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Text File | 1989-07-07 | 10.3 KB | 270 lines

PLT: Version 1.2 July 5, 1989 Jim Miller Rich Champeaux This archive includes a file-handler (plt-handler), a portion of mountlist, a program for setting an environment variable for the handler (SetPltInfo), and a example plot file (amiga.clr). PLT: is a file-handler that accepts HP-GL commands, produces a raster image, then dumps it to your printer. The handler inquires from Preferences your printer's current resolution in order to maximize your plot quality. There is also an ability to preview a plot in order to see what it will look like on paper before you waste the time printing it. When previewing a plot, a separate screen appears that illustrates your plot's layout relative to the size of the paper. The basic HP-GL commands are implemented, but none of the advanced commands that are usually held in an external ROM cartridge. Feel free to copy, use and distribute this handler as you wish, as long as this handler remains in the public domain. No financial profit should be obtained by distributing this handler without the consent of Richard Champeaux or James Miller. Please respond with any problems, comments, or instructions. The handler is uuencoded. It must be uudecoded and placed in your L: directory. A portion of a mountlist in included and must be inserted into your mountlist. (Alterations to the startup-string will be necessary if you want different colors or pen thicknesses.) ____________________________________________________________________ MOUNTLIST PORTION plt: Handler = l:plt-handler Startup = SW/000-1/f00-2/0f0-2/00f/ff0-1 Stacksize = 5000 Priority = 5 GlobVec = 1 # ____________________________________________________________________ OPERATION PLT: can be used in a variety of manners. 1. You can copy files containing HP-GL commands to the handler. ex. copy <filename> PLT: 2. You can direct a CAD package to plot to a file and give the filaname as "PLT:" 3. You can redirect output from a CAD package heading towards the serial port to the handler. ex. cmd serial.device PLT: 4. You can write your own applications that write directly to the handler (PLT:). ____________________________________________________________________ MEMORY PLT: does take up quite a bit of memory. Not as much as a full raster image, but still quite alot. PLT: code needs 35K printer.device needs 35K raster varies from 5K - 14K each lines takes 28 bytes (or 16 in the Memory Conserve mode) Before data is read, PLT: removes 90K from your system. An average plot will usually require an additional 30-50k. A complex plot will usually require about 180K or more. ______________________________________________________________________ COLORS and LINE THICKNESSES Pen plotters usually have a variety of pens that can be different colors or thicknesses. PLT: emulates this by allowing you to set the number of pens you wish to emulate, their respective colors, and their respective thicknesses. By default, PLT: assumes you want one black pen of thickness one. If you wish to redefine this default, you can use a "Startup String" similar to one displayed in the above mountlist. The startup string allows you to customize PLT: by instructing it whether it should plot to the screen or to the printer, whether to display a status window when dumping to the printer, and by setting the colors and thicknesses of the pens you wish to emulate. The format is: SWITCHES/RGB-t/RGB-t/RGB-t/... where: SWITCHES could be: S Plot to screen W Display status window (default) M Memory Conserve mode (A '-' can be prefixed to the switches to negate them) PENS are decribed as: RGB-t where: RGB is the pen color (in hex) t is the pen thickness (optional, defaults to 1) Ex. Startup = S/000-1/f00-3/0c3-2 Startup = SW/0f0/000/0f0-2 Startup = ff0-2/05f The StartUp field of the mountlist appears to be limited to only 39 characters. This is enough for a couple of switches and about 5 pens. If more pens are needed, use the method discussed below. (NOTE: Due to an programming error, v1.0 negated all switches that occured after a '-'. I guess it was a valid way to do it, but it wasn't what I intended, and it's not the way this version works. As an example, to negate both the S and W switches, you must use '-S-W'. The only switch that might need to be negated in the default string is 'W'. The other switches default off. The '-' is there mainly for switches passed when PLT: is called so that the switches defined in the default strings can be turned off. ) Another way to redefine the defaults of PLT: is to specify a string similar to the startup string by using environment variables. This may be performed by setting the AmigaDOS enviroment variable "PltInfo" with the SetEnv command. The format for