Csharp/C Sharp/2D Graphics/Blend

Blend Alpha

<source lang="csharp"> /* GDI+ Programming in C# and VB .NET by Nick Symmonds Publisher: Apress ISBN: 159059035X

• /

using System; using System.Drawing; using System.Drawing.Imaging; using System.Drawing.Drawing2D; using System.Collections; using System.ruponentModel; using System.Windows.Forms; using System.Data; namespace Blend_c {

   public class Blend : System.Windows.Forms.Form
   {
   private System.Windows.Forms.HScrollBar AlphaScroll;
   private System.Windows.Forms.HScrollBar GammaScroll;
   /// <summary>
       /// Required designer variable.
       /// </summary>
       private System.ruponentModel.Container components = null;
   private int AlphaFactor = 255;
   private float GammaFactor = 1.0f;
   private Rectangle R = new Rectangle(40, 20, 100, 100 );
   private Image I = Image.FromFile("Colorbars.jpg");
   private int ImWidth;
   private int ImHeight;
   private ImageAttributes Ia = new ImageAttributes();

       public Blend()
       {
           //
           // Required for Windows Form Designer support
           //
           InitializeComponent();
     AlphaScroll.Minimum = 20;
     AlphaScroll.Maximum = 245;
     AlphaScroll.SmallChange = 5;
     AlphaScroll.LargeChange = 5;
     AlphaScroll.Left = R.Left;
     AlphaScroll.Width = R.Width;
     AlphaScroll.Top = R.Bottom;
     GammaScroll.Minimum=1;
     GammaScroll.Maximum = 50;
     GammaScroll.SmallChange=1;
     GammaScroll.LargeChange=5;
     GammaScroll.Left = R.Left;
     GammaScroll.Top = R.Top - GammaScroll.Height;
     GammaScroll.Width = R.Width;
     ImWidth = I.Width;
     ImHeight = I.Height;
     AlphaScroll.Value = (AlphaScroll.Maximum-AlphaScroll.Minimum )/2;
     GammaScroll.Value = (GammaScroll.Maximum-GammaScroll.Minimum )/2;
     AlphaFactor = AlphaScroll.Value;
     GammaFactor = (float)GammaScroll.Value / 10;
   }
       protected override void Dispose( bool disposing )
       {
           if( disposing )
           {
               if (components != null) 
               {
                   components.Dispose();
               }
       if ( I != null )
         I.Dispose();
       if ( Ia != null )
         Ia.Dispose();
     }
           base.Dispose( disposing );
       }
       #region Windows Form Designer generated code
       /// <summary>
       /// Required method for Designer support - do not modify
       /// the contents of this method with the code editor.
       /// </summary>
       private void InitializeComponent()
       {
     this.AlphaScroll = new System.Windows.Forms.HScrollBar();
     this.GammaScroll = new System.Windows.Forms.HScrollBar();
     this.SuspendLayout();
     // 
     // AlphaScroll
     // 
     this.AlphaScroll.Location = new System.Drawing.Point(32, 128);
     this.AlphaScroll.Maximum = 255;
     this.AlphaScroll.Name = "AlphaScroll";
     this.AlphaScroll.Size = new System.Drawing.Size(160, 16);
     this.AlphaScroll.TabIndex = 1;
     this.AlphaScroll.Scroll += new System.Windows.Forms.ScrollEventHandler(this.AlphaScroll_Scroll);
     // 
     // GammaScroll
     // 
     this.GammaScroll.Location = new System.Drawing.Point(32, 8);
     this.GammaScroll.Name = "GammaScroll";
     this.GammaScroll.Size = new System.Drawing.Size(160, 16);
     this.GammaScroll.TabIndex = 2;
     this.GammaScroll.Scroll += new System.Windows.Forms.ScrollEventHandler(this.GammaScroll_Scroll);
     // 
     // Blend
     // 
     this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
     this.ClientSize = new System.Drawing.Size(292, 273);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                 this.GammaScroll,
                                                                 this.AlphaScroll});
     this.Name = "Blend";
     this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
     this.Text = "Blend";
     this.Load += new System.EventHandler(this.Blend_Load);
     this.ResumeLayout(false);
   }
       #endregion
       /// <summary>
       /// The main entry point for the application.
       /// </summary>
       [STAThread]
       static void Main() 
       {
           Application.Run(new Blend());
       }
   private void Blend_Load(object sender, System.EventArgs e)
   {
   }
   protected override void OnPaint(PaintEventArgs e)
   {
     AlphaBlend(e.Graphics);
     base.OnPaint(e);
   }
   private void AlphaBlend( Graphics G )
   {
     //AlphaFactor is variable depeneding upon scroll bars
     Pen P = new Pen( Color.FromArgb (AlphaFactor, 200, 0, 100 ), 20);
     Bitmap bmp = new Bitmap( 120, 120 );
     Graphics G2 = Graphics.FromImage(bmp);
     Brush B = new SolidBrush(Color.FromArgb( AlphaFactor, 50, 200, 50 ));
     try
     {
       // Set the brightness while rendering image
       Ia.SetGamma( GammaFactor );
       G.DrawImage(I, R, 0, 0, ImWidth, ImHeight, GraphicsUnit.Pixel, Ia);
       //Draw transparent line on top of image
       G.DrawLine(P, 10, 100, 200, 100 );
       // Draw inside the image contained in memory
       G2.FillEllipse( B, 0, 0, 75, 75 );
       G.DrawImage( I, new Rectangle(140, 140, 120, 120 ) );
       G.rupositingQuality = CompositingQuality.GammaCorrected;
       G.rupositingMode = CompositingMode.SourceOver;
       G.DrawImage( bmp, new Rectangle( 150, 150, 150, 150 ) );
     }
     finally
     {
       if (bmp != null )
         bmp.Dispose();
       if ( G2 != null )
         G2.Dispose();
       if ( B != null )
         B.Dispose();
       if ( P != null )
         P.Dispose();
     }
   }
   private void AlphaScroll_Scroll(object sender, 
                                   System.Windows.Forms.ScrollEventArgs e)
   {
     AlphaFactor = AlphaScroll.Value;
     this.Refresh();
   }
   private void GammaScroll_Scroll(object sender, 
                                   System.Windows.Forms.ScrollEventArgs e)
   {
     GammaFactor = (float)GammaScroll.Value / 10;
     this.Refresh();
   }
   }

}

      </source>

<A href="http://www.nfex.ru/Code/CSharpDownload/Blend-c.zip">Blend-c.zip( 5 k)</a>