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128 lines
4.6 KiB
Python
128 lines
4.6 KiB
Python
#Copyright ReportLab Europe Ltd. 2000-2012
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#see license.txt for license details
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#history http://www.reportlab.co.uk/cgi-bin/viewcvs.cgi/public/reportlab/trunk/reportlab/pdfgen/pathobject.py
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__version__=''' $Id$ '''
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__doc__="""
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PDFPathObject is an efficient way to draw paths on a Canvas. Do not
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instantiate directly, obtain one from the Canvas instead.
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Progress Reports:
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8.83, 2000-01-13, gmcm: created from pdfgen.py
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"""
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from reportlab.pdfgen import pdfgeom
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from reportlab.lib.rl_accel import fp_str
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class PDFPathObject:
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"""Represents a graphic path. There are certain 'modes' to PDF
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drawing, and making a separate object to expose Path operations
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ensures they are completed with no run-time overhead. Ask
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the Canvas for a PDFPath with getNewPathObject(); moveto/lineto/
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curveto wherever you want; add whole shapes; and then add it back
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into the canvas with one of the relevant operators.
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Path objects are probably not long, so we pack onto one line
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the code argument allows a canvas to get the operatiosn appended directly so
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avoiding the final getCode
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"""
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def __init__(self,code=None):
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self._code = (code,[])[code is None]
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self._code_append = self._init_code_append
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def _init_code_append(self,c):
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assert c.endswith(' m') or c.endswith(' re'), 'path must start with a moveto or rect'
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code_append = self._code.append
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code_append('n')
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code_append(c)
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self._code_append = code_append
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def getCode(self):
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"pack onto one line; used internally"
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return ' '.join(self._code)
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def moveTo(self, x, y):
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self._code_append('%s m' % fp_str(x,y))
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def lineTo(self, x, y):
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self._code_append('%s l' % fp_str(x,y))
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def curveTo(self, x1, y1, x2, y2, x3, y3):
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self._code_append('%s c' % fp_str(x1, y1, x2, y2, x3, y3))
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def arc(self, x1,y1, x2,y2, startAng=0, extent=90):
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"""Contributed to piddlePDF by Robert Kern, 28/7/99.
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Draw a partial ellipse inscribed within the rectangle x1,y1,x2,y2,
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starting at startAng degrees and covering extent degrees. Angles
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start with 0 to the right (+x) and increase counter-clockwise.
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These should have x1<x2 and y1<y2.
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The algorithm is an elliptical generalization of the formulae in
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Jim Fitzsimmon's TeX tutorial <URL: http://www.tinaja.com/bezarc1.pdf>."""
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self._curves(pdfgeom.bezierArc(x1,y1, x2,y2, startAng, extent))
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def arcTo(self, x1,y1, x2,y2, startAng=0, extent=90):
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"""Like arc, but draws a line from the current point to
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the start if the start is not the current point."""
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self._curves(pdfgeom.bezierArc(x1,y1, x2,y2, startAng, extent),'lineTo')
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def rect(self, x, y, width, height):
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"""Adds a rectangle to the path"""
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self._code_append('%s re' % fp_str((x, y, width, height)))
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def ellipse(self, x, y, width, height):
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"""adds an ellipse to the path"""
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self._curves(pdfgeom.bezierArc(x, y, x + width,y + height, 0, 360))
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def _curves(self,curves,initial='moveTo'):
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getattr(self,initial)(*curves[0][:2])
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for curve in curves:
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self.curveTo(*curve[2:])
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def circle(self, x_cen, y_cen, r):
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"""adds a circle to the path"""
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x1 = x_cen - r
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y1 = y_cen - r
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width = height = 2*r
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self.ellipse(x1, y1, width, height)
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def roundRect(self, x, y, width, height, radius):
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"""Draws a rectangle with rounded corners. The corners are
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approximately quadrants of a circle, with the given radius."""
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#use a precomputed set of factors for the bezier approximation
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#to a circle. There are six relevant points on the x axis and y axis.
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#sketch them and it should all make sense!
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t = 0.4472 * radius
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x0 = x
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x1 = x0 + t
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x2 = x0 + radius
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x3 = x0 + width - radius
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x4 = x0 + width - t
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x5 = x0 + width
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y0 = y
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y1 = y0 + t
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y2 = y0 + radius
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y3 = y0 + height - radius
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y4 = y0 + height - t
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y5 = y0 + height
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self.moveTo(x2, y0)
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self.lineTo(x3, y0) #bottom row
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self.curveTo(x4, y0, x5, y1, x5, y2) #bottom right
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self.lineTo(x5, y3) #right edge
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self.curveTo(x5, y4, x4, y5, x3, y5) #top right
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self.lineTo(x2, y5) #top row
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self.curveTo(x1, y5, x0, y4, x0, y3) #top left
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self.lineTo(x0, y2) #left edge
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self.curveTo(x0, y1, x1, y0, x2, y0) #bottom left
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self.close()
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def close(self):
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"draws a line back to where it started"
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self._code_append('h')
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