wpf 占位符文本框 Windows Phone 8
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Placeholder Textbox Windows Phone 8
提问by Edward Anthony
I have read this Adding placeholder text to textbox
我已阅读此 将占位符文本添加到文本框
The problem is, the placeholder TextBox must be easy to reuse. Either with XAML or Code. Maybe it's something like this
问题是，占位符 TextBox 必须易于重用。使用 XAML 或代码。也许是这样的
<my:TextBoxPlaceholder Placeholder="this is the placeholder"/>
or
或者
<TextBox Placeholder="this is the placeholder"
Type="/*staticresources*/PlaceholderTextBox"/>
This is what I'm referring to. (the screen shot I got from Instagram Beta).
这就是我所指的。（我从 Instagram Beta 中获得的屏幕截图）。
As you can see, on the second picture, the "Add a comment" placeholder is on the top most of TextBox, it covers the stripe line. Is the placeholder a picture or a TextBlock on top of it?
如您所见，在第二张图片中，“添加评论”占位符位于 TextBox 的最顶部，它覆盖了条纹线。占位符是图片还是上面的 TextBlock？
回答by anderZubi
You can use the PhoneTextBoxcontrol from Windows Phone Toolkit.
您可以使用Windows Phone Toolkit 中的PhoneTextBox控件。
It has a Hintproperty which allows you to set a placeholder:
它有一个Hint允许你设置占位符的属性：
<toolkit:PhoneTextBox Hint="Add a coment" Text={Binding ...} .../>
回答by Martin Zikmund
The third comment by MacGileon the thread you mentioned shows a fairly simple way to extend the normal TextBox with a special style. If you apply this style on your TextBox, you can use it simply as he illustrates:
MacGile在您提到的线程上的第三条评论显示了一种使用特殊样式扩展普通 TextBox 的相当简单的方法。如果你在你的 TextBox 上应用这个样式，你可以像他说明的那样简单地使用它：
<TextBox Style="{StaticResource placeHolder}"
Tag="Name of customer" Width="150" Height="24"/>
The Tagattribute is where you enter the placeholder text. The style is designed to change the color according to the text entered and will return to full color black when user edits.
该Tag属性是您输入占位符文本的位置。该样式旨在根据输入的文本更改颜色，并在用户编辑时返回全黑。
A second way to achieve your goal is to place the TextBox in a Grid and add a TextBlock over it, which you will hide when the TextBlock is not empty (user has entered something). Sample:
实现目标的第二种方法是将 TextBox 放在网格中并在其上添加一个 TextBlock，当 TextBlock 不为空时（用户输入了一些内容），您将隐藏它。样本：
<Grid>
<TextBox x:Name="MyTextBox" />
<TextBlock Text="enter name..." Foreground="#CCC"
Visibility="{Binding ElementName=MyTextBox, Path=Text, Converter={StaticResource StringLengthToVisibilityConverter}}" />
</Grid>
Where the StringLengthToVisibilityConverteris a IValueConverterthat returns Visibility.Visiblewhen the string parameter is empty. You can turn this into a custom control or UserControl and it will work just the way you need.
其中StringLengthToVisibilityConverteris a在字符串参数为空时IValueConverter返回Visibility.Visible。您可以将其转换为自定义控件或 UserControl，它将按照您需要的方式工作。
回答by Shawn Kendrot
You can accomplish this with a WatermarkTextBox. First create a new class titled WatermarkTextBox.cs
您可以使用 WatermarkTextBox 完成此操作。首先创建一个名为 WatermarkTextBox.cs 的新类
public class WatermarkTextBox : TextBox
{
public WatermarkTextBox()
{
TextChanged += OnTextChanged;
}
private void OnTextChanged(object sender, TextChangedEventArgs textChangedEventArgs)
{
// Show or hide the watermark based on the text length
if (Text.Length > 0)
{
WatermarkVisibility = Visibility.Collapsed;
}
else
{
WatermarkVisibility = Visibility.Visible;
}
}
public string Watermark
{
get { return (string)GetValue(WatermarkProperty); }
set { SetValue(WatermarkProperty, value); }
}
// Using a DependencyProperty as the backing store for Watermark. This enables animation, styling, binding, etc...
public static readonly DependencyProperty WatermarkProperty =
DependencyProperty.Register("Watermark", typeof(string), typeof(WatermarkTextBox), new PropertyMetadata(null));
public Visibility WatermarkVisibility
{
get { return (Visibility)GetValue(WatermarkVisibilityProperty); }
set { SetValue(WatermarkVisibilityProperty, value); }
}
// Using a DependencyProperty as the backing store for WatermarkVisibility. This enables animation, styling, binding, etc...
public static readonly DependencyProperty WatermarkVisibilityProperty =
DependencyProperty.Register("WatermarkVisibility", typeof(Visibility), typeof(WatermarkTextBox), new PropertyMetadata(System.Windows.Visibility.Visible));
}
In your xaml, use this in place of your normal Textbox
在你的 xaml 中，用它代替你的普通文本框
<controls:WatermarkTextBox Watermark="Add a comment" Text="{Binding MyProperty}" Style={StaticResource WaterMarkTextBoxStyle/>
Notice the style defined, add the following style to your app.xaml
注意定义的样式，将以下样式添加到您的 app.xaml
<Style x:Key="WatermarkTextBoxStyle" TargetType="local:WatermarkTextBox">
<Setter Property="FontFamily" Value="{StaticResource PhoneFontFamilyNormal}"/>
<Setter Property="FontSize" Value="{StaticResource PhoneFontSizeMediumLarge}"/>
<Setter Property="Background" Value="{StaticResource PhoneTextBoxBrush}"/>
<Setter Property="Foreground" Value="{StaticResource PhoneTextBoxForegroundBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource PhoneTextBoxBrush}"/>
<Setter Property="SelectionBackground" Value="{StaticResource PhoneAccentBrush}"/>
<Setter Property="SelectionForeground" Value="{StaticResource PhoneTextBoxSelectionForegroundBrush}"/>
<Setter Property="BorderThickness" Value="{StaticResource PhoneBorderThickness}"/>
<Setter Property="Padding" Value="2"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:WatermarkTextBox">
<Grid Background="Transparent">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver"/>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="MainBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="Transparent"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="MainBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneDisabledBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentElement">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneDisabledBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="ReadOnly">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="MainBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="ReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="ReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentElement">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxReadOnlyBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="MainBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxEditBackgroundBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="MainBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxEditBorderBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="MainBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Margin="{StaticResource PhoneTouchTargetOverhang}"/>
<Border x:Name="ReadonlyBorder" BorderBrush="{StaticResource PhoneDisabledBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="Transparent" Margin="{StaticResource PhoneTouchTargetOverhang}" Visibility="Collapsed"/>
<Border BorderBrush="Transparent" BorderThickness="{TemplateBinding BorderThickness}" Background="Transparent" Margin="{StaticResource PhoneTouchTargetOverhang}">
<Grid>
<ContentControl x:Name="ContentElement" BorderThickness="0" HorizontalContentAlignment="Stretch" Margin="{StaticResource PhoneTextBoxInnerMargin}" Padding="{TemplateBinding Padding}" VerticalContentAlignment="Stretch"/>
<TextBlock Text="{TemplateBinding Watermark}" Foreground="Gray" Margin="3,4,0,0" Visibility="{TemplateBinding WatermarkVisibility}"/>
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
