete example:
XAML
<Window x:Class="ButtonPathHelp.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:ButtonPathHelp"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
WindowStartupLocation="CenterScreen"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<SolidColorBrush x:Key="Green_Brush" Color="Green" />
<SolidColorBrush x:Key="Black_Brush" Color="Black" />
<Style x:Key="Button_Style" TargetType="{x:Type Button}">
<Setter Property="Foreground" Value="{StaticResource Green_Brush}" />
<Setter Property="HorizontalAlignment" Value="Center" />
<Setter Property="VerticalAlignment" Value="Center" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid x:Name="grid">
<ContentPresenter x:Name="MyContent"
Content="{TemplateBinding Content}"
HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
VerticalAlignment="{TemplateBinding VerticalAlignment}" />
<Path x:Name="MyPath"
SnapsToDevicePixels="True"
Width="20"
Height="18"
Stretch="Fill"
Fill="{Binding Path=Foreground, RelativeSource={RelativeSource AncestorType={x:Type Button}}}"
Data="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(local:MyDependencyClass.DataForPath)}" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Foreground" Value="{StaticResource Black_Brush}"/>
</Trigger>
<Trigger Property="Tag" Value="OnlyText">
<Setter TargetName="MyPath" Property="Visibility" Value="Collapsed" />
<Setter TargetName="MyContent" Property="Visibility" Value="Visible" />
</Trigger>
<Trigger Property="Tag" Value="OnlyPath">
<Setter TargetName="MyPath" Property="Visibility" Value="Visible" />
<Setter TargetName="MyContent" Property="Visibility" Value="Collapsed" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<WrapPanel>
<WrapPanel.Resources>
<sys:String x:Key="Save">
F1 M 20.5833,20.5833L 55.4167,20.5833L 55.4167,55.4167L 45.9167,55.4167L 45.9167,44.3333L 30.0833,44.3333L 30.0833,
55.4167L 20.5833,55.4167L 20.5833,20.5833 Z M 33.25,55.4167L 33.25,50.6667L 39.5833,50.6667L 39.5833,55.4167L 33.25,
55.4167 Z M 26.9167,23.75L 26.9167,33.25L 49.0833,33.25L 49.0833,23.75L 26.9167,23.75 Z
</sys:String>
<sys:String x:Key="Search">
F1 M 23.4454,49.2637L 31.7739,41.1598C 30.6986,39.2983 30.4792,37.1377 30.4792,34.8333C 30.4792,27.8377 35.7544,
22.1667 42.75,22.1667C 49.7456,22.1667 55.4167,27.8377 55.4167,34.8333C 55.4167,41.8289 49.7456,47.1042 42.75,
47.1042C 40.5639,47.1042 38.5072,46.9462 36.7125,45.9713L 28.3196,54.1379C 27.0829,55.3746 24.6821,55.3746 23.4454,
54.1379C 22.2088,52.9013 22.2088,50.5004 23.4454,49.2637 Z M 42.75,26.9167C 38.3777,26.9167 34.8333,30.4611 34.8333,
34.8333C 34.8333,39.2056 38.3777,42.75 42.75,42.75C 47.1222,42.75 50.6667,39.2056 50.6667,34.8333C 50.6667,
30.4611 47.1222,26.9167 42.75,26.9167 Z
</sys:String>
</WrapPanel.Resources>
<Button Name="SaveButton"
Style="{StaticResource Button_Style}"
Tag="OnlyPath"
local:MyDependencyClass.DataForPath="{StaticResource Save}"
Margin="10" />
<Button Name="JustText"
Style="{StaticResource Button_Style}"
Tag="OnlyText"
Content="Just Text"
Margin="10" />
<Button Name="SearchButton"
Style="{StaticResource Button_Style}"
Tag="OnlyPath"
local:MyDependencyClass.DataForPath="{StaticResource Search}"
Margin="10" />
</WrapPanel>
</Window>
Code behind
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
public class MyDependencyClass : DependencyObject
{
#region IsCheckedOnDataProperty
public static readonly DependencyProperty DataForPathProperty;
public static void SetDataForPath(DependencyObject DepObject, string value)
{
DepObject.SetValue(DataForPathProperty, value);
}
public static string GetDataForPath(DependencyObject DepObject)
{
return (string)DepObject.GetValue(DataForPathProperty);
}
#endregion
static MyDependencyClass()
{
PropertyMetadata MyPropertyMetadata = new PropertyMetadata(String.Empty);
DataForPathProperty = DependencyProperty.RegisterAttached("DataForPath",
typeof(string),
typeof(MyDependencyClass),
MyPropertyMetadata);
}
}
Note: In the Style I have not used TemplateBinding for attached property, because TemplateBinding doesn’t work outside a template or outside its VisualTree property, so you can’t even use TemplateBinding inside a template’s trigger. Therefore, we must use the construction {RelativeSource TemplatedParent} and a Path equal to the dependency property whose value you want to retrieve.
Output
To download the entire example please follow this link.
I stumbled across simillar problem but was wondering how to get to the 'Foreground Colour' of the Button in its DISABLED state (to have correct colour of my drawing). Here is a finally simple sollution. No templates, No styles, no code, nothing at all. Just the right relative binding :-) :
<StackPanel Orientation="Horizontal">
<Button Height="22" IsEnabled="False">
<Polygon Points="4,0 4,5 5,5 2.5,10 0,5 1,5 1,0 "
Fill="{Binding (TextElement.Foreground), RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContentPresenter}}}">
<Polygon.LayoutTransform>
<RotateTransform Angle="90"></RotateTransform>
</Polygon.LayoutTransform>
</Polygon>
</Button>
<Button Height="22" IsEnabled="True">
<Polygon Points="4,0 4,5 5,5 2.5,10 0,5 1,5 1,0 "
Fill="{Binding (TextElement.Foreground), RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContentPresenter}}}">
<Polygon.LayoutTransform>
<RotateTransform Angle="180"></RotateTransform>
</Polygon.LayoutTransform>
</Polygon>
</Button>
</StackPanel>

