Question

我希望能够从一个鼠标点击位置绘制一个直箭头，就像你在PowerPoint中一样。它也需要能够在PictureBox上绘图。

Answer 1

以下是在图片框中从鼠标到当前位置绘制线条的一些基本代码你只需要为箭头绘制更多的线条或三角形。

public partial class Form1 : Form
{
    private bool isMoving = false;
    private Point mouseDownPosition = Point.Empty;
    private Point mouseMovePosition = Point.Empty;
    private List<Tuple<Point, Point>> lines = new List<Tuple<Point, Point>>();
    public Form1()
    {
        InitializeComponent();

        // 
        // pictureBox1
        // 
        this.pictureBox1.Location = new System.Drawing.Point(0, 0);
        this.pictureBox1.Name = "pictureBox1";
        this.pictureBox1.Size = new System.Drawing.Size(231, 235);
        this.pictureBox1.TabIndex = 0;
        this.pictureBox1.TabStop = false;
        this.pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);
        this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
        this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
        this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);
        this.Controls.Add(this.pictureBox1);
    }

    private void pictureBox1_Paint(object sender, PaintEventArgs e)
    {
        var g = e.Graphics;
        if (isMoving)
        {
            g.Clear(pictureBox1.BackColor);
            g.DrawLine(Pens.Black, mouseDownPosition, mouseMovePosition);
            foreach (var line in lines)
            {
                g.DrawLine(Pens.Black, line.Item1, line.Item2);
            }
        }
    }

    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        isMoving = true;
        mouseDownPosition = e.Location;
    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (isMoving)
        {
            mouseMovePosition = e.Location;
            pictureBox1.Invalidate();
        }
    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        if (isMoving)
        {
            lines.Add(Tuple.Create(mouseDownPosition, mouseMovePosition));
        }
        isMoving = false;
    }
}

Answer 2

以与制定a previous question中PictureBox的方式相同的方式绘制箭头很容易。

您所要做的就是为已用于绘制线条的StartCap对象指定EndCap或Pen。直观地，StartCap属性允许您指定在使用Pen对象绘制的任何行的开头使用的上限样式，而EndCap属性允许您指定上限线条末端的风格。

有几种不同的LineCap款式可供选择，包括：

Flat          Specifies a flat line cap.
Square        Specifies a square line cap.
Round         Specifies a round line cap.
Triangle      Specifies a triangular line cap.
NoAnchor      Specifies no anchor.
SquareAnchor  Specifies a square anchor line cap.
RoundAnchor   Specifies a round anchor cap.
DiamondAnchor Specifies a diamond anchor cap.
ArrowAnchor   Specifies an arrow-shaped anchor cap.
Custom        Specifies a custom line cap.
AnchorMask    Specifies a mask used to check whether a line cap is an anchor cap.

在这种情况下，您可能会发现ArrowAnchor样式最有用：只需将ArrowAnchor指定为行的开头或结尾的LineCap样式（取决于在你想要箭头指向的方向上。）

以下代码将绘制一条绿色，右向箭头，线条粗细为4：

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
 //Create a new pen to draw the arrow with
 using (Pen p = new Pen(Brushes.Green, 4f))
 {
  //Specify the EndCap, because we're drawing a right-facing arrow
  p.EndCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;

  //Draw the arrow
  e.Graphics.DrawLine(p, 0, 0, 30, 45);
 }
}

Answer 3

参考 Albin Sunnanbo 回答这是很棒的事情

如果您想绘制箭头，只需替换

 g.DrawLine(Pens.Black, mouseDownPosition, mouseMovePosition);

到

Pen p = new Pen(Color.Black,3);
p.StartCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;
g.DrawLine(p, mouseDownPosition, mouseMovePosition);
p.Dispose();

在C＃中的Picturebox上绘制一个箭头

3 个答案: