Resize text size of a label when the text gets longer than the label size?

Question

I have a label that shows the file name .. I had to set AutoSize of the label to False for designing.
So when the file name text got longer tha

Answer 1

this method worked for me

simply you will reduce font size until it reach the width you want.

while (label1.Width >150 )
{
    label1.Font = new Font(label1.Font.FontFamily, label1.Font.Size - 0.5f, label1.Font.Style);
}

Answer 2

You can use my code snippet below. System needs some loops to calculate the label's font based on text size.

while(label1.Width < System.Windows.Forms.TextRenderer.MeasureText(label1.Text, 
     new Font(label1.Font.FontFamily, label1.Font.Size, label1.Font.Style)).Width)
{
    label1.Font = new Font(label1.Font.FontFamily, label1.Font.Size - 0.5f, label1.Font.Style);
}

Answer 3

Based on the article provided by @brgerner, I'll provide the alternative implementation here, as that one marked as an answer is not so efficient nor complete as this one below:

public class FontWizard
{
    public static Font FlexFont(Graphics g, float minFontSize, float maxFontSize, Size layoutSize, string s, Font f, out SizeF extent)
    {
        if (maxFontSize == minFontSize)
            f = new Font(f.FontFamily, minFontSize, f.Style);

        extent = g.MeasureString(s, f);

        if (maxFontSize <= minFontSize)
            return f;

        float hRatio = layoutSize.Height / extent.Height;
        float wRatio = layoutSize.Width / extent.Width;
        float ratio = (hRatio < wRatio) ? hRatio : wRatio;

        float newSize = f.Size * ratio;

        if (newSize < minFontSize)
            newSize = minFontSize;
        else if (newSize > maxFontSize)
            newSize = maxFontSize;

        f = new Font(f.FontFamily, newSize, f.Style);
        extent = g.MeasureString(s, f);

        return f;
    }

    public static void OnPaint(object sender, PaintEventArgs e, string text)
    {
        var control = sender as Control;
        if (control == null)
            return;

        control.Text = string.Empty;    //delete old stuff
        var rectangle = control.ClientRectangle;

        using (Font f = new System.Drawing.Font("Microsoft Sans Serif", 20.25f, FontStyle.Bold))
        {
            SizeF size;
            using (Font f2 = FontWizard.FlexFont(e.Graphics, 5, 50, rectangle.Size, text, f, out size))
            {
                PointF p = new PointF((rectangle.Width - size.Width) / 2, (rectangle.Height - size.Height) / 2);
                e.Graphics.DrawString(text, f2, Brushes.Black, p);
            }
        }
    }
}

and the usage:

val label = new Label();
label.Paint += (sender, e) => FontWizard.OnPaint(sender, e, text);

Answer 4

I use the following weighted scaling trick to provide a good fit, i.e. a weighted tradeoff is made between fitting the height and fitting the width. It's in VB .net, but I think you can translate to C# easily.

Function shrinkFontToFit(f As Font, text As String, requiredsize As SizeF) As Font
    Dim actualsize As SizeF = TextRenderer.MeasureText(text, f)
    Return New Font(f.FontFamily, f.Size * (requiredsize.Width + requiredsize.Height ) _
        / (actualsize.Width + actualsize.Height), f.Style, GraphicsUnit.Pixel)
End Function

Answer 5

With inspiration from @bnguyen82 i came up with something that works all the way.

public static void ScaleLabel(Label label, float stepSize = 0.5f)
{
    //decrease font size if text is wider or higher than label
    while (lblTextSize() is Size s && s.Width > label.Width || s.Height > label.Height)
    {
        label.Font = new Font(label.Font.FontFamily, label.Font.Size - stepSize, label.Font.Style);
    }

    //increase font size if label width is bigger than text size
    while (label.Width > lblTextSize().Width)
    {
        var font = new Font(label.Font.FontFamily, label.Font.Size + stepSize, label.Font.Style);
        var nextSize = TextRenderer.MeasureText(label.Text, font);

        //dont make text width or hight bigger than label
        if (nextSize.Width > label.Width || nextSize.Height > label.Height)
            break;

        label.Font = font;
    }

    Size lblTextSize() => TextRenderer.MeasureText(label.Text,
        new Font(label.Font.FontFamily, label.Font.Size, label.Font.Style));
}

PS: In order for this to work the label needs to have AutoSize = false and either to be docked or anchored.

Answer 6

Label scaling

private void scaleFont(Label lab)
{
    Image fakeImage = new Bitmap(1, 1); //As we cannot use CreateGraphics() in a class library, so the fake image is used to load the Graphics.
    Graphics graphics = Graphics.FromImage(fakeImage);

    SizeF extent = graphics.MeasureString(lab.Text, lab.Font);

    float hRatio = lab.Height / extent.Height;
    float wRatio = lab.Width / extent.Width;
    float ratio = (hRatio < wRatio) ? hRatio : wRatio;

    float newSize = lab.Font.Size * ratio;

    lab.Font = new Font(lab.Font.FontFamily, newSize, lab.Font.Style);
}

TextRenderer Approach pointed out by @ToolmakerSteve in the comments

private void ScaleFont(Label lab)
{
    SizeF extent = TextRenderer.MeasureText(lab.Text, lab.Font);

    float hRatio = lab.Height / extent.Height;
    float wRatio = lab.Width / extent.Width;
    float ratio = (hRatio < wRatio) ? hRatio : wRatio;

    float newSize = lab.Font.Size * ratio;

    lab.Font = new Font(lab.Font.FontFamily, newSize, lab.Font.Style);
}