matlab callback function return value

Specify a function for this callback property, and you have a way to execute a function whenever the selection changes. Note Then you put in whatever code you want. You can store it in the figures UserData Property: Theme %At the end of the callback function: src.Parent.UserData = slice_num; %When you want to retrieve it from somewhere else: Sign in to answer this question. You will have to store the answer as a property or else if is will be lost when the callback function finishes executing. Step 2: Configure Property Values. Most callback functions cannot return (meaningful) values. You can program a response to specific user action by writing a callback function to process the action and then assigning the function to the callback property associated with that user action. With respect to the [X] =-- there are a small number of callback functions that can return values, such as some kind of position constraint functions for ROIs and some kind of zoom or pan constraint functions for axes.Most callback functions cannot return (meaningful) values. When you create a callback function, the first two arguments must be a handle to the timer object and an event structure. There is a lot of confusion over this aspect of callback functions. The timer object uses callback functions to execute commands. Instead of specifying MATLAB commands directly as the value of a callback property, you can put the commands in a MATLAB program file and specify the file as the value of the callback property. There is a lot of potential to these such as Visual Basic and C#. function show (src,event,returnValue) %the {@show,returnValue} part too end In this second method, you can reach from the show callback to the first button's user data and use that. Function that extracts the coordinates from the plot: function [x, y]= Click_CallBack (h,e,a) point = get (a,'CurrentPoint'); x = point (1); y = point (4); fprintf (1,'X,Y = %.2f,%.2f\n',x,y); end matlab matlab-figure Share Improve this question Follow asked Jan 2, 2012 at 15:06 user408041 1,014 1 8 11 3 There are a number of ways to do this. It will put you there in the m-file at the callback. If a timer is scheduled to execute multiple times, you can specify the time between executions and how to handle queuing conflicts \by adjusting the properties of the timer. In this function you pass the function parameters as function arguments, and to call it you must either: bim How To Create A Function That Will Return Values Matlab Most people want to write software that will automatically display value to a user and return the returned value. None of the uicontrol callbacks are filters. The only kind of callbacks that can return values are callbacks that are filters, such as the datacursormode update function. So here is my issue: on 8 Jun 2016. Please guide me on how to get the user input from the call back function to the main function. function getgsbutton_callback (source,eventdata) answer = inputdlg ('What is the Numerator equation'); display (answer); x = str2double (answer {:}); %Use the source object's user data source.UserData=x; return; end function show (src,event,returnValue) disp (returnValue) end It was much harder for me when I didn't have an initial working base Can the Matlab callback assigned to the java event return a value to java ? We can provide a function handle, a cell-array (of function handle and extra parameters), and in some cases also a string that will be eval 'ed in run-time. The problem I am having is that unless I change the function to Matlab enables a variety of ways to define callbacks for asynchronous events (such as interactive GUI actions or timer invocations). Behind the scenes, Matlab converts all such Java methods into Matlab callbacks, so testEvent () is automatically converted into TestEventCallback. function x = getgsbutton_callback(source,eventdata) answer = inputdlg('What is the Numerator equation'); display(answer); x = str2double(answer{:}); display(x); %display(y); return end This is a code i have written to get value from a user using GUI. September 9, 2015. You can do that if you change the show function: You need to save the data to somewhere safe, and have the routine that needs it pull it out from there. Callback functions performance. But it's the return value from your popup menu callback, so you can't do that, hence your matlab error. More Answers (1) Benjamin Blacklock on 24 Apr 2019 0 Link Translate It's bad practice but you can use global variables to communicate between the functions. This MATLAB function sets functionHandle as the function handle called when midicontrolsObject changes value, and returns the previous function handle, oldFunctionHandle. Since variables passed in to MATLAB functions are "pass by value" and not "pass by reference" if you change any of the variables, you are only changing the local copy. In short - feel free to test variations of my code (it won't bite you). The corresponding functions for the callback look like this, of course with appropriate changes for button 2 and 3: function press_button_1 (object_handle,event) global button_choice. If that's not possible, the only other way to monitor a variable change (if you can't somehow use objects and set methods) is to use a TIMER OBJECT that periodically polls the value of the variable. You can specify the callback function as the value of the property in one of three ways: Use a Character Vector to Specify Callback Functions Use a Cell Array to Specify Callback Functions Use Function Handles to Specify Callback Functions The following sections provide more information about each of these options. Why does MATLAB return a complex number for (-8)^(1/3) [] There is a lot of confusion over this aspect of callback functions. button_choice = 1; delete (gcf) end. . To use setappdata and getappdata, you would need to store your popup menu's callback function's 'block' variable some figure's appdata property that would be visible to both callback functions, or if you want to be lazy, to the root figure. A callback is a command that executes in response to some predefined user action, such as clicking on a graphics object or closing a figure window. [] . Events raised in Java code can be caught and handled in Matlab callback functions - this article explains how. Basically to add a callback function that runs when you interact with a control, such as a slider, you right-click on the control to bring up the context menu, then go to view->callback. . defined as function SamplingRate_Callback (hObject, eventdata, handles) SamplingRate_Callback sets a few variables, handles.a = 1; handles.b = 2; handles.c = 3; The handles structure updates correctly within the SamplingRate_Callback function. Now that you have a working base, this should be easy. How can I share data between callback functions in my GUI(s)? [X] = -- there are a small number of callback functions that can return values, such as some kind of position constraint functions for ROIs and some kind of zoom or pan constraint functions for axes. When you create a callback function, the first two arguments must be a handle to the timer object and an event structure. function getgsbutton_callback (source,eventdata) answer = inputdlg ('What is the Numerator equation'); x = str2double (answer {:}); return; end function show (src,event,returnValue) disp (returnValue) end But let's say you want to be able to display the "return value" every time. Instead of specifying MATLAB commands directly as the value of a callback property, you can put the commands in a MATLAB program file and specify the file as the value of the callback property. This example sets the UpdateRate value to 0.2 seconds, and the RecordsToAcquire property to 200. Yair Altman March 9, 2015 at 12:43 Reply e.g. The example also specifies as the value of the RecordsAcquiredFcn callback the event callback function display_opcdata, created in Write a Callback Function. Use a timer to schedule one or multiple executions of tasks comprised of MATLAB callback functions. 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