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piddlePS.py

00001 """
piddlePS - a PostScript backend for the PIDDLE drawing module

   Magnus Lie Hetland
   
   1999
"""
# some fixups by Chris Lee (clee@users.sourceforge.net)

# $Id: piddlePS.py,v 1.26 2002/01/08 01:28:40 clee Exp $
#
# For each page, the coordinate system is intialized with "0 canvasHeight translate" so
# that coordiante (0,0) is at the top left of the page
# Therefore all y coordinates must be entered in opposite sign to go down
# Also, remember that angles are reversed relative to postscript standard -cwl

# TODO for version 1.0:
#     X add greyscale image support for smaller images (added to level 2)
#     X add Level2 postscript options
#     X add underline implementation from piddlePDF
#     X ** fix \n breaking in drawString
#     ? Bezier curve thing (Robert Kern's fix is in piddlePDF)
#          Hmm..drawCurve(..) already uses postscript's bezier curveto-- is there anything else
#          to be done? 
#     X drawArc stuff from Eric

# In the Future:
#    _ Base85 ecooding just use hex encoding involves 1:2 expansion of image data vs 4:5
#    _ Don't see a flate/deflate filter for Postscript, jpeg DCTEncode could be added.
#         PIL may have a LZW encoder 
#    _ check Adobe Document struturing conventions (half done)
#    _ look at symbol's font metrics--they appear to be a little off
#    X postscript native implementation of drawRoundRect 
#    _ improve underlining placement...doesn't look good for courier and symbol

#  DSC: plan uses flags for keeping track of BeginX/EndX pairs.
#            convention: use flag _inXFlag


from piddle import *
import string, cStringIO
import piddlePSmetrics # for font info
import math

linesep = '\n'
### constants for fonts ###

# This is actually a mapping between legal font names and PSFontMapXXX keys
# note: all piddle font names are lower-cased before running against this mapping)
PiddleLegalFonts = {"helvetica": "helvetica",  # note: keys are lowercased 
                    "times": "times",
                    "courier": "courier",
                    "serif": "times",
                    "sansserif": "helvetica",
                    "monospaced": "courier",
                    "symbol" : "symbol"} # Could add more...


Roman="Roman"; Bold="Bold"; Italic="Italic"



PSFontMapStdEnc = { ("helvetica", Roman): "Helvetica-Roman",
                    ("helvetica", Bold): "Helvetica-Bold",
                    ("helvetica", Italic): "Helvetica-Oblique",
                    ("times", Roman) : "Times-Roman",
                    ("times", Bold) : "Times-Bold",
                    ("times", Italic) : "Times-Italic",
                    ("courier", Roman) : "Courier-Roman",
                    ("courier", Bold) : "Courier-Bold",
                    ("courier", Italic) : "Courier-Oblique",
                    ("symbol", Roman) : "Symbol",
                    ("symbol", Bold) :  "Symbol",
                    ("symbol", Italic) : "Symbol",
                    "EncodingName" : 'StandardEncoding' }


PSFontMapLatin1Enc = { ("helvetica", Roman): "Helvetica-Roman-ISOLatin1",
                       ("helvetica", Bold): "Helvetica-Bold-ISOLatin1",
                       ("helvetica", Italic): "Helvetica-Oblique-ISOLatin1",
                       ("times", Roman) : "Times-Roman-ISOLatin1",
                       ("times", Bold) : "Times-Bold-ISOLatin1",
                       ("times", Italic) : "Times-Italic-ISOLatin1",
                       ("courier", Roman) : "Courier-Roman-ISOLatin1",
                       ("courier", Bold) : "Courier-Bold-ISOLatin1",
                       ("courier", Italic) : "Courier-Oblique-ISOLatin1",
                       ("symbol", Roman) : "Symbol",
                       ("symbol", Bold) :  "Symbol",
                       ("symbol", Italic) : "Symbol",
                       "EncodingName" : 'Latin1Encoding' }


###############################################################



00097 def latin1FontEncoding(fontname):

    """use this to generating PS code for re-encoding a font as ISOLatin1
    from font with name 'fontname' defines reencoded font, 'fontname-ISOLatin1'"""
    
    latin1FontTemplate =  """/%s findfont
dup length dict begin
  {1 index /FID ne
        {def}
        {pop pop}
      ifelse
   } forall
   /Encoding ISOLatin1Encoding  def
   currentdict
end
/%s-ISOLatin1 exch definefont pop
"""
    #
    return latin1FontTemplate % (fontname, fontname)


class EpsDSC:

