Updated 2012-08-05 22:04:02 by Googie

Mac Cody's nearly pure-Tcl PDF-savvy extension, whose home is on SourceForge at http://trampoline.sourceforge.net

RS: Trampoline is also a coding concept to allow unbounded recursion.

Trampoline is an extension to enable Adobe PDF output from the canvas. From SourceForge:-

Trampoline! is a nearly pure-Tcl library extension that generates an Adobe Portable Document Format (PDF) document based upon the content of a Tk canvas. The intent of this extension is to provide a "modern" replacement for the Tk canvas widget command postscript, which generates a Postscript document based upon the content of a Tk canvas. Trampoline! is striving to be compliant with Adobe PDF Reference version 1.4.

DPE 10 May 2005 Thanks for a useful package. I found a bug with text that contains nothing but whitespace that causes generate to fail. This can be fixed by adding the following lines near the top of TextConvert:
      # Do not process blank text
      if {[string trim [$w itemcget $item -text]] == ""} {
          return ""
      }

[MP] 13 August 2005 Great package.

I also found a bug, only the visible part of the canvas is placed in the pdf. This can be overcome when replacing
      AppendPageObject [winfo width $w] [winfo height $w]

by
      set Size [$w cget -scrollregion]
      AppendPageObject [lindex $Size 2] [lindex $Size 3]

In the generate proc. I have not tested it when scrollregion is not set in the canvas definition

SH 27 November 2006 This isn't a bug, but an intended feature as one can see in the comment line above this command:
      # The page size mirrors the actual displayed geometry of the canvas.

If you want to "capture" all items you can change the proc generate as follows:
      # get the current bbox-coords and store them into variables
      foreach {topLeftX topLeftY bottomRightX bottomRightY} [$w bbox all] {break}
      # move all items so that the top left corner has the coords 0,0
      $w move all [expr {-$topLeftX}] [expr {-$topLeftY}]

      # use the bbox-coords for width and heigth, instead of the winfo-stuff
      #AppendPageObject [winfo width $w] [winfo height $w]
      AppendPageObject [expr {$bottomRightX - $topLeftX}] [expr {$bottomRightY - $topLeftY}]
    
      AppendContentObject $w
      # move the items back to their original positions
      $w move all [expr {$topLeftX}] [expr {$topLeftY}]

Alastair Davies uses this on the MacOS X platform, for which it needs one modification. The output file must be fconfigured with -translation binary instead of -translation lf (16 Aug 2006)

KPV (2008-01-28): Tried capturing the display of TkGoldberg and the resulting pdf fails to display with the error 'Too few operands'.

Also, I uncovered an 8.5 bug: InlineImage incorrectly treats the list rawRow as a string. Tcl 8.5 is now adding some braces to lists and so the call to binary will fail.