How to compute the correct width of a digit in pixels?

问题

I have a custom control that may have user customizable Font in future (the zoom is already implemented). I must fill a rectangle under two digits that form a base-10 number. I have different colors for zero, one or both of the digits.

With the font {Name = Microsoft Sans Serif Size=16} and the following Graphics.MeasureString method calls:

g.MeasureString("00", Font);
g.MeasureString("0", Font);

I get:

The size of "00" is {Width = 31.5486088 Height = 26.8124962}
The size of "0" is {Width = 19.3298588 Height = 26.8124962}

The width of "0" is a lot bigger that half of the width of "00".

I know of the methods Graphics.MeasureString, it has many overloads, and I also know of the StringFormat class. How can I correctly compute the width of the '0' char?

Because the font will be user-customizable, I do not want to solve the problem using a monospace font.

If I use the following calls:

g.MeasureString("00", Font, 999, StringFormat.GenericTypographic);
g.MeasureString("0", Font, 999, StringFormat.GenericTypographic);

The width of "0" seems to be half of the width of "00", but the digits overlap when drawn with a smaller font size:

Update: In the OnPaint method of an UserControl I have this code:

Graphics g = e.Graphics;

int[] indices = { 0, 1 };
CharacterRange[] charRanges = new CharacterRange[indices.Length];
for (int chx = 0; chx < indices.Length; ++chx)
{
    charRanges[chx] = new CharacterRange(indices[chx], 1);
}

StringFormat sf = new StringFormat(StringFormat.GenericDefault);
sf.SetMeasurableCharacterRanges(charRanges);

Region[] regions = e.Graphics.MeasureCharacterRanges("01", Font, e.ClipRectangle, sf);

RectangleF[] r = new RectangleF[regions.Length];
int i = 0;
foreach (Region rr in regions)
{
    r[i] = rr.GetBounds(g);
    g.DrawRectangle(Pens.Blue, r[i].X, r[i].Y, r[i].Width, r[i].Height);
    ++i;
}

g.DrawString("0", Font, Brushes.Black, r[0], sf);
g.DrawString("1", Font, Brushes.Black, r[1], sf);

The font is {Name = "Microsoft Sans Serif" Size=25}. When running the program, this is what is visible:

I want to make the digits centered in the blue rectangles. The rectangles must be as big as possible in the UserControl but also leaving space for a percent of the Height of the UserControl. The Font should adapt to the rectangles.

回答1:

Small adjustments are required to make this work as intended:

TextRenderingHint.ClearTypeGridFit gives a better result when rendering the Text.
It's more precise and works well with the grid-fitting nature of Graphics.DrawString.
See the notes you can find in the answer linked below for more informations on this matter.
StringFormat alignment in both horizontal and vertical dimensions.
A modified method that allows to draw strings of any length.
If the string is larger than the container, it will be wrapped, with the current settings.
Irrelevant: Brush and Pen are declared outside the Paint event, to allow their re-definition when required.

Different implementations of MeasureCharacterRanges here:
How to highlight wrapped text in a control

About Graphics.DrawString and TextRenderingHint.ClearTypeGridFit:
Drawing a Long String on to a Bitmap results in Drawing Issues

Font 48em:

Font 16em:

Font 9em:

Pen pen = new Pen(Color.LightGreen, 1);
Brush brush = new SolidBrush(Color.White);
string sourceDigits = "010011001";

private void panel1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;

    CharacterRange[] charRanges = new CharacterRange[sourceDigits.Length];
    for (int chx = 0; chx < sourceDigits.Length; ++chx) {
        charRanges[chx] = new CharacterRange(chx, 1);
    }

    using (StringFormat sf = new StringFormat())
    {
        sf.Alignment = StringAlignment.Center;
        sf.LineAlignment = StringAlignment.Center;
        sf.SetMeasurableCharacterRanges(charRanges);

        Region[] regions = e.Graphics.MeasureCharacterRanges(sourceDigits, Font, e.ClipRectangle, sf);
        for (int i = 0; i < regions.Length; i++) {
            RectangleF rect = regions[i].GetBounds(e.Graphics);
            e.Graphics.DrawRectangle(pen, rect.X, rect.Y, rect.Width, rect.Height);
            e.Graphics.DrawString(char.ToString(sourceDigits[i]), Font, brush, rect, sf);
        }
    }
}

来源：https://stackoverflow.com/questions/54365948/how-to-compute-the-correct-width-of-a-digit-in-pixels

标签

winforms

measurestring