Center text output from Graphics DrawString

Question

I m using the  NETCF  Windows Mobile  Graphics class and the DrawString   method to render a single character to the screen   The problem is that I can t seem to get it centred properly  No matter what I set for the Y coordinate of the location of the string render  it always comes out lower than that and the larger the text size the greater the Y offset   For example  at text size 12  the offset is about 4  but at 32 the offset is about 10   I want the character to vertically take up most of the rectangle it s being drawn in and be centred horizontally  Here s my basic code  this is referencing the user control it s being drawn in   Graphics g   this CreateGraphics     float padx     float this Size Width     0 05F   float pady     float this Size Height     0 05F    float width     float this Size Width  - 2   padx  float height     float this Size Height  - 2   pady   float emSize   height   g DrawString letter  new Font FontFamily GenericSansSerif  emSize  FontStyle Regular               new SolidBrush Color Black   padx  pady     Yes  I know there is the label control that I could use instead and set the centring with that  but I actually do need to do this manually with the Graphics class

User · Accepted Answer

Through a combination of the suggestions I got, I came up with this:

    private void DrawLetter()
    {
        Graphics g = this.CreateGraphics();

        float width = ((float)this.ClientRectangle.Width);
        float height = ((float)this.ClientRectangle.Width);

        float emSize = height;

        Font font = new Font(FontFamily.GenericSansSerif, emSize, FontStyle.Regular);

        font = FindBestFitFont(g, letter.ToString(), font, this.ClientRectangle.Size);

        SizeF size = g.MeasureString(letter.ToString(), font);
        g.DrawString(letter, font, new SolidBrush(Color.Black), (width-size.Width)/2, 0);

    }

    private Font FindBestFitFont(Graphics g, String text, Font font, Size proposedSize)
    {
        // Compute actual size, shrink if needed
        while (true)
        {
            SizeF size = g.MeasureString(text, font);

            // It fits, back out
            if (size.Height <= proposedSize.Height &&
                 size.Width <= proposedSize.Width) { return font; }

            // Try a smaller font (90% of old size)
            Font oldFont = font;
            font = new Font(font.Name, (float)(font.Size * .9), font.Style);
            oldFont.Dispose();
        }
    }

So far, this works flawlessly.

The only thing I would change is to move the FindBestFitFont() call to the OnResize() event so that I'm not calling it every time I draw a letter. It only needs to be called when the control size changes. I just included it in the function for completeness.

User · Answer

Here s some code  This assumes you are doing this on a form  or a UserControl   Graphics g   this CreateGraphics    SizeF size   g MeasureString  string to measure     int nLeft   Convert ToInt32  this ClientRectangle Width   2  -  size Width   2    int nTop   Convert ToInt32  this ClientRectangle Height   2  -  size Height   2      From your post  it sounds like the ClientRectangle part  as in  you re not using it  is what s giving you difficulty

User · Answer

I d like to add another vote for the StringFormat object  You can use this simply to specify  center  center  and the text will be drawn centrally in the rectangle or points provided   StringFormat format   new StringFormat    format LineAlignment   StringAlignment Center  format Alignment   StringAlignment Center    However there is one issue with this in CF  If you use Center for both values then it turns TextWrapping off  No idea why this happens  it appears to be a bug with the CF

User · Answer

To align a text use the following   StringFormat sf   new StringFormat    sf LineAlignment   StringAlignment Center  sf Alignment   StringAlignment Center  e Graphics DrawString  My String   this Font  Brushes Black  ClientRectangle  sf     Please note that the text here is aligned in the given bounds  In this sample this is the ClientRectangle

User · Answer

You can use an instance of the StringFormat object passed into the DrawString method to center the text   See Graphics DrawString Method and StringFormat Class

User · Answer

To draw a centered text   TextRenderer DrawText g   my text   Font  Bounds  ForeColor  BackColor     TextFormatFlags HorizontalCenter      TextFormatFlags VerticalCenter     TextFormatFlags GlyphOverhangPadding     Determining optimal font size to fill an area is a bit more difficult  One working soultion I found is trial-and-error  start with a big font  then repeatedly measure the string and shrink the font until it fits    Font FindBestFitFont Graphics g  String text  Font font     Size proposedSize  TextFormatFlags flags          Compute actual size  shrink if needed   while  true          Size size   TextRenderer MeasureText g  text  font  proposedSize  flags           It fits  back out     if   size Height  lt   proposedSize Height  amp  amp            size Width  lt   proposedSize Width    return font            Try a smaller font  90  of old size      Font oldFont   font      font   new Font font FontFamily   float  font Size    9         oldFont Dispose            You d use this as   Font bestFitFont   FindBestFitFont g  text  someBigFont  sizeToFitIn  flags      Then do your drawing using the bestFitFont    Don t forget to dispose the font  if when needed

[c#] Center text output from Graphics.DrawString()

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