Add replace_medias() utility (useful for header/footer images)

CHANGES.rst

@@ -1,3 +1,7 @@
+0.4.0 (2017-09-03)
+------------------
+- Add replace_medias() utility (useful for header/footer images)
+
 0.3.9 (2017-06-27)
 ------------------
 - Fix exception in fix_table()

docs/index.rst

@@ -165,6 +165,20 @@ in your python code ::
 in your docx template just use ``{{ mylisting }}``
 With ``Listing()``, you will keep the current character styling (except after a ``\a`` as you start a new paragraph).
 
+Replace docx medias
+-------------------
+
+It is not possible to dynamically add images in header/footer, but you can change them.
+The idea is to put a dummy picture in your template, render the template as usual, then replace the dummy picture with another one.
+You can do that for all medias at the same time.
+Note: for images, the aspect ratio will be the same as the replaced image
+Note2 : it is important to have the source media files as they are required to calculate their CRC to find them in the docx
+
+Syntax to replace dummy_header_pic.jpg and dummy2.jpg in mydoc.docx::
+
+   replace_medias('mydoc.docx',[('dummy_header_pic.jpg','header_pic_i_want.jpg'),('dummy2.png','mycompany.png')])
+
+
 Jinja custom filters
 --------------------
 

docxtpl/__init__.py

@@ -5,7 +5,7 @@ Created : 2015-03-12
 @author: Eric Lapouyade
 '''
 
-__version__ = '0.3.9'
+__version__ = '0.4.0'
 
 from lxml import etree
 from docx import Document
@@ -14,6 +14,9 @@ from jinja2 import Template
 from cgi import escape
 import re
 import six
+import binascii
+import os
+import zipfile
 
 NEWLINE =  '</w:t><w:br/><w:t xml:space="preserve">'
 NEWPARAGRAPH = '</w:t></w:r></w:p><w:p><w:r><w:t xml:space="preserve">'
@@ -297,6 +300,35 @@ class InlineImage(object):
     def __str__(self):
         return self.xml
 
+def replace_medias(docx_filename,src_dst_lst):
+    """Utility function replace any media by another into a docx
 
+    This has been done mainly because it is not possible to add images in docx header/footer.
+    With this function, put a dummy picture in your header/footer, then specify it with its replacement in this function
 
+    Syntax: replace_medias('mydoc.docx',[('dummy_header_pic.jpg','header_pic_i_want.jpg'),('dummy2.png','mycompany.png')])
 
+    Note: for images, the aspect ratio will be the same as the replaced image
+    Note2 : it is important to have the source media files as they are required to calculate their CRC to find them in the docx
+    """
+    crc_to_new_media = {}
+    for src,dst in src_dst_lst:
+        with open(src,'rb') as fh:
+            buf = fh.read()
+            crc = (binascii.crc32(buf) & 0xFFFFFFFF)
+        with open(dst,'rb') as fh:
+            crc_to_new_media[crc] = fh.read()
+
+    backup_filename = '%s_before_replace_medias' % docx_filename
+    os.rename(docx_filename,backup_filename)
+
+    with zipfile.ZipFile(backup_filename) as zin:
+        with zipfile.ZipFile(docx_filename, 'w') as zout:
+            for item in zin.infolist():
+                buf = zin.read(item.filename)
+                if item.filename.startswith('word/media/') and item.CRC in crc_to_new_media:
+                    zout.writestr(item, crc_to_new_media[item.CRC])
+                else:
+                    zout.writestr(item, buf)
+
+    os.remove(backup_filename)

tests/header_footer_image.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+'''
+Created : 2017-09-03
+
+@author: Eric Lapouyade
+'''
+
+from docxtpl import DocxTemplate, replace_medias
+
+DEST_FILE = 'test_files/header_footer_image.docx'
+
+tpl=DocxTemplate('test_files/header_footer_image_tpl.docx')
+
+context = {
+    'mycompany' : 'The World Wide company',
+}
+
+tpl.render(context)
+tpl.save(DEST_FILE)
+replace_medias(DEST_FILE,[('test_files/dummy_pic_for_header.png','test_files/python.png')])

tests/runtests.py

@@ -2,7 +2,7 @@ import subprocess
 import glob
 import six
 
-tests = glob.glob('[A-Za-z]*.py')
+tests = sorted(glob.glob('[A-Za-z]*.py'))
 excludes = ['runtests.py']
 
 for test in tests: