Printing

The function PrintCanvas is in the file print.c . It prints out the contents of the plot window, and all four of its borders in postscript format.

It is very easy in Tcl/Tk to dump out a postscript file of a canvas. The trick here was to combine five postscript files from five canvases (plot window and four borders) into one postscript file.

The way this is accomplished is, perhaps, not too elegant, but it does work. A brief outline of the algorithm is given below.

First the five canvases are dumped into five seperate postscript files. The file names are:

• .ipl.f0.ps
• .ipl.f1.ps
• .ipl.f2.ps
• .ipl.f3.ps
• .ipl.f4.ps

• .ipl.total.ps

• .ipl.iplot.ps

The input file (.ipl.total.ps) is scanned line by line, searching for keywords or phrases and replaces them with hard coded information.

These changes include.

• Search for a line that begins %%BoundingBox and replace with the line %%BoundingBox: 0 200 600 700

• Search for the line %%BeginProlog and add these two lines before it.

  -80 250 translate
  .5 .5 scale
  

• Search for a line that begins restore showpage and if we are on one of the first four pages, we replace it with the line restore

• Finally, we search for the page marker, %%Page: we replace this line and the four lines that followed it with the following.

  %%Page: n 5 where n is the page number
  save
  306.0 396.0 translate
  1.44 1.44 scale
  

  Here we add another translation line which depends upon the page number. Below are the page numbers and their translations.
  

  Page 0: -50 225 translate
  Page 1: -50 -225 translate
  Page 2: 50 -225 translate
  Page 3: 500 -225 translate
  Page 4: -50 -302 translate
  

  After writing the final line, the algorithm reads four lines of input and ignores them, to skip whatever four lines were replaced by the last four shown above.

Note in the code you will see the input being compared to something like %%BoundingBox and be replaced with %%%%BoudingBox. This is because % is a special character in C and requires printing %% to actually print %.

Finally, the file .ipl.iplot.ps is sent off to the default printer. If the user wishes to print to a printer other than the default one, the easiest way is to just go to the UNIX command line. The file will not be erased, although it will be replaced by the next printing.

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