    # remeber %% will be reduced to % when using string substitution
    # returned strings do not end with \n
    
    def __init__(self):
        pass 
        
    ## Genral DSC conventions
    def documentHeader(self):
        return  "%!PS-Adobe-3.0 EPSF-3.0"


    def boundingBoxStr(self, x0, y0, x1,y1):
        "coordinates of bbox in default PS coordinates"
        return "%%BoundingBox: " + "%s %s %s %s" % (x0, y0, x1,y1)

    def BeginPageStr(self, pageSetupStr, pageName=None):

        """Use this at the beginning of each page, feed it your setup code
        in the form of a string of postscript.  pageName is the "number" of the
        page.  By default it will be 0."""

        self.inPageFlag = 1  # keep track
        
        if not pageName:
            pageDeclaration = r"%%Page: " +  "%d" % 0  # default 0
        else:
            pageDeclaration = "%%Page: " + pageName
            
        ret = pageDeclaration + "\n" + \
"""%%BeginPageSetup
/pgsave save def
"""
        # print pageSetupStr ???
        return ret  + pageSetupStr  + "\n%%EndPageSetup"

    def EndPageStr(self):
        self.inPageFlag = 0
        return ""


##########################################################################

00162 class PSCanvas(Canvas):

    """This canvas is meant for generating encapsulated PostScript files
    (EPS) used for inclusion in other documents; thus really only
    single-page documents are supported.  For historical reasons and
    because they can be printed (a showpage is included), the files are
    given a .ps extension by default, and a primitive sort of multipage
    document can be generated using nextPage() or clear().  Use at your own
    risk!  Future versions of piddlePS will include an EPSCanvas and a
    PSCanvas which will clearly delineate between single and multipage
    documents.

    Note: All font encodings must be taken care in __init__, you can't add
          more after this"""

    def __init__(self,size=(300,300),name='piddlePS',
                 PostScriptLevel=2,
                 fontMapEncoding=PSFontMapLatin1Enc):
        
       Canvas.__init__(self,size,name)
       width, height = self.size = size
       self.filename = name
       if len(name) < 3 or string.lower(name[-3:]) != '.ps':
           self.filename = name + ".ps"

       # select between postscript level 1 or level 2
       if PostScriptLevel == 1 :
           self.drawImage = self._drawImageLevel1
       elif PostScriptLevel == 2 :
           self.drawImage = self._drawImageLevel2
       else :
           raise 'PostScriptLevelException'
00194 

       self.code = []
       self.dsc = EpsDSC()  # handle document structing conventions
       
       c = self._currentColor = self.defaultLineColor
       r,g,b = c.red, c.green, c.blue
       
       w = self._currentWidth = self.defaultLineWidth
       self.setLineCap( 0) # sets butt as default cap style

       self.defaultFont = Font(face='serif') 
       self.fontMapEncoding = fontMapEncoding
       
       self._currentFont = self.defaultFont
       f = self._findFont(self._currentFont)
       s = self._currentFont.size

       # Page Structure State
       #----------------------
       self._inDocumentFlag = 0  # this is set in psBeginDocument
       self._inPageFlag = 0   # we have't started a page

       self.pageNum = 1   # User is free to reset this or even make this a string


       self.psBeginDocument()

       ## finally begin the first page ##
       self.psBeginPage() # each psBeginPage() needs to be closed w/ a psEndPage()


    def psBeginDocument(self):
        # General DSC Prolog := <header> [<defaults>] <procedures>
        self.code.append(self.dsc.documentHeader())
        self.code.append(self.dsc.boundingBoxStr(0,0,self.size[0],self.size[1]))
        self.code.append("%%Pages: (atend)")
        self._inDocumentFlag = 1  # we need a Trailer to fix this up

        ######  Defaults Procedures Prolog Setup  ??? ######
        # are these procedures??? check this chris
       
        # Now create Latin1ISO font encodings for non-symbol fonts (need to add pdf fonts too)
        shapes = {"Helvetica": ["Roman", "Bold", "Oblique"],
                  "Times": ["Roman", "Bold", "Italic"],
                  "Courier": ["Roman", "Bold", "Oblique"] }
        fntnames = []
        
        for basename in ['Helvetica', 'Times', 'Courier']:
            for mys in shapes[basename]:
                fntnames.append(basename + '-' + mys)

