Merge pull request matplotlib#21904 from ambi7/repr-html-fonts

Added _repr_html_ for fonts

Author: timhoffm

lib/matplotlib/font_manager.py

@@ -23,8 +23,10 @@
 #   - setWeights function needs improvement
 #   - 'light' is an invalid weight value, remove it.
 
+from base64 import b64encode
 import dataclasses
 from functools import lru_cache
+from io import BytesIO
 import json
 import logging
 from numbers import Number
@@ -380,6 +382,22 @@ def findSystemFonts(fontpaths=None, fontext='ttf'):
     return [fname for fname in fontfiles if os.path.exists(fname)]
 
 
+def fontentry_helper_repr_png_(fontent):
+    from matplotlib.figure import Figure  # Circular import.
+    fig = Figure()
+    font_path = Path(fontent.fname) if fontent.fname != '' else None
+    fig.text(0, 0, fontent.name, font=font_path)
+    with BytesIO() as buf:
+        fig.savefig(buf, bbox_inches='tight', transparent=True)
+        return buf.getvalue()
+
+
+def fontentry_helper_repr_html_(fontent):
+    png_stream = fontentry_helper_repr_png_(fontent)
+    png_b64 = b64encode(png_stream).decode()
+    return f"<img src=\"data:image/png;base64, {png_b64}\" />"
+
+
 FontEntry = dataclasses.make_dataclass(
     'FontEntry', [
         ('fname', str, dataclasses.field(default='')),
@@ -395,7 +413,11 @@ def findSystemFonts(fontpaths=None, fontext='ttf'):
     A class for storing Font properties.
 
     It is used when populating the font lookup dictionary.
-    """})
+    """,
+        '_repr_html_': lambda self: fontentry_helper_repr_html_(self),
+        '_repr_png_': lambda self: fontentry_helper_repr_png_(self),
+    }
+)
 
 
 def ttfFontProperty(font):

lib/matplotlib/tests/test_font_manager.py

@@ -2,6 +2,7 @@
 import multiprocessing
 import os
 from pathlib import Path
+from PIL import Image
 import shutil
 import subprocess
 import sys
@@ -11,9 +12,10 @@
 import pytest
 
 from matplotlib.font_manager import (
-    findfont, findSystemFonts, FontProperties, fontManager, json_dump,
-    json_load, get_font, is_opentype_cff_font, MSUserFontDirectories,
-    _get_fontconfig_fonts, ft2font, ttfFontProperty, cbook)
+    findfont, findSystemFonts, FontEntry, FontProperties, fontManager,
+    json_dump, json_load, get_font, is_opentype_cff_font,
+    MSUserFontDirectories, _get_fontconfig_fonts, ft2font,
+    ttfFontProperty, cbook)
 from matplotlib import pyplot as plt, rc_context
 
 has_fclist = shutil.which('fc-list') is not None
@@ -268,6 +270,24 @@ def test_fontcache_thread_safe():
                     f"{proc.returncode}.")
 
 
+def test_fontentry_dataclass():
+    fontent = FontEntry(name='font-name')
+
+    png = fontent._repr_png_()
+    img = Image.open(BytesIO(png))
+    assert img.width > 0
+    assert img.height > 0
+
+    html = fontent._repr_html_()
+    assert html.startswith("<img src=\"data:image/png;base64")
+
+
+def test_fontentry_dataclass_invalid_path():
+    with pytest.raises(FileNotFoundError):
+        fontent = FontEntry(fname='/random', name='font-name')
+        fontent._repr_html_()
+
+
 @pytest.mark.skipif(sys.platform == 'win32', reason='Linux or OS only')
 def test_get_font_names():
     paths_mpl = [cbook._get_data_path('fonts', subdir) for subdir in ['ttf']]