Add basic support for adding SVG pictures to docx files #1343

[takis]

See issues #351, #651, #659.

This replaces both earlier pull requests:

• Add basic support for adding SVG pictures to docx files #1343: 2024-02-22
• Add basic support for adding SVG pictures to docx files #1107: two years ago

[marcuoli]

Hello, Is there a target date for this code to be committed to the master ?

I really need this implementation.

Thanks for the awesome software.

[takis]

Hi @marcuoli,

No, unfortunately not.

I do try to keep my fork in sync with the main repository.

[pank]

I hope this patch will be merged soon.

I'm trying to use your patch, but it doesn't appear to work with matplotlib figures since their sizes are in pt rather than pixels.

Example:

import docx
from docx.shared import Inches

import numpy as np
import matplotlib.pyplot as plt
from io import BytesIO

from tempfile import mktemp

x = np.linspace(-2*np.pi, 2*np.pi, 100)

fig, ax = plt.subplots()
ax.plot(x, np.sin(x), color="C0")
ax.plot(x, np.cos(x), color="C1")

buf = BytesIO()
fig.savefig(buf, format="svg")
w, h = (Inches(s) for s in fig.get_size_inches())

p = mktemp(suffix=".svg")
fig.savefig(p)

# doesn't work
doc = docx.Document()
doc.add_picture(buf, w, h)

Traceback:

File c:\Users\rpr\.conda\envs\funandgames\Lib\site-packages\docx\image\svg.py:43, in Svg._dimensions_from_stream(cls, stream)
     40 root = ET.fromstring(data)
     41 # FIXME: The width could be expressed as '4cm'
     42 # See https://www.w3.org/TR/SVG11/struct.html#NewDocument
---> 43 width = int(root.attrib["width"])
     44 height = int(root.attrib["height"])
     45 return width, height

I think a pt is 1.33x a pixel in svgs. If so, it might be easy to at least handle pt. But maybe it depends on dpi?
For matplotlib at least, I think dpi is fixed at 72 (e.g. here)

An example of an mpl svg is attached.

[pank]

With this patch I can insert mpl figures. It's written rather verbose, as I don't really know the style of python-docx.
@takis would you consider adding this patch or something similar?

From 458df2e57c57be410e6d2486ae67e44cebbd177e Mon Sep 17 00:00:00 2001
From: Rasmus <[email protected]>
Date: Fri, 18 Oct 2024 10:02:49 +0200
Subject: [PATCH] svg: Handle non-pixels units

---
 src/docx/image/svg.py | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/docx/image/svg.py b/src/docx/image/svg.py
index 0247a77..4be43e1 100644
--- a/src/docx/image/svg.py
+++ b/src/docx/image/svg.py
@@ -33,13 +33,37 @@ class Svg(BaseImageHeader):
         """
         return "svg"
 
+    @classmethod
+    def _dimension_to_px(cls, s):
+        """Convert SVG unit *s* to pixels.
+
+        Based on the `table`_ on absolute length in W3 CSS Values 3.
+
+        .. table: https://www.w3.org/TR/css-values-3/#absolute-lengths
+        """
+        s = str(s)
+        unit = s.lstrip("0123456789.").casefold()
+        snumber = s[:-len(unit)] if len(unit) > 0 else s
+        number = float(snumber)
+        inch = 96
+        cm = inch/2.54
+        units = {"cm": cm,
+                 "mm": cm/10,
+                 "q": cm/40,  # 'Q' in W3 table
+                 "in": inch,
+                 "pc": inch/6,
+                 "pt": inch/72,
+                 "px": 1}
+        # Unitless is pixels
+        number_px = number * units.get(unit, 1)
+        return int(number_px)
+
     @classmethod
     def _dimensions_from_stream(cls, stream):
         stream.seek(0)
         data = stream.read()
         root = ET.fromstring(data)
-        # FIXME: The width could be expressed as '4cm'
-        # See https://www.w3.org/TR/SVG11/struct.html#NewDocument
-        width = int(root.attrib["width"])
-        height = int(root.attrib["height"])
+        # The width could be expressed as '4cm'
+        width = cls._dimension_to_px(root.attrib["width"])
+        height = cls._dimension_to_px(root.attrib["height"])
         return width, height
-- 
2.44.0.windows.1
```

[lsaint]

This PR broke a unitest which need to add xmlns:asvg="http://schemas.microsoft.com/office/drawing/2016/SVG/main
to
tests/test_files/snippets/inline.txt.

some of svg files without "width" and "height" not supported yet.
eg:
<svg viewBox="0 0 96 96" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" id="Icons_CheckboxCrossed" overflow="hidden"><path d="M37.076 62.948 48.008 52.201 58.939 62.948 63.146 58.67 52.286 47.994 63.146 37.318 58.939 33.04 48.008 43.787 37.076 33.04 32.87 37.318 43.729 47.994 32.87 58.67 37.076 62.948Z"/><path d="M21 21 21 75 75 75 75 21ZM69 69 27 69 27 27 69 27Z"/></svg>

I have fixed them and added some unittests in my private fork