如何避免閃爍使用繪畫方法在面板上繪製矩形？

public Form1() 
    { 
     InitializeComponent(); 
     SetStyle(ControlStyles.UserPaint, true); 
     SetStyle(ControlStyles.AllPaintingInWmPaint, true); 
     SetStyle(ControlStyles.OptimizedDoubleBuffer, true); 
     SetStyle(ControlStyles.ResizeRedraw, true); 
     SetStyle(ControlStyles.UserMouse, true); 
    } 

    private void Form1_Load(object sender, EventArgs e) 
    { 
     this.SetStyle(ControlStyles.UserPaint, true); 
     this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); 
     this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); 


     //this.SetStyle(ControlStyles.UserPaint, true); 
     //this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); 
     //this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); 


     this.DoubleBuffered = true; 

     Rect1LT.Width = 10; 
     Rect1LT.Height = 10; 
     Rect1L.Width = 10; 
     Rect1L.Height = 10; 
     Rect1RT.Width = 10; 
     Rect1RT.Height = 10; 
     Rect1B.Width = 10; 
     Rect1B.Height = 10; 
     Rect1RB.Width = 10; 
     Rect1RB.Height = 10; 
     Rect1R.Width = 10; 
     Rect1R.Height = 10; 
     Rect1LB.Width = 10; 
     Rect1LB.Height = 10; 
     Rect1T.Width = 10; 
     Rect1T.Height = 10; 

     Rect1.X = panel1.Location.X + 50; 
     Rect1.Y = panel1.Location.Y + 50; 
     Rect1.Width = 100; 
     Rect1.Height = 100; 

     Rect1LT.X = Rect1.X - 5; 
     Rect1LT.Y = Rect1.Y - 5; 

     Rect1RT.X = Rect1.X - 5 + Rect1.Width; 
     Rect1RT.Y = Rect1.Y - 5; 

     Rect1LB.X = Rect1.X - 5; 
     Rect1LB.Y = Rect1.Y - 5 + Rect1.Height; 

     Rect1RB.X = Rect1.X - 5 + Rect1.Width; 
     Rect1RB.Y = Rect1.Y - 5 + Rect1.Height; 

     Rect1T.X = Rect1.X - 5 + (Rect1.Width/2); 
     Rect1T.Y = Rect1.Y - 5; 

     Rect1B.X = Rect1.X - 5 + (Rect1.Width/2); 
     Rect1B.Y = Rect1.Y - 5 + Rect1.Height; 

     Rect1L.X = Rect1.X - 5; 
     Rect1L.Y = Rect1.Y - 5 + (Rect1.Height/2); 

     Rect1R.X = Rect1.X - 5 + Rect1.Width; 
     Rect1R.Y = Rect1.Y - 5 + (Rect1.Height/2); 



    } 

    private void panel1_Paint(object sender, PaintEventArgs e) 
    { 


    Pen mypen = default(Pen); 
    mypen = new Pen(System.Drawing.Color.Red, 3); 
    mypen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash; 
    //For Dash Line in Rectangle 
    Pen mypen1 = default(Pen); 
    mypen1 = new Pen(System.Drawing.Color.Blue, 1); 
    mypen1.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash; 

    L1 = Rect1LT.X + 5; 
    T1 = Rect1LT.Y + 5; 
    W1 = Rect1RB.X - Rect1LT.X; 
    H1 = Rect1RB.Y - Rect1LT.Y; 
    e.Graphics.DrawRectangle(mypen, new System.Drawing.Rectangle(L1, T1, W1, H1)); 
    e.Graphics.DrawRectangle(mypen1, new System.Drawing.Rectangle(L1, T1, W1, H1)); 

    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1LT.X, Rect1LT.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1RT.X, Rect1RT.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1LB.X, Rect1LB.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1RB.X, Rect1RB.Y, 10, 10)); 

    e.Graphics.FillRectangle(Brushes.Blue, Rect1LT); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1RT); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1LB); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1RB); 

    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1T.X, Rect1T.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1R.X, Rect1R.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1B.X, Rect1B.Y, 10, 10)); 
    e.Graphics.DrawRectangle(Pens.Blue, new System.Drawing.Rectangle(Rect1L.X, Rect1L.Y, 10, 10)); 

    e.Graphics.FillRectangle(Brushes.Blue, Rect1T); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1R); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1B); 
    e.Graphics.FillRectangle(Brushes.Blue, Rect1L); 


