要在 WPF 中获得这些漂亮的 L 形角，您必须分别绘制水平和垂直边框，因为 StrokeDashArray 不会（总是）对两者相同。
您对StrokeDashArray 的要求是：
- 每一行都应该以一个完整的破折号开始和结束
- 破折号的长度应保持不变
- 应通过拉伸破折号之间的空间来填充超出/缺少的距离
要获得绘制这样一条线所需的精确长度，您必须计算虚线中的行数 (+1) 和空格，例如像这样：
private IEnumerable<double> GetDashArray(double length)
{
double useableLength = length - StrokeDashLine;
int lines = (int)Math.Round(useableLength/(StrokeDashLine + StrokeDashSpace));
useableLength -= lines*StrokeDashLine;
double actualSpacing = useableLength/lines;
yield return StrokeDashLine / StrokeThickness;
yield return actualSpacing / StrokeThickness;
}
将其封装在自定义控件中，您将得到如下内容：
<local:NiceCornersControl Fill="LightGray" Stroke="Black"
StrokeThickness="2" StrokeDashLine="5" StrokeDashSpace="5">
<TextBlock HorizontalAlignment="Center" VerticalAlignment="Center"
Text="Drop files here"/>
</local:NiceCornersControl>
您应该注意的几件事：
- 要将线条置于矩形“内部”，您需要将它们偏移
StrokeThickness / 2
-
DashStyle 将与您的StrokeThickness 一起扩展
- 这对于半透明的笔触颜色可能看起来很奇怪
控件的完整代码：
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace InsertNamespaceHere
{
public class NiceCornersControl : ContentControl
{
public static readonly DependencyProperty StrokeProperty = DependencyProperty.Register(
"Stroke", typeof(Brush), typeof(NiceCornersControl), new PropertyMetadata(default(Brush), OnVisualPropertyChanged));
public Brush Stroke
{
get { return (Brush)GetValue(StrokeProperty); }
set { SetValue(StrokeProperty, value); }
}
public static readonly DependencyProperty StrokeThicknessProperty = DependencyProperty.Register(
"StrokeThickness", typeof(double), typeof(NiceCornersControl), new PropertyMetadata(default(double), OnVisualPropertyChanged));
public double StrokeThickness
{
get { return (double)GetValue(StrokeThicknessProperty); }
set { SetValue(StrokeThicknessProperty, value); }
}
public static readonly DependencyProperty StrokeDashLineProperty = DependencyProperty.Register(
"StrokeDashLine", typeof(double), typeof(NiceCornersControl), new PropertyMetadata(default(double), OnVisualPropertyChanged));
public double StrokeDashLine
{
get { return (double)GetValue(StrokeDashLineProperty); }
set { SetValue(StrokeDashLineProperty, value); }
}
public static readonly DependencyProperty StrokeDashSpaceProperty = DependencyProperty.Register(
"StrokeDashSpace", typeof(double), typeof(NiceCornersControl), new PropertyMetadata(default(double), OnVisualPropertyChanged));
public double StrokeDashSpace
{
get { return (double)GetValue(StrokeDashSpaceProperty); }
set { SetValue(StrokeDashSpaceProperty, value); }
}
public static readonly DependencyProperty FillProperty = DependencyProperty.Register(
"Fill", typeof(Brush), typeof(NiceCornersControl), new PropertyMetadata(default(Brush), OnVisualPropertyChanged));
public Brush Fill
{
get { return (Brush)GetValue(FillProperty); }
set { SetValue(FillProperty, value); }
}
private static void OnVisualPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((NiceCornersControl)d).InvalidateVisual();
}
public NiceCornersControl()
{
SnapsToDevicePixels = true;
UseLayoutRounding = true;
}
protected override void OnRender(DrawingContext drawingContext)
{
double w = ActualWidth;
double h = ActualHeight;
double x = StrokeThickness / 2.0;
Pen horizontalPen = GetPen(ActualWidth - 2.0 * x);
Pen verticalPen = GetPen(ActualHeight - 2.0 * x);
drawingContext.DrawRectangle(Fill, null, new Rect(new Point(0, 0), new Size(w, h)));
drawingContext.DrawLine(horizontalPen, new Point(x, x), new Point(w - x, x));
drawingContext.DrawLine(horizontalPen, new Point(x, h - x), new Point(w - x, h - x));
drawingContext.DrawLine(verticalPen, new Point(x, x), new Point(x, h - x));
drawingContext.DrawLine(verticalPen, new Point(w - x, x), new Point(w - x, h - x));
}
private Pen GetPen(double length)
{
IEnumerable<double> dashArray = GetDashArray(length);
return new Pen(Stroke, StrokeThickness)
{
DashStyle = new DashStyle(dashArray, 0),
EndLineCap = PenLineCap.Square,
StartLineCap = PenLineCap.Square,
DashCap = PenLineCap.Flat
};
}
private IEnumerable<double> GetDashArray(double length)
{
double useableLength = length - StrokeDashLine;
int lines = (int)Math.Round(useableLength / (StrokeDashLine + StrokeDashSpace));
useableLength -= lines * StrokeDashLine;
double actualSpacing = useableLength / lines;
yield return StrokeDashLine / StrokeThickness;
yield return actualSpacing / StrokeThickness;
}
}
}