PyObjC and Quartz - CGContextDrawGlyphsAtPoint

PyObjC on Snow Leopard and Xcode 3.2.  I've been trying to draw some text into a PDF context with a custom barcode font.  I've tried translating this source, found here to Python:

http://www.gogo-robot.com/2009/06/07/two-awkward-things-about-iphone-development/

And here is the relevant code for drawing the barcode:

class Barcode(Graphic):
		initialized = NO
		def __init__(self, rect, string, size):
				self.string = string
				self.font = None
				self.size = size
				if not self.initialized:
					fontpath = NSBundle.mainBundle().pathForResource_ofType_("FRE3OF9X", "TTF")
					datap = CGDataProviderCreateWithFilename(fontpath.UTF8String())
					self.font = CGFontCreateWithDataProvider(datap)
					#CGDataProviderRelease(datap)
					self.initialized = YES
				Graphic.__init__(self, rect)
		def draw(self,c):
				length = len(self.string)
				glyphs = objc.allocateBuffer(length)
				chars = objc.allocateBuffer(length + 1)
				self.string.getCString_maxLength_encoding_(chars, length + 1, NSASCIIStringEncoding)
				for i in range(length):
					glyphs[i] = chr(ord(chars[i]) - 29)
				CGContextSaveGState(c)
				CGContextSetFont(c, self.font)
				CGContextSetFontSize(c, self.size)
				CGContextSetRGBFillColor(c, 0, 0, 0, 1)
				CGContextSetRGBStrokeColor (c, 0, 0, 0, 1)
				CGContextSetTextMatrix (c, self.xform)
				CGContextShowGlyphsAtPoint(c, 0, 0, glyphs, length)
				CGContextRestoreGState(c)

Getting this error:

CGContextShowGlyphsAtPoint(c, 0, 0, glyphs, length)
ValueError: depythonifying 'unsigned short', got 'str'

Can anybody point me in the right direction in how to properly prepare a data structure to pass to the CGContextShowGlyphsAtPoint(..) function.  Can I use ctypes?




Any help appreciated. Thanks.

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