Measure a String without using a Graphics object?

问题:

I am using pixels as the unit for my font. In one place, I am performing a hit test to check if the user has clicked within the bounding rectangle of some text on screen. I need to use something like MeasureString for this. Unfortunately, the code doing the hit test is deep within a library which does not have access to a Graphics object or even a Control.

How do I get the bounding box of a string given the font without using the Graphics class? Why do I even need a Graphics object when my font is in pixels?

回答1:

If you have a reference to System.Windows.Forms, try using the TextRenderer class. There is a static method (MeasureText) which takes the string and font and returns the size. MSDN Link

回答2:

You don't need to use the graphics object that you are using to render to do the measuring. You could create a static utility class:

public static class GraphicsHelper
{
    public static SizeF MeasureString(string s, Font font)
    {
        SizeF result;
        using (var image = new Bitmap(1, 1))
        {
            using (var g = Graphics.FromImage(image))
            {
                result = g.MeasureString(s, font);
            }
        }

        return result;
    }
}

It might be worthwile, depending on your situation to set the dpi of the bitmap as well.

回答3:

MeasureString method in @NerdFury answer will give a higher string width than expected.Additional info you can find here. If you want to measure only the physical length please add this two lines :

g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
result = 
  g.MeasureString(measuredString, font, int.MaxValue, StringFormat.GenericTypographic);

回答4:

This example does great job of illustrating the use of FormattedText. FormattedText provides low-level control for drawing text in Windows Presentation Foundation (WPF) applications. You can use it to measure the Width of a string with a particular Font without using a Graphics object.

public static float Measure(string text, string fontFamily, float emSize)
{
    FormattedText formatted = new FormattedText(
        item, 
        CultureInfo.CurrentCulture, 
        System.Windows.FlowDirection.LeftToRight, 
        new Typeface(fontFamily), 
        emSize, 
        Brushes.Black);

    return formatted.Width;
}

Include WindowsBase and PresentationCore libraries.

回答5:

This may not be but a repeat of others, but my problem was the unwanted Graphics object as well. After listening to the above frustrations I simply tried:

Size proposedSize = new Size(int.MaxValue, int.MaxValue);
TextFormatFlags flags = TextFormatFlags.NoPadding;
Size ressize = TextRenderer.MeasureText(content, cardfont, proposedSize, flags);

(where 'content' is the string to measure and cardfont the font it is in)

... and was in luck. I could use the result to set the width of my column in VSTO.