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Selection problem: impossible to select more than one word

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RichTextBox

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Art asked on 27 Apr 2015, 07:46 AM

I'm trying to create an extended control, which will display tips for writing. And everything is good, but the last step was faced with a problem.

Typing more then one word causes selection like "\r\n".

For example, type "Lorem" - it's ok. But type "Lorem " (with space) - broken.

01.public class ImprovedRichTextBox : RadRichTextBox

02.{

03. private static readonly DependencyProperty IsSuggestionConsistentProperty =

04. DependencyProperty.Register(

05. "IsSuggestionConsistent",

06. typeof (bool),

07. typeof (ImprovedRichTextBox),

08. new PropertyMetadata(default(bool))

09. );

10.

11. public bool IsSuggestionConsistent

12. {

13. get { return (bool)GetValue(IsSuggestionConsistentProperty); }

14. set { SetValue(IsSuggestionConsistentProperty, value); }

15. }

16.

17. private DocumentPosition _startPosition;

18. private DocumentPosition _previousPosition;

19.

20. // My custom added functionality

21. protected override void OnDocumentContentChanged()

22. {

23. base.OnDocumentContentChanged();

24.

25. var position = new DocumentPosition(Document.CaretPosition);

26.

27. var back = new DocumentPosition(position);

28.

29. if (!back.MoveToPrevious())

30. {

31. IsSuggestionConsistent = false;

32. return;

33. }

34.

35. if (IsSuggestionConsistent)

36. {

37. var i = _previousPosition.CompareTo(back);

38.

39. var end = new DocumentPosition(position);

40. end.MoveToLastPositionInDocument();

41.

42. if (i != 0 && (end.CompareTo(position) != 0 || end.CompareTo(_previousPosition) != 0))

43. {

44. IsSuggestionConsistent = false;

45. }

46. }

47.

48. _previousPosition = new DocumentPosition(position);

49.

50. if (!IsSuggestionConsistent)

51. {

52. _startPosition = new DocumentPosition(back);

53. IsSuggestionConsistent = true;

54. }

55.

56. var selection = Document.Selection;

57.

58. // KEY feature: begin

59. var selectionStart = _startPosition;

60.

61. // KEY feature: actual end of typing phrase

62. var selectionEnd = position;

63.

64. //

65. // The problem area is here:

66. //

67.

68. selection.SetSelectionStart(selectionStart);

69. selection.AddSelectionEnd(selectionEnd);

70.

71. // Everything is good while typing a word like "Lorem"

72. //

73. // But it will break if you put a space... Actually, it should be "Lorem ipsum", but catches only "\r\n"

74.

75. Debug.WriteLine("|" + selection.GetSelectedText() + "|");

76. selection.Clear();

77. }

78.}

9 Answers, 1 is accepted

Accepted

answered on 28 Apr 2015, 01:53 PM

ImprovedRichTextBox.rar

Hi Art,

The DocumentPosition is a complex object, which depends on the RadDocument's state and when you are modifying the position and the document at the same time it is possible to experience some issues. We looked at the code and modified it to work and you can find it in the attached file, but we are not sure what exactly the end goal is. Could you give us more details about the scenario and what you need to do on the DocumentContentChanged event? Do you want to select the last word, the whole text/sentence or something else? We might be able to provide advice on another, more applicable approach.

As to the modifications in the code, when the DocumentPosition is initialized, now it is using another constructor with additional TrackDocumentChangeEvents parameter, which specifies that the DocumentPosition should be kept in sync with the text even if the latter is changed.

Additionally, note that the implementation of such scenario could lead to some performance issues due to the frequent execution of the code in the DocumentContentChanged event handler.

Regards,
Tanya
Telerik

See What's Next in App Development. Register for TelerikNEXT.

answered on 28 Apr 2015, 02:49 PM

I'm trying to do something like IntelliSense in VisualStudio. It catches user input from start (when the caret was placed and text input occurs) to last typed letter (while typing sequentially). This sequence later will be transferred to the search engine for a dynamic autocompletion. If the database has no query matches, then it set IsSuggestionConsistent to false.

When the caret moved out, the start position will be changed to a new location of the caret (sets IsSuggestionConsistent into false too).

Great! I just paid attention to this document state with your example. And I found another (perhaps, the last) problem...

If you type "custom test" and place the cursor back to "cus|" (for example), then type any letter and space. In theory, sequence should have "2_" (with space), but in all gaps, it starts a new countdown from last typed space.

But! We typed first "custom test" with space and it goes without break like "custom" and " test".

answered on 29 Apr 2015, 07:49 AM

1a.png

1s.png

There is "correct" insertion (pic. 1) and "broken" (pic. 2)

Accepted

answered on 08 May 2015, 12:23 PM

Hello Art,

We thoroughly investigated the case and noticed that there is a bug with the DocumentPosition in the RadRichTextBox, which is preventing us to give you a suitable suggestion. When you type a space, the position jumps back and changes its expected location.

At this point I could not give you a specific time-frame when this issue will be fixed, but I logged it in our backlog and you could track our progress on the matter by following the related public item in the feedback portal. Your Telerik points were updated as a token of appreciation for this report.

I am afraid that I am not able to give you a workaround of this issue.

Please, excuse us for the inconvenience.

Regards,
Tanya
Telerik

See What's Next in App Development. Register for TelerikNEXT.