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Michael
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Pull String out of Edit Text without user hitting enter

Asked by Michael
on 7 Jun 2011
Latest activity Commented on by Bhushan N on 1 Dec 2016
Hi,
I am building a GUI with an EditText box and I want to pull the String out of it in my program, essentially as follows:
s = get(handles.edittext, 'String');
However, I want to get whatever the user currently has typed in there, which appears only to update after the user hits enter, etc.
I have tried updating the edittext box programmatically by calling its callback, but it still does not give the currently typed String (it gives the prior-updated string). Example:
edittext_Callback(handles.edittext, [], handles);
I have also tried updating the focus using the 'uicontrol' function. Example:
uicontrol(handles.edittext);
But again, it only gives the string that was in the box when the user caused it to update.
I am at a loss. Is there any way to snag what the user currently has typed in the EditText without the user having to cause it to update manually?

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3 Answers

Answer by Loginatorist on 7 Jun 2011
 Accepted Answer

The only way I know to do this (that doesn't involve Java), is to capture the user's input using the keypressfcn. As the user types, store the string using the keypressfcn and concatenation, then if the user does hit return clear the stored variable from the callback.
Here is a small example. You may want to add more checks, but I tried to cover enough to make it functional.
function [] = gui_keypress()
% Typing in the editbox puts the string in a textbox.
S.fh = figure('units','pixels',...
'position',[500 500 200 100],...
'menubar','none',...
'name','keypress',...
'numbertitle','off',...
'resize','off');
S.ed = uicontrol('style','edit',...
'unit','pix',...
'position',[10 10 180 30],...
'fontsize',14,...
'callback',@ed_call,...
'keypressfcn',@ed_kpfcn);
S.tx = uicontrol('style','text',...
'units','pix',...
'position',[10 60 180 30]);
S.STR = [];
guidata(S.fh,S);
uicontrol(S.ed)
function [] = ed_call(H,E)
% Callback for editbox.
S = guidata(gcbf); % Get the structure.
set(S.tx,'str',get(S.ed,'string'));
S.STR = [];
guidata(gcbf,S)
function [] = ed_kpfcn(H,E)
% Keypressfcn for editbox
S = guidata(gcbf); % Get the structure.
if strcmp(E.Key,'backspace')
S.STR = S.STR(1:end-1);
elseif isempty(E.Character)
return
else
S.STR = [S.STR E.Character];
end
set(S.tx,'string',S.STR)
guidata(gcbf,S)

  3 Comments

Thanks, I think I can get that to work actually.
However, I need to use the text I'm capturing and there's a small problem:
I tried concatenating all the characters, but the invisible characters (backspace, etc.) are there too. Is there a relatively painless way to clean up the string?
Example of problem: I type 'this', then hit backspace twice, then type 'at' for a visible result of 'that'. However, the total length of the string is 8 characters because of 8 total key presses.
I need to be able to test just the visible components of the string against other strings.
Much appreciated :)
I changed the engine to make it more robust than my first post...

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Answer by Jim Hokanson on 1 Apr 2013

Here's another approach involving changing control focus.
Here's some relevant documentation, with summaries for 2013a:
edit text boxes don't update their strings until you click somewhere else, press enter (single line) or ctl+enter (multiline)
huh?
for multiline editable text boxes, the string property is set when the control loses focus
oh!
With some help from the always helpful Jan:
My approach involves setting the focus to a small text box and then setting the focus back. I haven't played with the extent to which the static text box needs to be visible.
uicontrol(obj.h.static__busy_status) %Set focus to another control
uicontrol(obj.h.edit__cmd_window) %Set it back
get(obj.h.edit__cmd_window,'String') %Returns updated string
For me with 2013a the focus switch is imperceptible, returning the cursor to where I was typing without any noticeable blinking.

  1 Comment

Jim,
This kind of works cause when the focus returns to edit text box, it selects all the text. So if you are typing like normal it keeps replacing the text.
Bhushan

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Answer by Pooya89
on 17 Nov 2013

Using Yair's FingJObj and by accessing the java properties it is possible: (As he explains in this example)
jEditbox = findjobj(hEditbox); % get java object
set(jEditbox, 'KeyPressedCallback', @Key_Press);
function Key_Press(jEditbox, eventData)
char(jEditbox.getText)
end

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