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Text File | 1987-12-15 | 23.8 KB | 576 lines

1m An author's description of IntroCAD PrtDef files0m A printer definition file ("1mPrtDef0m" file) describes, to IntroCAD, the physical specifications of a single printer when it is in (one or each of its several) graphics mode(s). Normally, a 1mPrtDef0m file also contains information about the escape sequences which are to be sent to the printer along with graphics data. Alternatively, a 1mPrtDef0m file can be used to describe a "virtual printer" for the purpose of generating a file which is to be translated into printer commands and data for an actual printer that IntroCAD cannot be made to support directly. In such a 1mPrtDef0m file it might be convenient to include messages to the translator program in place of or in addition to the printer escape sequences. First, the format of a 1mPrtDef0m file. The first line of the file must begin with the word "1mPrtDef0m" followed by whitespace. The rest of the line may contain anything at all including nothing. The remainder of the file is divided into two sections: the color information section and the graphics mode description section. (There is no separating blank line between these sections, nor are there blank lines between the several graphics mode descriptions. Generally, a 1mPrtDef0m file may contain no blank lines.) To simplify the following text, let's agree from the start that a number can be called a "word", since it is an uninterrupted sequence of non-blank characters. Numbers which are to be part of escape sequences to be sent to the printer must be given as two hexadecimal digits. With one general exception--the representation of bit masks--all other numbers in a 1mPrtDef0m file are decimal. Most of a 1mPrtDef0m file is escape sequences. These are always represented in the file on a single line in the following manner: 1mD H H H H0m ... 1mH0m where 1mD0m is the decimal number of 1mH0m's that occur on the line, and where each 1mH0m is a hexadecimal number that can be encoded into a single byte. 1mD0m is not part of the escape sequence. 1m********************************* * THE COLOR INFORMATION SECTION * *********************************0m The color information section occupies a variable number of lines. Generally the number is one greater than the number of colors the printer supports, but for the special case of a one-color printer the entire color information section is a single line with a zero in column 1. For color-capable printers, the section is terrifically easy to write once the format is understood. Unfortunately, the format is quite a bit more difficult to describe than to understand, and so this description is long and careful. The color information section is divided into three parts. Part one describes the color capability of the printer to IntroCAD. Part two lists lists the colors available on the print ribbon, characterizes those colors with "1mnames0m" (hexadecimal numbers that represent one byte bit masks), and includes the escape sequences which select those colors. Part three lists the colors which can be printed by mixing two or more of the colors on the print ribbon and indicates which colors to mix, again with one-byte bit masks. 1mCOLOR INFORMATION: Part 10m Part one is a single line which contains four words. The first word is the number of different colors available on the printer ribbon--these colors will be called "1mpcolors0m" in this description; we'll say there are 1m#pcolors0m of them. The printer is assumed capable of switching freely between 1mpcolors0m, but will never be directed by IntroCAD to switch in the middle of a line of graphics. The second word is the number of additional colors that can be printed by mixing two or more of the ribbon colors--these colors will be called "1mscolors0m" here; we'll say there are 1m#scolors0m of them. Word three of part one specifies the correspondence between IntroCAD color numbers and printer color numbers. IntroCAD color numbers run from zero to fifteen: from left to right and top to bottom as seen in IntroCAD's "Color" menu; from left to right as seen in IntroCAD's palette requester. Printer numbers run from zero to (1m#pcolors0m + 1m#scolors0m - 1) in the order in which the lines describing them occur in the 1mPrtDef0m file. It is assumed that (part of) the range of colors in IntroCAD exactly reproduces the range of colors available from the printer. Calling the number represented in word three "1mc_off0m", the printer color which