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.NET LCD MatrixControl and GDI+

, 19 Jun 2004
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Implementation of a LCD User Control in .NET using C#.

Sample Image - LCDMatrixControl_screen.gif


Once, it was required for me, a control similar to LCD, for data presentation. Having looked in the Internet, I found a nice realization from Nic Wilson. But the code was written in C++, and my project was in C#. Therefore, I decided to rewrite Nic's code, and at the same time I wanted to estimate how quick GDI+ works in .NET.

Using the code

In your project, you need to refer to the library with our control, then you should place the control in design time in your project.

After you finish with design time, start initializing our control in the constructor.

public Form1()
  BkColor = Color.FromArgb(R,G,B);
  OnColor = Color.FromArgb(R,G,B);
  OffColor = Color.FromArgb(R,G,B);
  //Set up initial text.
  this.matrixControl1.ScreenText = " Info Text ";
  //In this case pad symbol is empty.
  matrixControl1.SetAutoPadding(true,' ');
  //If you want immeditely start scrolling, 
  //please uncomment next line.
  //    MatrixLib.MatrixControl.ScrollDirection.Left);

The main "magic" occurs in a method OnPaint.

protected override void OnPaint(PaintEventArgs pea) 
  Rectangle m_rect = this.DisplayRectangle;
  //Create buffer image
  Bitmap _buffImage = new Bitmap(m_rect.Width,m_rect.Height);
  Graphics _buff = Graphics.FromImage(_buffImage);
  int x = 0, y = 0;
  int strlen = m_StrText.Length;
  if (strlen == 0)
  //Create array of color maps
  System.Drawing.Imaging.ColorMap []_ColorMap = 
            new System.Drawing.Imaging.ColorMap[3];
  _ColorMap[0] = new System.Drawing.Imaging.ColorMap();
  _ColorMap[1] = new System.Drawing.Imaging.ColorMap();
  _ColorMap[2] = new System.Drawing.Imaging.ColorMap();
  _ColorMap[0].OldColor = SEGM_COLORS[0];
  _ColorMap[0].NewColor = m_crOnColor;
  _ColorMap[1].OldColor = SEGM_COLORS[1];
  _ColorMap[1].NewColor = m_OffColor;
  _ColorMap[2].OldColor = SEGM_COLORS[2];
  _ColorMap[2].NewColor = m_crBackColor;
  //Obtain image attributes
  System.Drawing.Imaging.ImageAttributes bmpAttr = 
          new System.Drawing.Imaging.ImageAttributes();
  catch(System.Exception ex)
  int charcount = 0;
  int linecount = 1;
  SolidBrush hbBkBrush = new SolidBrush(m_crBackColor);
  //Fill control rectangle 
  //Initialize two rectangeles
  Rectangle clipDstn = Rectangle.Empty;
  Rectangle clipSrc = Rectangle.Empty;

  //Now we will start main processing.
  for (int ix = 0; ix < strlen; ix++)
    //This method calculates clip region for current char.
    GetCharBmpOffset((char)m_StrText[ix], ref clipSrc);
    //Initializes target clip.
    clipDstn = new Rectangle(x,y,clipSrc.Width,clipSrc.Height);
    //Draw current symbol in buffer
    _buff.DrawImage(m_ImageMatrix, clipDstn, clipSrc.X, 
              clipSrc.Y, clipSrc.Width, clipSrc.Height, 
              GraphicsUnit.Pixel, bmpAttr);

    x += m_CharWidth + m_XSpacing;
    if ((charcount == m_MaxXChars) && m_MaxYChars == 1)
    else if ((charcount == m_MaxXChars) && m_MaxYChars > 1)
      if (linecount == m_MaxYChars)
      x = charcount = 0;
      y += m_CharHeight + m_YSpacing;
  //And finally draw our image on control surface.
  //Next lines are necessary...
  hbBkBrush= null;
  bmpAttr = null;
  _buff.Dispose();_buff = null;

  _buffImage.Dispose(); _buffImage = null;

Conclusion and current issues

The control works perfect, without flickering, but, if you will use the control without scrolling. If you will need scrolling, your application will consume 100% CPU!!!.

Probably, the following line causes the strong consumption of CPU time:


//Draw current symbol in buffer 
_buff.DrawImage(m_ImageMatrix, clipDstn, clipSrc.X, 
          clipSrc.Y, clipSrc.Width, clipSrc.Height, 
          GraphicsUnit.Pixel, bmpAttr);

It's really so... if you comment out this line, you will get 0% CPU usage.


For heavy operations, it is better to use native methods of API. You may try replacing this line with another one, and try using the API method:

private static extern bool BitBlt(
IntPtr hdcDest, // handle to destination DC
int nXDest, // x-coord of dest upper-left corner
int nYDest, // y-coord of dest upper-left corner
int nWidth, // width of destination rectangle
int nHeight, // height of destination rectangle
IntPtr hdcSrc, // handle to source DC
int nXSrc, // x-coord of source upper-left corner
int nYSrc, // y-coord of source upper-left corner
System.Int32 dwRop // raster operation code


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Mikhail Cholokhov
Web Developer
Germany Germany
No Biography provided

Comments and Discussions

Questionpositioning Pinmemberdano215-Nov-12 11:30 
QuestionI need your some help ! Pinmemberpainterargon30-Aug-12 1:29 
SuggestionI just tried Pinmembercyprussun25-Aug-12 0:28 
Questionmatrix.size ? Pinmemberdavor_saguaro20-Aug-07 1:50 
GeneralFull CharSet... PinmemberRazorino29-Nov-04 22:57 
GeneralGerman character Pinmemberwestfale4-Aug-04 21:44 
GeneralRe: German character PinmemberMikhail Cholokhov7-Aug-04 3:39 
GeneralRe: German character Pinmemberwestfale18-Aug-04 2:31 
GeneralRe: German character Pinmemberloizzi19-Jun-05 17:18 
What about giving these 'Umlaute' to all? I have tried to create my own set of characters with no luck. The only thing I could solve is the wrong ';' and ':' placement. If I add a new line in the bitmap and extend the the line in code from 127 to 159 nothing really happend. I don't know which charset this library is using. ASCII or ANSI or ASCII with DOS extending or whatever...
Frank Loizzi
GeneralWrong Characters being displayed Pinmembergarythom_usa22-Jun-04 1:39 

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