为什么 TextBlock 可以显示代码隐藏属性值,但 border/padding 却无法使用它?
在以下 Silverlight 应用程序中尽管 TextBlock 正确显示了 OuterPadding 的值,但为什么属性 OuterPadding 不更改外边框中的填充?如果我将边框填充更改为简单整数,则填充会起作用很好,但当它是由后面的代码中的属性定义时就不行了。
相同的代码在 WPF 中运行良好。
XAML:
<UserControl x:Class="Test222.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:pages="clr-namespace:Test222.Pages"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Width="600" Height="480">
<Border Background="#eee" Padding="{Binding OuterPadding}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="34"/>
<RowDefinition Height="426"/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Grid.Column="0">
<StackPanel x:Name="QuickMenu" Orientation="Horizontal"/>
</StackPanel>
<Border Grid.Row="1" Grid.Column="0"
Background="#fff"
Padding="10"
Width="580"
Height="426"
VerticalAlignment="Top"
CornerRadius="5">
<TextBlock Text="{Binding OuterPadding}"/>
</Border>
</Grid>
</Border>
</UserControl>
代码隐藏:
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
namespace Test222
{
public partial class MainPage : UserControl, INotifyPropertyChanged
{
#region ViewModelProperty: OuterPadding
private int _outerPadding;
public int OuterPadding
{
get
{
return _outerPadding;
}
set
{
_outerPadding = value;
OnPropertyChanged("OuterPadding");
}
}
#endregion
public MainPage()
{
InitializeComponent();
DataContext = this;
RefreshApplication();
}
void RefreshApplication()
{
OuterPadding = 5;
for (int i = 0; i < 5; i++)
{
var button = new Button();
button.Content = "Button " + i;
button.Margin = new Thickness { Right = 3 };
QuickMenu.Children.Add(button);
}
}
#region INotifyPropertyChanged Member
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
}
In the following Silverlight application why does the property OuterPadding not change the padding in the outer border, although the TextBlock correctly displays the value of OuterPadding? If I change the Border padding to a simple integer it the padding works fine, but not when it is defined by the property in code behind.
This same code works fine in WPF.
XAML:
<UserControl x:Class="Test222.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:pages="clr-namespace:Test222.Pages"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Width="600" Height="480">
<Border Background="#eee" Padding="{Binding OuterPadding}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="34"/>
<RowDefinition Height="426"/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Grid.Column="0">
<StackPanel x:Name="QuickMenu" Orientation="Horizontal"/>
</StackPanel>
<Border Grid.Row="1" Grid.Column="0"
Background="#fff"
Padding="10"
Width="580"
Height="426"
VerticalAlignment="Top"
CornerRadius="5">
<TextBlock Text="{Binding OuterPadding}"/>
</Border>
</Grid>
</Border>
</UserControl>
Code Behind:
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
namespace Test222
{
public partial class MainPage : UserControl, INotifyPropertyChanged
{
#region ViewModelProperty: OuterPadding
private int _outerPadding;
public int OuterPadding
{
get
{
return _outerPadding;
}
set
{
_outerPadding = value;
OnPropertyChanged("OuterPadding");
}
}
#endregion
public MainPage()
{
InitializeComponent();
DataContext = this;
RefreshApplication();
}
void RefreshApplication()
{
OuterPadding = 5;
for (int i = 0; i < 5; i++)
{
var button = new Button();
button.Content = "Button " + i;
button.Margin = new Thickness { Right = 3 };
QuickMenu.Children.Add(button);
}
}
#region INotifyPropertyChanged Member
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
}
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评论(2)
在 xaml 中定义值时 int 可以工作,但在代码中定义值时则不行。但如果你将属性从 int 更改为 ThickNess ,它就可以正常工作。
An int works when defining the value in xaml, but when you do it in code it doesn't. But if you change your property from an int to a ThickNess it works fine.
如果我不得不猜测,我会说它是因为厚度的值转换器不处理 Int32 ->厚度换算。如果将 OuterPadding 设置为 Thickness 而不是 int 会发生什么?
编辑刚刚检查了Reflector,似乎ThicknessConverter被硬编码来处理从String或Double到Thickness的转换,但不是Int32。我误解了我在Reflector中看到的内容。看起来它应该可以正常处理 Int32 。
If I had to guess I'd say its because the value converter for Thickness does not handle Int32 -> Thickness conversion. What happens if you make OuterPadding a Thickness instead of int?
EDIT Just checked Reflector and it seems ThicknessConverter is hard coded to handle conversion from either String or Double to Thickness, but not Int32.I misunderstood what I saw in Reflector. It looks like it should handle Int32 ok.