corresponds to a given IntroCAD color is: Printer_color = ((IntroCAD_color + 1mc_off0m) % (1m#pcolors0m + 1m#scolors0m)) where "%" is the modulus operator. The fourth and last word is a hexadecimal number. It represents the one-byte code which directs the printer to perform a carriage return without advancing the page. 1mCOLOR INFORMATION: Part 20m Part two of the color information section comprises 1m#pcolors0m lines. The first word on each line is the hexadecimal number which forms a one byte bit map--by which bit map the color is "1mnamed0m". There is absolutely no flexibility in this "1mnaming0m" system: the first color is "1mnamed0m" "1m010m", the second "1m020m", the third "1m040m", the fourth "1m080m", and so on. IntroCAD will enforce this if you don't. The names, then, give IntroCAD no information; they are there for your use in writing part three of the color information section. The remainder of each 1mpcolor0m line represents an escape sequence: a decimal number followed by exactly that many two-digit hexadecimal numbers. The hex numbers form the escape sequence which is to be sent to the printer to select the 1mpcolor0m. There may be at most five bytes in a color selection escape sequence. Printer manufacturers generally recommend that light colors be printed first when colors are to be mixed. IntroCAD prints 1mpcolors0m in the order in which they appear in the 1mPrtDef0m file. 1mCOLOR INFORMATION: Part 30m Part three of the color information section comprises 1m#scolors0m lines of one word each. The word is the hexadecimal number which is the sum of the "1mnames0m" of the 1mpcolors0m, given in the previous section, which are to be combined to print the 1mscolor0m. 1m***************************************** * THE GRAPHICS MODE DESCRIPTION SECTION * *****************************************0m There may be up to four graphics mode descriptions in a 1mPrtDef0m file; each description takes six lines which I'll describe one by one. (Refer to the appended template files.) Line one contains instructions to IntroCAD. This line is very much more complicated than the rest and so each word on the line will be explained in detail. The first three words on line 1 will be displayed in an Amiga requester so that the user can know some details of the available graphics modes. The first word should be five characters long and followed by a blank because the first six characters of the line are copied verbatim for use in the requester; this word should tersely describe the printout a user can expect from the graphics mode. The second and third words are, respectively, the horizontal and vertical resolutions of the printer expressed in dots per inch. The fourth and fifth words are the total numbers of dot locations available on a page--again, horizontally and vertically, respectively. These specify the page size to IntroCAD since the dot resolution has been given. The number of dots horizontally usually must agree with information specified later in an escape sequence. There is no limit to the vertical size of the page, but if the number of vertical dot locations is specified as zero, IntroCAD will enforce the default vertical page size of ten inches. The sixth word is the number of print head pins to be used for graphics printing. The number of pins must be one of the following: [1,2,3,4,5,6,7,8,16,24]. The seventh and last word on line 1 is the "1minterlace level0m". The 1minterlace level0m is one less than the number of passes the print head must make for each "1mstrip0m" of printing. (Here, a "1mstrip0m" is the area covered by a single pass of the print head.) Only printers which use eight or fewer pins for graphics can be made, by IntroCAD, to produce interlaced printouts. For printers which use more than eight pins, the interlace level is ignored but should, for clarity's sake, be zero. Lines two through six normally contain printer escape sequences encoded in the usual way. IntroCAD derives no information from these sequences, but simply converts them to sequences of binary bytes and parrots those to the printer at the appropriate times. There may be at most 24 bytes in each of these escape sequences. The first word in each escape sequence line is different from the rest: it is not part of the escape sequence. It is the (decimal) number of bytes in the escape sequence. It is, therefore, the number of hexadecimal numbers which follow on the rest of the line. Line two contains the printer initialization sequence. This line is called "1mINIT0m" in the template file. The 1mINIT0m