
Technical Reference Manual

Including Information For:
Publisher's Paintbrush~
PC Paintbrush~ Plus
PC Paintbrush
FRIEZE Graphics~









ZSoft Corporation
450 Franklin Rd. Suite 100
Marietta, GA  30067
(404) 428-0008




Copyright 1988 ZSoft Corporation
Table of Contents
Introduction                            3
Image File (.PCX) Format                4
Decoding the .PCX File Format           6
Palette Information Description         7
PC Paintbrush Bitmap Font Format        9
Sample "C" Routines                     10
FRIEZE Technical Information            13
Pre-7.00 FRIEZE Specifications          14
Pre-7.00 FRIEZE Function Calls          15
Pre-7.00 FRIEZE Error Codes             16
7.00 and later FRIEZE Specifications    17
7.00 and later FRIEZE Function Calls    18
7.00 and later FRIEZE Error Codes       19
The .PCX Programmer's Toolkit           21




Introduction
This booklet was designed to aid developers and users in understanding the technical aspects of the .PCX file format and the use of FRIEZE.
Any comments, questions or suggestions about this booklet should be sent to:
ZSoft Corporation
Technical Support Department
ATTN: Technical Reference Manual
450 Franklin Rd. Suite 100
Marietta, GA  30067




IMAGE FILE (.PCX) FORMAT
The information in this section will be useful if you want to write a program to read or write PCX files (images).  If you want to write a special case program for one particular image format you should be able to produce something that runs twice as fast as "Load from..." in PC Paintbrush.
Image files used by PC Paintbrush product family and FRIEZE (those with a .PCX extension) begin with a 128 byte header.  Usually you can ignore this header, since your images will all have the same resolution.  If you want to process different resolutions or colors, you will need to interpret the header correctly.  The remainder of the image file consists of encoded graphic data.  The encoding method is a simple byte oriented run-length technique.  We reserve the right to change this method to improve space efficiency.  When more than one color plane is stored in the file, each line of the image is stored by color plane (generally ordered red, green, blue, intensity), As shown below.
Scan line 0:    RRR...
		GGG...
		BBB...
		III...
Scan line 1:    RRR...
		GGG...
		BBB...
		III...
(etc.)
The encoding method is:
FOR  each  byte,  X,  read from the file
	IF the top two bits of X are  1's then
		count = 6 lowest bits of X
		data = next byte following X
	ELSE
		count = 1
		data = X
Since the overhead this technique requires is, on average,  25% of the non-repeating data and is at least offset whenever  bytes are repeated, the file storage savings are usually considerable.
The format of the file header is shown below.

ZSoft .PCX FILE HEADER FORMAT

Byte    Item            Size    Description/Comments

0       Manufacturer    1       Constant Flag  10 = ZSoft .PCX
1       Version         1       Version information:
				0 = Version 2.5
				2 = Version 2.8 w/palette information
				3 = Version 2.8 w/o palette information
				5 = Version 3.0
2       Encoding        1       1 = .PCX run length encoding
3       Bits per pixel  1       Number of bits/pixel per plane
4       Window          8       Picture Dimensions 
				(Xmin, Ymin) - (Xmax - Ymax)
				in pixels, inclusive
12      HRes            2       Horizontal Resolution of creating device
14      VRes            2       Vertical Resolution of creating device
16      Colormap        48      Color palette setting, see text
64      Reserved        1
65      NPlanes         1       Number of color planes
66      Bytes per Line  2       Number of bytes per scan line per 
				color plane (always even for .PCX files)
68      Palette Info    2       How to interpret palette - 1 = color/BW,
				2 = grayscale
70      Filler          58      blank to fill out 128 byte header

~NOTES:
~All sizes are measured in BYTES.
All variables of size 2 are integers.



