Thread Subject: Key characters and read the length of the string problem

Hi.

I set the Callback of a edit uicontrol to read the string length of its
String property.
But I found a odd thing that when I get the length of string by keying
characters, calling Callback and executing this command:
   length(get(hObject, 'String'))
the length value is not always the same as the actual length of the string
keying on edit uicontrol.
However, I changed the focus back and forth on edit uicontrol, the length
evaled by above command
became the actual length of string on edit uicontrol.
How do I solve this problem?

MYH wrote:
>
>
> Hi.
>
> I set the Callback of a edit uicontrol to read the string length of
> its
> String property.
> But I found a odd thing that when I get the length of string by
> keying characters, calling Callback and executing this command:
> length(get(hObject, 'String'))
> the length value is not always the same as the actual length of the
> string keying on edit uicontrol.
> However, I changed the focus back and forth on edit uicontrol, the
> length evaled by above command
> became the actual length of string on edit uicontrol.
> How do I solve this problem?

Another poster had a similar problem a few months ago (I can't find
the post, though). I believe the problem (which you should report as
a bug to MathWorks) is due to the fact that the 'string' property of
the editbox is only updated after hitting <Enter> or changing
the focus, not during typing.

You could try to call drawnow in your callback. Or, use FindJObj from
the File Exchange to directly access the editbox's string (there's no
problem there - it's updated online during typing).

Yair Altman
 <http://www.ymasoftware.com>

----- Original Message -----
From: "Yair Altman" <altmanyDEL@gmailDEL.comDEL>
Newsgroups: comp.soft-sys.matlab
Sent: Tuesday, July 10, 2007 12:22 AM
Subject: Re: Key characters and read the length of the stri


> MYH wrote:
>>
>>
>> Hi.
>>
>> I set the Callback of a edit uicontrol to read the string length of
>> its
>> String property.
>> But I found a odd thing that when I get the length of string by
>> keying characters, calling Callback and executing this command:
>> length(get(hObject, 'String'))
>> the length value is not always the same as the actual length of the
>> string keying on edit uicontrol.
>> However, I changed the focus back and forth on edit uicontrol, the
>> length evaled by above command
>> became the actual length of string on edit uicontrol.
>> How do I solve this problem?
>
> Another poster had a similar problem a few months ago (I can't find
> the post, though). I believe the problem (which you should report as
> a bug to MathWorks) is due to the fact that the 'string' property of
> the editbox is only updated after hitting <Enter> or changing
> the focus, not during typing.
>
> You could try to call drawnow in your callback. Or, use FindJObj from

I have tried drawnow in my KeyPressFcn like this:

    drawnow;
    length(get(hObject, 'String'))
    drawnow;

But it seems to me that have no effect.

I also tried findjobj, but its performance was not very good.
I would like more graceful methods.
However, thank for your advises.

> the File Exchange to directly access the editbox's string (there's no
> problem there - it's updated online during typing).
>
> Yair Altman
> <http://www.ymasoftware.com>

MYH wrote:
>
> I also tried findjobj, but its performance was not very good.

Use findjobj with the 'nomenu' option - this will significantly
improve performance

Yair Altman
 <http://www.ymasoftware.com>

"Yair Altman" <altmanyDEL@gmailDEL.comDEL>
???????:ef5ce2f.2@webcrossing.raydaftYaTP...
> MYH wrote:
>>
>> I also tried findjobj, but its performance was not very good.
>
> Use findjobj with the 'nomenu' option - this will significantly
> improve performance
>
> Yair Altman
> <http://www.ymasoftware.com>

I saw some codes of findjobj for getting some ideas and decided to
substisute java components for
MATLAB built-in edit components.
I was successful to achieve reading the actual length of string which
displayed on JTextField object.
This is my part codes (It's a CRC Calculator):

function varargout = CRCCalculator(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
                   'gui_Singleton', gui_Singleton, ...
                   'gui_OpeningFcn', @CRCCalculator_OpeningFcn, ...
                   'gui_OutputFcn', @CRCCalculator_OutputFcn, ...
                   'gui_LayoutFcn', [] , ...
                   'gui_Callback', []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT

    global initialzated;
    % 'initialzated' variable is used to indicate whether the GUI had
    % initialzated, or not.

% --- Executes just before CRCCalculator is made visible.
function CRCCalculator_OpeningFcn(hObject, eventdata, handles, varargin)

    handles.output = hObject;

    % Update handles structure
    guidata(hObject, handles);

    global initialzated;

    % If the GUI had initialzated, we do nothing but return.
    if initialzated == 1
        return;
    end

    % Following codes, we will instatiate java classes for a text field
    % component. We don't use the text field components of MATLAB built-in
    % edit, because it has some bug on KeyPressFCN callback.

    % Import java classes.
    import javax.swing.*;
    import java.awt.*;

    % Set up JTextField GUI component.
    DataIn = JTextField();
    DataIn.setFont(Font('Sans Serif', Font.PLAIN, 16));
    DataIn.setHorizontalAlignment(JTextField.CENTER);
    % Add DataIn component to the figure.
    javacomponent(DataIn, [50 300 650 50]);

    % Add a field for DataIn to handles.
    handles.DataIn = DataIn;
    % Update handles structure
    guidata(hObject, handles);

    % Set the KeyReleasedCallback for DataIn component.
    set(DataIn, 'KeyReleasedCallback', @(hObject,
eventdata)CountBitNum(handles));

    % Clear bits of DataIn to zeros.
    ClearBits(handles);

    % Initialzating completely.
    initialzated = 1;

function CountBitNum(handles)

    % Display the bit count in BitCount component.
    set(handles.BitCount, 'String', length(handles.DataIn.getText()));

function figure1_DeleteFcn(hObject, eventdata, handles)

    % Set initialzated to 0 for next starting GUI.
    global initialzated;
    initialzated = 0;
...