如何在对象上绘制虚线？

Question

我正在 Windows 窗体上的控件上画一条线，如下所示：

            // Get Graphics object from chart
            Graphics graph = e.ChartGraphics.Graphics;

            PointF point1 = PointF.Empty;
            PointF point2 = PointF.Empty;

            // Set Maximum and minimum points
            point1.X = -110;
            point1.Y = -110;
            point2.X = 122;
            point2.Y = 122;

            // Convert relative coordinates to absolute coordinates.
            point1 = e.ChartGraphics.GetAbsolutePoint(point1);
            point2 = e.ChartGraphics.GetAbsolutePoint(point2);

            // Draw connection line
            graph.DrawLine(new Pen(Color.Yellow, 3), point1, point2);

我想知道是否可以绘制虚线（点）而不是常规实线？

Answer 1

一旦您弄清楚定义破折号的格式，事情就非常简单了：

float[] dashValues = { 5, 2, 15, 4 };
Pen blackPen = new Pen(Color.Black, 5);
blackPen.DashPattern = dashValues;
e.Graphics.DrawLine(blackPen, new Point(5, 5), new Point(405, 5));

float数组中的数字代表不同颜色的破折号长度。因此，对于每个亮 2 个像素（黑色）和亮 2 个像素的简单破折号，您的阵列将如下所示：

{2,2}

然后该图案会重复。如果您想要 5 宽的破折号，间隔为 2 个像素，您可以使用

{5,2}

在你的代码中它看起来像：

// Get Graphics object from chart
Graphics graph = e.ChartGraphics.Graphics;

PointF point1 = PointF.Empty;
PointF point2 = PointF.Empty;

// Set Maximum and minimum points
point1.X = -110;
point1.Y = -110;
point2.X = 122;
point2.Y = 122;

// Convert relative coordinates to absolute coordinates.
point1 = e.ChartGraphics.GetAbsolutePoint(point1);
point2 = e.ChartGraphics.GetAbsolutePoint(point2);

// Draw (dashed) connection line
float[] dashValues = { 4, 2 };
Pen dashPen= new Pen(Color.Yellow, 3);
dashPen.DashPattern = dashValues;
graph.DrawLine(dashPen, point1, point2);

Answer 2

我认为你可以通过改变你用来画线的笔来实现这一点。 因此，将示例中的最后两行替换为：

        var pen = new Pen(Color.Yellow, 3);
        pen.DashStyle = DashStyle.Dash;
        graph.DrawLine(pen, point1, point2);

Answer 3

Pen

有一个公共属性，定义为

public DashStyle DashStyle { get; set; }

如果你想画虚线，可以设置

DasStyle.Dash

。

Answer 4

Pen.DashPattern 可以做到这一点。 看这里的例子。

Answer 5

在更现代的 C# 中：

var dottedPen = new Pen(Color.Gray, width: 1) { DashPattern = new[] { 1f, 1f } };

Answer 6

要回答有关使用隐藏代码生成虚线的问题：

        Pen dashPenTest = new(Brushes.DodgerBlue, 1);

        Line testLine = new()
        {
            Stroke = dashPenTest.Brush, //Brushes.Aqua,
            StrokeThickness = dashPenTest.Thickness,//1,
            StrokeDashArray = new DoubleCollection() { 8,4 },
            X1 = 0,
            X2 = canvas.Width,
            Y1 = 10,
            Y2 = 10
        }; 
        canvas.Children.Add(testLine);

这个答案利用了 xaml 中画布的生成：

        <Canvas x:Name ="canvas" Background="White" Height="300" Width="300">

这里重要的方法是“StrokeDashArray”，它为绘制的线生成虚线。更多信息如下：Shape.StrokeDashArray