} 

int L1; 
int T1; 
int W1; 
int H1; 
bool flg1_LT = false; 
bool flg1_RT = false; 
bool flg1_LB = false; 
bool flg1_RB = false; 
bool flg1_mid = false; 
bool flg1_T = false; 
bool flg1_B = false; 
bool flg1_L = false; 

bool flg1_R = false; 
public System.Drawing.Rectangle Rect1; 
public System.Drawing.Rectangle Rect1LT; 
public System.Drawing.Rectangle Rect1RT; 
public System.Drawing.Rectangle Rect1LB; 
public System.Drawing.Rectangle Rect1RB; 
public System.Drawing.Rectangle Rect1T; 
public System.Drawing.Rectangle Rect1B; 
public System.Drawing.Rectangle Rect1L; 

public System.Drawing.Rectangle Rect1R; 
public Point Point1LT; 
public Point Point1RT; 
public Point Point1LB; 
public Point Point1RB; 
public Point Point1L; 
public Point Point1T; 
public Point Point1R; 

public Point Point1B; 

private void panel1_MouseDown(object sender, MouseEventArgs e) 
{ 
    if (e.Location.X >= Rect1LT.X & e.Location.Y >= Rect1LT.Y & e.Location.X <= (Rect1LT.X + 10) & e.Location.Y <= (Rect1LT.Y + 10)) 
    { 
     flg1_LT = true; 
    } 
    else if (e.Location.X >= Rect1RT.X & e.Location.Y >= Rect1RT.Y & e.Location.X <= (Rect1RT.X + 10) & e.Location.Y <= (Rect1RT.Y + 10)) 
    { 
     flg1_RT = true; 
    } 
    else if (e.Location.X >= Rect1LB.X & e.Location.Y >= Rect1LB.Y & e.Location.X <= (Rect1LB.X + 10) & e.Location.Y <= (Rect1LB.Y + 10)) 
    { 
     flg1_LB = true; 
    } 
    else if (e.Location.X >= Rect1RB.X & e.Location.Y >= Rect1RB.Y & e.Location.X <= (Rect1RB.X + 10) & e.Location.Y <= (Rect1RB.Y + 10)) 
    { 
     flg1_RB = true; 
    } 
    else if (e.Location.X >= Rect1B.X & e.Location.Y >= Rect1B.Y & e.Location.X <= (Rect1B.X + 10) & e.Location.Y <= (Rect1B.Y + 10)) 
    { 
     flg1_B = true; 
    } 
    else if (e.Location.X >= Rect1R.X & e.Location.Y >= Rect1R.Y & e.Location.X <= (Rect1R.X + 10) & e.Location.Y <= (Rect1R.Y + 10)) 
    { 
     flg1_R = true; 
    } 
    else if (e.Location.X >= Rect1T.X & e.Location.Y >= Rect1T.Y & e.Location.X <= (Rect1T.X + 10) & e.Location.Y <= (Rect1T.Y + 10)) 
    { 
     flg1_T = true; 
    } 
    else if (e.Location.X >= Rect1L.X & e.Location.Y >= Rect1L.Y & e.Location.X <= (Rect1L.X + 10) & e.Location.Y <= (Rect1L.Y + 10)) 
    { 
     flg1_L = true; 
    } 
    else if (e.Location.X >= (Rect1LT.X + 10) & e.Location.Y >= (Rect1LT.Y + 10) & e.Location.X <= (Rect1RB.X + 10) & e.Location.Y <= (Rect1RB.Y + 10)) 
    { 
     flg1_mid = true; 

     temp1X = e.Location.X; 
     temp1Y = e.Location.Y; 

     Point1L.X = Rect1L.X; 
     Point1T.X = Rect1T.X; 
     Point1B.X = Rect1B.X; 
     Point1R.X = Rect1R.X; 
     Point1L.Y = Rect1L.Y; 
     Point1T.Y = Rect1T.Y; 
     Point1B.Y = Rect1B.Y; 
     Point1R.Y = Rect1R.Y; 
     Point1LT.X = Rect1LT.X; 
     Point1LB.X = Rect1LB.X; 
     Point1RT.X = Rect1RT.X; 
     Point1RB.X = Rect1RB.X; 
     Point1LT.Y = Rect1LT.Y; 
     Point1LB.Y = Rect1LB.Y; 
     Point1RT.Y = Rect1RT.Y; 
     Point1RB.Y = Rect1RB.Y; 

