Graphics |
The Figure Close Request Function
MATLAB executes a callback routine defined by the figure's
CloseRequestFcn
whenever you
close
command on a figure.
Visible
property is set to off
, MATLAB does not execute its close request function when you quit MATLAB; the figure is just deleted).
The close request function enables you to prevent or delay the closing of a figure or the termination of a MATLAB session. This is useful to perform such actions as
The default callback routine for the CloseRequestFcn
is an M-file called closereq
. It contains the statements
shh=get(0,'ShowHiddenHandles'); set(0,'ShowHiddenHandles','on'); delete(get(0,'CurrentFigure')); set(0,'ShowHiddenHandles',shh);
This callback disables HandleVisibility
control by setting the root ShowHiddenHandles
property to on
, which makes all figure handles visible.
Quitting MATLAB
When you quit MATLAB, the current figure's CloseRequestFcn
is called, and if the figure is deleted, the next figure in the root's list of children (i.e., the root's Children
property) becomes the current figure, and its CloseRequestFcn
is in turn executed, and so on. You can, therefore, use gcf
to specify the figure handle from within the close request function.
If you change a figure's CloseRequestFcn
so that it does not delete the figure (e.g., defining this property as an empty string), then issuing the close command on that figure does not cause it to be deleted. Furthermore, if you attempt to quit MATLAB, the quit is aborted because MATLAB does not delete the figure.
Errors in the Close Request Function
If the CloseRequestFcn
generates an error when executed, MATLAB aborts the close operation. However, errors in the CloseRequestFcn
do not abort attempts to quit MATLAB. If an error occurs in a figure's CloseRequestFcn
, MATLAB closes the figure unconditionally following a quit
or exit
command.
Overriding the Close Request Function
The delete
command always deletes the specified figure, regardless of the value of its CloseRequestFcn
. For example, the statement
deletes all figures whose handles are not hidden (i.e., the HandleVisibility
property is set to off
). If you want to delete all figures regardless of whether their handles are hidden, you can set the root ShowHiddenHandles
property to on
. The root Children
property then contains the handles of all figures. For example, the statements
unconditionally delete all figures.
Protecting Figures and Axes | Handle Validity Versus Handle Visibility |
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