如何删除表单上的绘制线？

Question

其实有关于这个话题的一些类似的问题，但我看不到答案我在找什么。

例如我在Windows窗体上绘制了2行并且我想删除其中一个并保留其他，我该怎么做？我想删除特定行。你有其他解决方案吗？

Answer 1

以下操作将以相反的时间顺序删除所有创建的行。

Graphics g; 
    Pen p; 
    Bitmap bmp; 
    List<Point> Lines = new List<Point>(); 

    private void Form2_Load(object sender, EventArgs e) 
    { 
     bmp = new Bitmap(Width, Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb); 
     BackgroundImage = bmp; 
     g = Graphics.FromImage(BackgroundImage); 
     g.Clear(Color.DeepSkyBlue); //This is our backcolor 
    } 

    private void btnLine1_Click(object sender, EventArgs e) 
    { 
     Point A = new Point(50, 50); 
     Point B = new Point(100, 50); 
     p = new Pen(Color.Red); 
     g.DrawLine(p, A, B); //Use whatever method to draw your line 
     Lines.Add(A); //Grab the first point; add to list 
     Lines.Add(B); //Grab the second point; add to list 
     Refresh(); //Refresh drawing to bitmap. 
    } 

    private void btnDrawLine2_Click(object sender, EventArgs e) 
    { 
     Point A = new Point(50, 60); 
     Point B = new Point(100, 60); 
     p = new Pen(Color.White); 
     g.DrawLine(p, A, B); //Same logic as above 
     Lines.Add(A); 
     Lines.Add(B); 
     Refresh(); 
    } 

    private void btnUndo_Click(object sender, EventArgs e) 
    { 
     c = new Pen(Color.DeepSkyBlue); 
     r = new Pen(lastColor.ElementAt(lastColor.Count - 2)); 
     try 
     { 
      g.DrawLine(c, Lines.ElementAt(Lines.Count - 2), Lines.ElementAt(Lines.Count - 1)); 
      Lines.RemoveAt(Lines.Count - 2); 
      Lines.RemoveAt(Lines.Count - 1); 
      for (int i = Lines.Count; i > 0; i--) 
      { 
      g.DrawLine(r, Lines.ElementAt(Lines.Count - 2), Lines.ElementAt(Lines.Count - 1)); 
      } 
     } 
     catch { } 
     Refresh(); 
    } 

下面是两行并排：

下面是两行重叠：

*请记住，处置您的图形对象！