        # assign the default FontMapping (which also determines the encoding)

        for fontname in fntnames:
            self.code.append(latin1FontEncoding(fontname))



    def psEndDocument(self):
        
        if self._inDocumentFlag:
            # Take care of Trailer
            self.code.append("%%Trailer")
            self.code.append("%%%%Pages: %d" % self.pageNum)

            # signal end of file
            # check on need for %%EOF
            self.code.append("%%EOF\n")
            


    def psBeginPage(self, pageName=None):
        # call this function when beginning a new page but before any piddle drawing commands
        # pagesetup contains code to insert into DSC page 'header'
        if not pageName:
            pageName = "%s" % self.pageNum
        pagesetup = self._psPageSetupStr(self.size[1], self.defaultLineColor,
                                       self._findFont(self.defaultFont),
                                       self.defaultFont.size,
                                       self.defaultLineWidth)
        self.code.append(self.dsc.BeginPageStr(pageSetupStr= pagesetup, pageName=pageName ))
        self._inPageFlag = 1
        

    def _psPageSetupStr(self,pageheight, initialColor, font_family, font_size, line_width):
        "ps code for settin up coordinate system for page in accords w/ piddle standards"
        r,g,b = initialColor.red, initialColor.green, initialColor.blue
        return '''
%% initialize

2 setlinecap

0 %d
translate

%s %s %s setrgbcolor
(%s) findfont %s scalefont setfont
%s setlinewidth''' % (pageheight, r, g, b, font_family, font_size, line_width)



    def psEndPage(self):
        self.code.append("pgsave restore")
        self.code.append("showpage")
        self._inPageFlag = 0

       
       

    def _findFont(self,font):

        requested = font.face or "Serif"  # Serif is the default
        if type(requested) == StringType:
            requested = [requested]

        # once again, fall back to default, redundant, no?
        face = string.lower(PiddleLegalFonts["serif"])  
        for reqFace in requested:
            if PiddleLegalFonts.has_key(string.lower(reqFace)):
                face = string.lower(PiddleLegalFonts[string.lower(reqFace)])
                break

        if font.bold:
            shape = Bold
        elif font.italic:
            shape = Italic
        else:
            shape = Roman

        return self.fontMapEncoding[(face, shape)]





00330     def _findExternalFontName(self, font):       #copied from piddlePDF by cwl- hack away!
        """Attempts to return proper font name.
        PDF uses a standard 14 fonts referred to
        by name. Default to self.defaultFont('Helvetica').
        The dictionary allows a layer of indirection to
        support a standard set of PIDDLE font names."""

        piddle_font_map = {
            'Times':'Times',
            'times':'Times',
            'Courier':'Courier',
            'courier':'Courier',
            'helvetica':'Helvetica',
            'Helvetica':'Helvetica',
            'symbol':'Symbol',
            'Symbol':'Symbol',
            'monospaced':'Courier',
            'serif':'Times',
            'sansserif':'Helvetica',
            'ZapfDingbats':'ZapfDingbats',
            'zapfdingbats':'ZapfDingbats',
            'arial':'Helvetica'
            }

        try:
            face = piddle_font_map[string.lower(font.face)]
        except:
            return 'Helvetica'

        name = face + '-'
        if font.bold and face in ['Courier','Helvetica','Times']:
            name = name + 'Bold'
        if font.italic and face in ['Courier', 'Helvetica']:
            name = name + 'Oblique'
        elif font.italic and face == 'Times':
            name = name + 'Italic'

        if name == 'Times-':
            name = name + 'Roman'
        # symbol and ZapfDingbats cannot be modified!

        #trim and return
        if name[-1] == '-':
            name = name[0:-1]
        return name



    def _psNextPage(self):
        "advance to next page of document.  "
        self.psEndPage()
        self.pageNum = self.pageNum + 1
        self.psBeginPage()

    def nextPage(self):
        self.clear()

00387     def clear(self):

        """clear resets the canvas to it's default state.  Though this
        canvas is really only meant to be an EPS canvas, i.e., single page,
        for historical reasons we will allow multipage documents.  Thus
        clear will end the page, clear the canvas state back to default,
        and start a new page.  In the future, this PSCanvas will become
        EPSCanvas and will not support multipage documents.  In that case,
        the canvas will be reset to its default state and the file will be
        emptied of all previous drawing commands"""

        self.resetToDefaults()
        self._psNextPage()

    def resetToDefaults(self):
        self._currentColor = self.defaultLineColor
        self._currentWidth = self.defaultLineWidth
        self._currentFont  = self.defaultFont

        
    def flush(self):
        pass

        # Comment the following out to make flush() a null function
        # file = open(self.filename,'w')
        # from string import join
        # file.write(join(self.code,linesep))
        # file.write('\nshowpage\n')
        # file.close()


