I Don't want message "SELECT DATE" in DatePicker - wpf

Question

I don't want display "Select Date" in textbox of DatePicker but I want see something like this //____ or another text.
This is my RESOURCE
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="ABC" TargetType="DatePicker">
<Setter Property="Foreground" Value="#FF333333" />
<Setter Property="IsTodayHighlighted" Value="True" />
<Setter Property="SelectedDateFormat" Value="Short" />
<Setter Property="Background" Value="Transparent" />
<Setter Property="DisplayDateStart" Value=" 01/01/1990" />
<Setter Property="DisplayDateEnd" Value="12/31/2090" />
<Setter Property="Padding" Value="2"/>
<Setter Property="FontFamily" Value="Verdana" />
<Setter Property="FontSize" Value="14" />
<Setter Property="BorderThickness" Value="1" />
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
<Setter Property="HorizontalAlignment" Value ="Center" />
<Setter Property="VerticalAlignment" Value= "Center" />
<Setter Property = "Text" Value="{x:Null}" />
<Setter Property = "SelectedDate" Value="{x:Null}" />
<Style.Triggers>
<Trigger Property ="IsMouseOver" Value="True">
<Setter Property= "Background" Value="Coral"/>
</Trigger>
<Trigger Property="IsFocused" Value="True">
<Setter Property= "Background" Value="LemonChiffon"/>
</Trigger>
</Style.Triggers>
</Style>

Answer 1

You can modify the default template for the DatePickerTextBox
The thing to change is the 'PART_Watermark' ContentControl. The code for the DatePicker sets the Content property of this control, so we can't just change the Content. Instead override the ControlTemplate for this control and just make it a TextBlock with the text you want.
<ContentControl x:Name="PART_Watermark"
Opacity="0"
Focusable="False"
IsHitTestVisible="False"
Padding="2">
<ContentControl.Template>
<ControlTemplate>
<TextBlock Text="//____"/>
</ControlTemplate>
</ContentControl.Template>
</ContentControl>
Here's the whole thing:
<Style TargetType="{x:Type DatePickerTextBox}">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}" />
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" />
<Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="DatePickerTextBox">
<Grid>
<Grid.Resources>
<SolidColorBrush x:Key="WatermarkBrush" Color="#FFAAAAAA"/>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup Name="CommonStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0" />
<VisualTransition To="MouseOver" GeneratedDuration="0:0:0.1" />
</VisualStateGroup.Transitions>
<VisualState Name="Normal" />
<VisualState Name="MouseOver">
<Storyboard>
<ColorAnimation Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" To="#FF99C1E2" Duration="0"/>
<ColorAnimation Storyboard.TargetName="watermark_decorator" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" To="#FF99C1E2" Duration="0"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup Name="WatermarkStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0" />
</VisualStateGroup.Transitions>
<VisualState Name="Unwatermarked" />
<VisualState Name="Watermarked">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Opacity" To="0" Duration="0" />
<DoubleAnimation Storyboard.TargetName="PART_Watermark" Storyboard.TargetProperty="Opacity" To="1" Duration="0" />
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup Name="FocusStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0" />
</VisualStateGroup.Transitions>
<VisualState Name="Unfocused" />
<VisualState Name="Focused">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="FocusVisual" Storyboard.TargetProperty="Opacity" To="1" Duration="0" />
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="Border"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}"
CornerRadius="1"
Opacity="1">
<Grid x:Name="WatermarkContent"
HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
<Border x:Name="ContentElement" BorderThickness="1">
<Border.BorderBrush>
<SolidColorBrush Color="#FFFFFFFF"/>
</Border.BorderBrush>
</Border>
<Border x:Name="watermark_decorator" BorderThickness="1">
<Border.BorderBrush>
<SolidColorBrush Color="#FFFFFFFF"/>
</Border.BorderBrush>
<ContentControl x:Name="PART_Watermark"
Opacity="0"
Focusable="False"
IsHitTestVisible="False"
Padding="2">
<ContentControl.Template>
<ControlTemplate>
<TextBlock Text="//____"/>
</ControlTemplate>
</ContentControl.Template>
</ContentControl>
</Border>
<ScrollViewer x:Name="PART_ContentHost"
Margin="0"
HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
<Border x:Name="FocusVisual" BorderBrush="#FF45D6FA" CornerRadius="1" Opacity="0" IsHitTestVisible="False"/>
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Answer 2

Extending #wizzardz's answer, you may introduce a DependencyProperty in Code to set the value in XAML on DesingTime:
public class CustomDatePicker : DatePicker
{
public string WatermarkText
{
get { return (string)GetValue(WatermarkTextProperty); }
set { SetValue(WatermarkTextProperty, value); }
}
public static readonly DependencyProperty WatermarkTextProperty =
DependencyProperty.Register("WatermarkText", typeof(string), typeof(CustomDatePicker), new PropertyMetadata("Datum wählen..."));
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
DatePickerTextBox box = base.GetTemplateChild("PART_TextBox") as DatePickerTextBox;
box.ApplyTemplate();
ContentControl watermark = box.Template.FindName("PART_Watermark", box) as ContentControl;
watermark.Content = WatermarkText;
}
}
and in XAML
<local:CustomDatePicker WatermarkText="Start"/>
This way you may also set Binding on the Watermarktext.

Answer 3

This is another solution from the code
public class CustomWatermarkedDatePicker : DatePicker
{
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
DatePickerTextBox box = base.GetTemplateChild("PART_TextBox") as DatePickerTextBox;
box.ApplyTemplate();
ContentControl watermark = box.Template.FindName("PART_Watermark", box) as ContentControl;
watermark.Content = "Custom Text";
}
}
Hope this helps.