this string is identical to the startup string in the mountlist. If the enviroment variable is found, the string in the mountlist is ignored. Ex. setenv pltinfo S/000-1/f00-3/0c3-2 This is useful if you want to alter the way the next several plots look, without having to alter your mountlist and rebooting your computer. If you want to override the defaults for the current plot, you can add a startup string to the invocation of the handler. For instance, if you have a file of HP-GL commands that you want plotted; you could normally type: copy <filename> PLT: If for this particular plot, you wanted all the parameters identical to your previously defined defaults (from environment variables, mountlist string, or handler defaults) except you wanted it to plot to the screen; then you could type: copy <filename> PLT:S If you wanted it to plot to the screen using only one pen, you could type: copy <filename> PLT:S/000 With these three methods of altering how your plot will look, you have the greatest flexibility for customizing your plots on the fly. The string passed through the invocation of the handler only affects the parameters defined. If you add the switch to plot to the screen, it will no affect the pen colors. To negate one of the switches set as a default, prefix a '-' to it. Ex. -W. PLT: decides how many bitplanes to use by the number of different colors you request, not the number of pens. This allows you to have many pens of the same color but of different thicknesses with out requiring extra bit planes. The usable colors are dependent upon the number of colors that your printer can display in a single pixel. For example, the Okidata ML-292 can display only 14 colors in a single pixel. If a color is used that the printer can't support, the driver will try to dither. This causes oddities such as lines with alternating yellow and green dots. (Who knows? This may actually be desired.) Also, the RGB colors may not always match up to printer colors like you might expect. For instance, 00f prints as violet on the Okidata ML-292, and 0ff prints as cyan, which is the blue I expected 00f to print as. It might take a bit of playing with the RGB values to get the colors you desire. MEMORY CONSERVE MODE This mode reduces the amount of memory required for each plot, allowing more complex plots to be printed. PLT: builds a sorted list of the lines to be plotted, and then prints the page in strips. In it's normal mode, PLT: requires 28 bytes per line, however, in the Memory Conserve mode, only 16 bytes are required per line. This allows you to plot almost twice as many lines, but causes a serious performance degradation. The normal mode implements a linked list with a binary tree on top of it for insertion. The Memory Conserve mode does not use the binary tree, and must do a linear search of the list to insert a new line. The performance degradation becomes most noticable when the plot has more than 2000 lines. As an example, a 9800 line plot that I have takes 2 minutes and 10 seconds to process the input using the normal mode, but takes 8 minutes and 7 seconds using the Memory Conserve mode. STATUS WINDOW When the 'W' switch is set, PLT: displays a status window. As well as displaying the status of the plot, this window has a close box that can be used to abort the plot. It also displays the number of lines processed and the amount of free memory. ESTIMATING MEMORY USAGE When the output is sent to the screen, the number of lines processed is displayed in the title bar. Since sending the plot to the screen is considerably faster than sending it to the printer, you can estimate the amount of memory needed by multiplying the number of lines by either 16 or 28 and adding 80-100k. When the output is sent to the screen, the line list is not built, and thus takes much less memory. AF AND PG COMMANDS The AF and PG commands are now implemented. These commands cause the page to be dumped, and a new one started. If the output is sent to the screen, the close box must be clicked to display the next page. __________________________________________________________________________ FUTURE PLANS 1. There are some more HP-GL commands that I wish to implement but are not currently implemented, because they are seldom used by CAD packages. 2. Making the previewer more powerful, by letting you alter the shape of the plot, laying two plot files on the same page, or adding borders and additional text. 3. Implementing another font and symbol set. 4. Optimizing the code to make the handler process information faster. 5. Preparing a document describing the purpose, operation and features of PLT: __________________________________________________________________________ My e-mail address is: jvmiller@rdrc.rpi.edu if you have any questions, comments, or requests.