[英]WPF Combobox Colors Binding issues
简单起见,我有一组颜色和一个绑定到它的组合框。 工作,没有道具。
但是,当我想使用某些“渐变功能”来扩展颜色时,绑定将不起作用,因此我尝试了很多方法。 我真的没有看到大的区别。
这是我所拥有的及其工作方式:
XAML
<ComboBox x:Name="colorCombo" Style="{StaticResource myComboBoxStyle}" Height="25" ItemsSource="{Binding ColorCollection}" HorizontalAlignment="Left" Margin="5" Grid.Row="3" Grid.Column="4" Width="110">
<ComboBox.ItemTemplate>
<DataTemplate>
<Border Height="15" Width="{Binding ElementName=colorCombo, Path=Width}" Background="{Binding Converter={StaticResource ColorToBrushConverter} }"/>
</DataTemplate>
</ComboBox.ItemTemplate>
ViewModel:
private Collection<Color> _colorCollection;
public Collection<Color> ColorCollection
{
get { return _colorCollection; }
set
{
_colorCollection = value;
this.NotifyPropertyChanged( x => x.ColorCollection );
}
}
集合的viewModel的OnLoad已填充,因此不必担心。 再次,这是工作!
现在为什么这不起作用:
XAML
<ComboBox x:Name="colorCombo2" Style="{StaticResource myComboBoxStyle}" Height="25" ItemsSource="{Binding ColorCollection2}" HorizontalAlignment="Right" Margin="5" Grid.Row="3" Grid.Column="4" Width="110">
<ComboBox.ItemTemplate>
<DataTemplate>
<Border Height="15" Width="{Binding ElementName=colorCombo2, Path=Width}" BorderBrush="{Binding BorderColor, Converter={StaticResource ColorToBrushConverter}}" >
<Border.Background >
<LinearGradientBrush EndPoint="0.504,1.5" StartPoint="0.504,0.03">
<GradientStop Color="{Binding Color1, Converter={StaticResource ColorToBrushConverter}}" Offset="0"/>
<GradientStop Color="{Binding Color2, Converter={StaticResource ColorToBrushConverter}}" Offset="0.567"/>
</LinearGradientBrush>
</Border.Background>
</Border>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
ViewModel:
private Collection<ColorGradientHelper> _colorCollection2;
public Collection<ColorGradientHelper> ColorCollection2
{
get { return _colorCollection2; }
set
{
_colorCollection2 = value;
this.NotifyPropertyChanged( x => x.ColorCollection2 );
}
}
助手类:
Public class ColorGradientHelper:ObservableBase {
private Color _color1;
public Color Color1
{
get { return _color1; }
set
{
_color1 = value;
this.NotifyPropertyChanged( x => x.Color1 );
}
}
private Color _color2;
public Color Color2
{
get { return _color2; }
set
{
_color2 = value;
this.NotifyPropertyChanged( x => x.Color2 );
}
}
private Color _borderColor;
public Color BorderColor
{
get { return _borderColor; }
set
{
_borderColor = value;
this.NotifyPropertyChanged( x => x._borderColor );
}
}
转换器:
public class ColorToBrushConverter : IValueConverter {
public object Convert( object value, Type targetType, object parameter, CultureInfo culture ) {
System.Drawing.Color col = (System.Drawing.Color) value;
Color c = Color.FromArgb( col.A, col.R, col.G, col.B );
return new SolidColorBrush( c );
}
public object ConvertBack( object value, Type targetType, object parameter, CultureInfo culture ) {
SolidColorBrush c = (SolidColorBrush) value;
System.Drawing.Color col = System.Drawing.Color.FromArgb( c.Color.A, c.Color.R, c.Color.G, c.Color.B );
return col;
}
}
正如肖恩·维尔德默斯(Shawn Wildermuth)所说 :
GradientStop不是从FrameworkElement派生的,因此不能进行数据绑定。
一种解决方法是巧妙地使用 FrameworkElement 的Tag
属性 。 最后,受rmoore的回答启发,我得出了以下解决方案:
XAML
<ComboBox x:Name="colorCombo2" Height="25" ItemsSource="{Binding ColorCollection}" HorizontalAlignment="Right" Margin="5" Width="110">
<ComboBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.Resources>
<local:ColorToBrushConverter x:Key="ColorToBrushConverter"/>
</Grid.Resources>
<Border Height="20" Width="{Binding ElementName=colorCombo2, Path=Width}"
BorderThickness="1"
BorderBrush="{Binding BorderColor, Converter={StaticResource ColorToBrushConverter}}">
<Border.Background>
<LinearGradientBrush EndPoint="0.504,1.5" StartPoint="0.504,0.03">
<GradientStop Color="{Binding ElementName=Border1, Path=Tag}" Offset="0" />
<GradientStop Color="{Binding ElementName=Border2, Path=Tag}" Offset="0.567" />
</LinearGradientBrush>
</Border.Background>
</Border>
<Grid Visibility="Collapsed">
<FrameworkElement Tag="{Binding Color1}" x:Name="Border1" />
<FrameworkElement Tag="{Binding Color2}" x:Name="Border2" />
</Grid>
</Grid>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
ViewModel (与OP的ViewModel完全相同)
public partial class MainWindow6 : Window, INotifyPropertyChanged {
public MainWindow6() {
DataContext = this;
InitializeComponent();
var colors = new Collection<ColorGradientHelper>();
colors.Add(new ColorGradientHelper {
BorderColor = Colors.Orange,
Color1 = Colors.Purple,
Color2 = Colors.White
});
colors.Add(new ColorGradientHelper {
BorderColor = Colors.Orange,
Color1 = Colors.Black,
Color2 = Colors.Yellow
});
ColorCollection = colors;
}
private Collection<ColorGradientHelper> _colorCollection;
public Collection<ColorGradientHelper> ColorCollection {
get {
return _colorCollection;
}
set {
_colorCollection = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null) {
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
该输出看起来像这样:
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