MATLAB Function Reference (Volume 2: Graphics)

Image Properties• xor – Draw and erase the image by performing an exclusive OR (XOR) withthe color of the screen beneath it. This mode does not damage the color of theobjects beneath the image. However, the image’s color depends on the colorof whatever is beneath it on the display.• background – Erase the image by drawing it in the axes’ background Color,or the figure background Color if the axes Color is set to none. This damagesobjects that are behind the erased image, but images are always properlycolored.Printing with Non-normal Erase Modes. MATLAB always prints figures as if theEraseMode of all objects is normal. This means graphics objects created withEraseMode set to none, xor, or background can look different on screen than onpaper. On screen, MATLAB may mathematically combine layers of colors (e.g.,XORing a pixel color with that of the pixel behind it) and ignorethree-dimensional sorting to obtain greater rendering speed. However, thesetechniques are not applied to the printed output.You can use the MATLAB getframe command or other screen captureapplication to create an image of a figure containing non-normal mode objects.HandleVisibility {on} | callback | offControl access to object’s handle by command-line users and GUIs. Thisproperty determines when an object’s handle is visible in its parent’s list ofchildren. HandleVisibility is useful for preventing command-line users fromaccidentally drawing into or deleting a figure that contains only user interfacedevices (such as a dialog box).Handles are always visible when HandleVisibility is on.Setting HandleVisibility to callback causes handles to be visible fromwithin callback routines or functions invoked by callback routines, but not fromwithin functions invoked from the command line. This provide a means toprotect GUIs from command-line users, while allowing callback routines tohave complete access to object handles.Setting HandleVisibility to off makes handles invisible at all times. Thismay be necessary when a callback routine invokes a function that mightpotentially damage the GUI (such as evaling a user-typed string), and sotemporarily hides its own handles during the execution of that function.2-239