Matlab: set default values for GUI edit text and use them in push button callback

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Andrea Vaccari
Andrea Vaccari 2015-8-14
回答： Andrea Vaccari 2015-8-14
I'm trying to initialize a GUI (built with GUIDE) with default values and then, if the user does not change the defaults, use these values in a function triggered by a push button callback.
To do this, inside the `_CreateFcn`, I first store the default values within the `handles`, then set the default of the GUI with `set(hObject, ...)` and finally update the guidata with `guidata(hObject, handles);`
If the user changes the value, I store the updated value in the handles inside the `_Callback` function reading the value with `get(hObject, ...)` and updating the guidata with `guidata(hObject, handles);`
When the button is pushed, inside the button `_Callback` function, I extract the value from the `handles`.
What happen is the following:
  • if the user *does not* change the value on the GUI and simply pushes the button, what I read out from the variable stored in the handles is *not* the value of the variable, but the actual handle to the variable. This will return, for example: `27.0098876953125` or, for the newer versions -R2015b-:
UIControl (ampmin) with properties:
Style: 'edit'
String: '1'
BackgroundColor: [1 1 1]
Callback: @(hObject,eventdata)GUI('ampmin_Callback',hObject,eventdata,guidata(hObject))
Value: 0
Position: [15.6000 14.6154 10.2000 1.6923]
Units: 'characters'
Use get to show all properties
  • If, on the other hand, the user *does* change the value before pushing the button, then everything works fine and I get the actual variable value.
What am I missing?
UPDATE
I've noticed the following behavior:
  • If I start the `.fig` file, the behavior is as expected
  • If I start the `.m` file by pushing the `run` button, then I observe the strange behavior described above.
Here is the code (I've also attached a copy of the `.m` and `.fig` files):
function varargout = GUI2(varargin)
% GUI2 MATLAB code for GUI2.fig
% GUI2, by itself, creates a new GUI2 or raises the existing
% singleton*.
%
% H = GUI2 returns the handle to a new GUI2 or the handle to
% the existing singleton*.
%
% GUI2('CALLBACK',hObject,eventData,handles,...) calls the local
% function named CALLBACK in GUI2.M with the given input arguments.
%
% GUI2('Property','Value',...) creates a new GUI2 or raises the
% existing singleton*. Starting from the left, property value pairs are
% applied to the GUI2 before GUI2_OpeningFcn gets called. An
% unrecognized property name or invalid value makes property application
% stop. All inputs are passed to GUI2_OpeningFcn via varargin.
%
% *See GUI2 Options on GUIDE Tools menu. Choose "GUI2 allows only one
% instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES
% Edit the above text to modify the response to help GUI2
% Last Modified by GUIDE v2.5 14-Aug-2015 10:39:46
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', @GUI2_OpeningFcn, ...
'gui_OutputFcn', @GUI2_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
% --- Executes just before GUI2 is made visible.
function GUI2_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% varargin command line arguments to GUI2 (see VARARGIN)
% Choose default command line output for GUI2
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% UIWAIT makes GUI2 wait for user response (see UIRESUME)
% uiwait(handles.figure1);
% --- Outputs from this function are returned to the command line.
function varargout = GUI2_OutputFcn(hObject, eventdata, handles)
% varargout cell array for returning output args (see VARARGOUT);
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Get default command line output from handles structure
varargout{1} = handles.output;
% --- Executes on button press in startAnalysis.
function startAnalysis_Callback(hObject, eventdata, handles)
% hObject handle to startAnalysis (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
disp(handles.ampmin)
function ampmin_Callback(hObject, eventdata, handles)
% hObject handle to ampmin (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of ampmin as text
% str2double(get(hObject,'String')) returns contents of ampmin as a double
handles.ampmin = str2double(get(hObject,'String'));
% Update handles structure
guidata(hObject, handles);
% --- Executes during object creation, after setting all properties.
function ampmin_CreateFcn(hObject, eventdata, handles)
% hObject handle to ampmin (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles empty - handles not created until after all CreateFcns called
% Hint: edit controls usually have a white background on Windows.
% See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
handles.ampmin = 1.0;
disp(handles.ampmin)
set(hObject, 'String', num2str(handles.ampmin))
% Update handles structure
guidata(hObject, handles);

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采纳的回答

Andrea Vaccari
Andrea Vaccari 2015-8-14
I actually found the issue. Buy using `handles.ampmin` as name of the variable I was effectively overwriting the `uicontrol` handle thus causing the described behavior. By changing the name of the variable to `handles.ampminvalue`, the behavior changed to the expected one.

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