     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeAll; 
} 


} 
int temp1X; 
int temp1Y; 
private void panel1_MouseMove(object sender, MouseEventArgs e) 
{ 
    System.Drawing.Rectangle Rect_TEMP1 = default(System.Drawing.Rectangle); 
    System.Drawing.Rectangle Rect_TEMP2 = default(System.Drawing.Rectangle); 
    System.Drawing.Rectangle Rect_TEMP3 = default(System.Drawing.Rectangle); 
    System.Drawing.Rectangle Rect_TEMP4 = default(System.Drawing.Rectangle); 
    System.Drawing.Rectangle Rect_TEMP5 = default(System.Drawing.Rectangle); 
    System.Drawing.Rectangle Rect_TEMP6 = default(System.Drawing.Rectangle); 

    if (e.Button == MouseButtons.Left) 
    { 
     Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
     Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
     Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
     Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 


     if (flg1_LT) 
     { 
      if (e.Location.X > Rect1LT.X) 
      { 
       Rect1LT.X = e.Location.X; 
       Rect1LB.X = e.Location.X; 
       Rect1L.X = e.Location.X; 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y > Rect1LT.Y) 
      { 
       Rect1LT.Y = e.Location.Y; 
       Rect1RT.Y = e.Location.Y; 
       Rect1T.Y = e.Location.Y; 
       Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 
      if (e.Location.X < Rect1LT.X) 
      { 
       Rect1LT.X = e.Location.X; 
       Rect1LB.X = e.Location.X; 
       Rect1L.X = e.Location.X; 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y < Rect1LT.Y) 
      { 
       Rect1LT.Y = e.Location.Y; 
       Rect1RT.Y = e.Location.Y; 
       Rect1T.Y = e.Location.Y; 
       Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 



     } 
     else if (flg1_RT) 
     { 
      if (e.Location.X > Rect1RT.X) 
      { 
       Rect1RT.X = e.Location.X; 
       Rect1RB.X = e.Location.X; 
       Rect1R.X = e.Location.X; 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y > Rect1RT.Y) 
      { 
       Rect1RT.Y = e.Location.Y; 
       Rect1LT.Y = e.Location.Y; 
       Rect1T.Y = e.Location.Y; 
       Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 
      if (e.Location.X < Rect1RT.X) 
      { 
       Rect1RT.X = e.Location.X; 
       Rect1RB.X = e.Location.X; 
       Rect1R.X = e.Location.X; 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y < Rect1RT.Y) 
      { 
       Rect1RT.Y = e.Location.Y; 
       Rect1LT.Y = e.Location.Y; 
       Rect1T.Y = e.Location.Y; 
       Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 


     } 
     else if (flg1_LB) 
     { 
      if (e.Location.X > Rect1LB.X) 
      { 
       Rect1LB.X = e.Location.X; 
       Rect1LT.X = e.Location.X; 
       Rect1L.X = e.Location.X; 
       Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y > Rect1LB.Y) 
      { 
       Rect1LB.Y = e.Location.Y; 
       Rect1RB.Y = e.Location.Y; 
       Rect1B.Y = e.Location.Y; 
       Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 
      if (e.Location.X < Rect1LB.X) 
      { 
       Rect1LB.X = e.Location.X; 
       Rect1LT.X = e.Location.X; 
       Rect1L.X = e.Location.X; 
       Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y < Rect1LB.Y) 
      { 
       Rect1LB.Y = e.Location.Y; 
       Rect1RB.Y = e.Location.Y; 
       Rect1B.Y = e.Location.Y; 
       Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 


