Flickering drawing on image / slight trail also..

Hi all, I have also just started playing with GDI+. I wrote a little mini-app that rotates some rectangles. The problem is that the screen flickers quite badly during the app. My collegaue suggested that is might be possible to buffer the graphics and then copy them over in the (overridden) OnPaint method of the form. However I cannot find any information on how this is done. Does anyone out there know how to optimise my little app? I don't really want to move on to more advanced topics until I can stop the screen flickering. using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Drawing2D; namespace RotatingSquare { #region Generated Code public class Form1 : System.Windows.Forms.Form { private System.ComponentModel.IContainer components; ///

Constructor

public Form1() { InitializeComponent(); } ///

Clean up any resources being used.

protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } #region Windows Form Designer generated code ///

/// Required method for Designer support - do not modify /// the contents of this method with the code editor. ///

private void InitializeComponent() { this.components = new System.ComponentModel.Container(); this.timer1 = new System.Windows.Forms.Timer(this.components); this.button1 = new System.Windows.Forms.Button(); this.button2 = new System.Windows.Forms.Button(); this.button3 = new System.Windows.Forms.Button(); this.button4 = new System.Windows.Forms.Button(); this.button5 = new System.Windows.Forms.Button(); this.button6 = new System.Windows.Forms.Button(); this.lblX = new System.Windows.Forms.Label(); this.lblY = new System.Windows.Forms.Label(); this.lblZ = new System.Windows.Forms.Label(); this.SuspendLayout(); // // timer1 // this.timer1.Enabled = true; this.timer1.Tick += new System.EventHandler(this.timer1_Tick); // // button1 // this.button1.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button1.ForeColor = System.Drawing.Color.Yellow; this.button1.Location = new System.Drawing.Point(114, 344); this.button1.Name = "button1"; this.button1.Size = new System.Drawing.Size(72, 23); this.button1.TabIndex = 0; this.button1.Text = "Y UP"; this.button1.Click += new System.EventHandler(this.button1_Click); // // button2 // this.button2.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button2.ForeColor = System.Drawing.Color.Yellow; this.button2.Location = new System.Drawing.Point(114, 376); this.button2.Name = "button2"; this.button2.Size = new System.Drawing.Size(72, 23); this.button2.TabIndex = 1; this.button2.Text = "Y DOWN"; this.button2.Click += new System.EventHandler(this.button2_Click); // // button3 // this.button3.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button3.ForeColor = System.Drawing.Color.Yellow; this.button3.Location = new System.Drawing.Point(26, 376); this.button3.Name = "button3"; this.button3.Size = new System.Drawing.Size(72, 23); this.button3.TabIndex = 3; this.button3.Text = "X DOWN"; this.button3.Click += new System.EventHandler(this.button3_Click); // // button4 // this.button4.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button4.ForeColor = System.Drawing.Color.Yellow; this.button4.Location = new System.Drawing.Point(26, 344); this.button4.Name = "button4"; this.button4.Size = new System.Drawing.Size(72, 23); this.button4.TabIndex = 2; this.button4.Text = "X UP"; this.button4.Click += new System.EventHandler(this.button4_Click); // // button5 // this.button5.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button5.ForeColor = System.Drawing.Color.Yellow; this.button5.Location = new System.Drawing.Point(202, 376); this.button5.Name = "button5"; this.button5.Size = new System.Drawing.Size(72, 23); this.button5.TabIndex = 5; this.button5.Text = "Z DOWN"; this.button5.Click += new System.EventHandler(this.button5_Click); // // button6 // this.button6.FlatStyle = System.Windows.Forms.FlatStyle.Flat; this.button6.ForeColor = System.Drawing.Color.Yellow; this.button6.Location = new System.Drawing.Point(202, 344); this.button6.Name = "button6"; this.button6.Size = new System.Drawing.Size(72, 23); this.button6.TabIndex = 4; this.button6.Text = "Z UP"; this.button6.Click += new System.EventHandler(this.button6_Click); // // lblX // this.lblX.Location = new System.Drawing.Point(30, 312); this.lblX.Name = "lblX"; this.lblX.Size = new System.Drawing.Size(64, 23); this.lblX.TabIndex = 6; this.lblX.TextAlign = System.Drawing.ContentAlignment.MiddleCenter; // // lblY // this.lblY.Location = new System.Drawing.Point(118, 312); this.lblY.Name = "lblY"; this.lblY.Size = new System.Drawing.Size(64, 23); this.lblY.TabIndex = 7; this.lblY.TextAlign = System.Drawing.ContentAlignment.MiddleCenter; // // lblZ // this.lblZ.Location = new System.Drawing.Point(206, 312); this.lblZ.Name = "lblZ"; this.lblZ.Size = new System.Drawing.Size(64, 23); this.lblZ.TabIndex = 8; this.lblZ.TextAlign = System.Drawing.ContentAlignment.MiddleCenter; // // Form1 // this.AutoScaleBaseSize = new System.Drawing.Size(5, 13); this.BackColor = System.Drawing.Color.Black; this.ClientSize = new System.Drawing.Size(300, 409); this.Controls.Add(this.lblZ); this.Controls.Add(this.lblY); this.Controls.Add(this.lblX); this.Controls.Add(this.button5); this.Controls.Add(this.button6); this.Controls.Add(this.button3); this.Controls.Add(this.button4); this.Controls.Add(this.button2); this.Controls.Add(this.button1); this.ForeColor = System.Drawing.Color.Yellow; this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Fixed3D; this.MaximizeBox = false; this.Name = "Form1"; this.Text = "Rotating Squares"; this.Load += new System.EventHandler(this.Form1_Load); this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint); this.ResumeLayout(false); } #endregion private System.Windows.Forms.Timer timer1; private System.Windows.Forms.Button button1; private System.Windows.Forms.Button button2; private System.Windows.Forms.Button button3; private System.Windows.Forms.Button button4; private System.Windows.Forms.Button button5; private System.Windows.Forms.Button button6; private System.Windows.Forms.Label lblX; private System.Windows.Forms.Label lblY; private System.Windows.Forms.Label lblZ; #endregion private float fAngleX = 0; // angle at which to rotate the largest square private float fAngleY = 0; // angle at which to rotate the largest square private float fAngleZ = 0; // angle at which to rotate the largest square private int intX = 0; // value by which fAngleX is incremented on each timer tick private int intY = 0; // value by which fAngleY is incremented on each timer tick private int intZ = 0; // value by which fAngleZ is incremented on each timer tick private Pen ThisPen; private SolidBrush ThisBrush; private Rectangle ThisSmallRec; private Rectangle ThisMediumRec; private Rectangle ThisLargeRec; private GraphicsPath gpX; private GraphicsPath gpY; private GraphicsPath gpZ; private Matrix MatrixX; private Matrix MatrixY; private Matrix MatrixZ; ///

