Basics of MATLAB and Beyond

1. Use graphical elements that serve no other purpose than to allowthe user to interact (virtual buttons, switches, knobs, sliders, popupmenus, and so on). (See demo for examples of these.)2. Use graphical elements that perform a dual function: display dataand interaction. For example, a plotted line can both display dataand can alter data when a user clicks on the line and drags it to anew position. (See sigdemo1 in the signal processing toolbox foran example.)3. Use mouse-downs, drags, and mouse-ups anywhere within the Figureto perform an action. (For example, typing rotate3d wheneveryou are displaying a three-dimensional plot allows you to click anddrag to change the viewpoint.)The first group of GUIelements (buttons, etc.) are the easiest to workwith, so we deal with those first.There are three GUI-specific graphical objects in matlab: uicontrols,uimenus, and uicontextmenus.These are at the same level as Axes objects in matlab’s object hierarchy.They are children of Figures; they have no children. Their appearanceand behaviour are defined by their property values. We first look at thedifferent styles of uicontrol. Then we will look at how you can programa uicontrol to do something by setting its callback property. Finally,we will go through the various uicontrols in a bit more detail, beforeconsidering uimenus. Uicontextmenus control matlab’s behaviour whenyou do a “right-click” (or equivalent menu-getting click on your system)on a graphical object. They will not be described here, but you can finda description in the helpdesk entry under Handle Graphics Objects.If you type uicontrol, you will get matlab’s default uicontrol (weassign its handle to h for later use):h = uicontrol;As usual, get(h) will give you a list of properties for this object. Animportant property for uicontrols is the style property. The style of thisobject is>> get(h,’style’)ans =pushbuttonc○ 2000 by CRC Press LLC