sequence is sent once before printing starts. Normally this sequence resets the printer and sets the distance the paper is advanced by the line feed command which will be defined in line four or five. Some printers are capable of bi-directional graphics printing; for these, the initialization sequence must disable the capability because IntroCAD cannot take advantage of it. Also, it is a good idea to include one or more line feeds in this sequence so that the paper tension during the first pass of the print head will be the same as that during the remaining passes. Line three contains the escape sequence which readies the printer to receive graphics data. This line is called "1mGSTART0m" in the template file. It is sent before each pass of the print head. For most printers, the 1mGSTART0m sequence contains either the number of horizontal locations the print head can assume or the total number of bytes of graphics data which will be sent during a single pass of the print head. The number is used by the printer to distinguish graphics data from escape sequence data and printer manuals normally specify the maximum value of this number for each graphics mode. The number must agree with the number on line one of the graphics mode description which tells IntroCAD how many dots to print horizontally. EXAMPLE: For the Epson_LQ-1000 printer. The 1mINIT0m line for the "QUICK" graphics mode is: "1mQUICK 60 60 480 0 8 00m" The 1mGSTART0m sequence line for this mode is: "1m4 1B 4B E0 010m" Here, "1mE0 010m" is the Epson method of specifying the number 480--the number that occurs on the 1mINIT0m line. Some printers implement a different method of distinguishing graphics data from escape sequence data: a special character, different from any possible graphics data "character", is used to end graphics printing. IntroCAD does not support such printers directly unless very special and difficult-to-describe circumstances obtain. A translator program is normally required. Line four contains the escape sequence which is sent immediately after a complete 1mstrip0m of graphics data. This line is called "1mSTRIP_FEED0m" in the template file. For non-interlaced printing, a complete 1mstrip0m is the data for a single pass of the print head. For interlaced printing it is the data for (1minterlace level0m + 1) passes, plus the "1mLACE_FEEDm" escape sequences--described later--which are sent after each pass but the last. For non-interlaced printing, this sequence normally instructs the printer to simply do a carriage return and line feed. Line five is ignored if the 1minterlace level0m specified on line one is zero. Otherwise, it contains the escape sequence which instructs the printer to do a carriage return and the tiny paper advance appropriate for interlaced printing. This line is called "1mLACE_FEED0m" in the template file. The sixth and last line contains the escape sequence sent after printing is finished. This line is called "1mCLOSE0m" in the template file. Normally this will be simply a form feed. 1m***************** * SPECIAL NOTES * *****************0m About the data bytes: The most significant bit of the first byte maps to the topmost pin of the print head, the MSB of the second byte (if there is one) maps to the ninth pin from the top, and so on. This assumption, on the part of IntroCAD, is perhaps the major source of incompatibility with printers IntroCAD doesn't support. The size of a line feed, normally encoded into the 1mINIT0m escape sequence should be equal to the number of print head pins used for graphics multiplied by the pin spacing. Printer manuals rarely document the pin spacing and one must usually resort to trial and error here. For eight pin printers, the spacing is normally either two or three times the smallest possible page advance: if that advance is 1/216 in. or 1/144 in., the pin spacing is almost certainly 1/72 in.