Decoding .PCX Files
First, find the pixel dimensions of the image by calculating [XSIZE = Xmax - Xmin + 1] and [YSIZE = Ymax - Ymin + 1].  Then calculate how many bytes are required to hold one complete uncompressed scan line:
TotalBytes = NPlanes * BytesPerLine
Note that since there are always an integral number of bytes, there will probably be unused data at the end of each scan line.  TotalBytes shows how much storage must be available to decode each scan line, including any blank area on the right side of the image.  You can now begin decoding the first scan line - read the first byte of data from the file.  If the top two bits are set, the remaining six bits in the byte show how many times to duplicate the MDULnextMDNM byte in the file.  If the top two bits are not set, the first byte is the data itself, with a count of one.
Continue decoding the rest of the line.  Keep a running subtotal of how many bytes are moved and duplicated into the output buffer.  When the subtotal equals TotalBytes, the scan line is complete.  There will always be a decoding break at the end of each scan line.  But there will not be a decoding break at the end of each plane within each scan line.  When the scan line is completed, there may be extra blank data at the end of each plane within the scan line.  Use the MDBOXSIZEMDNM and MDBOYSIZEMDNM values to find where the valid image data is.  If the data is multi-plane BytesPerLine shows where each plane ends within the scan line.
Continue decoding the remainder of the scan lines.  There may be extra scan lines at the bottom of the image, to round to 8 or 16 scan lines.
Palette Information Description
EGA/VGA 16 Color Palette Information
The palette information is stored in one of two different formats.  In standard RGB format (IBM EGA, IBM VGA) the data is stored as 16 triples.  Each triple is a 3 byte quantity of Red, Green, Blue values.  The values can range from 0-255 so some interpretation into the base card format is necessary.  On an IBM EGA, for example, there are 4 possible levels of RGB for each color.  Since 256/4 = 64, the following is a list of the settings and levels:
Setting         Level
0-63            0
64-127          1
128-192         2
193-254         3

VGA 256 Color Palette Information
ZSoft has recently added the capability to store palettes containing more than 16 colors in the .PCX image file.  The 256 color palette is formatted and treated the same as the 16 color palette, except that it is substantially longer.  The palette (number of colors x 3 bytes in length) is appended to the end of the .PCX file, and is preceded by a 12 decimal.  To determine the VGA BIOS palette you need only divide the values read in the palette by 4.
To access a 256 color palette:
First, check the version number in the header, if it contains a 5 there is a palette.
Second, read to the end of the file and count back 769 bytes.  The value you find should be a 12 decimal, showing the presence of a 256 color palette.
CGA Color Palette Information
For a standard IBM CGA board, the palette settings are a bit more complex.  Only the first byte of the triple is used.  The first triple has a valid first byte which represents the background color.  To find the background, take the (unsigned) byte value and divide by 16.  This will give a result between 0-15, hence the background color.  The second triple has a valid first byte, which represents the foreground palette.  PC Paintbrush supports 8 possible CGA palettes, so when the foreground setting is encoded between 0 and 255, there are 8 ranges of numbers and the divisor is 32.
MDUL
CGA Color MapMDNM
Header Byte #16 
Background color is determined in the upper four bits.
Header Byte #19
Only upper 3 bits are used, lower 5 bits are ignored.  The first three bits that are used are ordered C, P, I.  These bits are interpreted as follows:
c: color burst enable - 0 = color; 1 = monochrome
p: palette - 0 = yellow; 1 = white
i: intensity - 0 = dim; 1 = bright

PC Paintbrush Bitmap Character Format
The bitmap character fonts are stored in a particularly simple format.  The format of these characters is as follows:
Header (2 bytes)
font width      db      0a0h + character width (in dots)
font height     db      character height (in dots)
Character Widths (256 bytes)
char widths     db      256 dup(each char's width +1)
Character Images
(remainder of the file)
The characters are stored in ASCII order and as many as 256 may be provided.  Each character is left justified in the character block, all characters take up the same number of bytes.
Bytes are organized as N strings, where each string is one scan line of the character.  See figure 2.
For example, each character in a 5x7 font requires 7 bytes.  A 9x14 font uses 28 bytes per character (stored two bytes per scan line in 14 sets of 2 byte packets).  Custom fonts may be any size up to the current maximum of 10K bytes allowed for a font file.

Sample "C" Routines
The following is a simple set of C subroutines to read data from a .PCX file.
/* This procedure reads one encoded block from the image file and stores a count and data byte. Result:
0 = valid data stored
EOF = out of data in file */
encget(pbyt, pcnt, fid)
int *pbyt;     /* where to place data */
int *pcnt;     /* where to place count */
FILE *fid;     /* image file handle */
{
int i;
	*pcnt = 1;     /* safety play */
	if(EOF    ==    (i    =    getc(fid))) return(EOF);
	if(0xc0 == (0xc0 & i))   {
	*pcnt = 0x3f&i;
	if(EOF == (i=getc(fid)))
			return(EOF);
}
*pbyt = i;
return(0);
}
/* Here's a program fragment using encget.   This reads an entire file and stores it in a (large) buffer, pointed to by the variable "bufr". "fp" is the file pointer for the image */
while (EOF != encget(&chr, &cnt, fp))
		for (i = 0; i ~                 *bufr++ = chr;
The following is a set of C subroutines to write data to a .PCX file.
 /* This subroutine encodes one scanline and writes it to a file */
encLine(inBuff, inLen, fp)
unsigned char *inBuff;  /* pointer to scanline data */
int inLen;                      /* length of raw scanline in bytes */
FILE *fp;                       /* file to be written to */
{  /* returns number of bytes written into outBuff, 0 if failed */
	unsigned char this, last;
int srcIndex, i;
register int total;
register unsigned char runCount; /* max single runlength is 63 */
total = 0;
last = *(inBuff);               runCount = 1;