    
00419     def save(self, file=None, format=None):
        """Write the current document to a file or stream and close the file
        Computes any final trailers, etc. that need to be done in order to
        produce a well formed postscript file.  At least for now though,
        it still allows you to add to the file after a save by not actually
        inserting the finalization code into self.code

        the format argument is not used"""
        
        # save() will now become part of the spec.
        file = file or self.filename
        fileobj = getFileObject(file)
        fileobj.write(string.join(self.code, linesep))
        # here's a hack. we might want to be able to add more after saving so
        # preserve the current code ???
        preserveCode = self.code        
        self.code = finalizationCode = [""]

        # might be able to move these things into DSC class & use a save state call
        preserve_inPageFlag = self._inPageFlag
        preserve_inDocumentFlag = self._inDocumentFlag
        
        # now do finalization code in via self.code
        # first question: are we in the middle of a page?

        if self._inPageFlag:
            self.psEndPage()

        self.psEndDocument()  # depends on _inDocumentFlag :(

        fileobj.write(string.join(finalizationCode, linesep))
        #  fileobj.close()  ### avoid this for now
        ## clean up my mess: This is not a good way to do things FIXME!!! ???
        self.code = preserveCode
        self._inPageFlag = preserve_inPageFlag
        self._inDocumentFlag = preserve_inDocumentFlag 


       
    def stringWidth(self, s, font=None):
        "Return the logical width of the string if it were drawn \
        in the current font (defaults to self.font)."
        if not font:
            font = self.defaultFont
        fontname = self._findExternalFontName(font)
        return piddlePSmetrics.psStringWidth(s, fontname, self.fontMapEncoding["EncodingName"]) * font.size * 0.001

    
    ### def fontHeight(self, font=None) ### use default piddle method
    # distance between baseline of two lines of text 1.2 * font.size for piddle.py
    # Thus is 1.2 times larger than postscript minimum baseline to baseline separation
    # for single-spaced text.  fontHeight() used internally for drawString() multi-line text

    def fontAscent(self, font=None):
        if not font:
            font = self.defaultFont
        fontname = self._findExternalFontName(font)
        return piddlePSmetrics.ascent_descent[fontname][0] * 0.001 * font.size


    def fontDescent(self, font=None):
        if not font:
            font = self.defaultFont
        fontname = self._findExternalFontName(font)
        return -piddlePSmetrics.ascent_descent[fontname][1] * 0.001 * font.size



    def _updateLineColor(self, color):
       color = color or self.defaultLineColor
       if color != self._currentColor:
          self._currentColor = color
          r,g,b = color.red, color.green, color.blue
          self.code.append('%s %s %s setrgbcolor' % (r,g,b))


    def _updateFillColor(self, color):
       color = color or self.defaultFillColor
       if color != self._currentColor:
          self._currentColor = color
          r,g,b = color.red, color.green, color.blue
          self.code.append('%s %s %s setrgbcolor' % (r,g,b))


    def _updateLineWidth(self, width):
       if width == None: width = self.defaultLineWidth
       if width != self._currentWidth:
          self._currentWidth = width
          self.code.append('%s setlinewidth' % width)


##     def _updateLineCap(self, cap):
##        """0 is butt, 1 is round, 2 is projecting"""
##        assert cap in (0,1,2), "The lineCap is allowed to be only one of 0,1,2"  
##        if cap == None: cap = self.defaultLineCap
##        if cap != self._currentCap:
##           self._currentCap = cap
##           self.code.append('%s setlinecap' % cap)
          

00519     def _updateFont(self, font):
       font = font or self.defaultFont
       if font != self._currentFont:
          self._currentFont = font
          f = self._findFont(font)
          s = font.size
          self.code.append('(%s) findfont %s scalefont setfont' % (f, s))


    def setLineCap( self, cap):
       assert cap in (0,1,2), "The lineCap is allowed to be only one of 0,1,2"          
       self._currentCap = cap


    def drawLine(self, x1, y1, x2, y2, color=None, width=None):
       self._updateLineColor(color)
       self._updateLineWidth(width)
       if self._currentColor != transparent:
          self.code.append('%d setlinecap %s %s neg moveto %s %s neg lineto stroke' %
                           (self._currentCap, x1, y1, x2, y2))


    def drawLines(self, lineList, color=None, width=None):
       self._updateLineColor(color)
       self._updateLineWidth(width)
       codeline = ('%d setlinecap' % self._currentCap) + '%s %s neg moveto %s %s neg lineto stroke'
       if self._currentColor != transparent:
          for line in lineList:
             self.code.append(codeline % line)


    def _escape(self, s):
        # return a copy of string s with special characters in postscript strings
        # escaped" with backslashes."""
        # Have not handled characters that are converted normally in python strings
        # i.e. \n -> newline 
        str = string.replace(s, chr(0x5C), r'\\' )
        str = string.replace(str, '(', '\(' )
        str = string.replace(str, ')', '\)')
        return str 

    # ??? check to see if \n response is handled correctly (should move cursor down)
       
    def _drawStringOneLineNoRot(self, s, x, y, font=None) :
       # PRE: x and y and position at which to place text
       # PRE: helper function, only called from drawString(..)
       text = self._escape(s)
       self.code.append('%s %s neg moveto (%s) show' % (x,y,text))
       if self._currentFont.underline:
           swidth = self.stringWidth(s, self._currentFont)
           ypos =  (0.5 * self.fontDescent(self._currentFont))
           thickness = 0.08 * self._currentFont.size  # relate to font.descent?
           self.code.extend(['%s setlinewidth' % thickness,
                             '0 %s neg rmoveto' % (ypos),
                             '%s 0 rlineto stroke' % -swidth])
       


    def _drawStringOneLine(self, s, x, y, font=None, color=None, angle=0):
       # PRE: assumes that coordinate system has already been set for rotated strings
       # PRE: only meant to be called by drawString(..)
       text = self._escape(s)
       self.code.extend(['%f %f neg moveto (%s) show' % (x, y, text)])

       if self._currentFont.underline:
          swidth = self.stringWidth(s, self._currentFont)
          dy =  (0.5 * self.fontDescent(self._currentFont))
          thickness = 0.08 * self._currentFont.size  # relate to font.descent?
          self.code.extend(['%s setlinewidth' % thickness,
                            '%f %f neg moveto' % (x, dy+y),
                            '%f 0 rlineto stroke' % swidth])


00592     def drawString(self, s, x, y, font=None, color=None, angle=0):
        """drawString(self, s, x, y, font=None, color=None, angle=0)
        draw a string s at position x,y"""
        self._updateLineColor(color)
        self._updateFont(font)
        if self._currentColor != transparent:

            lines = string.split(s, '\n')   
            lineHeight = self.fontHeight(font)

            if angle == 0 :   # do special case of angle = 0 first. Avoids a bunch of gsave/grestore ops
               for line in lines:
                  self._drawStringOneLineNoRot(line, x, y, font=font)
            else : # general case, rotated text
               self.code.extend([
                  'gsave',
                  '%s %s neg translate' % (x,y),
                  `angle`+' rotate'])
               down = 0
               for line in lines :
                  self._drawStringOneLine(line, 0, 0+down, font, color, angle)
                  down = down + lineHeight
               self.code.extend(['grestore'])

    def drawCurve(self, x1, y1, x2, y2, x3, y3, x4, y4,
                  edgeColor=None, edgeWidth=None, fillColor=None, closed=0):
       codeline = '%s %s neg moveto %s %s neg %s %s neg %s %s neg curveto'
       data = (x1, y1, x2, y2, x3, y3, x4, y4)
       self._updateFillColor(fillColor)
       if self._currentColor != transparent:
          self.code.append((codeline % data) + ' eofill')
       self._updateLineWidth(edgeWidth)
       self._updateLineColor(edgeColor)
       if self._currentColor != transparent:
          self.code.append((codeline % data)
                           + ((closed and ' closepath') or '')
                           + ' stroke')

    ########################################################################################

    def drawRoundRect(self, x1,y1, x2,y2, rx=8, ry=8,
                      edgeColor=None, edgeWidth=None, fillColor=None):
        "Draw a rounded rectangle between x1,y1, and x2,y2, \
        with corners inset as ellipses with x radius rx and y radius ry. \
        These should have x1<x2, y1<y2, rx>0, and ry>0."
        # Path is drawn in counter-clockwise direction"
        
        x1, x2 = min(x1,x2), max(x1, x2) # from piddle.py
        y1, y2 = min(y1,y2), max(y1, y2)

