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SHOWHPGL A viewing program for HP-GL and HP-GL/2 plotting programs. Version 1.9 Introduction This program is designed to preview HP-GL and HP-GL/2 plotting programs on the console screen of an IBM PC or compatible computer. It impliments 47 of 97 HP-GL or HP-GL/2 instruction. Of the 97 instruction, 22 either have no meaning for this type of program or are otherwise unrelated to drawing. Four instructions are included to provide backward compatibility with the HP9872 plotter. These instructions are interpreted as NOP's. It is written in Microsoft C, version 6.0. It requires MS-DOS version 3.0 or above to run. This program is meant to be used as a preview tools for HP-GL files. It is as accurate as it could be made with the limited information and resources available at the time it was written. Known bugs or deficiencies are listed after the instruction set summary. Version 1.9 adds solid fills to RR and RA (relative and absolute filled rectangles), and fixes a bug which allowed drawing outside the hard clip border when using IW (windowing). Revision History Version 1.9 17 August, 1992 - Added solid fill types to RA and RR. - Added transparent data (TD) instruction. - Fixed bug allowing drawing outside P1/P2 border using IW. Version 1.8 8 August, 1992 - The LB command would not draw labels with more non-printing characters than printing characters. This caused labels which used embedded backspaces for positioning to not be drawn. Fixed. - The LB command would not terminate properly at the end-of-file without a label terminator present. Fixed. - Relative text size on the CRT increased as paper size enlarged. 'Should have decreased. Fixed. - IW clipping window incorrectly placed when P1/P2 (the corner hard clip limits) were not lower-left and upper-right, respectively. This resulted in no visible lines being drawn. Fixed. It also failed to restore the correct clipping when turned off if scaling was on. Fixed. - DR drew characters in the wrong direction when P1/P2 were exchanged. Fixed. - HP-GL/2 defaults to SI (absolute character sizes) at initialization (IN) or when issuing the DF (default) instruction, as does the DraftPro plotter. However, the HP7475 and HP7470 plotters specify SR (relative character sizes for these cases. Two switches were added (-70 and -75) to select relative character scaling as the default condition. - XT and YT (tick drawing commands: not HP-GL/2 instructions) were able to draw ticks outside the P1/P2 hard clip border. Fixed. Also, tick length was not rescaling when P1/P2 changed unless TL was executed after P1/P2 changed. Fixed - Type 1 scaling (isotropic, with no left and bottom parameters specified) did not result in symmetric spacing on the axis which was lengthened to achieve isotropic scaling. Fixed. - A single pixel line would terminate the program with an integer divide overflow. Fixed. - Filled rectangles didn't work properly if scaling was on. Fixed. - Operation of IR not clearly specified for the case of P1/P2 being exchanged. IR as implimented is based on hard clip borders and assumes, for reference, P1 is the lower left corner and P2 is the upper left corner. Version 1.6 25 July, 1992 - Fixed bug in graphix.lib preventing labeling from having more non- printing characters than printing chars and still be drawn. - Relative character sizes increased as larger paper sizes were selected. They should have decreased due to the necessary reduction in size to fit the drawing to the screen. - DR set the wrong character direction when P1/P2 (the hard clip corner points) were exchanged. - IW set the wrong window coordinates when P1/P2 were exchanged. The result was no drawing on the screen. Version 1.5 30 December, 1991 - Added debugging flag. Error messages regarding the source file are now suppressed. The -db flag turns them on. Error messages are printed to stdout and may be redirected to a file. - Added four instructions for HP9872 plotter backward compatibility. - re-wrote the graphics adapter identification code to make maintaining the code easier. - Added PE (polyline encoded) instruction. Version 1.0 3 September, 1991 - Original release. The P1/P2 Exchange Problem There is an issue of semantics which arises for the case of P1/P2 being exchanged. On a plotter, entering the P1 and P2 points is a physical process whereby the operator mechanically places the cursor at the desired corner points. When one places P1 in the upper left corner and P2 in the lower left corner of the page, the logical coordinate system and the physical coordinate system of the plotter become reflected and inverted. The plotter defines P1 as the lower left corner of the page and P2 as the upper right corner of the page. Thus, if you move the pen to the physical location P1 or P2 coordinates (using the control panel), the plotter moves the pen to the upper right or lower left corner, respectively. However, if you told the plotter to move to the coordinates of P1 or P2, it would move to a point opposite of the respective location. For example, if one sets P1 = (10250, 7479) and P2 = (250, 279), issuing "PU250,279;" would move the plotter to the upper right corner of the page, even though the physical P2 location is in the lower left corner of the page. The plotter is being forced to perform a translation from physical