这难道不是你正在寻找的吗?
<StackPanel Margin="0,10,0,0" />
第一个值是左边距,接着是上边距,然后右边距,最后是下边距。
我不确定你是否想将其绑定到某个东西上,但如果不需要,那么它就可以工作。
关键在于要意识到像这样在代码中设置:
sp2.Margin = new System.Windows.Thickness{ Left = 5 };
等同于:
sp2.Margin = new System.Windows.Thickness{ Left = 5, Top = 0, Right = 0, Bottom = 0 };
无论是在代码还是XAML中,都不能只设置Thickness
实例的单个值。如果您没有设置某些值,它们将被隐式设置为零。因此,您只需执行以下操作即可将其他问题中接受的代码示例转换为XAML等效代码:
<StackPanel Margin="{Binding TopMargin, Converter={StaticResource MyConverter}}"/>
其中MyConverter
只返回一个将Top
设置为非零值,而将所有其他值设置为零的Thickness
。
当然,您可以编写自己的控件,将这些单独的值作为依赖属性公开,以使您的代码更加清晰:
<CustomBorder TopMargin="{Binding TopMargin}">
</CustomBorder>
比起自定义控件,更好的选择是编写一个附加属性,并在依赖属性的setter中使用上述代码来更改Thickness。下面的代码可用于所有具有Margin的控件。public static readonly DependencyProperty TopMarginProperty =
DependencyProperty.RegisterAttached("TopMargin", typeof(int), typeof(FrameworkElement),
new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.AffectsRender));
public static void SetTopMargin(FrameworkElement element, int value)
{
// set top margin in element.Margin
}
public static int GetTopMargin(FrameworkElement element)
{
// get top margin from element.Margin
}
如果你将这个属性与Behavior相结合,就可以在TopMargin属性发生改变时得到通知。var margin = sp2.Margin; margin.Left = 5; sp2.Margin = margin;
这将保留其他值不变。 - bugged87Thickness
实例中进行初始化,除了Left
之外,其他所有值都将为0。也就是说,在这里没有“未设置”的Top
、Bottom
、Left
或Right
的概念,因为它是一个值类型。它们要么由你的代码设置,要么隐式地设置为0。引用我自己的话,就是在你引用的那句话之后直接说的:“如果你不设置某些值,它们将被隐式地设置为零。” - Kent Boogaart以下是WPF/XAML的戒律:
bool
可见性属性。我是WPF/XAML。你的罪行列在第9位。
我刚刚编写了一些附加属性,可以轻松地通过绑定或静态资源设置单个Margin值:
public class Margin
{
public static readonly DependencyProperty LeftProperty = DependencyProperty.RegisterAttached(
"Left",
typeof(double),
typeof(Margin),
new PropertyMetadata(0.0));
public static void SetLeft(UIElement element, double value)
{
var frameworkElement = element as FrameworkElement;
if (frameworkElement != null)
{
Thickness currentMargin = frameworkElement.Margin;
frameworkElement.Margin = new Thickness(value, currentMargin.Top, currentMargin.Right, currentMargin.Bottom);
}
}
public static double GetLeft(UIElement element)
{
return 0;
}
public static readonly DependencyProperty TopProperty = DependencyProperty.RegisterAttached(
"Top",
typeof(double),
typeof(Margin),
new PropertyMetadata(0.0));
public static void SetTop(UIElement element, double value)
{
var frameworkElement = element as FrameworkElement;
if (frameworkElement != null)
{
Thickness currentMargin = frameworkElement.Margin;
frameworkElement.Margin = new Thickness(currentMargin.Left, value, currentMargin.Right, currentMargin.Bottom);
}
}
public static double GetTop(UIElement element)
{
return 0;
}
public static readonly DependencyProperty RightProperty = DependencyProperty.RegisterAttached(
"Right",
typeof(double),
typeof(Margin),
new PropertyMetadata(0.0));
public static void SetRight(UIElement element, double value)
{
var frameworkElement = element as FrameworkElement;
if (frameworkElement != null)
{
Thickness currentMargin = frameworkElement.Margin;
frameworkElement.Margin = new Thickness(currentMargin.Left, currentMargin.Top, value, currentMargin.Bottom);
}
}
public static double GetRight(UIElement element)
{
return 0;
}
public static readonly DependencyProperty BottomProperty = DependencyProperty.RegisterAttached(
"Bottom",
typeof(double),
typeof(Margin),
new PropertyMetadata(0.0));
public static void SetBottom(UIElement element, double value)
{
var frameworkElement = element as FrameworkElement;
if (frameworkElement != null)
{
Thickness currentMargin = frameworkElement.Margin;
frameworkElement.Margin = new Thickness(currentMargin.Left, currentMargin.Top, currentMargin.Right, value);
}
}
public static double GetBottom(UIElement element)
{
return 0;
}
}
使用方法:
<TextBlock Text="Test"
app:Margin.Top="{Binding MyValue}"
app:Margin.Right="{StaticResource MyResource}"
app:Margin.Bottom="20" />
在UWP中进行了测试,但这应该适用于任何基于XAML的框架。好处是它们不会覆盖Margin上的其他值,因此您也可以将它们组合在一起。
您无法仅使用绑定来定义顶部边距,因为Margin
是Thickness
类型,它不是依赖对象。但是,您可以使用MultiValueConverter
,该转换器将采用4个边距值以创建1个Thickness
对象。
转换器:
public class ThicknessMultiConverter : IMultiValueConverter
{
#region IMultiValueConverter Members
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
double left = System.Convert.ToDouble(values[0]);
double top = System.Convert.ToDouble(values[1]);
double right = System.Convert.ToDouble(values[2]);
double bottom = System.Convert.ToDouble(values[3]);
return new Thickness(left, top, right, bottom);
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
Thickness thickness = (Thickness)value;
return new object[]
{
thickness.Left,
thickness.Top,
thickness.Right,
thickness.Bottom
};
}
#endregion
}
XAML :
<StackPanel>