--a very common spacing. For 16 and 24 pin printers emulating eight pin graphics modes, the pin spacing is usually either 1/60 in. or 1/80 in. There is a potential problem with serial printers because the author of the 1mPrtDef0m file cannot know in advance whether or not the MSB of each data byte will be appropriated by the SER: device for use as a parity bit. The user has complete control of this bit via Preferences. If this bit is unavailable for graphics and the 1mPrtDef0m file indicates that all eight bits are to be used, narrow horizontal blank lines will occur in the printout. (Normally though, blank lines indicate an inappropriate line feed size.) It seems like a bad idea to limit all 1mPrtDef0m files to seven bits as a method of avoiding this problem, since most printers do not communicate serially. For 16 and 24 pin serial printers, parity cannot ever be used because IntroCAD demands all eight bits of every data byte. For some printers, there is a hidden difficulty that makes the writing of a 1mPrtDef0m file for interlaced or color printing almost into a matter of trial and error. The difficulty is that many printers buffer data as it arrives and only print the buffered data on receipt of one of a small number of control codes. (The code for a carriage return can usually be relied on to cause a buffer flush.) For such printers, the 1mSTRIP_FEED0m command must always contain one of those special codes. Interlaced and color printing can present apparent problems with these printers if 1) the desired 1mLACE_FEED0m and 1mCOLOR_SELECT0m escape sequences don't happen to contain buffer-flushers, and 2) the printer's buffer isn't large enough to contain more than a single line of graphics. The problem is especially difficult if the only buffer-flusher is a combined carriage return/line feed. 1m*************************************** * IMPLEMENTING AND USING A TRANSLATOR * ***************************************0m If IntroCAD cannot be made to support a certain printer, at least a program can be written to translate IntroCAD's output into something that printer will accept. Since IntroCAD can direct its output to a file, as well as to the PAR: and SER: devices, the use of a translator is certainly practical. Since the Amiga multitasks, such use can be nearly transparent. Obviously, writing a translator requires detailed knowledge of the file IntroCAD is to write. At the time you write the 1mPrtDef0m file, you will know some of the numbers which describe the file IntroCAD will write. The number of dots to be printed horizontally, for example, is "hardwired" into the file. You can cause the 1mINIT0m string to contain a message to the translator program, giving it this information. This might be nice if you want to use more than one printer resolution and don't want to have to keep track of sevaral translator programs. You can never know in advance, however, what the number of dots to be printed vertically will be since it depends on the drawing and how it is scaled. All that's required to work around this problem is the ability, on the part of your translator, to distinguish the 1mCLOSE0m string from the 1mGSTART0m string--quite easy if the 1mCLOSE0m string is a form feed. Your translator will probably need to know how many bytes each escape sequence comprises. The easiest way might be to prepend the number to the sequence--that is, put the (hex) number in the 1mPrtDef0m file so that IntroCAD will write it as the first byte of the sequence, and arrange that the translator "eat" the byte and send the rest of the sequence to the printer. Certainly you can get IntroCAD to "print" the graphics to disk or to RAM:. It would be nice if you didn't have to manually run your translator in the background each time you printed a drawing, though. Also, it would be nice if you didn't have to always have enough space available (possibly as much as a megabyte) for an entire print dump. There are two solutions I know of. 1) Use Matt Dillon's PIPE: device. This solves the memory problem, but you still have to run a background job each time you print. An example: you tell IntroCAD to print to the "file" PIPE:myfile. In a background CLI, you run the command "translate PIPE:myfile PAR:". Here I've assumed your program is called "translate" and that it's first command line argument is the name of the input file. To run the translator, you will need to remember "Left-Amiga-M" brings the Workbench screen to the front because IntroCAD has no screen gadgets. 2) Write an Amiga device driver. (I don't mean a printer driver here, although it might be possible to combine the translator function with general purpose printing.) This is the prettiest solution, but undoubtedly has the steepest learning curve. 