The main entry point for the application.

[STAThread] static void Main() { Application.Run(new Form1()); } ///

Form initialisation.

/// Sending object i.e. Form1. /// Event arguments. private void Form1_Load(object sender, System.EventArgs e) { // create a new pen and brush ThisPen = new Pen(Color.Red, 1); ThisBrush = new SolidBrush(Color.Yellow); // create the three rectangles ThisLargeRec = new Rectangle(50, 50, 200, 200); ThisMediumRec = new Rectangle(75, 100, 150, 100); ThisSmallRec = new Rectangle(110, 125, 80, 50); // label text RefreshForm(); } ///

Sets the text of the labels.

private void RefreshForm() { lblX.Text = intX.ToString(); lblY.Text = intY.ToString(); lblZ.Text = intZ.ToString(); timer1.Enabled = CheckInts(); } ///

Draws the form.

/// Sending object i.e. Form1. /// Event arguments. private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e) { // get the graphics from the event args Graphics g = e.Graphics; // create three graphics paths gpX = new GraphicsPath(); gpY = new GraphicsPath(); gpZ = new GraphicsPath(); // create three matrices MatrixX = new Matrix(); MatrixY = new Matrix(); MatrixZ = new Matrix(); // set the matrices to rotate MatrixX.RotateAt(fAngleX, new Point(150, 150)); MatrixY.RotateAt(fAngleY, new Point(150, 150)); MatrixZ.RotateAt(fAngleZ, new Point(150, 150)); // add the three rectangles to the graphics paths gpX.AddRectangle(ThisLargeRec); gpY.AddRectangle(ThisMediumRec); gpZ.AddRectangle(ThisSmallRec); // apply the matrices to the graphics paths gpX.Transform(MatrixX); gpY.Transform(MatrixY); gpZ.Transform(MatrixZ); // draw the path to the graphics object g.DrawPath(ThisPen, gpX); g.DrawPath(ThisPen, gpY); g.DrawPath(ThisPen, gpZ); // increment the rotation angles fAngleX+=intX; fAngleY+=intY; fAngleZ+=intZ; } private void timer1_Tick(object sender, System.EventArgs e) { Invalidate(); } private void button4_Click(object sender, System.EventArgs e) { intX+=5; RefreshForm(); } private void button3_Click(object sender, System.EventArgs e) { intX-=5; RefreshForm(); } private void button1_Click(object sender, System.EventArgs e) { intY+=5; RefreshForm(); } private void button2_Click(object sender, System.EventArgs e) { intY-=5; RefreshForm(); } private void button6_Click(object sender, System.EventArgs e) { intZ+=5; RefreshForm(); } private void button5_Click(object sender, System.EventArgs e) { intZ-=5; RefreshForm(); } private bool CheckInts() { if((intX != 0) || (intY != 0) || (intZ != 0)) return true; else return false; } }