<StackPanel.Margin>
<MultiBinding Converter="{StaticResource myThicknessConverter}">
<Binding Path="LeftMargin"/>
<Binding Path="TopMargin"/>
<Binding Path="RightMargin"/>
<Binding Path="BottomMargin"/>
</MultiBinding>
</StackPanel.Margin>
</StackPanel>
<Window.Resources>
<!-- Define the default amount of space -->
<system:Double x:Key="Space">10.0</system:Double>
<!-- Border space around a control -->
<Thickness
x:Key="BorderSpace"
Left="{StaticResource Space}"
Top="{StaticResource Space}"
Right="{StaticResource Space}"
Bottom="{StaticResource Space}"
/>
<!-- Space between controls that are positioned vertically -->
<Thickness
x:Key="TopSpace"
Top="{StaticResource Space}"
/>
</Window.Resources>
system
被定义为xmlns:system="clr-namespace:System;assembly=mscorlib"
。<Grid
Margin="{StaticResource BorderSpace}"
>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Button
Grid.Row="0"
Content="Button 1"
/>
<Button
Grid.Row="1"
Content="Button 2"
Margin="{StaticResource TopSpace}"
/>
</Grid>
public class MarginConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (!(value is Thickness)) return new Thickness();
Thickness retMargin = (Thickness) value;
List<string> singleMargins = (parameter as string)?.Split(';').ToList() ?? new List<string>();
singleMargins.ForEach(m => {
switch (m.Split(':').ToList()[0].ToLower().Trim()) {
case "left":
retMargin.Left = double.Parse(m.Split(':').ToList()[1].Trim());
break;
case "top":
retMargin.Top = double.Parse(m.Split(':').ToList()[1].Trim());
break;
case "right":
retMargin.Right = double.Parse(m.Split(':').ToList()[1].Trim());
break;
case "bottom":
retMargin.Bottom = double.Parse(m.Split(':').ToList()[1].Trim());
break;
}
}
);
return retMargin;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
xaml
<TextBlock Margin="{Binding RelativeSource={RelativeSource Self},
Path=Margin,
Converter={StaticResource MarginConverter},
ConverterParameter='top:0'}"
Style="{StaticResource Header}"
Text="My Header" />
TextBlock将使用Style给出的Margin,除了Margin-Top,它将被覆盖为0。
玩得开心!
我认为你可以使用属性语法,来自MSDN:
<object.Margin>
<Thickness Top="{Binding Top}"/>
</object.Margin>
那么您就不需要任何转换器了
但是顶部不是依赖项属性 - 回到转换器
这里有一个巧妙的解决方案:
public class Nifty
{
private static double _tiny;
private static double _small;
private static double _medium;
private static double _large;
private static double _huge;
private static bool _resourcesLoaded;
#region Margins
public static readonly DependencyProperty MarginProperty =
DependencyProperty.RegisterAttached("Margin", typeof(string), typeof(Nifty),
new PropertyMetadata(string.Empty,
new PropertyChangedCallback(OnMarginChanged)));
public static Control GetMargin(DependencyObject d)
{
return (Control)d.GetValue(MarginProperty);
}
public static void SetMargin(DependencyObject d, string value)
{
d.SetValue(MarginProperty, value);
}
private static void OnMarginChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
FrameworkElement ctrl = d as FrameworkElement;
if (ctrl == null)
return;
string Margin = (string)d.GetValue(MarginProperty);
ctrl.Margin = ConvertToThickness(Margin);
}
private static Thickness ConvertToThickness(string Margin)
{
var result = new Thickness();
if (!_resourcesLoaded)
{
_tiny = (double)Application.Current.FindResource("TinySpace");
_small = (double)Application.Current.FindResource("SmallSpace");
_medium = (double)Application.Current.FindResource("MediumSpace");
_large = (double)Application.Current.FindResource("LargeSpace");
_huge = (double)Application.Current.FindResource("HugeSpace");
_resourcesLoaded = true;
}
result.Left = CharToThickness(Margin[0]);
result.Top = CharToThickness(Margin[1]);
result.Bottom = CharToThickness(Margin[2]);
result.Right = CharToThickness(Margin[3]);
return result;
}
private static double CharToThickness(char p)
{
switch (p)
{
case 't':
case 'T':
return _tiny;
case 's':
case 'S':
return _small;
case 'm':
case 'M':
return _medium;
case 'l':
case 'L':
return _large;
case 'h':
case 'H':
return _huge;
default:
return 0.0;
}
}
#endregion
}
<system:Double x:Key="TinySpace">2</system:Double>
<system:Double x:Key="SmallSpace">5</system:Double>
<system:Double x:Key="MediumSpace">10</system:Double>
<system:Double x:Key="LargeSpace">20</system:Double>
<system:Double x:Key="HugeSpace">20</system:Double>
local:Nifty.Margin="H000"
或者
local:Nifty.Margin="_S_S"
使用转换器,下面的示例代码将把您绑定到的双精度数值转换为厚度。它将把厚度的“顶部”设置为绑定字段。您还可以选择使用ConverterParameter来确定您是否绑定到左侧、顶部、右侧或底部。
<StackPanel Margin="{Binding TopMargin, Converter={StaticResource MyThicknessConverter}">
.
public class ThicknessSingleValueConverter : IValueConverter
{
override Convert(...)
{
return new Thickness(0, (double)object, 0, 0);
}
//etc...