别名问题

Question

下面的代码在画布上绘制两条垂直线。这些线在屏幕上看起来有不同的厚度，尽管它们在代码中是相同的。我想找到一种方法让它们看起来像画布周围的边框一样锋利。设置Path.SnapsToDevicePixels没有任何效果。代码是一个人为的例子，一般来说，绘制这些线条的画布可以嵌套在可视树中更深处。

感谢您的帮助 康斯坦丁

<Window x:Class="wpfapp.MyWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Grid>
    <Border BorderBrush="Black"
            BorderThickness="1"
            Margin="10">
      <Canvas x:Name="Canvas"
              SizeChanged="OnCanvasSizeChanged" />
    </Border>
  </Grid>
</Window>

using System.Windows;
using System.Windows.Media;
using System.Windows.Shapes;

namespace wpfapp
{
    public partial class MyWindow : Window
    {
        public MyWindow()
        {
            InitializeComponent();
        }

        private void OnCanvasSizeChanged(object sender, SizeChangedEventArgs e)
        {
            StreamGeometry g = new StreamGeometry();
            double h = this.Canvas.ActualHeight;

            using (StreamGeometryContext c = g.Open())
            {
                c.BeginFigure(new Point(7, 0), false, false);
                c.LineTo(new Point(7, h), true, false);

                c.BeginFigure(new Point(14, 0), false, false);
                c.LineTo(new Point(14, h), true, false);
            }
            g.Freeze();

            Path p = new Path();

            p.Data = g;
            p.SnapsToDevicePixels = true;
            p.Stroke = new SolidColorBrush(Colors.Black);
            p.StrokeThickness = 1;

            this.Canvas.Children.Clear();
            this.Canvas.Children.Add(p);
        }
    }
}

Answer 1

需要使用GuidelineSet：

        protected override void OnRender(DrawingContext c)
        {
            base.OnRender(c);

            Pen pen = new Pen(Brushes.Black, 1);
            double h = this.ActualHeight;
            double d = pen.Thickness / 2;

            foreach (double x in new double[] { 7, 14 })
            {
                GuidelineSet g = new GuidelineSet(new double[] { x + d },
                                                  new double[] { 0 + d, h + d });

                c.PushGuidelineSet(g);
                c.DrawLine(pen, new Point(x, 0), new Point(x, h));
                c.Pop();
            }
        }