coordinates into logical coordinates. By choosing P1 = (10250, 7479) and P2 = (250, 279), we have inverted and reflected the logical coordinate system. Thus, moving the pen to the logical coordinates of P1 (we are not commanding the plotter to move to the physical location of P1) moves the pen to the lower left corner of the page. Our choice of coordinate values for P1 and P2 has placed larger numerical values in the lower left corner of the page and smaller values in the upper right corner. What does this mean? If you examine the display for program SHOW_TST.DPF, two of the four frames show P2 in the lower left corner of the frame. These frames have P1 and P2 exchanged. If you examine the program, the coordinate values given for point P2 are the values of the P1 coordinate. The labels are intended to show where the physical location of P2 would be if you could display it. However, the P2 logical coordinate is always in the upper right corner, and the P1 logical coordinate is always in the lower left corner. Thus, wer are forced to appear to mislabel the graph in order to show the physical P1 and P2 coordinate locations. Usage SHOWHPGL -[video][paper][plotter][debug] [filename] where filename optional filename for HP-GL source file. If a filename is not supplied, standard input is assumed. video option to force usage of a particular video mode. Values are: c, e, v, for CGA, EGA, or VGA. 'c' will force CGA 640 x 200 monochrome mode, 'e' will force EGA 640 x 350 16 color mode, 'v' will force VGA 640 x 480 16 color mode. Default mode is autodetect and select highest resolutions standard mode available. No SVGA modes are supported. paper One of the following standard paper sizes: A, B, C, D, E, or A4, A3, A2, A1, A0 . Default size is A. Case is important!! A0 is a paper size option: a0 is unknown. plotter Default emulation is HPGL/2. 'dp' will select DraftPro emulation. '70' will select HP7470 emulation. '75' will select HP7475 emulation. The HP 7470/7475 have the plotter units coordinate origin in the lower left corner. The DraftPro uses the center of the page as the origin. Note also that the 7470 and 7475 emulations do NOT limit the number of pens available to 2 and 6, respectively. Pen colors are limited to those available on the graphics mode you are running (i.e., CGA, EGA, or VGA). debug Default is to silently pass errors. -db will turn on error output to stdout. The user may also set the environment variable HP-GL to a default set of switches, i.e., set hpgl=dpA3 specifies default options of DraftPro mode and A3 size paper. If command line switches are present, the environment settings are ignored. Multiple paper size selections will cause the program to abort. Multiple video mode selections will default to the highest resolution autodetected mode. The switch character is defined as '-'. It is hard coded into the program. Directory path names may include either or both '\' and '/' directory separators. This program has been tested under MS-DOS 3.20 and MS-DOS 5.0 . All video graphics functions draw using the video BIOS. No direct screen I/O is used. Additional BIOS supported graphics modes may be supported by defining the appropriate structures in graphix.h and the macros in graph.h and making appropriate changes to the mode lists in autogrph.c and showhpgl.c . When the debugging flag is turned on, this program generates diagnostic output text strings when illegal or unsupported instructions are encountered. THESE STRINGS APPEAR IN THE GRAPHICS DISPLAY AND MAY INTERFERE WITH THE DRAWING IF SUFFICIENT ERRORS OCCUR. If you expect large numbers of errors and wish to retain a listing of the output, redirect any generated output to a file. Note that this program DOES NOT restore the video mode which was in use prior to calling this program. Although the EGA and VGA display systems are capable of better than 80 columns and 25 rows on the screen, they do not appear as supported IBM BIOS video modes. Determination of nonstandard video mode parameters was beyond the scope of this program. If you want to restore a recognized video mode at the end of program execution, add the following code to showhpgl.c just before the end of main (): twait (infile, 50); graphics_off (); This will introduce a 50 second delay before restoring the video mode. Shorter delays can be had by changing the value 50 to a more reasonable number. If the initial video mode was not a BIOS standard video mode, graphics_off () may not be able to restore it properly. Compilation The entire package is compiled as follows: cl showhpgl.c hpgl1.c hpgl2.c getargs.c autogrph.c graphix.lib Note that this package is compiled with the default optimizations. Failure use at least the default optimizations when compiling showhpgl.c may result in a _TEXT segment which exceeds 64K and linking will fail. graphix.lib is compiled in the small memory model. Because graphix.lib internally uses Microsoft interrupt calling functions, showhpgl must be compiled using the Microsoft compiler. The object module mscio.obj, which is in graphix.lib, contains all Microsoft, and PC in general, specific functions. This module must be replace in order to use this package with other compilers and platforms. Contact the author for the required information. Distribution Package The distribution package includes the following: showhpgl.doc this