Word-wrapping in a rectangle, while allowing words to be truncated

Question

I'm making a scheduling application which looks similar to Google Calendar, iCalendar, Outlook's calendar, and similar... As you may have seen in such apps, scheduled events are represented in rectangles, which can be very small especially if you're viewing a whole week.

My challenge is to give the user a "meaningful summary" of the event before they click it, using text in the rectangle. The text should be very compact. To that end, I want it to wrap lines in a way that isn't very common, but I suspect .NET is capable of handling it natively.

If a single word is wider than the rectangle, only the beginning of that word should show. But wrapping should still occur upon encountering spaces, if the word which follows would fall partly outside the rectangle. Not every space will cause wrapping to the next line, because if two or more words happen to fit on a line that's fine.

I suspect that the answer lies in the capabilities of StringFormat, StringTrimming, and FormatFlags, but I haven't found the right combination to accomplish the goals.

For example if we have...

Chuck Norris
Dentist Appointment

Due to limited space it might become...

Chuc
Norr
Denti
Appo

I do NOT want it to become:

Chuc
k
Norr
is
Dent
ist
Appo
intme
nt

As you see in this example, if the user already knows who Chuck Norris is, the presence of letter "k" and the letters "is" don't help the user recognize the name. In fact, the presence of those letters may force "Dentist Appointment" to be hidden from view because vertical space is also limited.

I already know how to draw text in a rectangle that wraps in the normal way, and I also know how to get it to avoid drawing any text that falls outside the rectangle. What I DON'T know is how to get it to wrap upon encountering a space (or carriage return) while preventing it from wrapping mid-word if a single word is wider than the rectangle. Any help there?

Answer 1

Try using the TextRenderer.DrawText method with the TextFormatFlags.WordBreak flag:

Example using a panel's paint event:

Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles Panel1.Paint
  Dim sb As New StringBuilder
  sb.AppendLine("Chuck Norris")
  sb.AppendLine("Dentist Appointment")

  e.Graphics.Clear(Color.White)
  TextRenderer.DrawText(e.Graphics, sb.ToString, Panel1.Font, _
                        Panel1.ClientRectangle, Color.Black, Color.Empty, _
                        TextFormatFlags.WordBreak)
End Sub

You can also add TextFormatFlags.WordEllipsis to add the "..." to the end of the words that are getting cut off at the edge of the rectangle:

TextRenderer.DrawText(e.Graphics, sb.ToString, Panel1.Font, _
                      Panel1.ClientRectangle, Color.Black, Color.Empty, _
                      TextFormatFlags.WordBreak Or TextFormatFlags.WordEllipsis)

Answer 2

I don't see any way to do this other than manually.

To my knowledge, there aren't any standard controls which behave the way you want - the next step from there is to implement it yourself or find someone else who already has.

That said, you can make small improvements over the method you described in comments. Hopefully you can move it from "a bit kludgy" to "minimalist"

• Create a custom control which inherits from label
• Override the Paint event so that you can control what gets drawn (Here's another clear example and a more advanced one)
• Only calculate string width where whitespace occurs - You don't care if you draw extra characters off-canvas and you won't break without whitespace.
• Cache the final string info and only recalculate if a resize/invalidate occurs or the text changes (You need to monitor the appropriate events)

By using a custom control, you don't change the underlying Text property - so if you ever wanted to read it out, it would be the same way you put it in. This has another bonus in that you don't have to remember to do the same conversion everywhere you want this to appear - just reuse your control.

If you inherit from a control which does almost what you want (most likely label unless you have other requirements), it shouldn't be too much code / too much processing.

If you haven't already. you almost certainly want a custom object to represent a schedule entry anyway - easier to read, maintain and code against, provides a standard appearance across the app, etc.

Apologies if you know all this already - as you don't have many SO Questions/Answers, it's difficulkt to gauge your level of experience.