Fix and improve variable font instantiation

Anonymous squash of #1190.
Kozea · Jan 7, 2024 · c3f0307 · c3f0307
1 parent daeee33
commit c3f0307
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Showing 2 changed files with 46 additions and 17 deletions.
diff --git a/weasyprint/pdf/stream.py b/weasyprint/pdf/stream.py
@@ -11,6 +11,7 @@
 
 from ..logger import LOGGER
 from ..matrix import Matrix
+from ..text.constants import PANGO_STRETCH_PERCENT
 from ..text.ffi import ffi, harfbuzz, pango, units_to_double
 
 
@@ -34,8 +35,31 @@ def __init__(self, pango_font):
         self.style = pango.pango_font_description_get_style(description)
         self.family = ffi.string(
             pango.pango_font_description_get_family(description))
+
+        self.variations = {}
+        variations = pango.pango_font_description_get_variations(
+            self.description)
+        if variations != ffi.NULL:
+            self.variations = {
+                part.split('=')[0]: float(part.split('=')[1])
+                for part in ffi.string(variations).decode().split(',')}
+        if 'wght' in self.variations:
+            pango.pango_font_description_set_weight(
+                self.description, int(round(self.variations['wght'])))
+        if self.variations.get('ital'):
+            pango.pango_font_description_set_style(
+                self.description, pango.PANGO_STYLE_ITALIC)
+        elif self.variations.get('slnt'):
+            pango.pango_font_description_set_style(
+                self.description, pango.PANGO_STYLE_OBLIQUE)
+        if 'wdth' in self.variations:
+            stretch = min(
+                PANGO_STRETCH_PERCENT.items(),
+                key=lambda item: abs(item[0] - self.variations['wdth']))[1]
+            pango.pango_font_description_set_stretch(self.description, stretch)
         description_string = ffi.string(
             pango.pango_font_description_to_string(description))
+
         # Never use the built-in hash function here: it’s not stable
         self.hash = ''.join(
             chr(65 + letter % 26) for letter
@@ -122,20 +146,13 @@ def clean(self, cmap, hinting):
 
         # Transform variable into static font
         if 'fvar' in self.ttfont:
-            variations = pango.pango_font_description_get_variations(
-                self.description)
-            if variations == ffi.NULL:
-                variations = {}
-            else:
-                variations = {
-                    part.split('=')[0]: float(part.split('=')[1])
-                    for part in ffi.string(variations).decode().split(',')}
-            if 'wght' not in variations:
-                variations['wght'] = pango.pango_font_description_get_weight(
+            if 'wght' not in self.variations:
+                weight = pango.pango_font_description_get_weight(
                     self.description)
-            if 'opsz' not in variations:
-                variations['opsz'] = units_to_double(self.font_size)
-            if 'slnt' not in variations:
+                self.variations['wght'] = weight
+            if 'opsz' not in self.variations:
+                self.variations['opsz'] = units_to_double(self.font_size)
+            if 'slnt' not in self.variations:
                 slnt = 0
                 if self.style == 1:
                     for axe in self.ttfont['fvar'].axes:
@@ -145,12 +162,12 @@ def clean(self, cmap, hinting):
                             else:
                                 slnt = axe.maxValue
                             break
-                variations['slnt'] = slnt
-            if 'ital' not in variations:
-                variations['ital'] = int(self.style == 2)
+                self.variations['slnt'] = slnt
+            if 'ital' not in self.variations:
+                self.variations['ital'] = int(self.style == 2)
             partial_font = io.BytesIO()
             try:
-                ttfont = instantiateVariableFont(self.ttfont, variations)
+                ttfont = instantiateVariableFont(self.ttfont, self.variations)
                 for key, (advance, bearing) in ttfont['hmtx'].metrics.items():
                     if advance < 0:
                         ttfont['hmtx'].metrics[key] = (0, bearing)

diff --git a/weasyprint/text/constants.py b/weasyprint/text/constants.py
@@ -19,6 +19,18 @@
     'extra-expanded': pango.PANGO_STRETCH_EXTRA_EXPANDED,
     'ultra-expanded': pango.PANGO_STRETCH_ULTRA_EXPANDED,
 }
+# From https://drafts.csswg.org/css-fonts/#font-stretch-prop
+PANGO_STRETCH_PERCENT = {
+    50: pango.PANGO_STRETCH_ULTRA_CONDENSED,
+    62.5: pango.PANGO_STRETCH_EXTRA_CONDENSED,
+    75: pango.PANGO_STRETCH_CONDENSED,
+    87.5: pango.PANGO_STRETCH_SEMI_CONDENSED,
+    100: pango.PANGO_STRETCH_NORMAL,
+    112.5: pango.PANGO_STRETCH_SEMI_EXPANDED,
+    125: pango.PANGO_STRETCH_EXPANDED,
+    150: pango.PANGO_STRETCH_EXTRA_EXPANDED,
+    200: pango.PANGO_STRETCH_ULTRA_EXPANDED,
+}
 PANGO_WRAP_MODE = {
     'WRAP_WORD': pango.PANGO_WRAP_WORD,
     'WRAP_CHAR': pango.PANGO_WRAP_CHAR,