document showhpgl.exe the executable program file showhpgl.c main program hpgl1.c additional functions hpgl2.c additional functions hpgl.h header file for showhpgl.c, hpgl1.c hpgl2.c getargs.c command line options and arguments autogr.c video graphix adapter detection labels.c labeling font for showhpgl (part of graphix.lib) graphix.lib graphics functions library graphix.h header file for main program (showhpgl.c) graph.h header file for additional modules (hpgl1.c, hpgl2.c) license.doc license agreement HP-GL test programs aa_artst.dpf AA, AR, CI, IP, SC, CT, PR: test general performance of arc and circle drawing with fixed and adaptive segment lengths attest.dpf AT: 3-point arc, absolute actest.dpf AC: anchor corner test cptest.dpf CP: character plot ct_citst.dpf CI, CT: circles with fixed and adaptive segment lengths di_drtst.dpf DI, DR: absolute and relative label directions. dv_sltst.dpf SL, DV: test slant with DV command. dvtest.dpf DV: variable text path (fails this test) ea_ertst.dpf EA, ER: edge rectangle absolute and relative estest.dpf ES: extra inter-character spacing ewtest.dpf EW: outline wedge ip_irtst.dpf IP, IR: test & display usage of IP and IR iwtest.dpf IW: soft-clip window labels.dpf LB, LO, SL, SR, DV: labels and label origins, char. slant, char. size (relative), direction vertical. lttest.dpf LT: line type: note that types 6-9 are identical as types 7-9 are unsupported. pa_prtst.dpf PA, PR: test absolute and relative line drawing petest.dpf PE: polyline encoded ra_rrtst.dpf RA, RR: filled rectangle, absolute (no solid fills) rttest.dpf RT: 3-point arc, relative sc_test.dpf SC, DR, DI, LB: test all scaling types, DI, DR, and LB instructions in normal and P1/P2 exchanged coordinate systems. smtest.dpf SM: symbol mode tl_lotst.dpf LB,LO,TL,XT,YT: test labels, label origins, x-, & y-ticks fwdaltbx.dpf drawing to demonstrate the -dp drawing option. Use -C or larger for paper size. Note: many of these program are dependent on using A-size paper to correctly display the intended test functions. Different results may occur from using other paper sizes unless another paper size is specifically noted. Some of these test programs are taken from "The HP-GL/2 Reference Guide" and, as such are copyright 1990 by Hewlett-Packard. This book provides illustrations of what the output of some of these programs should look like accompanying the description of the instruction. The file labels.c is included for those who wish to modify the font used for labeling. This font is incorporated into graphix.lib. To modify the font, make the required changes to labels.c, compile it to a ".obj" file, and update the library using "LIB -+labels;" (Microsoft library manager). You may then re-link the remaining files to create a new program which uses the new fonts. Licensing Please refer to the license agreement in license.doc. Use of this software and the enclosed source code is limited to the terms of the license. Bug Reports: Please report any bugs to becker@lennon.src.honeywell.com (Robert Becker). If you prefer, mail them to me at Robert Becker 15836 Quebec Circle Eden Prairie, MN 55346 Instructions Status The following is a list of instructions and the level of implimentation in showhpgl.exe of HP-GL/2 instructions. Note that not all instructions are HP-GL/2 instructions. Those with notations in the source column indicate where this instruction was found. Status indicates the level of implimentation of the instruction. There are four levels of implimentation: Full: instruction is fully functional as per HP-GL/2 Partial: instruction implimentation is incomplete NOP: no action or action not meaningful for this application N/A: not available: instruction was not implimented. There are 38 Full, 8 partial, 26 NOP, and 29 N/A instructions. Of the N/A instructions, 11 are related to character set or font selection. Of the NOP instructions, 12 are related to output or digitizing a point and 4 are for backward compatibility with earlier products. All output instruction that have no meaning in this application and are implimented as NOP instructions. No dual context mode instructions (HP-GL & PCL) have been inplimented. Command Description Status source Comments AA arc absolute Full AC anchor corner Full AD alternate font definition N/A AF advance full page NOP compatibility w/HP9872 AH advance half-page NOP compatibility w/HP9872 AR arc relative Full AT 3 point arc absolute Full BP begin plot Partial waits TWAIT seconds before clearing plot from screen CA designate alternate char. set N/A 7470 CF char. fill mode N/A CI circle Full CP character plot Full CS designate std. character set N/A CR color range N/A CT chord tolerance Full DC digitizer clear NOP DF default Full DI absolute label direction Full DL download character N/A DP digitize point NOP DR relative label direction Full DS designate char. set into slot N/A DraftPro DT Define label terminator Full DV Define variable text path Partial No line feed reversal EA edge rectangle absolute Full EC enable cutter NOP EP edge polygon N/A ER edge rectangle relative Full ES extra space Full ESC escape code instructions Partial No PCL mode switch commands EW edge wedge Full FI primary font selection by ID N/A FN secondary font selection by ID N/A FP fill polygon N/A FR frame advance N/A FT fill type Partial Only hatched and cross-hatched fills