Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!pcad!rob
From: rob@pcad.UUCP (Ralph Brown)
Newsgroups: comp.windows.ms.programmer
Subject: Drawing Speed
Message-ID: <319@pcad.UUCP>
Date: 14 Nov 90 17:38:03 GMT
Organization: Personal CAD Systems, Westford, MA
Lines: 32

Hopefully this isn't a reposting.

I'm looking at Win 3.0 for a heavy graphics application and have done some
drawing timings which seem pretty odd. Perhaps I've just overlooked some
obvious setting for the PEN or GC which will make it all fine, if so, please
let me know.

On a 20 MHz 386 with EGA (640x480x16 colors) I got the following times for
drawing 50000 lines 130x4 horizontally:

Using a pen width 4 and LineTo,Moveto  - 272 Sec.

Using a NULL_PEN and BLACK_BRUSH and
        Polygon                        - 146 Sec.

Using the stock BLACK_PEN and drawing
        adjacent lines with LineTo     -  90 Sec.

Using the stock BLACK_PEN and adjacent
        lines with Polyline            -  56 Sec.

Using NULL_PEN and BLACK_BRUSH and
        Rectangle                      -  31 Sec.

It appears that the pen does something like redrawing the 4 unit diameter
circle repeatedly at each point on the line which isn't very efficient.

While I could use rectangles for horizontal and vertical lines, it won't
help much for diagonals or for arcs.

Thanks,
Ralph Brown - PCAD Westford Ma.