MATLAB Answers

Nigel
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GUI: Change backround of "Edit text" box using if structure

Asked by Nigel
on 26 Nov 2012
Hello! In my GUI I have two inputs and output (they are "Edit text" boxes) and a button which executes a function. As I said, the final output goes to Edit Text box. I want to analyze this output with if structure, and, depending on the value, assign different background color for the box.
I tried using set(hObject,'BackgroundColor','color'), (example below) And it worked..
function box_CreateFcn(hObject, eventdata, handles)
set(hObject,'BackgroundColor','color')
But when it is inside IF structure, MATLAB returns many errors and code doesn't work (see code below)
function box_CreateFcn(hObject, eventdata, handles)
if value <-30
set(hObject,'BackgroundColor','blue');
elseif value>=-30
set(hObject,'BackgroundColor','grey');
elseif value<=100
set(hObject,'BackgroundColor','black');
else
set(hObject,'BackgroundColor','red');
end
What am I doing wrong? :)

  1 Comment

When ever you mention, that errors appear, it is a good idea to post the messages also.

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2 Answers

Answer by Arthur
on 26 Nov 2012
 Accepted Answer

Explain 'many errors'. How can we fix many errors with we don't know what they are?? I'm going to make an estimated guess. If your code is exactly as you showed here, than you forgot to get the string of the textbox. Include this above your if.
value = str2double(get(hObject,'String'))
Also, the way you programmed your if's is not going to work; it will never reach the last two options. Note that matlab always goes to the first if that is true, and value will always be <-30 or >=-30....

  2 Comments

numbers in if structure are given just for example, don't pay attention to that :)
Well, when even the code in your question isn't the correct one, I don't know how we can help you. You'll have to give us some more info (=errors & code).
But I see that this code is in the CreateFcn. Shoudn't it be in the Callback?

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Answer by Image Analyst
on 26 Nov 2012
Edited by Image Analyst
on 26 Nov 2012

Have you tried to use the debugger? Set a breakpoint and see if it actually gets into any of the "if" conditions that you list.
And what is "value" - have you assigned that yet?
And you can try using handles.box instead of hObject.

  1 Comment

value is the number, calculated using function

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