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From: stripes@eng.umd.edu (Joshua Osborne)
Newsgroups: comp.windows.x
Subject: Re: strip-chart display
Message-ID: <1990Dec29.045757.840@eng.umd.edu>
Date: 29 Dec 90 04:57:57 GMT
References: <9012281317.AA10469@jargon.whoi.edu>
Sender: news@eng.umd.edu (C-News)
Reply-To: stripes@eng.umd.edu (Joshua Osborne)
Organization: College of Engineering, Maryversity of Uniland, College Park
Lines: 39

In article <9012281317.AA10469@jargon.whoi.edu>, kens@JARGON.WHOI.EDU (Ken Stewart) writes:

[...]
You may wel get some more speed from this:

> **************************************************************************
> 
> 1) BITBLT
>     .
>     .
>     /* scroll the display right */
>     XCopyArea( dpy, xwin, xwin, gc, 0, min_height, 
>                 canvas_width - horiz_incr, canvas_height, horiz_incr, 0 );
[replce w/]       canvas_width - horiz_incr,    max_height, horiz_incr, 0 );
> 
>     /* clear a small region at left */
>     XClearArea( dpy, xwin, 0, 0, horiz_incr, canvas_height, False );     
[replace w/]
      XClearArea( dpy, xwin, 0, min_height, horiz_incr, max_height, False );     
> 
>     new_y = ...
> 
>     /* connect the new data point */
>     XDrawLine( dpy, xwin, gc, horiz_incr, last_y, 0, new_y );
> 
>     last_y = new_y;
>     .
>     .

Less bits to blt most of the time.  Should end up being faster.  (but you will
have to track the max/min values correctly)


-- 
           stripes@eng.umd.edu          "Security for Unix is like
      Josh_Osborne@Real_World,The          Multitasking for MS-DOS"
      "The dyslexic porgramer"                  - Kevin Lockwood
"Don't over-comment"     - p151 The Elements of Programming Style 2nd Edition
                                   Kernighan and Plauger