misc: use poppler to create PDF thumbnails (#34492)

debian/control

@@ -28,7 +28,7 @@ Recommends: python-dns,
     python-qrcode,
     python-magic,
     python-docutils,
-    graphicsmagick
+    poppler-utils
 Suggests: python-libxml2,
     python-lasso,
     python-psycopg2

wcs/qommon/form.py

@@ -75,7 +75,7 @@ from wcs.conditions import Condition, ValidationError
 from qommon import _, ngettext
 import misc
 from .humantime import humanduration2seconds, seconds2humanduration, timewords
-from .misc import strftime, C_, HAS_GM
+from .misc import strftime, C_, HAS_PDFTOPPM
 from publisher import get_cfg
 from .template_utils import render_block_to_string
 
@@ -707,7 +707,7 @@ class FileWithPreviewWidget(CompositeWidget):
             return False
 
         if filetype == 'application/pdf':
-            return HAS_GM
+            return HAS_PDFTOPPM
 
         if not filetype.startswith('image/'):
             return False

wcs/qommon/misc.py

@@ -54,10 +54,10 @@ from qommon.template import Template
 from django.utils.six import StringIO
 
 try:
-    subprocess.check_call(['which', 'gm'], stdout=open('/dev/null', 'w'))
-    HAS_GM = True
+    subprocess.check_call(['which', 'pdftoppm'], stdout=open('/dev/null', 'w'))
+    HAS_PDFTOPPM = True
 except subprocess.CalledProcessError:
-    HAS_GM = False
+    HAS_PDFTOPPM = False
 
 
 EXIF_ORIENTATION = 0x0112
@@ -570,7 +570,7 @@ def file_digest(content, chunk_size=100000):
 
 def can_thumbnail(content_type):
     if content_type == 'application/pdf':
-        return bool(HAS_GM and Image)
+        return bool(HAS_PDFTOPPM and Image)
     if content_type and content_type.startswith('image/'):
         return bool(Image is not None)
     return False
@@ -583,7 +583,7 @@ def get_thumbnail(filepath, content_type=None):
     if content_type == 'application/pdf':
         try:
             fp = StringIO(subprocess.check_output(
-                    ['gm', 'convert', '-geometry', '500x', 'pdf:%s' % filepath, 'png:-']))
+                    ['pdftoppm', '-png', '-scale-to-x', '500', '-scale-to-y', '-1', filepath]))
         except subprocess.CalledProcessError:
             raise ThumbnailError()
     else: