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Download images as png or pdf

Author:
gkelly
Posted:
April 3, 2007
Language:
Python
Version:
.96
Tags:
pdf png custom-response subprocess
Score:
0 (after 0 ratings)

This is an example of how I am providing downloads of dynamic images in either PNG or PDF formats. The PDF format requires ImageMagick's convert, and temporary disk space to save the intermediary image. If anyone knows a way to avoid writing to disk, I'd be happy to include it here. I realize there may be uses where it isn't necessary to use the PIL Image class if the image is already stored as a file. This is used for downloading dynamic images without saving them to disk (unless pdf format is used).

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# This is not a full working example, just a starting point
# for downloading images in different formats.

import subprocess
import Image

def image_as_png_pdf(request):
  output_format = request.GET.get('format')
  im = Image.open(path_to_image) # any Image object should work
  if output_format == 'png':
    response = HttpResponse(mimetype='image/png')
    response['Content-Disposition'] = 'attachment; filename=%s.png' % filename
    im.save(response, 'png') # will call response.write()
  else:
    # Temporary disk space, server process needs write access
    tmp_path = '/tmp/'
    # Full path to ImageMagick convert binary
    convert_bin = '/usr/bin/convert' 
    im.save(tmp_path+filename+'.png', 'png')
    response = HttpResponse(mimetype='application/pdf')
    response['Content-Disposition'] = 'attachment; filename=%s.pdf' % filename
    ret = subprocess.Popen([ convert_bin, 
                            "%s%s.png"%(tmp_path,filename), "pdf:-" ],
                            stdout=subprocess.PIPE)
    response.write(ret.stdout.read())
  return response
 

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Comments

gkelly (on April 5, 2007):

doh!

That's much simpler. Well, at least I figured out how to use subprocess and pipe stdout to a django response...

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