Template Binding in Control template

I have the following control template.

I wish to set the source property for the image control in the control template using Template Binding.

But since this is a control template for button control and the button control doesn't have source property, i can't use TemplateBinding in this case.

<ControlTemplate x:Key="BtnTemplate" TargetType="Button">
        <Border CornerRadius="5"  Margin="15" Cursor="Hand">
            <StackPanel>
                <Image Name="Img" Style="{StaticResource ImageStyle}" Source="temp.jpg" Height="100" Width="100" Margin="5"></Image>
                <Label Content="{TemplateBinding Content}" Background="Transparent" Margin="2"></Label>
            </StackPanel>
        </Border>
    </ControlTemplate>

Since i have to set different images for different instances of button, i can't hardcode the path as well.

Please let me know how to tackle this situation.

I'd suggest using dynamic resources, e.g. define the template as follows:

<ControlTemplate x:Key="buttonTemplate" TargetType="Button">
    <Border CornerRadius="5"  Margin="15" Cursor="Hand">
        <StackPanel Orientation="Horizontal" Background="Yellow">
            <Image Source="{DynamicResource ResourceKey=Img}" Height="100" Width="100" Margin="5"></Image>
            <Label Content="{TemplateBinding Content}" Background="Transparent" Margin="2"></Label>
        </StackPanel>
    </Border>
</ControlTemplate>

And use it like this:

<Button Content="Button" Template="{StaticResource ResourceKey=buttonTemplate}">
    <Button.Resources>
        <ImageSource x:Key="Img">SomeUri.png/</ImageSource>
    </Button.Resources>
</Button>

TemplateBinding is a lightweight "binding", it doesn't support some features of traditional Binding, such as automatically type conversion using the known type converters associated with the target property (such as converting the string URI into a BitmapSource instance).

The following code can work properly:

<Window x:Class="GridScroll.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window2">
<Window.Resources>
    <Style TargetType="{x:Type Button}" x:Key="ButtonStyle">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border CornerRadius="5"  Margin="15" Cursor="Hand" Background="Red">
                        <StackPanel Orientation="Horizontal" Background="White">
                            <Image Name="Img" Source="{Binding Path=Tag, RelativeSource={RelativeSource TemplatedParent}}" Margin="5"></Image>
                            <Label Content="{TemplateBinding Content}" Margin="2"></Label>
                        </StackPanel>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>


</Window.Resources>
<StackPanel Orientation="Horizontal">
    <Button Style="{StaticResource ButtonStyle}" Tag="a.jpeg" Content="a"/>
    <Button Style="{StaticResource ButtonStyle}" Tag="b.png" Content="b"/>
</StackPanel>

You haven't really said how you expect consumers of your button to set the source. You could use the Button.Tag property, for example, and then bind to that in your template. Or you could define your own control:

public class ImageButton : Button
{
    // add Source dependency property a la Image
}

And then the template:

<ControlTemplate TargetType="ImageButton">
    <Border CornerRadius="5"  Margin="15" Cursor="Hand">
        <StackPanel>
            <Image Name="Img" Style="{StaticResource ImageStyle}" Source="{TempateBinding Source}" Height="100" Width="100" Margin="5"></Image>
            <Label Content="{TemplateBinding Content}" Background="Transparent" Margin="2"></Label>
        </StackPanel>
    </Border>
</ControlTemplate>

I'm not sure that I understood your problem very well but why don't you use ContentPresenter? It allows to move the code for your Image at the higher level.

<ControlTemplate x:Key="BtnTemplate" TargetType="Button">
  ...
  <ContentPresenter/>
</ControlTemplate>
...
<Button Template="{StaticResource BtnTemplate}">
  <Image .../>
</Button>