Why do my graphics still flicker?

[adonisv]

Why won't this double buffer? :sigh: I'm drawing this graph that allows you to either move value sliders or input values and redraw the graph. I've looked at tons of double buffering examples and they all seem to be doing the same or similar type of code. But my graph still flickers. BAH! :(( [code]public void DrawGraph() { this.UpdateGraphVariables(); Point[] pointarray=new Point[5]; Pen newpen = new Pen(Color.Black); this.m_bmImageOffScreen = new Bitmap(this.Width, this.Height); this.m_gOffScreen = Graphics.FromImage(this.m_bmImageOffScreen); this.m_gBuffer=Graphics.FromHwnd(this.Handle); //computational stuff //not interesting I do all my drawing on the bitmap... //Set point of origin to be 50,50 on the form this.m_gOffScreen.TranslateTransform(50,130); this.m_gOffScreen.DrawLine(newpen,1,1,1,150); this.m_gOffScreen.DrawLine(newpen,1,150,150,150); //Draw X and y axis this.m_gOffScreen.DrawLine(newpen,-3,30,3,30); this.m_gOffScreen.DrawLine(newpen,-3,60,3,60); this.m_gOffScreen.DrawLine(newpen,-3,90,3,90); ... //Join the points pointarray[0]=new Point(30,Convert.ToInt32(a)); pointarray[1]=new Point(60,Convert.ToInt32(b)); pointarray[2]=new Point(90,Convert.ToInt32(c)); pointarray[3]=new Point(120,Convert.ToInt32(d)); pointarray[4]=new Point(150,Convert.ToInt32(f)); this.m_gOffScreen.DrawLines(new Pen(Color.Yellow),pointarray); Then I attempt to double buffer! :doh: if (this.m_bmOldBitmap != null) { this.m_bmOldBitmap.Dispose(); } this.m_bmOldBitmap = this.m_bmImageOffScreen; this.m_gBuffer.Clear(this.BackColor); this.m_gBuffer.DrawImage(this.m_bmOldBitmap,30,50); }[/code] It still flickers! X|

[Roman Rodov]

In InitializeComponent put SetStyle(ControlStyles.DoubleBuffer);

[adonisv]

I've got that! SetStyle(ControlStyles.UserPaint, true); SetStyle(ControlStyles.DoubleBuffer, true);

[blackthunder001]

Have you enabled double buffering in your form? Do this in your initialisation (I put it in my Form constructor after the IntializeComonent() call. this.SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true); this.UpdateStyles();

[adonisv]

Nope, that didn't help. :sigh:

[Heath Stewart]

You also need ControlStyles.AllPaintingInWmPaint, which is documented in the ControlStyles enumeration documentation. Also, that enum is attributed with the FlagsAttribute, which means you can save your code some time and just use:

SetStyle(ControlStyles.AllPaintingInWmPaint |
ControlStyles.DoubleBuffer | ControlStyles.UserPaint, true);

This gets compiled as a constant value so SetStyle is only called once.

Microsoft MVP, Visual C# My Articles

[Anonymous]

How do you call your DrawGraph( ) function?

[adonisv]

Do I do one or the other or do I set the styles AND do the manual double buffering witht the bitmaps and the two graphics objects?

[adonisv]

The DrawGraph() function is called from OnPaint() Invalidate is called every time the draw graph button is clicked or a track bar is moved changing one of the values in the graph. protected override void OnPaint(PaintEventArgs e) { if(this.m_bmImageOffScreen==null) this.m_bmImageOffScreen=new Bitmap(this.ClientSize.Width,this.ClientSize.Height); this.m_gOffScreen =Graphics.FromImage(this.m_bmImageOffScreen); //this.m_gBuffer.Clear(this.BackColor); if(this.m_bgraphDrawn) this.DrawGraph(); else { this.textBox1.Text = "0"; this.textBox2.Text = "0"; this.textBox3.Text = "0"; this.textBox4.Text = "0"; this.textBox5.Text = "0"; this.m_bgraphDrawn = true; this.DrawGraph(); } this.m_gOffScreen.Dispose(); e.Graphics.DrawImageUnscaled(this.m_bmImageOffScreen,30,50); } private void trackBar5_Scroll(object sender, System.EventArgs e) { // Display the trackbar value in the text box. textBox5.Text = "" + trackBar5.Value; value5 += trackBar1.Value; //this.redrawChart(); //this.DrawGraph(); Invalidate(); }