     } 
     else if (flg1_RB) 
     { 
      if (e.Location.X > Rect1RB.X) 
      { 
       Rect1RB.X = e.Location.X; 
       Rect1RT.X = e.Location.X; 
       Rect1R.X = e.Location.X; 
       Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y > Rect1RB.Y) 
      { 
       Rect1RB.Y = e.Location.Y; 
       Rect1LB.Y = e.Location.Y; 
       Rect1B.Y = e.Location.Y; 
       Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 
      if (e.Location.X < (Rect1RB.X + 10)) 
      { 
       Rect1RB.X = e.Location.X; 
       Rect1RT.X = e.Location.X; 
       Rect1R.X = e.Location.X; 
       Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 
       Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
      } 
      if (e.Location.Y < (Rect1RB.Y + 10)) 
      { 
       Rect1RB.Y = e.Location.Y; 
       Rect1LB.Y = e.Location.Y; 
       Rect1B.Y = e.Location.Y; 
       Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
      } 


     } 
     else if (flg1_B) 
     { 
      if (e.Location.Y > Rect1B.Y) 
      { 
       Rect1B.Y = e.Location.Y; 
       Rect1LB.Y = e.Location.Y; 
       Rect1RB.Y = e.Location.Y; 
      } 
      if (e.Location.Y < (Rect1B.Y + 10)) 
      { 
       Rect1B.Y = e.Location.Y; 
       Rect1LB.Y = e.Location.Y; 
       Rect1RB.Y = e.Location.Y; 
      } 


     } 
     else if (flg1_T) 
     { 
      if (e.Location.Y > Rect1T.Y) 
      { 
       Rect1T.Y = e.Location.Y; 
       Rect1LT.Y = e.Location.Y; 
       Rect1RT.Y = e.Location.Y; 
      } 

      if (e.Location.Y < (Rect1T.Y + 10)) 
      { 
       Rect1T.Y = e.Location.Y; 
       Rect1LT.Y = e.Location.Y; 
       Rect1RT.Y = e.Location.Y; 
      } 


     } 
     else if (flg1_R) 
     { 
      if (e.Location.X > Rect1R.X) 
      { 
       Rect1R.X = e.Location.X; 
       Rect1RT.X = e.Location.X; 
       Rect1RB.X = e.Location.X; 
      } 

      if (e.Location.X < (Rect1R.X + 10)) 
      { 
       Rect1R.X = e.Location.X; 
       Rect1RT.X = e.Location.X; 
       Rect1RB.X = e.Location.X; 
      } 


     } 
     else if (flg1_L) 
     { 
      if (e.Location.X > Rect1L.X) 
      { 
       Rect1L.X = e.Location.X; 
       Rect1LT.X = e.Location.X; 
       Rect1LB.X = e.Location.X; 
      } 

      if (e.Location.X < (Rect1L.X + 10)) 
      { 
       Rect1L.X = e.Location.X; 
       Rect1LT.X = e.Location.X; 
       Rect1LB.X = e.Location.X; 
      } 


     } 
     else if (flg1_mid) 
     { 
      Rect1LT.X = Point1LT.X + (e.Location.X - temp1X); 
      Rect1RT.X = Point1RT.X + (e.Location.X - temp1X); 
      Rect1LB.X = Point1LB.X + (e.Location.X - temp1X); 
      Rect1RB.X = Point1RB.X + (e.Location.X - temp1X); 
      Rect1LT.Y = Point1LT.Y + (e.Location.Y - temp1Y); 
      Rect1RT.Y = Point1RT.Y + (e.Location.Y - temp1Y); 
      Rect1LB.Y = Point1LB.Y + (e.Location.Y - temp1Y); 
      Rect1RB.Y = Point1RB.Y + (e.Location.Y - temp1Y); 
      Rect1L.X = Point1L.X + (e.Location.X - temp1X); 
      Rect1R.X = Point1R.X + (e.Location.X - temp1X); 
      Rect1B.X = Point1B.X + (e.Location.X - temp1X); 
      Rect1T.X = Point1T.X + (e.Location.X - temp1X); 
      Rect1L.Y = Point1L.Y + (e.Location.Y - temp1Y); 
      Rect1R.Y = Point1R.Y + (e.Location.Y - temp1Y); 
      Rect1B.Y = Point1B.Y + (e.Location.Y - temp1Y); 
      Rect1T.Y = Point1T.Y + (e.Location.Y - temp1Y); 