for (srcIndex = 1; srcIndex  inLen; srcIndex++) {
	this = *(++inBuff);
	if (this == last)       {
		 runCount++;    /* it encodes */
		if (runCount == 63)     {
			if (!(i=encput(last, runCount, fp)))
				return(0);
			total += i;
			runCount = 0;
			}
		}
	else    {   /* this != last */
		if (runCount)   {
			if (!(i=encput(last, runCount, fp)))
				return(0);
			total += i;
			}
		last = this;
		runCount = 1;
		}
	}       /* endloop */
if (runCount)   {               /* finish up */
	if (!(i=encput(last, runCount, fp)))
		return(0);
	return(total + i);
	}
return(total);
}

/* subroutine for writing an encoded byte pair 
(or single byte  if it doesn't encode) to a file */
encput(byt, cnt, fid) /* returns count of bytes written, 0 if err */
unsigned char byt, cnt;
FILE *fid;
{
if(cnt) {
	if( (cnt==1) && (0xc0 != (0xc0&byt)) )  {
		if(EOF == putc((int)byt, fid))
			return(0); /* disk write error (probably full) */
		return(1);
		}
	else            {
		if(EOF == putc((int)0xC0 | cnt, fid))
			return(0);      /* disk write error */
		if(EOF == putc((int)byt, fid))
			return(0);      /* disk write error */
		return(2);
		}
	}
return(0);
}




FRIEZE Technical Information


FRIEZE Information

FRIEZE is a memory resident utility that allows you to capture and save graphic images from other programs.  You can then bring these images into PC Paintbrush for editing and enhancement.
FRIEZE was rewritten for use in PC Paintbrush Plus, and so the technical information about FRIEZE has changed dramatically.   To easily provide technical information for all versions of FRIEZE, we have split this section of the manual into two parts, one about PRE-7.00 versions of FRIEZE, and one about the current versions (7.00 or higher).
FRIEZE 7.10 and later can be removed from memory (this can return you almost 85K of DOS RAM, depending on your configuration).  To do this, you can choose to release FRIEZE from memory in the PCINSTAL menu, or at any time by changing directories to your PC PAINTBRUSH product directory and typing the word "FRIEZE."


Pre-7.00 FRIEZE Specifications


FRIEZE Print Option Settings

FRIEZE can easily adapt to incomplete printer cables (missing IBM specified status lines) and will drive either serial or parallel devices.  Note that FRIEZE always uses the standard BIOS calls, so a non-handshaking device will time out, but can be told to ignore such things as paper out.
The FRIEZE command syntax is:
FRIEZE Xnaarr
Where:
X = either Parallel or Serial
n = port number 
aa = a two digit hexadecimal code for which return bits cause an abort
rr = a two digit hexadecimal code for which return bits cause a retry
Examples:
FRIEZE P1 - use the default settings of Parallel output, port number 1, abort mask of 28h, and retry mask of 01h
FRIEZE P2 - use printer port #2
FRIEZE S1 - use serial port #1, and Xon/Xoff handshaking
FRIEZE P10028 - use printer port #1, abort mask of 00 (nothing is read as an error) and retry mask of 28h
Interpreting the codes:
On return from the parallel printer call, the bit interpretations are:
80h - busy signal (0=busy)
40h - acknowledge
20h - out of paper
10h - selected
08h - I/O error
04h - unused
02h - unused
01h - time out


