MATLAB: Do I receive a warning when calling the CLOSEPREVIEW function from the Image Acquisition Toolbox 1.8 (R14SP2)

cameraImage Acquisition Toolboxpreviewrecursionwindowwinvideo

I have written a graphical user interface (GUI) using GUIDE that uses the Image Acquisition Toolbox's preview window. In the CloseRequestFcn of my GUI, I call the CLOSEPREVIEW function to close the open preview window. This call generates the following warning:

 Warning: A callback recursively calls CLOSE.  Use DELETE to prevent this message.
 > In close>request_close at 139
   In close at 118
   In imaqdevice.closepreview at 46
   In repro>figure1_CloseRequestFcn at 110
   In gui_mainfcn at 75
   In repro at 42
   In close>request_close at 147
   In close at 118
   In repro>pushbutton2_Callback at 98
   In gui_mainfcn at 75
   In repro at 42

Best Answer

This bug has been fixed in Release 2006a (R2006a). For previous product releases, read below for any possible workarounds:

There is a bug in the Image Acquisition Toolbox 1.8 (R14SP2) in the way that the CLOSEPREVIEW function behaves when called in the CloseRequestFcn of a GUI created with GUIDE.

To work around this issue, avoid calling CLOSEPREVIEW from a GUI's CloseRequestFcn.

Related Solutions

MATLAB: Does the Image Acquisition Toolbox video preview window cause MATLAB to not respond or appear to hang

This enhancement has been incorporated in Release 14 Service Pack 3 (R14SP3). For previous product releases, read below for any possible workarounds:

This is a known limitation of the Handle Graphics based preview window and will be addressed in a future toolbox release.

If performance problems occur, or MATLAB appears to stop responding, the following steps may help alleviate some of these issues:

- Try previewing a smaller image size. The image size can be reduced by either:

1) Configuring the ROIPosition property such that a smaller resolution is acquired and previewed

2) Resize the preview window such that the entire image is not visible

3) Create a custom preview window GUI by following the example in the Previewing Data in Custom GUIs section of the User's Guide. Doing so will allow you to scale the image size down when the preview window is resized.

- Avoid previewing multiple video input objects simultaneously. In general, performance is best if only one video input object is previewed at a time.

If performance issues persist, the MATLAB Handle Graphics based preview window can be disabled by executing the following commands before issuing any other Image Acquisition Toolbox commands. Note that by disabling the new preview window, the Handle Graphics customization features will be unavailable.

imaqreset 
imaqmex('feature', '-useObsoletePreview', true)

Note, to re-enable the Handle Graphics based preview window, restart MATLAB or execute the following commands:

imaqreset 
imaqmex('feature', '-useObsoletePreview', false)

MATLAB: How to change ‘CloseRequestFcn’ property of a figure, so when the figure is reopened, it uses a different ‘CloseRequestFcn’

Modification of the 'CloseRequestFcn' can occur upon re-openging the figure using the 'CreateFcn'. Try the following example:

plot(1:10)
set(gcf, 'CloseRequestFcn', 'disp(''closing figure...''); closereq')
set(gcf, 'CreateFcn', 'set(gcf, ''CloseRequestFcn'', ''closereq'', ''CreateFcn'', '''')')
hgsave myFigure

This example creates a figure with a simple line plot. In line 2, the ‘CloseRequestFcn’ is altered to display “closing figure…” at the Command Prompt when the figure is closed. In line 3, the ‘CreateFcn’ is set to a command which resets both the ‘CloseRequestFcn’ and the ‘CreateFcn’ to their default values.

After executing the example, examine the ‘CloseRequestFcn’ and ‘CreateFcn’ properties by entering the following at the MATLAB Command Prompt:

get(gcf, ‘CloseRequestFcn’)
get(gcf, ‘CreateFcn’)

When you close the figure, you will see “closing figure…” at the MATLAB Command Prompt.

Reopen the figure by executing:

    open myFigure.fig

Then examine the ‘CloseRequestFcn’ and ‘CreateFcn’ properties. Note that both of these properties have been reset to their default values. The figure will now close properly when the user exits the figure. These new properties will be saved if you resave the figure, otherwise the ‘CloseRequestFcn’ and ‘CreateFcn’ will continue to be reset each time the figure file is loaded.

Best Answer

Related Solutions

MATLAB: Does the Image Acquisition Toolbox video preview window cause MATLAB to not respond or appear to hang

MATLAB: How to change ‘CloseRequestFcn’ property of a figure, so when the figure is reopened, it uses a different ‘CloseRequestFcn’

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