Warn users with cairo < 1.15.4

Related to #339, #565, #616.

docs/install.rst

@@ -4,7 +4,7 @@ Installing
 WeasyPrint |version| depends on:
 
 * CPython_ ≥ 3.4
-* cairo_ ≥ 1.15.0 [#]_
+* cairo_ ≥ 1.15.4 [#]_
 * Pango_ ≥ 1.29.3
 * CFFI_ ≥ 0.6
 * html5lib_ ≥ 0.999999999
@@ -75,11 +75,13 @@ If everything goes well, you’re ready to :doc:`start using </tutorial>`
 WeasyPrint! Otherwise, please copy the full error message and
 `report the problem <http://weasyprint.org/community/>`_.
 
-.. [#] cairo ≥ 1.15 is best but older versions may work too. The test suite
-       passes on cairo 1.12 and 1.14, and passes with some tests marked as
-       “expected failures” on 1.8 and 1.10 due to behavior changes or bugs in
-       cairo. With cairo 1.14, WeasyPrint sometimes creates PDF files that may
-       not be correctly interpreted by GhostScript or CUPS.
+.. [#] cairo ≥ 1.15.4 is best but older versions may work too. The test suite
+       passes on cairo 1.14, and passes with some tests marked as “expected
+       failures” on 1.10 and 1.12 due to behavior changes or bugs in cairo. If
+       you get incomplete SVG renderings, please read `#339
+       <https://github.com/Kozea/WeasyPrint/issues/339>`_. If you get invalid
+       PDF files, please read `#565
+       <https://github.com/Kozea/WeasyPrint/issues/565>`.
 
 .. [#] Without it, PNG and SVG are the only supported image formats.
        JPEG, GIF and others are not available.

weasyprint/document.py

@@ -11,6 +11,7 @@ import functools
 import io
 import math
 import shutil
+import warnings
 
 import cairocffi as cairo
 
@@ -27,6 +28,14 @@ from .logger import LOGGER
 from .pdf import write_pdf_metadata
 
 
+if cairo.cairo_version() < 11504:
+    warnings.warn(
+        'There are known rendering problems with cairo < 1.15.4. WeasyPrint '
+        'may work with older versions, but please read the note about the '
+        'needed cairo version on the "Install" page of the documentation '
+        'before reporting bugs.')
+
+
 def _get_matrix(box):
     """Return the matrix for the CSS transforms on this box.
 

weasyprint/text.py

@@ -10,7 +10,6 @@
 """
 
 import re
-import warnings
 
 import cairocffi as cairo
 import cffi
@@ -18,9 +17,6 @@ import pyphen
 
 from .logger import LOGGER
 
-if cairo.cairo_version() <= 11400:
-    warnings.warn('There are known rendering problems with Cairo <= 1.14.0')
-
 
 CAIRO_DUMMY_CONTEXT = {
     True: cairo.Context(cairo.ImageSurface(cairo.FORMAT_ARGB32, 1, 1)),