FRIEZE Function Calls

FRIEZE is operated using software interrupt number  10h (the video interrupt call).
To make a FRIEZE function call, load 75 (decimal) into the  AH register, the function call number into the CL register and then, either load AL with the function argument or load ES and BX with a segment and offset which point to the function argument then do an int 10h.
FRIEZE will return a result code number in AX--zero means  success, other values show error conditions.  All other registers are unchanged.
No.     Definition      Arguments
0       Print Window    AL = mode: 0 - character,
			1 - normal, 2 - sideways
1       Read Window     ES:BX - string
			(filename to read from)
2       Write Window    ES:BX - string
			(filename to write to)
3       Print Width     AL = width in 1/4 inches
4       Print Height    AL = height in 1/4 inches
5       Reserved
6       Set Left Margin AL = printout margin in 
			1/4 inches
7       Set Window Size ES:BX - 4 element word
			vector of window settings:
			Xmin, Ymin, Xmax, Ymax
8       Reserved
9       Set Patterns    ES:BX - 16 element vector
			of byte values containing the
			screen-to-printer color
			correspondence
10      Get Patterns    ES:BX - room for 16 bytes as
			above
11      Set Mode        AL = mode number
			(See SETMODE command)
12      Reserved
13      Reserved
14      Reserved
15      Get Window      ES:BX - room for 4 words of
			the current window settings
16      Set Print Options       ES:BX - character string of
			printer options.  Same format
			as for the FRIEZE command.
17      Initialize      ES:BX - 3 word array
			containing data from 
			PC Paintbrush Disk 1 file
			CARDS.DAT (Hres, Vres,
			optional code number)
All character strings are ended by a zero byte (ASCIIZ format).


FRIEZE Error Codes

When FRIEZE is called using interrupt 10 hex, it will return an error code in the AX register.  A value of zero shows that there was no error.  A nonzero result means there was an error.  These error codes are explained below.
0       No Error
1       Printout was stopped by user with the ESC key
2       Reserved
3       File read error
4       File write error or printer error
5       File not found
6       Invalid Header or can't create file
	(not a picture or wrong screen mode)
7       File close error
8       Disk error - usually drive door open
9       Not used
10      Invalid command - CL was set to call a nonexistent 
	FRIEZE function
11      Not used
12      Not used


7.00 and Later FRIEZE

The newer versions of FRIEZE have a different number of parameters on its command line.  The new FRIEZE command line format is:
FRIEZE {PD} {Xnaarr} {flags} {video} {hres} {vres} {vnum}
Where:
{PD}    Printer driver filename (without the .PDV extension)
{Xnaarr}
		X=S for Serial Printer X=P for Parallel Printer
		n = port number
		aa = Two digit hex code for which return bits cause
			 an abort
		rr = Two digit hex code for which return bits cause
			a retry
{flags} Four digit hex code
			First Digit controls Length Flag
			Second Digit controls Width Flag
			Third Digit controls Mode Flag
			Fourth Digit controls BIOS Flag
NOTE:   The length, width and mode flags are printer driver specific.
		See PRINTERS.DAT on disk 1 for correct use.  In 
		general width flag of 1 means wide carriage, and 
		0 means standard width.  Length flag of 0 and 
		mode flag of 0 means use standard printer driver 
		settings.
{video} Video driver combination, where the leading digit
		signifies the high level video driver and the rest
		signifies the low level video driver
		Example = 1EGA - uses DRIVE1 and EGA.DEV
{hres}  Horizontal resolution of the desired graphics mode
{vres}  Vertical resolution of the desired graphics mode
{vnum}  Hardware specific parameter (usually number of color planes)
Note: The last four parameters can be obtained from the CARDS.DAT file, on Disk 1 of your PC Paintbrush diskettes.
Parallel printer return codes:
	80h - Busy Signal (0=busy)
	40h - Acknowledge
	20h - Out of paper
	10h - Selected
	08h - I/O error
	04h - Unused
	02h - Unused
	01h - Time out


