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how to set image background in wpf

I am trying to set inactive buttons to have semi-transparent (i.e. greyed out) images. Yet for some reason the images become white/ yellow (as if on a bright background):
As you can see it's light yellow
Possibly better annotated screenshot
Here are the XAML Styles:
<Style x:Key="ToolButton" TargetType="{x:Type Button}" BasedOn="{x:Null}">
<Setter Property="Background" Value="#888"/>
<Setter Property="Padding" Value="10,2"/>
<Setter Property="BorderThickness" Value="0"/>
<Style.Resources>
<Style TargetType="Image">
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Opacity" Value="0.5"/>
</Trigger>
</Style.Triggers>
</Style>
</Style.Resources>
</Style>
<Style x:Key="ToolPanel" TargetType="{x:Type StackPanel}">
<Setter Property="Background" Value="#111"/>
<Style.Resources>
<Style TargetType="{x:Type Button}" BasedOn="{StaticResource ResourceKey=ToolButton}"/>
</Style.Resources>
</Style>
(StackPanel and buttons are dark for contrast, they are actually mean to be light grey)
What should I do to get the greyed out effect I want?

The problem is the default Button template: it changes its background based on the control's state, and that new background takes precedence over the one you're setting in your style.
In this case, the brush for the 'Disabled' state is something like #F4F4F4, or a very light gray.
The fix would be to declare a new Button template. For example:
<ControlTemplate TargetType="Button">
<!--Optional: Add border brush/thickness if you want a border-->
<Border x:Name="border" Background="{TemplateBinding Background}">
<ContentPresenter x:Name="contentSite" Margin="{TemplateBinding Padding}" />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="False">
<!--Optional: Remove background when disabled-->
<!--Setter TargetName="border" Property="Background" Value="Transparent" /-->
<Setter TargetName="contentSite" Property="Opacity" Value="0.5" />
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="border" Property="Background" Value="#AAA" />
</Trigger>
<Trigger Property="IsPressed" Value="True">
<Setter TargetName="border" Property="Background" Value="#333" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
Note that with this version, you do not need the Image style to change the Opacity; it's taken care of in the Button template.

Multiple styles and content on one button

I have a HomePage with a number of buttons on that I am trying to get to do a couple of things. Firstly, I have a Style in a ResourceDictionary that dictates the overall 'look and feel' of the buttons. It looks like this:
<Style TargetType="Button" x:Key="HomeButton">
<Setter Property="Foreground" Value="White"/>
<Setter Property="Background" Value="#06658D"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Border Background="{TemplateBinding Background}" BorderBrush="White" BorderThickness="1">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="FontWeight" Value="Bold"/>
<Setter Property="Background" Value="White"/>
<Setter Property="Foreground" Value="#06658D"/>
</Trigger>
</Style.Triggers>
</Style>
Nothing too complicated, however I want the MouseOver effect to persist after being clicked. So now I am looking at doing something like this:
<Button Grid.Row="0" Style="{StaticResource HomeButton}" Content="Contacts">
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<DataTrigger Binding="{Binding ContactsClicked}" Value="True">
<Setter Property="Background" Value="White"/>
<Setter Property="Foreground" Value="#06658D"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button>
I'll bind the command element of the Button to set ContactsClicked = true and reset this when another button is pressed. However, I get the error saying that Content is set multiple times.
Is it possible to have an overall Style of the Button set, as well as a 'Clickedstyle and to have aTextBlockdisplaying text on the button all at once or am I approaching this wrong? I am trying to not have an individual overall style for every singleButton`as that's a lot of repeated code.
For clarity this is what I am aiming for:

I've managed to find a solution myself, instead of using a Button us a ToggleButton instead:
<Style TargetType="ToggleButton" x:Key="HomeButton">
<Setter Property="Foreground" Value="White"/>
<Setter Property="Background" Value="#06658D"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<Border Background="{TemplateBinding Background}" BorderBrush="White" BorderThickness="1">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsPressed" Value="True">
<Setter Property="Background" Value="Black" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="FontWeight" Value="Bold"/>
<Setter Property="Background" Value="White"/>
<Setter Property="Foreground" Value="#06658D"/>
</Trigger>
<Trigger Property="IsChecked" Value="True">
<Setter Property="FontWeight" Value="Bold"/>
<Setter Property="Background" Value="White"/>
<Setter Property="Foreground" Value="#06658D"/>
</Trigger>
</Style.Triggers>
</Style>

I would add this as a comment but im not allowed.
If your goal is that the button will stay selected after it is clicked, why not use a RadioButton? A RadioButton has a built-in property called IsChecked but will also remain "Checked" or "Selected" even after multiple clicks.
Of course you can define the behavior and the styles in a similar manner, create a simple Trigger on the property IsChecked.
If more explanation is needed, just say so.

