Amiga.org
Amiga computer related discussion => General chat about Amiga topics => Topic started by: sim085 on September 09, 2010, 03:09:25 PM
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Hello, Is there a good explanation of how data types worked? Also was this the default way how files where handled/opened on workbench?
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Hello, Is there a good explanation of how data types worked?
http://en.wikipedia.org/wiki/Amiga_support_and_maintenance_software#Datatypes
Also was this the default way how files where handled/opened on workbench?
No
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http://en.wikipedia.org/wiki/Amiga_support_and_maintenance_software#Datatypes
Woah, that page could use some English fix-up. Good info, though; I never knew about Fireworks for MorphOS.
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Also was this the default way how files where handled/opened on workbench?
I always prefered to open application first, and then load files into them. I'm probably just being old fashioned now, huh?
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http://en.wikipedia.org/wiki/Amiga_support_and_maintenance_software#Datatypes
Yes, but is there any documentation of how this worked internally and how I might develop a new datatype?
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Yes, but is there any documentation of how this worked internally
You should be more specific in your questions then. There most certainly is.
and how I might develop a new datatype?
Googling does help.
http://aminet.net/package/dev/c/C_V44-DT
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I always prefered to open application first, and then load files into them. I'm probably just being old fashioned now, huh?
Im with you on that one Kolla, never liked datatypes and always removed them from my set ups, there are much better apps for viewing files/pics etc.. on the miggy. :)
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http://aminet.net/package/dev/c/C_V44-DT
First of all thank you very much for your help.
You should be more specific in your questions then. There most certainly is.
Sorry for not being specific. What I am looking for is an explanation of how datatypes work. For example what happens when the user clicks on a file? How does the system know which datatype is responsable for which file? Does it loop through every installed datatype and each datatype opens the file (or part of the file) to determine if it is responsable for it?
I am not an experianced amiga user and therefore do not know where to look for this information. I will see the code of that datatype but not sure if I'll be able to understand it.
Thanks again.
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What I am looking for is an explanation of how datatypes work. For example what happens when the user clicks on a file?
You are mixing datatypes with DefIcons. When a user clicks on a file, datatypes are not involved at all. Up to 3.1 the file to be clicked on is not even identified. All files without icons are assumed to be programs.
Only with NewIcons or OS 3.5 the DefIcons program was introduced. It lets Workbench examine the file to determine a better icon for it. But this is not done with datatypes.
Datatypes need to be used explicitely. Multiview for example uses datatypes to determine the file type and to load/display/play back the file.
How does the system know which datatype is responsable for which file?
You don't need to know this. It's internally to datatypes.library. You just use the functions of datatypes.library in your program, for example NewDTObject and GetDTAttrs.
Probably datatypes.library iterates through all available data types. The descriptors in devs/datatypes contain the information how to identify a file type. Usually the file is opened only once by datatypes.library and a small buffer is used for comparisons which contains the first few bytes of the file (64 bytes IIRC).
Most datatype descritors are held very simple, for example "compare the first 12 bytes with the pattern FORM????ILBM". The comparison is done by datatypes.library, there is no foreign code involved.
Only very few desctiptors actually contain code. In this code everything can be done, though. For example the code can close and reopen the file and read it entirely if needed. But this should not be done because identification needs to be very fast.
Once the file type is identified and the application wants to load the file, the class library from classes/datatypes is called. This library contains the code to decode the file contents and to make it available to datatypes.library.
I am not an experianced amiga user and therefore do not know where to look for this information.
Everything you need is contained on the Amiga Developer CD. This CD is a real treasure of information.
First you should learn about BOOPSI. If you understand BOOPSI, it's easy to understand datatypes, ReAction, MUI, ...
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No idea where I got this from. Maybe the author lives here...
Most all the DataTypes can be found at Aminet:/util/dtype
(As of 1-24-95 the DataTypes were moved form /util/wb to
/util/dtype , you also may check there)
Data
Type Type of data Archive Where
--------------------------------------------------------------------------
Amiga
Guide HyperText Amiga Format Comes with 3.xOS OS
FTXT Text Comes with 3.xOS OS
Binary Shows Binaries in Hex and ASCII binarydt_39.11.lha Aminet
c/c++ Highlights c/c++ keywords etc cdt_39.15.lha Aminet
CLI Runs external CLI prog display Output clidt_39.2.lha Aminet
DFA Address tool for Amiga dfadt-391.lha Aminet
EXE Shows hunk based-file as ASCII exeDT394.lha Aminet