FRIEZE Function Calls

FRIEZE is operated using software interrupt number  10h (the video interrupt call).
To make a FRIEZE function call, load 75 (decimal) into the  AH register, the function number into the CL register and then, either load AL with the function argument or load ES and BX with a segment and offset which point to the function argument then do an int 10h.
FRIEZE will return a result code number in AX--zero means  success, other values show error conditions.  All other registers are unchanged.
No.     Definition      Arguments
0       Reserved
1       Load Window     ES:BX - string
			(filename to read from)
2       Save Window     ES:BX - string
			(filename to write to)
3       Reserved
4       Reserved        
6       Reserved        
7       Set Window Size ES:BX - 4 element word
			vector of window settings:
			Xmin, Ymin, Xmax, Ymax
8       Reserved
9       Set Patterns    ES:BX - 16 element vector
			of byte values containing the
			screen-to-printer color
			correspondence
10      Get Patterns    ES:BX - room for 16 bytes as
			above
11      Set Mode        AL = mode number
			(See SETMODE command)
12      Reserved
13      Reserved
14      Reserved
15      Get Window      ES:BX - room for 4 words of
			the current window settings
16      Set Print Options       ES:BX - character string of
			printer options.  Same format
			as for the FRIEZE command.
17      Reserved
18      Reserved
19      Reserved
20      Get FRIEZE Version.     AH gets the whole number portion 
			and AL gets the decimal portion of
			the version number.  If AH=0, it
			can be assumed that it is a 
			pre-7.00 version of FRIEZE.
21      Set Parameters  ES:BX points to an 8 word table 
			(16 bytes) of parameter settings: 
			TopMargin, LeftMargin, HSize,VSize,
			Quality/Draft Mode, PrintHres, 
			PrintVres, Reserved.    
			Margins and sizes are specified in 
			hundredths of inches.
			Q/D mode parameter values:
			0 - draft print mode
			1 - quality print mode
			2 - use Hres, Vres for output 
			resolution.  Print resolutions are 
			specified in DPI.  Any parameter
			which should be left unchanged may      
			be filled with a (-1) (0FFFF hex).  
			The reserved setting should be filled
			with a (-1).
22      Get Parameters  ES:BX points to an 8 word table 
			(16 bytes) where parameter settings
			are held.
23      Get Printer Res ES:BX points to a 12 word table
			(24 bytes) where printer resolution
			pairs (6 pairs) are held.
NOTE: All character strings are ended by a zero byte 
	(ASCIIZ format).


FRIEZE Error Codes

When FRIEZE is called using interrupt 10 hex, it will return an error code in the AX register.  A value of zero shows that there was no error.  A nonzero result means there was an error.  These error codes are explained below.
0       No Error
1       Printout was stopped by user with the ESC key
2       Reserved
3       File read error
4       File write error
5       File not found
6       Invalid Header - not an image, wrong screen mode
7       File close error
8       Disk error - usually drive door open
9       Printer error - printer is off or out of paper
10      Invalid command - CL was set to call a nonexistent 
	FRIEZE function
11      Can't create file - write protect tab or disk is full
12      Wrong video mode - FRIEZE cannot capture text screens.



The PCX Programmer's Toolkit

The MDBOPCX Programmer's ToolkitMDNM, by Genus Microprogramming, allows developers to create applications with the ability to display, save, capture, and manipulate PCX format images.  Because it supports the most common display adapters and compilers, the toolkit can be used in a wide variety of areas.  Besides the library interfaces, many utility programs are provided for displaying and capturing screens, creating windows, inspecting image headers and locating coordinates. 
Over 35 routines for displaying and saving images from buffers and files, setting palettes, accessing image headers, and more.
Written in Assembler for maximum display speed
Fast enough for animation
Image library manager saves disk space and makes portability easy (group multiple PCX images in a single library file)
Display images within database applications
MDBO
Displays Supported:MDNM All Modes of the Hercules, CGA, EGA, and VGA graphics adapters.
MDBO
Compilers Supported:MDNM Linkable libraries are provided for Microsoft C, Turbo C, QuickC, Lattice C, QuickBasic, Turbo Pascal, and Clipper.  Quick libraries are provided for the Microsoft integrated compilers, and a unit is provided for Turbo Pascal.  Small, Medium, and Large model libraries are included for compilers that support multiple memory models.
MDBO
Software Supported:MDNM Paint packages such as ZSoft's PC Paintbrush and Microsoft Paintbrush are directly compatible.  Desktop Publishing packages supported include Xerox Ventura Publisher and Aldus PC PageMaker.
MDBO
What the Toolkit Requires:MDNM  An IBM PC/XT/AT or 100% compatible, 120disk drive, an IBM CGA/EGA/VGA, or Hercules adapter (or 100% compatible), and DOS 2.0 or above. 


Only 89.95!!!

Order direct from:
ZSoft Corporation
450 Franklin Rd., Suite 100
Marietta, GA.  30057
(404) 428-0008

Microsoft, Microsoft C, QuickC, QuickBasic, and Microsoft Paintbrush are trademarks of Microsoft Corporation. Turbo C, Turbo Basic, and Turbo Pascal are trademarks of Borland International.  Clipper is a trademark of Nantucket Software.  Lattice C is a trademark of Lattice Corporation.  Hercules is a trademark of Hercules Corporation.  Other software packages are trademarks of their respective companies.
