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# a Pythonesque Canvas v0.8
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# Author : Jerome Alet - <alet@librelogiciel.com>
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# License : ReportLab's license
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__doc__ = """pycanvas.Canvas : a Canvas class which can also output Python source code.
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pycanvas.Canvas class works exactly like canvas.Canvas, but you can
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call str() on pycanvas.Canvas instances. Doing so will return the
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Python source code equivalent to your own program, which would, when
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run, produce the same PDF document as your original program.
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Generated Python source code defines a doIt() function which accepts
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a filename or file-like object as its first parameter, and an
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optional boolean parameter named "regenerate".
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The doIt() function will generate a PDF document and save it in the
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file you specified in this argument. If the regenerate parameter is
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set then it will also return an automatically generated equivalent
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Python source code as a string of text, which you can run again to
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produce the very same PDF document and the Python source code, which
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you can run again... ad nauseam ! If the regenerate parameter is
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unset or not used at all (it then defaults to being unset) then None
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is returned and the doIt() function is much much faster, it is also
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much faster than the original non-serialized program.
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the reportlab/test/test_pdfgen_pycanvas.py program is the test suite
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for pycanvas, you can do the following to run it :
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First set verbose=1 in reportlab/rl_config.py
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then from the command interpreter :
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$ python test_pdfgen_pycanvas.py >n1.py
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this will produce both n1.py and test_pdfgen_pycanvas.pdf
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$ python n1.py n1.pdf >n2.py
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$ python n2.py n2.pdf >n3.py
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n1.py, n2.py, n3.py and so on will be identical files.
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they eventually may end being a bit different because of
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rounding problems, mostly in the comments, but this
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doesn't matter since the values really are the same
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(e.g. 0 instead of 0.0, or .53 instead of 0.53)
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n1.pdf, n2.pdf, n3.pdf and so on will be PDF files
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similar to test_pdfgen_pycanvas.pdf.
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Alternatively you can import n1.py (or n3.py, or n16384.py if you prefer)
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in your own program, and then call its doIt function :
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pythonsource = n1.doIt("myfile.pdf", regenerate=1)
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Or if you don't need the python source code and want a faster result :
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When the generated source code is run directly as an independant program,
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then the equivalent python source code is printed to stdout, e.g. :
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will print the python source code equivalent to n1.py
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Why would you want to use such a beast ?
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- To linearize (serialize?) a program : optimizing some complex
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- To debug : reading the generated Python source code may help you or
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the ReportLab team to diagnose problems. The generated code is now
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clearly commented and shows nesting levels, page numbers, and so
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on. You can use the generated script when asking for support : we
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can see the results you obtain without needing your datas or complete
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- To create standalone scripts : say your program uses a high level
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environment to generate its output (databases, RML, etc...), using
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this class would give you an equivalent program but with complete
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independance from the high level environment (e.g. if you don't
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- To contribute some nice looking PDF documents to the ReportLab website
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without having to send a complete application you don't want to
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- ... Insert your own ideas here ...
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- For fun because you can do it !
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from reportlab.pdfgen import canvas
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from reportlab.pdfgen import pathobject
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from reportlab.pdfgen import textobject
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PyHeader = '''#! /usr/bin/env python
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# This code was entirely generated by ReportLab (http://www.reportlab.com)
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from reportlab.pdfgen import pathobject
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from reportlab.pdfgen import textobject
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from reportlab.lib.colors import Color
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def doIt(file, regenerate=0) :
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"""Generates a PDF document, save it into file.
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file : either a filename or a file-like object.
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regenerate : if set then this function returns the Python source
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code which when run will produce the same result.
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if unset then this function returns None, and is
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from reportlab.pdfgen.pycanvas import Canvas
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from reportlab.pdfgen.canvas import Canvas
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# if we want the equivalent Python source code, then send it back
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if __name__ == "__main__" :
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if len(sys.argv) != 2 :
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# second argument must be the name of the PDF file to create
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sys.stderr.write("%s needs one and only one argument\\n" % sys.argv[0])
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# we've got a filename, we can proceed.
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print doIt(sys.argv[1], regenerate=1)
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def buildargs(*args, **kwargs) :
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"""Constructs a printable list of arguments suitable for use in source function calls."""
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arguments = arguments + ("%s, " % repr(arg))
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for (kw, val) in kwargs.items() :
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arguments = arguments+ ("%s=%s, " % (kw, repr(val)))
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if arguments[-2:] == ", " :
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arguments = arguments[:-2]
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"""Base class to fake method calls or attributes on PDF objects (Canvas, PDFPathObject, PDFTextObject)."""
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def __init__(self, parent, action) :
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"""Saves a pointer to the parent object, and the method name."""
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self._parent = parent
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self._action = action
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def __getattr__(self, name) :
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"""Probably a method call on an attribute, returns the real one."""
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return getattr(getattr(self._parent._object, self._action), name)
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def __call__(self, *args, **kwargs) :
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"""The fake method is called, print it then call the real one."""