     } 

     Rect1T.X = ((Rect1LT.X + Rect1RB.X)/2); 
     Rect1L.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
     Rect1R.Y = (Rect1LT.Y + Rect1LB.Y)/2; 
     Rect1B.X = ((Rect1LT.X + Rect1RB.X)/2); 

     if (Rect1LT.X > Rect1RT.X) 
     { 
      Rect_TEMP1 = Rect1RT; 
      Rect_TEMP2 = Rect1R; 
      Rect_TEMP3 = Rect1RB; 
      Rect1RT = Rect1LT; 
      Rect1R = Rect1L; 
      Rect1RB = Rect1LB; 
      Rect1LT = Rect_TEMP1; 
      Rect1L = Rect_TEMP2; 
      Rect1LB = Rect_TEMP3; 

     } 
     if (Rect1LT.Y > Rect1LB.Y) 
     { 
      Rect_TEMP4 = Rect1LB; 
      Rect_TEMP5 = Rect1B; 
      Rect_TEMP6 = Rect1RB; 
      Rect1LB = Rect1LT; 
      Rect1B = Rect1T; 
      Rect1RB = Rect1RT; 
      Rect1LT = Rect_TEMP4; 
      Rect1T = Rect_TEMP5; 
      Rect1RT = Rect_TEMP6; 
     } 
     this.DoubleBuffered= true; 
     this.SetStyle(ControlStyles.UserPaint | 
     ControlStyles.AllPaintingInWmPaint | 
     ControlStyles.ResizeRedraw | 
     ControlStyles.ContainerControl | 
     ControlStyles.OptimizedDoubleBuffer | 
     ControlStyles.SupportsTransparentBackColor 
     , true); 

     panel1.Invalidate(); 
     //public void Invalidate(Rectangle); 
     //panel1.Update(); 
     //panel1.Refresh(); 
     //panel1.Invalidate(Rect1T); 
     //invalidateRect(Rect_TEMP1); 
     //panel1.Invalidate(Rect_TEMP1); 
     //panel1.Invalidate(Rect_TEMP2); 
     //panel1.Invalidate(Rect_TEMP3); 
     //panel1.Invalidate(Rect_TEMP4); 
     //panel1.Invalidate(Rect_TEMP5); 
     //panel1.Invalidate(Rect_TEMP6); 
     //panel1.Invalidate(Rect1); 
     //panel1.Invalidate(Rect1B); 
     //Invalidate(Rect1L, true); 
     //Invalidate(Rect_TEMP1,true); 

     //panel1.Invalidate(Rect1LB); 
     //panel1.Invalidate(Rect1LT); 
     //panel1.Invalidate(Rect1R); 
     //panel1.Invalidate(Rect1RB); 
     //panel1.Invalidate(Rect1T); 
     //panel1.Invalidate(Rect1RT); 

     //panel1.Invalidate(Rect); 
    } 

    if (e.Location.X >= Rect1LT.X & e.Location.Y >= Rect1LT.Y & e.Location.X <= (Rect1LT.X + 10) & e.Location.Y <= (Rect1LT.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNWSE; 
    } 
    else if (e.Location.X >= Rect1RT.X & e.Location.Y >= Rect1RT.Y & e.Location.X <= (Rect1RT.X + 10) & e.Location.Y <= (Rect1RT.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNESW; 
    } 
    else if (e.Location.X >= Rect1LB.X & e.Location.Y >= Rect1LB.Y & e.Location.X <= (Rect1LB.X + 10) & e.Location.Y <= (Rect1LB.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNESW; 
    } 
    else if (e.Location.X >= Rect1RB.X & e.Location.Y >= Rect1RB.Y & e.Location.X <= (Rect1RB.X + 10) & e.Location.Y <= (Rect1RB.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNWSE; 
    } 
    else if (e.Location.X >= Rect1B.X & e.Location.Y >= Rect1B.Y & e.Location.X <= (Rect1B.X + 10) & e.Location.Y <= (Rect1B.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNS; 
    } 
    else if (e.Location.X >= Rect1R.X & e.Location.Y >= Rect1R.Y & e.Location.X <= (Rect1R.X + 10) & e.Location.Y <= (Rect1R.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeWE; 
    } 
    else if (e.Location.X >= Rect1T.X & e.Location.Y >= Rect1T.Y & e.Location.X <= (Rect1T.X + 10) & e.Location.Y <= (Rect1T.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeNS; 
    } 
    else if (e.Location.X >= Rect1L.X & e.Location.Y >= Rect1L.Y & e.Location.X <= (Rect1L.X + 10) & e.Location.Y <= (Rect1L.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeWE; 
    } 
    else if (e.Location.X >= (Rect1LT.X + 10) & e.Location.Y >= (Rect1LT.Y + 10) & e.Location.X <= (Rect1RB.X + 10) & e.Location.Y <= (Rect1RB.Y + 10)) 
    { 
     this.panel1.Cursor = System.Windows.Forms.Cursors.SizeAll; 
    } 
} 

