MATLAB Function Reference (Volume 2: Graphics)

Image PropertiesCreateFcnstringCallback routine executed during object creation. This property defines acallback routine that executes when MATLAB creates an image object. Youmust define this property as a default value for images. For example, thestatement,set(0,'DefaultImageCreateFcn','axis image')defines a default value on the root level that sets the aspect ratio and the axislimits so the image has square pixels. MATLAB executes this routine aftersetting all image properties. Setting this property on an existing image objecthas no effect.The handle of the object whose CreateFcn is being executed is accessible onlythrough the root CallbackObject property, which you can query using gcbo.DeleteFcnstringDelete image callback routine. A callback routine that executes when you deletethe image object (i.e., when you issue a delete command or clear the axes orfigure containing the image). MATLAB executes the routine before destroyingthe object’s properties so these values are available to the callback routine.The handle of the object whose DeleteFcn is being executed is accessible onlythrough the root CallbackObject property, which you can query using gcbo.EraseMode{normal} | none | xor | backgroundErase mode. This property controls the technique MATLAB uses to draw anderase image objects. Alternative erase modes are useful for creating animatedsequences, where control of the way individual objects redraw is necessary toimprove performance and obtain the desired effect.• normal (the default) — Redraw the affected region of the display, performingthe three-dimensional analysis necessary to ensure that all objects arerendered correctly. This mode produces the most accurate picture, but is theslowest. The other modes are faster, but do not perform a complete redrawand are therefore less accurate.• none – Do not erase the image when it is moved or changed. While the objectis still visible on the screen after erasing with EraseMode none, you cannotprint it because MATLAB stores no information about its former location.2-238