        # Note: arcto command draws a line from current point to beginning of arc
        # save current matrix, translate to center of ellipse, scale by rx ry, and draw
        # a circle of unit radius in counterclockwise dir, return to original matrix
        # arguments are (cx, cy, rx, ry, startAngle, endAngle)
        ellipsePath = 'matrix currentmatrix %s %s neg translate %s %s scale 0 0 1 %s %s arc setmatrix' 

        # choice between newpath and moveto beginning of arc
        # go with newpath for precision, does this violate any assumptions in code???
        # rrcode = ['%s %s neg moveto' % (x1+rx, y1)]  # this also works
        rrcode = ['newpath'] # Round Rect code path
        # upper left corner ellipse is first
        rrcode.append(ellipsePath % (x1+rx, y1+ry, rx, ry, 90, 180))
        rrcode.append(ellipsePath % (x1+rx, y2-ry, rx, ry, 180, 270))
        rrcode.append(ellipsePath % (x2-rx, y2-ry, rx, ry, 270, 360))
        rrcode.append(ellipsePath % (x2-rx, y1+ry, rx, ry, 0,  90) )
        rrcode.append('closepath')
        
        # This is what you are required to do to take care of all color cases
        # should fix this so it doesn't define path twice, just use gsave if need
        # to fill and stroke path-need to figure out this system
        self._updateFillColor(fillColor)
        if self._currentColor != transparent:
            self.code.extend(rrcode)
            self.code.append("eofill")
        self._updateLineWidth(edgeWidth)
        self._updateLineColor(edgeColor)
        if self._currentColor != transparent:
            self.code.extend(rrcode)
            self.code.append("stroke")



        
    def drawEllipse(self, x1,y1, x2,y2, edgeColor=None, edgeWidth=None, 
                    fillColor=None):
        "Draw an orthogonal ellipse inscribed within the rectangle x1,y1,x2,y2. \
        These should have x1<x2 and y1<y2."
        #Just invoke drawArc to actually draw the ellipse
        self.drawArc(x1,y1, x2,y2, edgeColor=edgeColor, edgeWidth=edgeWidth,
                fillColor=fillColor)

    def drawArc(self, x1,y1, x2,y2, startAng=0, extent=360, edgeColor=None,
                edgeWidth=None, fillColor=None):
        "Draw a partial ellipse inscribed within the rectangle x1,y1,x2,y2, \
        starting at startAng degrees and covering extent degrees.   Angles \
        start with 0 to the right (+x) and increase counter-clockwise. \
        These should have x1<x2 and y1<y2."
        #calculate centre of ellipse
        cx, cy = (x1+x2)/2.0, (y1+y2)/2.0
        rx, ry = (x2-x1)/2.0, (y2-y1)/2.0
        
        codeline = self._genArcCode(x1, y1, x2, y2, startAng, extent) 

        # fill portion
        self._updateFillColor(fillColor)

        if self._currentColor != transparent:
            self.code.append('%s %s neg moveto' % (cx,cy)) # move to center of circle
            self.code.append(codeline + ' eofill')

        # stroke portion
        self._updateLineWidth(edgeWidth)
        self._updateLineColor(edgeColor)

        if self._currentColor != transparent:
            # move current point to start of arc, note negative angle because y increases down
            self.code.append('%s %s neg moveto' % (cx+rx*math.cos(-startAng),
                                                   cy+ry*math.sin(-startAng))) 
            self.code.append(codeline + ' stroke')

    def _genArcCode(self, x1, y1, x2, y2, startAng, extent):
        "Calculate the path for an arc inscribed in rectangle defined by (x1,y1),(x2,y2)"
        #calculate semi-minor and semi-major axes of ellipse
        xScale = abs((x2-x1)/2.0)
        yScale = abs((y2-y1)/2.0)
        #calculate centre of ellipse
        x, y = (x1+x2)/2.0, (y1+y2)/2.0

        codeline = 'matrix currentmatrix '+\
                '%s %s neg translate %s %s scale 0 0 1 %s %s %s '+\
                'setmatrix'

        if extent >= 0:
            arc='arc'
        else:
            arc='arcn'
        data = (x,y, xScale, yScale, startAng, startAng+extent, arc)

