geospatialpython/PureShp2Img.py at master · GeospatialPython/geospatialpython · GitHub

39 lines (36 loc) · 986 Bytes

"""

PureShp2Img - Convert a shapefile polygon to a PNG image using pure python

Requires Rui Carmo's PNGCanvas module from http://the.taoofmac.com

"""

import shapefile

import pngcanvas

# Read in a shapefile and write png image

r = shapefile.Reader("mississippi")

xdist = r.bbox[2] - r.bbox[0]

ydist = r.bbox[3] - r.bbox[1]

iwidth = 400

iheight = 600

xratio = iwidth/xdist

yratio = iheight/ydist

pixels = []

# Only using the first shape record

for x,y in r.shapes()[0].points:

px = int(iwidth - ((r.bbox[2] - x) * xratio))

py = int((r.bbox[3] - y) * yratio)

pixels.append([px,py])

c = pngcanvas.PNGCanvas(iwidth,iheight)

c.polyline(pixels)

f = file("mississippi.png","wb")

f.write(c.dump())

f.close()

# Create a world file

wld = file("mississippi.pgw", "w")

wld.write("%s\n" % (xdist/iwidth))

wld.write("0.0\n")

wld.write("-%s\n" % (ydist/iheight))

wld.write("%s\n" % r.bbox[0])

wld.write("%s\n" % r.bbox[3])

wld.close

Expand file tree