反転OpacityMask

Question

はOpacityMask whosは唯一の非透明部分からのTextBlockのフォアグラウンドであるので、それは次のようになります

<Grid Background="Blue"> 
    <Border Width="100" Height="60" BorderBrush="Black" BorderThickness="2"> 
     <Border Background="Red"> 
      <Border.OpacityMask> 
       <VisualBrush> 
        <VisualBrush.Visual> 
         <TextBlock Text="Text" 
            Foreground="#FF000000" 
            Background="#00000000"/> 
        </VisualBrush.Visual> 
       </VisualBrush> 
      </Border.OpacityMask> 
     </Border> 
    </Border> 
</Grid> 

XAML

の以下の部分を考えてみましょう。私はこの

<TextBlock Text="Text" 
      Foreground="#00000000" 
      Background="#FF000000"/> 

ようTextBlock内の前景と背景の色を切り替えると、フォアグラウンドが、その結果、その背後にある背景がない透明であってもので

は今、私はこれを取得します役に立たないOpacityMask：

私はこれを得ることができますか？基本的に反転OpacityMask

私はここでこれを行うにはいくつかの方法がありませんか？

は、私の例では、TextBlockの程度であっても、明確にするために更新、それは何でもかまいません。など、私が後だ機能エリプス/イメージ/パスは、「反転OpacityMask」である

Answer 1

あなたが使用することができ、私と同じquestionに異なる答えですHollowTextBlock：

<Grid Background="Blue"> 
    <Border Width="100" Height="60" BorderBrush="Black" BorderThickness="2"> 
     <Border Background="Red"> 
      <Border.OpacityMask> 
       <VisualBrush Stretch="None"> 
        <VisualBrush.Visual> 
         <local:HollowTextBlock Width="200" Height="50" Text="Text" Background="White" HorizontalAlignment="Center"/> 
        </VisualBrush.Visual> 
       </VisualBrush> 
      </Border.OpacityMask> 
     </Border> 
    </Border> 
</Grid> 

更新：

HollowTextBlockの適切な測定機能、通常のテキストプロパティのプロパティ値の継承、および割り当てられたスペースにテキストを垂直方向にセンタリングするための新しいVerticalTextAlignmentプロパティが追加されました：

public class HollowTextBlock : FrameworkElement 
{ 
    public string Text 
    { 
     get { return (string)GetValue(TextProperty); } 
     set { SetValue(TextProperty, value); } 
    } 

    public static readonly DependencyProperty TextProperty = 
     DependencyProperty.Register("Text", typeof(string), typeof(HollowTextBlock), new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure, new PropertyChangedCallback(HollowTextBlock.OnTextChanged), new CoerceValueCallback(HollowTextBlock.CoerceText))); 

    public Brush Background 
    { 
     get { return (Brush)GetValue(BackgroundProperty); } 
     set { SetValue(BackgroundProperty, value); } 
    } 

    public static readonly DependencyProperty BackgroundProperty = 
     TextElement.BackgroundProperty.AddOwner(typeof(HollowTextBlock), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender)); 

    public double FontSize 
    { 
     get { return (double)GetValue(FontSizeProperty); } 
     set { SetValue(FontSizeProperty, value); } 
    } 

    public static readonly DependencyProperty FontSizeProperty = 
     TextElement.FontSizeProperty.AddOwner(typeof(HollowTextBlock)); 

    public FontFamily FontFamily 
    { 
     get { return (FontFamily)GetValue(FontFamilyProperty); } 
     set { SetValue(FontFamilyProperty, value); } 
    } 

    public static readonly DependencyProperty FontFamilyProperty = 
     TextElement.FontFamilyProperty.AddOwner(typeof(HollowTextBlock)); 

    public FontStyle FontStyle 
    { 
     get { return (FontStyle)GetValue(FontStyleProperty); } 
     set { SetValue(FontStyleProperty, value); } 
    } 

    public static readonly DependencyProperty FontStyleProperty = 
     TextElement.FontStyleProperty.AddOwner(typeof(HollowTextBlock)); 

