Question

I have panel that I have customized. I use it to display text. But sometimes that text is too long and wraps to the next line. Is there some way I can auto resize the panel to show all the text?

I am using C# and Visual Studio 2008 and the compact framework.

---

Here is the code I am wanting to adjust the size for:
(Note: HintBox is my own class that inherits from panel. So I can modify it as needed.)

public void DataItemClicked(ShipmentData shipmentData)
{
    // Setup the HintBox
    if (_dataItemHintBox == null)
        _dataItemHintBox = HintBox.GetHintBox(ShipmentForm.AsAnObjectThatCanOwn(),
                                             _dataShipSelectedPoint,
                                             new Size(135, 50), shipmentData.LongDesc,
                                             Color.LightSteelBlue);


    _dataItemHintBox.Location = new Point(_dataShipSelectedPoint.X - 100,
                                          _dataShipSelectedPoint.Y - 50);
    _dataItemHintBox.MessageText = shipmentData.LongDesc;
    // It would be nice to set the size right here
    _dataItemHintBox.Size = _dataItemHintBox.MethodToResizeTheHeightToShowTheWholeString()
    _dataItemHintBox.Show();

}

---

I am going to give the answer to Will Marcouiller because his code example was the closest to what I needed (and looks like it will work). However, this is what I think I will use:

public static class CFMeasureString
{
    private struct Rect
    {
        public readonly int Left, Top, Right, Bottom;
        public Rect(Rectangle r)
        {
            this.Left = r.Left;
            this.Top = r.Top;
            this.Bottom = r.Bottom;
            this.Right = r.Right;
        }
    }

    [DllImport("coredll.dll")]
    static extern int DrawText(IntPtr hdc, string lpStr, int nCount, 
                               ref Rect lpRect, int wFormat);
    private const int DT_CALCRECT = 0x00000400;
    private const int DT_WORDBREAK = 0x00000010;
    private const int DT_EDITCONTROL = 0x00002000;

    static public Size MeasureString(this Graphics gr, string text, Rectangle rect, 
                                     bool textboxControl)
    {
        Rect bounds = new Rect(rect);
        IntPtr hdc = gr.GetHdc();
        int flags = DT_CALCRECT | DT_WORDBREAK;
        if (textboxControl) flags |= DT_EDITCONTROL;
        DrawText(hdc, text, text.Length, ref bounds, flags);
        gr.ReleaseHdc(hdc);
        return new Size(bounds.Right - bounds.Left, bounds.Bottom - bounds.Top + 
                        (textboxControl ? 6 : 0));
    }
}

This uses the os level call to draw text. By P-Invoking it I can get the functionality I need (multi line wrapping). Note that this method does not include any margins. Just the actual space taken up by the text.

I did not write this code. I got it from http://www.mobilepractices.com/2007/12/multi-line-graphicsmeasurestring.html. That blog post had my exact problem and this fix. (Though I did make a minor tweak to make it a extension method.)

Answer 1

You could use the Graphics.MeasureString() method.

With a code sample of your text assignment onto your panel, I could perhaps provide a code sample using the MeasureString() method, if you need it.

I have no way to know whether the Graphics.MeasureString() method is part of the Compact Framework, as it is not said on the page I linked.

EDIT #1

Here’s a link where I answered to another text-size related question, while I look for writing a sample for you. =)

EDIT #2

Here’s another link related to your question. (Next edit is the sample code. =P)

EDIT #3

public void DataItemClicked(ShipmentData shipmentData) { 
    // Setup the HintBox 
    if (_dataItemHintBox == null) 
        _dataItemHintBox = HintBox.GetHintBox(ShipmentForm.AsAnObjectThatCanOwn(), 
                                             _dataShipSelectedPoint, 
                                             new Size(135, 50), shipmentData.LongDesc, 
                                             Color.LightSteelBlue); 

    // Beginning to measure the size of the string shipmentData.LongDesc here.

    // Assuming that the initial font size should be 30pt.
    Single fontSize = 30.0F;
    Font f = new Font("fontFamily", fontSize, FontStyle.Regular);

    // The Panel.CreateGraphics method provides the instance of Graphics object 
    // that shall be used to compare the string size against.
    using (Graphics g = _dataItemHintBox.CreateGraphics()) {
        while (g.MeasureString(shipmentData.LongDesc, f).Width > _dataItemHintBox.Size.Width - 5) {
            --fontSize;
            f = new Font("fontFamily", fontSize, FontStyle.Regular);
        }
    }

    // Font property inherited from Panel control.
    _dataItemHintBox.Font = f;

    // End of font resizing to fit the HintBox panel.

    _dataItemHintBox.Location = new Point(_dataShipSelectedPoint.X - 100, 
                                          _dataShipSelectedPoint.Y - 50); 
    _dataItemHintBox.MessageText = shipmentData.LongDesc; 
    // It would be nice to set the size right here 
    _dataItemHintBox.Size = _dataItemHintBox.MethodToResizeTheHeightToShowTheWholeString() 
    _dataItemHintBox.Show(); 
} 

Disclaimer: This code has not been tested and is off the top of my head. Some changes might be obligatory in order for you to test it. This provides a guideline to achieve what you seem to want to accomplish. There might be a better way to do this, but I know this one works. Well, the algorithm works, as you can see in my other answers.

Instead of the line:

SizeF fontSize = 30.0F;

You could as well do the following:

var fontSize = _dataItemHintBox.Font.Size;

Why is this?

Because Font.Size property is readonly. So, you need to create a new instance of the System.Drawing.Font class each time the Font.Size shall change.

In your comparison, instead of having the line:

while (g.MeasureString(shipmentData.LongDesc, f)...)

you could also have:

while (g.MeasureString(shipmentData.LongDesc, _dataItemHintBox.Font)...)

This would nullify the need for a second Font class instance, that is f.

Please feel free to post feedbacks as I could change my sample to fit your reality upon the feedbacks received, so that it better helps you. =)

I hope this helps! =)