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if not self._parent._parent._in :
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self._parent._parent._PyWrite(" %s.%s(%s)" % (self._parent._name, self._action, apply(buildargs, args, kwargs)))
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self._parent._parent._in = self._parent._parent._in + 1
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retcode = apply(getattr(self._parent._object, self._action), args, kwargs)
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self._parent._parent._in = self._parent._parent._in - 1
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return hash(getattr(self._parent._object, self._action))
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def __coerce__(self, other) :
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return coerce(getattr(self._parent._object, self._action), other)
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def _precomment(self) :
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"""To be overriden."""
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def _postcomment(self) :
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"""To be overriden."""
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"""Base class for PDF objects like PDFPathObject and PDFTextObject."""
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def __init__(self, parent) :
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"""Saves a pointer to the parent Canvas."""
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self._parent = parent
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def __getattr__(self, name) :
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"""The user's programs wants to call one of our methods or get an attribute, fake it."""
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return PDFAction(self, name)
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"""Returns the name used in the generated source code (e.g. 'p' or 't')."""
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def __call__(self, *args, **kwargs) :
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"""Real object initialisation is made here, because now we've got the arguments."""
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if not self._initdone :
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self.__class__._number = self.__class__._number + 1
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methodname = apply(self._postinit, args, kwargs)
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self._parent._PyWrite("\n # create PDF%sObject number %i\n %s = %s.%s(%s)" % (methodname[5:], self.__class__._number, self._name, self._parent._name, methodname, apply(buildargs, args, kwargs)))
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"""Our fake Canvas class, which will intercept each and every method or attribute access."""
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class TextObject(PDFObject) :
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def _postinit(self, *args, **kwargs) :
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self._object = apply(textobject.PDFTextObject, (self._parent, ) + args, kwargs)
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class PathObject(PDFObject) :
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def _postinit(self, *args, **kwargs) :
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self._object = apply(pathobject.PDFPathObject, args, kwargs)
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class Action(PDFAction) :
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"""Class called for every Canvas method call."""
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def _precomment(self) :
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"""Outputs comments before the method call."""
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if self._action == "showPage" :
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self._parent._PyWrite("\n # Ends page %i" % self._parent._pagenumber)
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elif self._action == "saveState" :
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d = self._parent._object.__dict__
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for name in self._parent._object.STATE_ATTRIBUTES:
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state[name] = d[name]
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self._parent._PyWrite("\n # Saves context level %i %s" % (self._parent._contextlevel, state))
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self._parent._contextlevel = self._parent._contextlevel + 1
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elif self._action == "restoreState" :
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self._parent._contextlevel = self._parent._contextlevel - 1
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self._parent._PyWrite("\n # Restores context level %i %s" % (self._parent._contextlevel, self._parent._object.state_stack[-1]))
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elif self._action == "beginForm" :
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self._parent._formnumber = self._parent._formnumber + 1
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self._parent._PyWrite("\n # Begins form %i" % self._parent._formnumber)
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elif self._action == "endForm" :
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self._parent._PyWrite("\n # Ends form %i" % self._parent._formnumber)
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elif self._action == "save" :
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self._parent._PyWrite("\n # Saves the PDF document to disk")
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def _postcomment(self) :
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"""Outputs comments after the method call."""
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if self._action == "showPage" :
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self._parent._pagenumber = self._parent._pagenumber + 1
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self._parent._PyWrite("\n # Begins page %i" % self._parent._pagenumber)
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elif self._action in [ "endForm", "drawPath", "clipPath" ] :
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self._parent._PyWrite("")
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def __init__(self, *args, **kwargs) :
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"""Initialize and begins source code."""
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self._parent = self # nice trick, isn't it ?
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self._contextlevel = 0
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self._footerpresent = 0
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self._object = apply(canvas.Canvas, args, kwargs)
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self._pyfile = cStringIO.StringIO()
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self._PyWrite(PyHeader)
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del kwargs["filename"]
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self._PyWrite(" # create the PDF document\n %s = Canvas(file, %s)\n\n # Begins page 1" % (self._name, apply(buildargs, args[1:], kwargs)))
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def __nonzero__(self) :
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"""This is needed by platypus' tables."""
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"""Returns the equivalent Python source code."""
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if not self._footerpresent :
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self._PyWrite(PyFooter)
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self._footerpresent = 1
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return self._pyfile.getvalue()
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def __getattr__(self, name) :
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"""Method or attribute access."""
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if name == "beginPath" :
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return self.PathObject(self)
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elif name == "beginText" :
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return self.TextObject(self)
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return self.Action(self, name)
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def _PyWrite(self, pycode) :
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"""Outputs the source code with a trailing newline."""
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self._pyfile.write("%s\n" % pycode)
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if __name__ == '__main__':
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print 'For test scripts, look in reportlab/test'
added
removed
bin/reportlab/pdfgen/pycanvas.py