    public FontWeight FontWeight 
    { 
     get { return (FontWeight)GetValue(FontWeightProperty); } 
     set { SetValue(FontWeightProperty, value); } 
    } 

    public static readonly DependencyProperty FontWeightProperty = 
     TextElement.FontWeightProperty.AddOwner(typeof(HollowTextBlock)); 

    public FontStretch FontStretch 
    { 
     get { return (FontStretch)GetValue(FontStretchProperty); } 
     set { SetValue(FontStretchProperty, value); } 
    } 

    public static readonly DependencyProperty FontStretchProperty = 
     TextElement.FontStretchProperty.AddOwner(typeof(HollowTextBlock)); 

    public TextAlignment TextAlignment 
    { 
     get { return (TextAlignment)GetValue(TextAlignmentProperty); } 
     set { SetValue(TextAlignmentProperty, value); } 
    } 

    public static readonly DependencyProperty TextAlignmentProperty = 
     Block.TextAlignmentProperty.AddOwner(typeof(HollowTextBlock)); 

    public VerticalAlignment VerticalTextAlignment 
    { 
     get { return (VerticalAlignment)GetValue(VerticalTextAlignmentProperty); } 
     set { SetValue(VerticalTextAlignmentProperty, value); } 
    } 

    public static readonly DependencyProperty VerticalTextAlignmentProperty = 
     DependencyProperty.Register("VerticalTextAlignment", typeof(VerticalAlignment), typeof(HollowTextBlock), new FrameworkPropertyMetadata(VerticalAlignment.Top, FrameworkPropertyMetadataOptions.AffectsRender)); 

    private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
    { 
     OnTextChanged(d, (string)e.NewValue); 
    } 

    private static void OnTextChanged(DependencyObject d, string newText) 
    { 
    } 

    private static object CoerceText(DependencyObject d, object baseValue) 
    { 
     return baseValue; 
    } 

    protected override Size MeasureOverride(Size availableSize) 
    { 
     var face = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch); 
     var size = FontSize; 
     var ft = new FormattedText(Text, Thread.CurrentThread.CurrentUICulture, FlowDirection.LeftToRight, face, size, Brushes.Black); 
     return new Size(ft.Width, ft.Height); 
    } 

    protected override void OnRender(DrawingContext drawingContext) 
    { 
     base.OnRender(drawingContext); 
     var extent = new RectangleGeometry(new Rect(0.0, 0.0, RenderSize.Width, RenderSize.Height)); 
     var face = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch); 
     var size = FontSize; 
     var ft = new FormattedText(Text, Thread.CurrentThread.CurrentUICulture, FlowDirection.LeftToRight, face, size, Brushes.Black); 
     var originX = GetHorizontalOrigin(ft.Width, RenderSize.Width); 
     var originY = GetVerticalOrigin(ft.Height, RenderSize.Height); 
     var hole = ft.BuildGeometry(new Point(originX, originY)); 
     var combined = new CombinedGeometry(GeometryCombineMode.Exclude, extent, hole); 
     drawingContext.PushClip(combined); 
     drawingContext.DrawRectangle(Background, null, new Rect(0.0, 0.0, RenderSize.Width, RenderSize.Height)); 
     drawingContext.Pop(); 
    } 

    private double GetHorizontalOrigin(double textWidth, double renderWidth) 
    { 
     switch (TextAlignment) 
     { 
      case TextAlignment.Center: 
       return (renderWidth - textWidth)/2; 
      case TextAlignment.Left: 
       return 0; 
      case TextAlignment.Right: 
       return renderWidth - textWidth; 
     } 
     return 0; 
    } 

    private double GetVerticalOrigin(double textHeight, double renderHeight) 
    { 
     switch (VerticalTextAlignment) 
     { 
      case VerticalAlignment.Center: 
       return (renderHeight - textHeight)/2; 
      case VerticalAlignment.Top: 
       return 0; 
      case VerticalAlignment.Bottom: 
       return renderHeight - textHeight; 
     } 
     return 0; 
    } 
}