FONT Shows Amiga Fonts FontDT-1.1.lha Aminet
MAN Shows Unix Man Pages (nice!) mandt_v39.4.lha Aminet
TEXT Patches text.datatype/support search textdtptch39_2.lha Aminet
8SVX Amiga Sound Comes with 3.xOS OS
ADPCM Lossy sample compression IN:util/pack ADPCM_Package.lha Aminet
AIFF Audio Interchange File Format (1.11) aiff_dtc.lha Aminet
AIFC AIFF Compressed (1.11) aiff_dtc.lha Aminet
AU Sun audio (42.1) ams.lha Aminet
MACSND Apple Macintosh Sound MacSND-dtc-107.lha Aminet
MAUD MAUD IFF Format 32Bit maudDTr1.lha Aminet
VOC VOC files with different frequencies fpVOC_dt40.2.lha Aminet³
WAV Windows sound file fpWAV_dt40.2.lha Aminet
ANIM Amiga Animation Comes With 3.xOS OS²
AOM RAW data pics (Applied Optical Media) AOM_Raw_dt40.2.lha Aminet
DEBOX Images fromsome CDTV/CD32 CD-ROMS DeBox_DT40.2.lha Aminet
BMP Windows Bitmap picdt_42_1.lha Aminet
BMP Windows Bitmap BMPdt404.lha Aminet
CDXL ~DataStream (mostly video) Comes With 3.xOS OS²
FAXX Fax format Comes with TrapFax TrapFax
GIF Graphics Interchange Format 87a & 89a GIFdatatype-39.lha Aminet
GIF Graphics Interchange Format ZGIFDataType.lha Aminet
GIF Graphics Interchange Format ZGIFDType39.16.lha Aminet
ICO Windows Icon File picdt_42_1.lha Aminet
ILBM Amiga Format (IFF) Comes With 3.xOS OS
INFO Amiga Icon File infoDataType.lha Aminet
INFO Amiga Icon File infoDT39.1.lha Aminet
INFO Amiga Icon File icon_394.lha Aminet
JPEG JPEG datatype JpegDataType.lha Aminet³
JPEG New JFIF/JPEG datatype jfif_dtc.lha Aminet
JPEG A fix for "jfif_dtc.lha" jfif_FIX.lha Aminet
PIC MacPaint picdt_42_1.lha Aminet
PCX Z-Soft PC-PaintBrush File (39.2) PCX.datatype.lha Aminet
PCX Z-Soft PC-PaintBrush File picdt_42_1.lha Aminet
PCX Z-Soft PC-PaintBrush File (39.7) TPD.lha Aminet
PNG Portable Network Graphics (43.1) PNG_dt.lha Aminet
PS PostScript ¹ (39.0) PostScriptDT.lha Aminet
QRT POV Dump format (39.1) QRT_DT.lha Aminet
SVG Superview-Library's graphics format SVGDT402.lha Aminet
TIFF Tag Image File Format (40.5) TIFFDT.lha Aminet
XBM X-Bitmap picture ams.lha Aminet
SUN Sun Raster picture SUNdt396.lha Aminet
TGA Targa graphical file format TGAdt391.lha Aminet
TGA Targa or TGA images (39.2) TargaDType.lha Aminet
WPG WordPerfect images (39.0) WPGdtype.lha Aminet
REKO REKO cardsets / Klondike Deluxe AGA REKOdt392.lha Aminet
REKO REKO cardsets / Klondike Deluxe AGA MREKO-1.0.lha Aminet
HNS "MaxonMagic" Files fpHSN_dt40.1.lha Aminet
Sample Vision - MS-DOS computers (prg) smpDTr1.lha Aminet³
Yamaha TX16W - 12bit sample by Yamaha tx16wDTr2.lha Aminet³
¹needs post.library, can be found in HWGPOSTbeta7.lha (Aminet:/text/print)
²Comes with 3.1OS
³Needs 68020 or higher
NOTE: Some of the DT files have been removed from Aminet for one reason
or another. If you are looking for a file that is not currently on
Aminet you might look on a older Aminet CDROM.
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Im with you on that one Kolla, never liked datatypes and always removed them from my set ups, there are much better apps for viewing files/pics etc.. on the miggy. :)
I don't follow the logic here, that I prefer to open apps first and then load files into them has nothing to do with datatypes. My comment was regarding "the default way how files where handled/opened on workbench", which again, has nothing to do with datatypes.
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I don't follow the logic here, that I prefer to open apps first and then load files into them has nothing to do with datatypes. My comment was regarding "the default way how files where handled/opened on workbench", which again, has nothing to do with datatypes.
He was probably refering to Multiview which truly was a dreadful application. I generally set all my files to be opened through Dopus. Much better.
I do recall each month getting AUI and Amiga Computing just to get the shed loads of new datatypes off the cover disks.
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The only problem I have with datatypes is that they aren't really bidirectional. You can generally only save in IFF.
In my minds eye, the ideal implementation would allow each datatype superclass (picture.datatype, sound.datatype etc) to provide a list of all currently known sub-classes that support encoding. You'd then be able to pick one and encode data for that datatype and write it out to disk in that format.
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I always prefered to open application first, and then load files into them. I'm probably just being old fashioned now, huh?
Interesting... I always preferred to launch data files with DirOpus, after configuring it to recognize file types from the file itself.... I still prefer to work that way on the peecee.
I guess I'm old and set in my ways. ;-)
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Interesting... I always preferred to launch data files with DirOpus, after configuring it to recognize file types from the file itself.... I still prefer to work that way on the peecee.
I guess I'm old and set in my ways. ;-)
I have to say that the day I found DOpus everything changed for me on the Amiga. It was like a massive door had just opened into a treasure vault I had never been in. I don`t think there has been another piece of software to match it. So much power from such a simple interface. Mastering DOpus was/is always interesting and a fun thing to do.
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Hello, Is there a good explanation of how data types worked?
They don't work. At least OS3.x gfx datatypes don't work in 256 color mode due to a mind-bogglingly stupid design flaw. So if you are going to make a gfx datatype it can only work 100% in 24-bit mode, which should be ok for you as most ppl use 24-bit gfx these days. :)
What kind of datatype do you want to make btw?