| Re: Adding Devices to PV~Wave/IDL [message #2214] |
Tue, 21 June 1994 15:52 |
c1dje
Messages: 2
Registered: March 1993
|
Junior Member |
|
|
One can add new builtin functions, procedures, and graphics device
drivers, to IDL (and I assume PV~WAVE as well). RSI has (had?) an IDL
Internals guide which described exactly such functionality.
GIF, however, is an image file format, so writing a graphics device
driver primarily requires duplication of all of the graphics primitives
writing to an internal buffer (not just inserting images from TV calls, but
drawing lines and text, color tables, magnification, etc.). The format only
comes into play when closing the file -- applying GIF compression algorithm
to the final state of the buffer and writing the data stream to a file.
IDL already provides a Z-buffer device which applies graphics
commands to an internal memory buffer. Instead of duplicating all of the
difficult graphics device driver functionality for an internal memory
buffer, I would recommend simply reading the final image of the Z-buffer
using TVRD and then writing that image to a file in GIF format, possibly
using CALL_EXTERNAL function if the library read_gif and write_gif
procedures do not fulfill your needs.
David
P.S. I wrote a device driver for the CELCO Film Recorder (based upon
a device driver for the Polaroid Digital Palette written by Mark Rivers of
Brookhaven) before IDL provided the Z-buffer. Once the Z-buffer was
introduced, I converted to using TVRD and a special function to generate the
CELCO-format files. I am much happier with the latter implementation as it
has many more features and is much easier to maintain.
============================================================ ===================
David Edelsohn T.J. Watson Research Center
c1dje@watson.ibm.com P.O. Box 218
+1 914 945 3011 (Tieline 862) Yorktown Heights, NY 10598
"I'm not weird, I'm different." -- Frank Zappa
"It's only a dream away ..." -- from Time Bandits ending credits song
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
