CODEWITHSUNDEEP
c++winapiedit
null
null

Reputation: 807

Constraining Edit Control content

I've scanned through all pages in MSDN, but still not found asnwers of following.

  1. Minimum Character Length of edit control.
  2. Specifying range for input values in edit control.
  3. Permitting only alphabets in edit control.
  4. Setting tooltip for button control.

Please tell me how to do this in Win32.

Upvotes: 2

Views: 1009

Answers (1)

jamesdlin
jamesdlin

Reputation: 89926

  1. This is hard to do properly. A naive approach would handle WM_KEYDOWN messages to intercept the backspace and delete keys (VK_BACK and VK_DELETE). However, you also need to handle a user selecting some of the existing text and then deleting it (via backspace or delete), cutting it, or replacing it (by typing a key or by pasting some other text). I don't think it's worthwhile, and even if you could do this well, it is likely to be confusing when you break all of those normal behaviors. (It also can be incredibly annoying. Imagine that you have some text "bar" in the control but you want to change it to "baz". If the control enforces a minimum length of 3, then attempting to backspace over the last character won't work. You would have to change it to "barz" first and before being able to delete the "r" character. Ugh.)

    If your control needs a minimum length, you're better off enforcing it during a separate validation step (such as when the user clicks an OK button or moves focus to another control) and showing an appropriate error message.

  2. I'm not sure whether you mean allowing only certain characters to be entered into an edit control or whether you want to restrict it to a range of numeric values. For the former, see 3.

    If you want to restrict values to a certain numeric range, I again recommend doing it during a separate validation step instead. Otherwise you again might prevent the user from inserting and deleting characters in a normal way. If you can, avoid using using an Edit control and use a Trackbar (slider) control.

  3. You would have to subclass the Edit control, handle WM_CHAR messages, and reject characters that you don't want. You additionally would need to handle WM_PASTE messages and perform similar validation.

  4. This doesn't have anything to do with Edit controls and probably should be a separate question. What have you tried? Have you read http://msdn.microsoft.com/en-us/library/bb760250.aspx ?

Upvotes: 5

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