uiguide

(/tools/hpmatlab/toolbox/matlab/graphics/uiguide.m)

Help text

   MATLAB4 User Interface and Handle Graphics Programming Guidelines 

   This help file contains useful tips, tricks, and methods for crafting
   MATLAB4 applications with a graphical user interface.  Obeying
   the guidelines listed has been found to yield code which is efficient 
   (executes quickly and requires fewer lines), changeable, extensible, and 
   intuitive.  


                AN EFFECTIVE GUI PROGRAMMING METHODOLOGY

  o Callbacks should be short and call functions.
    When MATLAB evals a string, it must interpret it statement by statement.
    MATLAB must do the same with a script m-file.  It behaves differently with
    a function: the first time MATLAB encounters the function, it compiles it.
    MATLAB does not re-interpret the function on subsequent calls.  Thus of the
    three possibilities (function m-file, script m-file, and long string), 
    making the callback a function m-file is by far the fastest, especially
    if the callback is long.

  o Switchyard concept of GUI programming.
    This involves coding an application with a GUI as a single function.
    Inside the function is a large if-then-else construct which executes
    portions of the function based on an input switch.  Callback functions
    of UI objects (uicontrols and uimenus) and mouse Button functions 
    (down/motion/up) simply call the function with the appropriate input 
    argument.  Callbacks are therefore very short and editing them is easier 
    than changing multi-line string definitions.  A call to the function
    with no input argument could by default start the program.  Program 
    specific data and UI object handles are stored either as globals to the 
    function or in the UserData of the objects.  This makes the application
    "clear-proof".  For an example of this sort of programming, see "sigdemo1".

    
                GETTING THE MOST OUT OF HANDLE GRAPHICS 
      (or, how to create fast and smooth click and drag applications)

  o Draw moveable or changing objects with the 'erasemode' property set to 
    'xor' or 'background'.  This prevents rerendering the axes when changing 
    these objects. 'erasemode' is a property of all objects which are children 
    of axes (line, text, surface, image, patch).

  o Set 'drawmode' (an axes property) to 'fast'.  This prevents MATLAB from
    sorting 3D objects, which can speed things up significantly.  The side-
    effect is that 3D surface plots will not work in this mode.

  o Set 'backingstore' (a figure property) to 'off'.  This should give 
    roughly a factor of two speed-up in normal drawing but turns off the 
    instantaneous update that normally ocurrs when windows are uncovered.

  o Set 'nextplot' (a figure property) to 'new' when creating a GUI.  That 
    way when you make plots from the command window they don't appear in the
    axes of the GUI's figure window.

  o Wherever possible, recycle figure windows by using the 'visible' property
    of figures instead of creating and destroying them.  When done with the
    window, set 'visible' to 'off'; when you need the window again, make any
    changes to the window and THEN set 'visible' to 'on'.  Creating figure
    windows involves much more overhead than unhiding them.

  o Set a uicontrol's style upon creation.  E.g. uicontrol('Style','edit')
    is much faster than h=uicontrol;set(h,'Style','edit').
 
  o Set a figure's position upon creation.  E.g. figure('Pos',[10 10 200 100])
    is much faster than f=figure;set(f,'Pos',[10 10 200 100]).