如何刪除表單上的繪製線？

Question

其實有關於這個話題的一些類似的問題，但我看不到答案我在找什麼。

例如我在Windows窗體上繪製了2行並且我想刪除其中一個並保留其他，我該怎麼做？我想刪除特定行。你有其他解決方案嗎？

Answer 1

以下操作將以相反的時間順序刪除所有創建的行。

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(); 
    } 

下面是兩行並排：

下面是兩行重疊：

*請記住，處置您的圖形對象！