        return codeline % data

    
    def drawPolygon(self, pointlist, 
                    edgeColor=None, edgeWidth=None, fillColor=None, closed=0):

       start = pointlist[0]
       pointlist = pointlist[1:]
       
       polyCode = []
       polyCode.append("%s %s neg moveto" % start)
       for point in pointlist:
          polyCode.append("%s %s neg lineto" % point)
       if closed:
          polyCode.append("closepath")

       self._updateFillColor(fillColor)
       if self._currentColor != transparent:
          self.code.extend(polyCode)
          self.code.append("eofill")
       self._updateLineWidth(edgeWidth)
       self._updateLineColor(edgeColor)
       if self._currentColor != transparent:
          self.code.extend(polyCode)
          self.code.append("stroke")


    def drawFigure(self, partList,
                   edgeColor=None, edgeWidth=None, fillColor=None, closed=0):
       
       figureCode = []
       first = 1
       
       for part in partList:
           op = part[0]
           args = list(part[1:])

           if op == figureLine:
               if first:
                   first = 0
                   figureCode.append("%s %s neg moveto" % tuple(args[:2]))
               else:
                   figureCode.append("%s %s neg lineto" % tuple(args[:2]))
               figureCode.append("%s %s neg lineto" % tuple(args[2:]))

           elif op == figureArc:
               first = 0
               x1,y1,x2,y2,startAngle,extent = args[:6]
               figureCode.append(self._genArcCode(x1,y1,x2,y2,startAngle,extent))

           elif op == figureCurve:
               if first:
                   first = 0
                   figureCode.append("%s %s neg moveto" % tuple(args[:2]))
               else:
                   figureCode.append("%s %s neg lineto" % tuple(args[:2]))
               figureCode.append("%s %s neg %s %s neg %s %s neg curveto" % tuple(args[2:]))
           else:
               raise TypeError, "unknown figure operator: "+op

       if closed:
           figureCode.append("closepath")

       self._updateFillColor(fillColor)
       if self._currentColor != transparent:
          self.code.extend(figureCode)
          self.code.append("eofill")
       self._updateLineWidth(edgeWidth)
       self._updateLineColor(edgeColor)
       if self._currentColor != transparent:
          self.code.extend(figureCode)
          self.code.append("stroke")

    ############################################################################################
    # drawImage(self. image, x1, y1, x2=None, y2=None) is now defined by either _drawImageLevel1
    #    ._drawImageLevel2, the choice is made in .__init__ depending on option 


00808     def _drawImageLevel1(self, image, x1, y1, x2=None,y2=None):
        # Postscript Level1 version available for fallback mode when Level2 doesn't work
       """drawImage(self,image,x1,y1,x2=None,y2=None) : If x2 and y2 are ommitted, they are
       calculated from image size.  (x1,y1) is upper left of image, (x2,y2) is lower right of
       image in piddle coordinates."""
       try:
           import Image
       except ImportError:
           print 'Python Imaging Library not available'
           return
       # For now let's start with 24 bit RGB images (following piddlePDF again)
       print "Trying to drawImage in piddlePS"
       component_depth = 8
       myimage = image.convert('RGB')
       imgwidth, imgheight = myimage.size
       if not x2:
            x2 = imgwidth + x1
       if not y2:
            y2 = y1 + imgheight
       drawwidth = x2 - x1
       drawheight = y2 - y1
       print 'Image size (%d, %d); Draw size (%d, %d)' % (imgwidth, imgheight, drawwidth, drawheight)
       # now I need to tell postscript how big image is

       # "image operators assume that they receive sample data from
       # their data source in x-axis major index order.  The coordinate
       # of the lower-left corner of the first sample is (0,0), of the
       # second (1,0) and so on" -PS2 ref manual p. 215
       #
       # The ImageMatrix maps unit squre of user space to boundary of the source image
       #

       # The CurrentTransformationMatrix (CTM) maps the unit square of
       # user space to the rect...on the page that is to receive the
       # image. A common ImageMatrix is [width 0 0 -height 0 height]
       # (for a left to right, top to bottom image )
       
       # first let's map the user coordinates start at offset x1,y1 on page

       self.code.extend([
           'gsave',
           '%s %s translate' % (x1,-y1 - drawheight), # need to start are lower left of image
           '%s %s scale' % (drawwidth,drawheight),
           '/scanline %d 3 mul string def' % imgwidth  # scanline by multiples of image width
           ])