1m************************************** * APPENDIX A: PrtDef template files. * **************************************0m -------------- for black-only printers ------------------------------------ 1mPrtDef filename "company name"0m 1m00m 1mQUICK Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m 1mDRAFT Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m 1mFINAL Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m --------------------------------------------------------------------------- ---------------- for color printers --------------------------------------- 1mPrtDef filename "company name"0m 1m#pcolors #scolors color_offset CR_no_LF0m 1m01 codes for pcolor #00m \ \ 1m02 codes for pcolor #10m | primary | if no colors, 1m04 codes for pcolor #20m | colors | these lines . | | do not occur . | | in PrtDef file. . / ________ | There must be exactly 1msmask10m smask is logical AND \ | (#pcolors + #scolors) . of above pmasks | secondary | lines here. . (01, 02, 04...) for | colors | . pcolors which contribute | | . to this scolor | | 1msmaskn0m / / 1mQUICK Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m 1mDRAFT Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m 1mFINAL Hdpi Vdpi HDots VDots PrtWires Interlace0m 1mINIT0m 1mGSTART0m 1mSTRIP_FEED0m 1mLACE_FEED0m 1mCLOSE0m --------------------------------------------------------------------------- --------------- sample 1mPrtDef0m file ---------------------------------------- 1mPrtDef Epson_JX-80 "Epson America, Inc."0m 1m4 4 7 0D0m 1m01 3 1B 71 340m !yel 1m02 3 1B 71 320m !cyn 1m04 3 1B 71 310m !mag 1m08 3 1B 71 300m !blk 1m030m !grn 1m050m !org 1m060m !blu 1m0C0m !brn 1mQUICK 60 72 480 0 8 00m 1m11 1B 40 1B 23 1B 55 01 1B 33 18 0A0m 1m4 1B 4B E0 010m 1m2 0D 0A0m 1m00m 1m3 0C 1B 400m 1mDRAFT 120 72 960 0 8 00m 1m11 1B 40 1B 23 1B 55 01 1B 33 18 0A0m 1m4 1B 59 C0 030m 1m2 0D 0A0m 1m00m 1m3 0C 1B 400m 1mFINAL 240 216 1920 0 8 20m 1m12 1B 40 1B 23 1B 55 01 1B 33 01 0A 0A0m 1m4 1B 5A 80 070m 1m2 0D 0A0m 1m9 0D 0A 1B 33 16 0A 1B 33 010m 1m3 0C 1B 400m --------------------------------------------------------------------------- 1m******************************************** * APPENDIX B: Details of the print output. * ********************************************0m Probably the best way to concisely illustrate the format of the print output is to give pseudo-code examples of the routine that generates that output. In the following examples, the words 1mINIT0m, 1mGSTART0m, 1mSTRIP_FEED0m, 1mLACE_FEED0m, 1mCLOSE0m, and 1mCR_no_LF0m refer to the escape sequences named and described above. --- non-interlaced black-only printing ------------------------------------ send 1mINIT0m for (i=0; i<num_lines; i++) { generate DATA if any of DATA are non-zero { send 1mGSTART0m send DATA } send 1mSTRIP_FEED0m } send 1mCLOSE0m --------------------------------------------------------------------------- --- black-only printing with Interlace = 1 -------------------------------- send 1mINIT0m for (i=0; i<num_lines; i++) { generate PASS_0_DATA and PASS_1_DATA if any of PASS_0_DATA are non-zero { send 1mGSTART0m send PASS_0_DATA } send 1mLACE_FEED0m if any of PASS_1_DATA are non-zero { send 1mGSTART0m send PASS_1_DATA } send 1mSTRIP_FEED0m } send 1mCLOSE0m --------------------------------------------------------------------------- --- black-only printing with Interlace = 2 -------------------------------- send 1mINIT0m for (i=0; i<num_lines; i++) { generate PASS_0_DATA, PASS_1_DATA, and PASS_2_DATA if any of PASS_0_DATA are non-zero { send 1mGSTART0m send PASS_0_DATA } send 1mLACE_FEED0m if any of PASS_1_DATA are non-zero { send 1mGSTART0m send PASS_1_DATA } send 1mLACE_FEED0m if any of PASS_2_DATA are non-zero { send 1mGSTART0m send PASS_2_DATA } send 1mSTRIP_FEED0m } send 1mCLOSE0m --------------------------------------------------------------------------- --- non-interlaced color printing (2 primary colors) ---------------------- send 1mINIT0m for (i=0; i<num_lines; i++) { generate COLOR_0_DATA and COLOR_1_DATA if any of COLOR_0_DATA are non-zero { send SET_COLOR_0 send 1mGSTART0m send COLOR_0_DATA send 1mCR_no_LF0m } if any of COLOR_1_DATA are non-zero { send SET_COLOR_1 send 1mGSTART0m send COLOR_1_DATA send 1mCR_no_LF0m } send 1mSTRIP_FEED0m } send 1mCLOSE0m --------------------------------------------------------------------------- --- color printing with Interlace = 1 ------------------------------------- send 1mINIT0m for (i=0; i<num_lines; i++) { for (j=0; j<num_primary_colors; j++) generate PASS_0_DATA[j] and PASS_1_DATA[j] for (j=0; j<num_primary_colors; j++) { if any of PASS_0_DATA[j] are non-zero { send SET_COLOR[j] send 1mGSTART0m send PASS_0_DATA[j] send 1mCR_no_LF0m } } send 1mLACE_FEED0m for (j=0; j<num_primary_colors; j++) { if any of PASS_1_DATA[j] are non-zero { send SET_COLOR[j] send 1mGSTART0m send PASS_1_DATA[j] send 1mCR_no_LF0m } } send 1mSTRIP_FEED0m } send 1mCLOSE0m --------------------------------------------------------------------------- Tim Mooney 12/7/87