GM graphics memory NOP DraftPro IM input mask NOP 7470 IN initialize Full Since there is no 'front panel', IN1 is same as IN IP input P1 & P2 Full IR input relative P1 & P2 Full IW input window Full LA line attributes NOP No wide lines available LB label Full LO label origin Full LT line type Partial No adaptive line patterns: types 0-6, only. MC merge control N/A MG message to panel NOP MT media type NOP NP number of pens NOP NR not ready Full OA output pen position & status NOP 7470 OC output commanded positon & sts NOP 7470 OD output digitized point & sts NOP OE output error NOP OH output hard-clip limits NOP OI output identification NOP OO output options NOP 7470 OP output P1 & P2 NOP OS output status NOP OW output window NOP 7470 PA plot absolute Full PC assign pen colors N/A PD pen down Full PE polyline encoded Full PG page advance Modified Waits 6 seconds before clearing screen PM polygon mode N/A PR plot relative Full PS plot size Full PU pen up Full PW pen width N/A QL quality level NOP RA fill rectangle absolute Partial no user defined fills RF raster fill definition N/A RO rotate coordinate system N/A RP replot N/A RR fill rectangle relative Partial no user defined fills RT relative arc 3-point Full SA select alternate font N/A SB scalable or bitmap font N/A SC scale plot Full SD standard font definition N/A SI absolute char. size Full SL char. slant Full SM symbol mode Full SP select pen Full SR relative char. size Full SS select standard char. set N/A ST sort vectors NOP SV screened vectors N/A TL tick length Full 7470 TD transparent data Partial fn. char. set limited. TR transparency mode N/A UC user defined character N/A UL user defined line pattern N/A VA adaptive pen velocity NOP compatibility w/HP9872 VN normal pen velocity NOP compatibility w/HP9872 VS velocity select NOP WG fill wedge Partial Outline of wedge, only (no filling available) WU pen width unit selection N/A XT x-tick Full 7470 YT y-tick Full 7470 Notes: BP instruction is checked for syntax. BP will wait PG_DELAY seconds before clearing the screen if the screen was plotted on. If the screen was not plotted on, the plotter is initialized. In either case, the plotter is initialized. PG instruction generates a wait of PG_DELAY seconds before clearing the screen. PG_DELAY is defined in hpgl.h as 6 seconds. HP-GL and HP-GL/2 distinguish between <cr> and <lf> for positioning on labels. The C-language, being based in UNIX, assumes the <lf> is the newline character and <cr> has no meaning. This assumption is also present in this program and some test case labeling and character plotting tests will fail because of this. The test program dvtest.dpf fails because of this. The display should look something like: D A ABC E B DEF F C GHI G H I Several of the HP-GL/2 specifications are incomplete. For example, when one is drawing a wedge with symbol mode on, placement of the symbol is unspecified. Similarly, when TD (transparent data) mode is on, the font used to display the control characters is not specified. Error handling is not always specified. For example, when CT is used to specify deviation distance on circles and arcs, this reference does not specify what action to take if a distance tolerance is not specified for subsequent circles and arcs. The DraftPro manual specifies that the default shall be 5 degrees in this case. The Addison-Wesley book does not specify what action to take. For hatch and cross-hatch fills, it is not clearly specified for the case of user-unit defined hatch x-spacing if the scale in the y-direction should affect the spacing of the hatch. In this implimentation, it was decided that the hatch spacing displayed on the screen should be invariant with the rotation angle. Additional questions arise in the case of the IR instruction. One would think that, for the case of P1 and P2 being opposite of their normal locations (lower left, and upper right, respectively), that the IR instruction would work off of these coordinates. However, there are indications of the HP-GL/2 reference guide that IR works off of the default P1 and P2 locations. That being the case, then an IR of two arguments (IR x,y;) following an IP which exchanges the P1 and P2 corners will take the x- and y-values as percentage values based on the corners of convention for P1 and P2. For example, if one assumes IP10250,7479,250,279; and later executes an IR 10,10;, for A-size paper, the IR corner plotter coordinates will be (1030, 765), which, because P2 tracks P1 changes for only one coordinate pair arguments to IR or IP, will force P2 to assume the value of (-8970, -6534). This is unlikely to be the assumed result. Further, executing an IR of four arguments (IR x1, y2, xy, y2;) following an IP which exchanges P1 and P2 corners will have the effect of reverting the coordinate system to the normal locations for the P1 and P2 corners To use IR to exchange the P1 and P2 corners, the first coordinate pair (x1, y2) must be greater than 50% (IR works in percent of the hardclip limits), and the second pair (x2, y2) should be less than 50%. HP-GL, HP-GL/2, HP, Hewlett-Packard, and DraftPro are registered trademarks of the Hewlett-Packard company. PC, CGA, EGA, VGA are or may be registered trademarks of the IBM company. UNIX is a trademark of AT&T. Reference: "The HP-GL/2 Reference Guide", Addison-Wesley Publishing Company.