       # now push the dimensions and depth info onto the stack
       # and push the ImageMatrix to map the source to the target rectangle (see above)
       # finally specify source (PS2 pp. 225 ) and by exmample
       self.code.extend([
           '%s %s %s' % (imgwidth, imgheight, component_depth),
           '[%s %s %s %s %s %s]' % (imgwidth, 0, 0, -imgheight, 0, imgheight),
           '{ currentfile scanline readhexstring pop } false 3',
           'colorimage '
           ])

       # data source output--now we just need to deliver a hex encode
       # series of lines of the right overall size can follow
       # piddlePDF again

       rawimage = myimage.tostring()
       assert(len(rawimage) == imgwidth*imgheight, 'Wrong amount of data for image') 
       #compressed = zlib.compress(rawimage) # no zlib at moment
       hex_encoded = self._AsciiHexEncode(rawimage)
       
       # write in blocks of 78 chars per line
       outstream = cStringIO.StringIO(hex_encoded)

       dataline = outstream.read(78)
       while dataline <> "":
           self.code.append(dataline)
           dataline= outstream.read(78)
       self.code.append('% end of image data') # for clarity
       self.code.append('grestore') # return coordinates to normal

    # end of drawImage

       
    def _AsciiHexEncode(self, input):  # also based on piddlePDF
        "Helper function used by images"
        output = cStringIO.StringIO()
        for char in input:
            output.write('%02x' % ord(char))
        output.reset()
        return output.read()

    def _drawImageLevel2(self, image, x1,y1, x2=None,y2=None): # Postscript Level2 version
        try:
            import Image
        except ImportError:
            print 'Python Imaging Library not available'
            return
               # I don't have zlib -cwl
#         try:
#             import zlib
#         except ImportError:
#             print 'zlib not available'
#             return
       

        ### what sort of image are we to draw
        if image.mode=='L' :
            print 'found image.mode= L'
            imBitsPerComponent = 8
            imNumComponents = 1
            myimage = image 
        elif image.mode == '1':
            print 'found image.mode= 1'
            myimage = image.convert('L')
            imNumComponents = 1
            myimage = image 
        else :
            myimage = image.convert('RGB')
            imNumComponents = 3
            imBitsPerComponent = 8

        imwidth, imheight = myimage.size
        # print 'imwidth = %s, imheight = %s' % myimage.size
        if not x2:
            x2 = imwidth + x1
        if not y2:
            y2 = y1 + imheight
        drawwidth = x2 - x1
        drawheight = y2 - y1
        self.code.extend([
            'gsave',
            '%s %s translate' % (x1,-y1 - drawheight), # need to start are lower left of image
            '%s %s scale' % (drawwidth,drawheight)])

        if imNumComponents == 3 :
            self.code.append('/DeviceRGB setcolorspace')
        elif imNumComponents == 1 :
            self.code.append('/DeviceGray setcolorspace')
            print 'setting colorspace gray'
        # create the image dictionary
        self.code.append("""
<<
/ImageType 1
/Width %d /Height %d  %% dimensions of source image
/BitsPerComponent %d""" % (imwidth, imheight, imBitsPerComponent) )

        if imNumComponents == 1:
            self.code.append('/Decode [0 1]')
        if imNumComponents == 3:
            self.code.append('/Decode [0 1 0 1 0 1]  %% decode color values normally')

        self.code.extend(['/ImageMatrix [%s 0 0 %s 0 %s]' % (imwidth, -imheight, imheight),
                          '/DataSource currentfile /ASCIIHexDecode filter',
                          '>> % End image dictionary',
                          'image'])
        # after image operator just need to dump image dat to file as hexstring
        rawimage = myimage.tostring()
        assert(len(rawimage) == imwidth*imheight, 'Wrong amount of data for image') 
        #compressed = zlib.compress(rawimage) # no zlib at moment
        hex_encoded = self._AsciiHexEncode(rawimage)
       
        # write in blocks of 78 chars per line
        outstream = cStringIO.StringIO(hex_encoded)

        dataline = outstream.read(78)
        while dataline <> "":
            self.code.append(dataline)
            dataline= outstream.read(78)
        self.code.append('> % end of image data') # > is EOD for hex encoded filterfor clarity
        self.code.append('grestore') # return coordinates to normal

        
        
                         
                       
            

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