    private void panel1_MouseUp(object sender, MouseEventArgs e) 
    { 
     flg1_LB = false; 
     flg1_LT = false; 
     flg1_RB = false; 
     flg1_RT = false; 
     temp1X = 0; 
     temp1Y = 0; 
     flg1_B = false; 
     flg1_L = false; 
     flg1_R = false; 
     flg1_T = false; 
     flg1_mid = false; 
    } 
}

如上所示我繪製矩形，它會導致面板上閃爍？我也設置雙緩衝屬性爲true，但仍然是零。我在面板中設置背景圖像，圖像屬性設置爲拉伸，如果圖像屬性是平鋪，它不閃爍。我應該做什麼改變以避免閃爍。如何避免閃爍使用繪畫方法在面板上繪製矩形？

來源

2014-12-02 Keyur Patel

我沒有仔細看過你的場景，但在構造函數中的SetStyle（）調用之後嘗試調用'UpdateStyles（）;'。 – 2014-12-02 16:26:10

我嘗試過，但仍然閃爍。 – 2014-12-03 04:34:34

設置DoubleBuffered屬性不是防止閃爍的魔法。該屬性只允許一次渲染繪製的曲面，而不是直接渲染漸變，您首先將所有圖形繪製到緩衝區中。然後將其交換到要繪製的有效表面。這對你來說是透明的，但這僅僅是一件事。

如果你仍然有閃爍，你可能會錯誤地訪問你正在繪製的表面。
有在您的程序驅動的圖形操作的方式主要有兩種：

活動消息隊列
遊戲循環

的事件消息隊列當圖形是主要用於在由用戶或系統觸發的動作時更新。點擊鼠標，系統通知，按下鍵盤按鍵，... 這是事件驅動的，等待新事件是阻止操作。因此，在處理cpu的每個事件之間可能有足夠的時間執行其他操作。這就是說，如果事件速度低於繪製到曲面所需的時間，則可以執行一些圖形操作，而不會出現太多的性能命中（因此閃爍）。

while (!exit) 
{ 
    var msg = WaitForMessage(); // Blocks until message arrives 
    switch (msg.Type) 
    { 
     case Message.MouseMove: OnMouseMove(msg); break; 
     case Message.Paint: OnPaint(msg); break; 
     ... 
    } 
}

來源：opentk

的遊戲循環是一個更好的方法，當你需要不斷地畫上的圖形表面和/或圖形無需用戶交互進行更新。

while (!exit) 
{ 
    var time = GetTime(); 
    Update(time); 
    Render(time); 
}

來源：opentk

用這種方法執行非阻塞操作，因此必須處理空閒CPU時間，其他應用程序或你會被消耗的CPU時間的100％。這是FPS控制的基礎。

您的代碼正在使用第一種方法，因爲在每次鼠標移動事件後，您都會使繪製的曲面無效並請求圖形更新。

這不是一個好方法，因爲與執行繪圖所用的時間相比，鼠標移動事件可能會更快。這可能會降低UI的響應速度。

你可以考慮以下幾點工作：

減少您的圖形更新所需的時間：
- 避免在你的繪製操作堆新對象的實例化系統。嘗試重新使用固定實例。設置一次使用的樣式和顏色。沒有必要一遍又一遍地重複它。
打破了鼠標移動和圖形失效之間的聯繫：
- 嘗試創建一個遊戲循環，你的來電無效將在衆所周知率獨立的鼠標移動事件來進行。這將使您能夠控制FPS。
的Invalidate只需要採取什麼無效：
- 您可以通過重繪只需要執行何種獲得性能。
  使方法無效，接受描述將在繪畫方法上重繪的區域的矩形。這將避免總是重繪不變的像素。

所有這些行動將提高性能和減少閃爍的效果。

來源

2014-12-04 11:33:11

如何避免閃爍使用繪畫方法在面板上繪製矩形？

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