c# - how to measure width of a string precisely?

Question

First of all, question How to measure width of character precisely? which is answered, doesn't really help for this case, so this isn't a duplicate of that.

I have a string. I draw using graphics.DrawString, however when I need to put another one after it, I need to know the precise width of previous string.

For this I use graphics.MeasureString with:

StringFormat format = new StringFormat(StringFormat.GenericTypographic);
format.Alignment = StringAlignment.Center;
format.Trimming = StringTrimming.None;
format.FormatFlags = StringFormatFlags.MeasureTrailingSpaces;

I have tried many other functions, just as TextRendered.MeasureText however all of them fail, with all possible combinations of parameters.

the mentioned combination of MeasureString is most close to what I need (it works in most cases, except for special characters), however using characters like # break it. The width is either shorter or longer.

Is there a way to get a precise size of text produced by DrawString function? How does the DrawString calculate the size of drawing area? It must be clearly some other function because the size always differ.

The source code of whole application is here https://gitorious.org/pidgeon/pidgeon-main/ (File where I work with this, is https://gitorious.org/pidgeon/pidgeon-main/blobs/master/scrollback/SBABox.cs)

Answer 1

You just need to eliminate extra width. You can do this by using string format:

GdipStringFormatGetGenericTypographic()

You could also use:

float doubleWidth = g.MeasureString(text+text,...).Width;
float singleWidth = g.MeasureString(text).Width;
float textWidth = doubleWidth-singleWidth;

This will allow you to work with other languages such as Japanese.

On codeproject, Pierre Anaud's solution was to use MeasureCharacterRanges, which returns a region matching exactly the bounding box of the specified string:

static public int MeasureDisplayStringWidth(Graphics graphics, string text, Font font)
{
    System.Drawing.StringFormat format  = new System.Drawing.StringFormat ();
    System.Drawing.RectangleF   rect    = new System.Drawing.RectangleF(0, 0, 1000, 1000);
    var ranges  = new System.Drawing.CharacterRange(0, text.Length);
    System.Drawing.Region[] regions = new System.Drawing.Region[1];

    format.SetMeasurableCharacterRanges (ranges);

    regions = graphics.MeasureCharacterRanges (text, font, rect, format);
    rect    = regions[0].GetBounds (graphics);

    return (int)(rect.Right + 1.0f);
}