bug in UILabel?

[niall]

I was trying to make individual words in a label tappable, for the purposes of highlighting them as they are tapped, and playing the audio for that word.  Colour me amazed to find NGUI already had a function for this!  However, it seems to throw exceptions when you tap on spaces in the label.  I was able to get around it with a dirty try/catch, but perhaps it needs fixing, or I am just missing something?  I'll paste my function for reference, if you're interested! (heavily commented for some new-to-Unity devs joining me soon.)  I'm not sure I can post any code from UILabel.cs where I believe the problem is, so I'll leave that out. 

1.         public void NarrationTapped()
2.         {
3.                 HighlightWord(-1);//passing -1 for the word index should clear any highlighting on the string.
4.                 Vector2 screenPos = Input.mousePosition; //grab screen coords where you tapped
5.                 Camera cam = NGUITools.FindCameraForLayer (gameObject.layer);
6.                 Vector3 worldPos = cam.ScreenToWorldPoint (screenPos);//fancy unity convert screen coords to world coords
7.                 int charIndex;
8.                 try{ //have to wrap this whole thing in a try/catch because NGUI throws exceptions when tapping on space characters...
9.                         charIndex = narrationTextLbl.GetCharacterIndexAtPosition(worldPos);//get the index into the string for the character you tapped.
10.                         string oldText = narrationTextLbl.text;//copy the page text locally so we can mess with it.
11.                         if(charIndex != -1 && charIndex < oldText.Length)
12.                         {
13.                                 if(narrationTextLbl.GetWordAtCharacterIndex(charIndex) != " ")
14.                                 {
15.                                         string hexBlue = @"[0000ff]";
16.                                         string endColorTag = "[-]";
17.                                         int linkStart = oldText.LastIndexOf(' ', charIndex) + 1; //find the char index for the first character of the selected word
18.                                         if(linkStart==0) linkStart+= hexBlue.Length;//if you hit the first word, we have to skip the initial bit of BBcode that makes the text black.
19.                                         int linkEnd = oldText.IndexOf(' ', charIndex);//gets the char index for the end of the selected word.
20.                                         if (linkEnd == -1) linkEnd = oldText.Length;
21.                                        
22.                                         if (linkStart != linkEnd)
23.                                         {
24.                                                 oldText = oldText.Insert(linkStart, hexBlue);//insert the blue BBcode before the word.
25.                                                 oldText = oldText.Insert((linkEnd+hexBlue.Length), "[-]");//and close the BBcode tag
26.                                         }
27.                                         narrationTextLbl.text = oldText;//then set the text back to the label
28.                                         string word = narrationTextLbl.GetWordAtCharacterIndex(charIndex).ToUpper();//get the word now, and uppercase it for the filename.
29.                                         string fileName = System.Text.RegularExpressions.Regex.Replace(word, "[?!,.;:]", "");//remove punctuations (add to that array if we missed a punctuation type!)
30.                                         AudioClip snd = (AudioClip)Resources.Load("Words/" + fileName, typeof(AudioClip));//load the sound clip for the word
31.                                         narrationAudio.clip = snd;//set it
32.                                         narrationAudio.Play();//play it!
33.                                 }
34.                         }
35.                 }
36.                 catch{
37.                         Debug.Log ("you probably clicked on a space");
38.                 }
39.         }

edit: here is the exception thrown as well:

ArgumentOutOfRangeException: Cannot be negative.
Parameter name: length
System.String.Substring (Int32 startIndex, Int32 length) (at /Users/builduser/buildslave/monoAndRuntimeClassLibs/build/mcs/class/corlib/System/String.cs:348)
UILabel.GetWordAtCharacterIndex (Int32 characterIndex) (at Assets/NGUI/Scripts/UI/UILabel.cs:1286)
NarrationLoader.NarrationTapped () (at Assets/Scripts/NarrationLoader.cs:115)

[ArenMook]

Try changing UILabel.GetWordAtCharacterIndex to:

1.         public string GetWordAtCharacterIndex (int characterIndex)
2.         {
3.                 if (characterIndex != -1 && characterIndex < mText.Length)
4.                 {
5.                         int linkStart = mText.LastIndexOf(' ', characterIndex) + 1;
6.                         int linkEnd = mText.IndexOf(' ', characterIndex);
7.                         if (linkEnd == -1) linkEnd = mText.Length;
8.  
9.                         if (linkStart != linkEnd)
10.                         {
11.                                 int len = linkEnd - linkStart;
12.  
13.                                 if (len > 0)
14.                                 {
15.                                         string word = mText.Substring(linkStart, len);
16.                                         return NGUIText.StripSymbols(word);
17.                                 }
18.                         }
19.                 }
20.                 return null;
21.         }

[niall]

Yep, that works of course!  Will you be including it in the next update?

[ArenMook]

Judging by the posting date, it should be already a part of 3.5.6.

[niall]

Hah, look at that!  I don't always check for my plugin updates, but when I do, they overwrite changes I made to them!  /DosEquis