Checkbox IsMouseOver wont work

When i add this controltemplate my checkboxes disapear and only the checkbox text is shown. And when mouse is over the textbackground becomes red, how do i get my checkbox background red when mouse is over?
<Style TargetType="CheckBox" x:Key="Checkbox">
<Setter Property="BorderThickness" Value="2" />
<Setter Property="VerticalAlignment" Value="Top" />
<Setter Property="Margin" Value="20,15,0,0" />
<Setter Property="FontFamily" Value="/Resources/Fonts/Source Sans Pro/#Source Sans Pro" />
<Setter Property="FontSize" Value="14" />
<Setter Property="HorizontalAlignment" Value="Left" />
<Setter Property="Foreground" Value="{DynamicResource CheckboxForegroundColor}" />
<Setter Property="Background" Value="{DynamicResource CheckboxBackgroundColor}" />
<Setter Property="BorderBrush" Value="{DynamicResource CheckboxBorderbrushColor}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type CheckBox}">
<CheckBox Background="{TemplateBinding Background}" >
<ContentPresenter />
</CheckBox>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" Value="Red"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>

This will work for some properties (try FontSize, for example), but not for others. The default template for the CheckBox has triggers of its own, and they don't bother with such things as TemplateBindings.
This post tells you how to extract the default template for a ComboBox. Here is an excerpt which shows your problem:
<ControlTemplate.Triggers>
...
<Trigger Property="IsMouseOver" Value="true">
<Setter
Property="Background"
TargetName="checkBoxBorder"
Value="{StaticResource OptionMark.MouseOver.Background}"/>
...
</Trigger>
...
</ControlTemplate.Triggers>
Your best bet is probably to override the entire template. Happily, it isn't too complex...
Remove your own template.
Follow the steps outlined in the post I linked to. That should give you a copy of the default CheckBox template.
Modify that copy. In particular, the IsMouseOver trigger that I excerpted: Change {StaticResource OptionMark.MouseOver.Background} to Red.
If this is still unclear, see this related post.

How to tell if text it ContentProvider has been edited?

I've got DataGrid with several DataGridTextColumn's, one of which is editable.
I need to intercept TextChanged event for the cell that is being edited.
I've tried editing style and adding
<EventSetter Event="TextChanged" Handler="TaskDescription_TextChanged"/>
but I'm getting
Cannot find the Style Event 'TextChanged' on the type 'System.Windows.Controls.DataGridCell'
Is there an easy way to get notified of the text change in DataGridTextColumn except by Two-Way binding?
Here's the XAML code:
<Style x:Key="CenteredTextColumn" TargetType="{x:Type DataGridCell}">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="BorderBrush" Value="Transparent"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGridCell}">
<Grid Height="30">
<Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
<ContentPresenter VerticalAlignment="Center" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="Foreground" Value="Black"/>
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="Background" Value="{StaticResource SelectedCellBackground}"/>
<Setter Property="Foreground" Value="White"/>
<!--<Setter Property="BorderBrush" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>-->
</Trigger>
<Trigger Property="IsKeyboardFocusWithin" Value="True">
<!--<Setter Property="BorderBrush" Value="{DynamicResource {x:Static DataGrid.FocusBorderBrushKey}}"/>-->
</Trigger>
<Trigger Property="IsEditing" Value="True">
<Setter Property="Background" Value="Transparent"/>
</Trigger>
</Style.Triggers>
</Style>
and the EventSetter:
<Style x:Key="ProjectInfoEditeableCell" TargetType="{x:Type DataGridCell}" BasedOn="{StaticResource CenteredTextColumn}">
<EventSetter Event="TextChanged" Handler="TaskDescription_TextChanged"/>
</Style>

combobox template problems wpf

I've created template for combobox but it has strange view, data is not displaying:
Here is XAML code:
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Border Background="{TemplateBinding Background}" x:Name="Bd" BorderBrush="Gray" BorderThickness="2" CornerRadius="2">
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" TargetName="Bd"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
<Trigger Property="IsFocused" Value="true">
<Setter Property="BorderBrush" Value="Blue" TargetName="Bd"/>
<Setter Property="BorderThickness" Value="2"/>
</Trigger>
<Trigger Property="IsFocused" Value="false">
<Setter Property="BorderBrush" Value="Gray" TargetName="Bd"/>
<Setter Property="BorderThickness" Value="2"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
What i missed here?

Your template creates near to nothing which makes the default one work, i.e. there is no items popup, and there is no ContentPresenter for the selected item either. Have a look at the default template and you will see exactly what you are missing (Here is a question explaining where to get them).