-------------------------------------------------------------------------- NOTE: FOLLOWING IS THE PCX FILE FORMAT TECHNICAL REFERENCE AS DESIGNED AND WRITTEN BY ZSOFT CORPORATION, THE INVENTORS OF THE PCX FILE FORMAT. IF YOU DO NOT WANT TO WRITE YOUR OWN ROUTINES, BUY THE PCX TOOLKIT FROM GENUS MICROPROGRAMMING INC 1155 DAIRY ASHFORD # 200 HOUSTON TX 77079-3012 (800) 227-0918 SALES (713) 870-0737 MAIN (713) 870-0288 FAX (713) 870-0601 BBS (N/8/1) GO GENUS COMPUSERVE -------------------------------------------------------------------------- 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 directed to - ZSoft Corporation Technical Services ATTN: Code Librarian 450 Franklin Rd. Suite 100 Marietta, GA 30067 (404) 428-0008 Image File (PCX) Format ------------------------- If you have technical questions on the format, please do not call technical support. If something is not clear leave a message on our BBS, Compuserve, or write us a letter at the above address. ZSoft does not accept any responsibility for this document or with how the reader uses it. The information in this section will be useful if you want to write a program to read or write PCX files (images). 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. 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 on the next page.ZSoft .PCX FILE HEADER FORMAT Byte item size Description/Comments 0 manufacturer 1 Constant Flag = ZSoft .pcx 1 Version 1 Version information 0 = Version 2.5 of PC Paintbrush 2 = Version 2.8 w/palette information 3 = Version 2.8 w/o palette information 4 = PC Paintbrush for Windows(Plus for Windows uses Ver 5) 5 = Version 3.0 and > of PC Paintbrush and PC Paintbrush +, includes Publisher's Paintbrush 2 Encoding 1 1 = .PCX run length encoding 3 Bits per pixel 1 Number of bits/pixel per plane 4 Window 8 Picture Dimentions 12 HDPI 2 Horizontal Resolution of image in DPI* 14 VDPI 2 Vertical Resolution of image in DPI* 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 68 Palette info 2 How to interpret palette 1 = Color/BW, 2 = Grayscale (ignored in PB IV/ IV +) 70 Hscreensize 2 Horizontal screen size in Pels 72 Vscreensize 2 Vertical screen size in Pels 74 Filler 54 Blank to fill out 128 byte header. NOTES: All sizes are measured in BYTES. All variables of SIZE are integers. HDpi and VDpi represent the Horizontal and Vertical resolutions which the image was created (either printer or scanner); ie. an image which was scanned might have 300 and 300 in each of these fields. 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, i 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. 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. 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 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 CGA Color Map 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 ------------------------------------- NOTE: This format is for PC Paintbrush (up to Vers 3.7) and PC Paintbrush Plus (up to Vers 1.65) 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. 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 cur 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 < cnt; 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 7.10 and later can be removed from memory (this can return you almost 85K of DOS RAM, depending on your configuration). 7.00 and Later FRIEZE The 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, P for Parallel Printer, D for disk file. (file is always named FRIEZE.PRN) 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 (or Setup Disk) 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 default 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 (or Setup Disk) 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 offs 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 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. 24 Reserved (8.00 FRIEZE ONLY) 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: 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.