Autofit WinForms RichTextBox to its contents - winforms

Question

Does anybody know how can I dynamically resize a RichTextBox control to its contents?

Answer 1

I guess I am far too late but take a look at this
It's just two code lines:
private void rtb_ContentsResized(object sender, ContentsResizedEventArgs e)
{
((RichTextBox)sender).Height = e.NewRectangle.Height + 5;
}

Answer 2

Again assuming a fixed font could you do something like:
using (Graphics g = CreateGraphics())
{
richTextBox.Height = (int)g.MeasureString(richTextBox.Text,
richTextBox.Font, richTextBox.Width).Height;
}

Answer 3

It's kind of a pain - the C# RichTextBox is often frustrating to work with. Are you trying to size the box big enough to hold its contents without any scrollbar?
If the RichTextBox has a constant font, you can use TextRenderer.MeasureText to simply measure the required size, and pass in the box's width as a constraint.
The ContentsResized event gives you a ContentsResizedEventsArgs, which gives you a NewRectangle which tells you how big the text area is. But it only fires when the text changes, which isn't as useful if you simply want to measure an existing richtextbox (although you could probably just do something hacky like set the box's text to itself, triggering this event).
There are also a bunch of Win32 api calls, like using EM_GETLINECOUNT (http://ryanfarley.com/blog/archive/2004/04/07/511.aspx), etc.

Answer 4

A really cheap solution (one that is potentially fraught with problems) is to simultaneously fill an autofit label with text using the same font and size, then just copy the width of the label to the width of the RTB.
So, like this:
RichTextBox rtb = new RichTextBox();
rtb.Text = "this is some text";
rtb.Font = new Font("Franklin Gothic Medium Cond", 10, FontStyle.Regular);
Label fittingLabel = new Label();
fittingLabel.Text = rtb.Text;
fittingLabel.Font = rtb.Font;
fittingLabel.AutoSize = true;
//Not sure if it's necessary to add the label to the form for it to autosize...
fittingLabel.Location = new Point(-1000,-1000);
this.Controls.Add(fittingLabel);
rtb.Width = fittingLabel.Width;
this.Controls.Remove(fittingLabel);

Answer 5

I found a solution for the Rich text box height issues.. i have modified it a for general use..
Create following structs in your application....
[StructLayout(LayoutKind.Sequential)]
public struct RECT {
public Int32 left;
public Int32 top;
public Int32 right;
public Int32 bottom;
}
[StructLayout(LayoutKind.Sequential)]
public struct SCROLLBARINFO {
public Int32 cbSize;
public RECT rcScrollBar;
public Int32 dxyLineButton;
public Int32 xyThumbTop;
public Int32 xyThumbBottom;
public Int32 reserved;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)]
public Int32[] rgstate;
}
Create following private variables in your class for form (where ever you need to calculate rich text height)
private UInt32 SB_VERT = 1;
private UInt32 OBJID_VSCROLL = 0xFFFFFFFB;
[DllImport("user32.dll")]
private static extern
Int32 GetScrollRange(IntPtr hWnd, UInt32 nBar, out Int32 lpMinPos, out Int32 lpMaxPos);
[DllImport("user32.dll")]
private static extern
Int32 GetScrollBarInfo(IntPtr hWnd, UInt32 idObject, ref SCROLLBARINFO psbi);
Add following method to your Class for form
private int CalculateRichTextHeight(string richText) {
int height = 0;
RichTextBox richTextBox = new RichTextBox();
richTextBox.Rtf = richText;
richTextBox.Height = this.Bounds.Height;
richTextBox.Width = this.Bounds.Width;
richTextBox.WordWrap = false;
int nHeight = 0;
int nMin = 0, nMax = 0;
SCROLLBARINFO psbi = new SCROLLBARINFO();
psbi.cbSize = Marshal.SizeOf(psbi);
richTextBox.Height = 10;
richTextBox.ScrollBars = RichTextBoxScrollBars.Vertical;
int nResult = GetScrollBarInfo(richTextBox.Handle, OBJID_VSCROLL, ref psbi);
if (psbi.rgstate[0] == 0) {
GetScrollRange(richTextBox.Handle, SB_VERT, out nMin, out nMax);
height = (nMax - nMin);
}
return height;
}
You may need to modify above method to make it work as per your requirement...
Make sure to send Rtf string as parameter to method not normal text and also make sure to assign available width and height to the Richtextbox variable in the method...
You can play with WordWrap depending on your requirement...

Answer 6

It's much easier to use GetPreferredSize, as described in this answer. Then you don't need to wait for a ContentsResized event.