WPF How to attach Popup to simple UIElement like rectangle

It took me hours to figure out the answer to this question, so I thought I would write an FAQ or answer for what I found. (it is based on the following thread Binding Textbox IsFocused to Popup IsOpen plus additional conditions)
I found lots of examples of binding popups to things like toggle buttons and other things that are based on windows chrome and have built in triggers. But in my application I wanted to bind a popup to a simple rectangle with a custom brush fill. I could not find an example on how to have a popup open ans stay open when a user mouses over the rectangle.
So I am posting this question and I will immediately post the answer I found so that hopefully someone else can benefit from it. I will also mark an answer for anyone who can help me understand if stackoverflow allows posts like this, or a better way I could have gone about it.
EDIT 1)
I can't self answer for 8 hours so here is the working code:
the following is a simple example of how to use the popup on a basic UIElement like a rectangle/ellipse/etc...
<Grid HorizontalAlignment="Stretch" Height="Auto">
<Rectangle x:Name="PopupRec"
Grid.Row="0"
Width="20" Height="20"
HorizontalAlignment="Right"
Fill="Gray" Margin="0,0,0,10" />
<Popup x:Name="SortPopup"
PlacementTarget="{Binding ElementName=PopupRec}"
StaysOpen="False"
PopupAnimation="Slide"
AllowsTransparency="True">
<Border Background="White" Padding="15">
<StackPanel Orientation="Vertical">
<Button Command="{Binding MyCommand}" CommandParameter="5">5</Button>
<Button Command="{Binding MyCommand}" CommandParameter="10">10</Button>
<Button Command="{Binding MyCommand}" CommandParameter="15">15</Button>
<Button Command="{Binding MyCommand}" CommandParameter="20">20</Button>
</StackPanel>
</Border>
<Popup.Style>
<Style TargetType="{x:Type Popup}">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=PopupRec, Path=IsMouseOver}" Value="True">
<Setter Property="IsOpen" Value="True" />
</DataTrigger>
<DataTrigger Binding="{Binding ElementName=SortPopup, Path=IsMouseOver}" Value="True">
<Setter Property="IsOpen" Value="True" />
</DataTrigger>
</Style.Triggers>
</Style>
</Popup.Style>
</Popup>
</Grid>
Just paste this inside window/usercontrol/etc...
I'd suggest the following improvement. It would make the Popup Style independent of any element names, and would thus enable you to use it as a default Style by putting it into the Window's or UserControl's Resources.
<Style TargetType="{x:Type Popup}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsMouseOver,
RelativeSource={RelativeSource Self}}"
Value="True">
<Setter Property="IsOpen" Value="True" />
</DataTrigger>
<DataTrigger Binding="{Binding Path=PlacementTarget.IsMouseOver,
RelativeSource={RelativeSource Self}}"
Value="True">
<Setter Property="IsOpen" Value="True" />
</DataTrigger>
</Style.Triggers>
</Style>
And please note that a Rectangle is not a "basic UIElement". It's a Shape, which itself is a FrameworkElement.

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