More generic handling of charts

src/data_common/charting/__init__.py

@@ -19,31 +19,46 @@
 alt.themes.register("mysoc_theme", lambda: altair_theme.mysoc_theme)
 alt.themes.enable("mysoc_theme")
 
-gb_format = {"decimal": ".", "thousands": ",", "grouping": [3], "currency": ["£", ""]}
 
-alt.renderers.register("mysoc_saver", render)  # type: ignore
-alt.renderers.enable("mysoc_saver")
-alt.renderers.set_embed_options(formatLocale=gb_format)
+gb_format = {
+    "decimal": ".",
+    "thousands": ",",
+    "grouping": [3],
+    "currency": ["£", ""],
+}
 
 
-def enable_ms_charts():
+def enable_ms_charts(include_renderer: bool = True):
     alt.themes.register("mysoc_theme", lambda: altair_theme.mysoc_theme)
     alt.themes.enable("mysoc_theme")
-    alt.renderers.set_embed_options(
-        formatLocale=gb_format,
-        logo=Logo.MYSOCIETY,
-        caption_font_url="https://github.com/nteract/assets/raw/master/fonts/source-sans-pro/WOFF/OTF/SourceSansPro-Regular.otf.woff",
-    )
+    if include_renderer:
+        alt.renderers.register("mysoc_saver", render)  # type: ignore
+        alt.renderers.enable("mysoc_saver")
+        alt.renderers.set_embed_options(
+            formatLocale=gb_format,
+            logo=Logo.MYSOCIETY,
+            caption_font="SourceSansPro-Regular.otf.woff",
+            fonts_to_load=[
+                "https://github.com/nteract/assets/raw/master/fonts/source-sans-pro/WOFF/OTF/SourceSansPro-Regular.otf.woff"
+            ],
+        )
+    else:
+        alt.renderers.set_embed_options(formatLocale=gb_format)
 
 
-def enable_sw_charts():
+def enable_sw_charts(include_renderer: bool = True):
     alt.themes.register("societyworks_theme", lambda: altair_sw_theme.sw_theme)
     alt.themes.enable("societyworks_theme")
-    alt.renderers.set_embed_options(
-        formatLocale=gb_format,
-        logo=Logo.SOCIETYWORKS,
-        caption_font_url="https://github.com/google/fonts/raw/main/ofl/lato/Lato-Regular.ttf",
-    )
-
-
-enable_ms_charts()
+    if include_renderer:
+        alt.renderers.register("mysoc_saver", render)  # type: ignore
+        alt.renderers.enable("mysoc_saver")
+        alt.renderers.set_embed_options(
+            formatLocale=gb_format,
+            logo=Logo.SOCIETYWORKS,
+            caption_font="Lato-Regular.ttf",
+            fonts_to_load=[
+                "https://github.com/google/fonts/raw/main/ofl/lato/Lato-Regular.ttf"
+            ],
+        )
+    else:
+        alt.renderers.set_embed_options(formatLocale=gb_format)

src/data_common/charting/renderer.py

@@ -10,6 +10,8 @@
 
 from .str_enum import StrEnum
 
+chart_temp_dir = Path(tempfile.gettempdir()) / "mysoc_charting"
+
 
 class Logo(StrEnum):
     MYSOCIETY = (
@@ -26,8 +28,9 @@ def url_to_temp(file_url: str) -> Path:
     """
     # get filename from url
     file_name = file_url.split("/")[-1]
-    temp_file = Path(tempfile.gettempdir()) / file_name
+    temp_file = chart_temp_dir / file_name
     if not temp_file.exists():
+        chart_temp_dir.mkdir(exist_ok=True)
         logo = requests.get(file_url)
         with open(temp_file, "wb") as f:
             f.write(logo.content)
@@ -61,10 +64,25 @@ def render(spec: dict, embed_options: dict[str, Any]) -> MimeBundle:
     scale_factor = display["scale_factor"]
     logo = display["logo"] or embed_options.get("logo", "")
     caption = display["caption"]
-    caption_font_url = embed_options.get("caption_font_url", "")
+    caption_font = embed_options.get("caption_font", "")
+    fonts_to_load = embed_options.get("fonts_to_load", [])
+
+    chart_temp_dir.mkdir(exist_ok=True)
+    font_paths = [url_to_temp(font) for font in fonts_to_load]
+    caption_font_path = None
+    if caption_font:
+        caption_font_path = [x for x in font_paths if caption_font == x.name]
+        if len(caption_font_path) == 1:
+            caption_font_path = caption_font_path[0]
+        elif len(caption_font_path) > 1:
+            raise ValueError(f"Multiple fonts with the same name: {caption_font_path}")
+        else:
+            raise ValueError(f"Font not found: {caption_font}")
 
     format_locale = embed_options.get("formatLocale", {})
 
+    vlc.register_font_directory(str(chart_temp_dir))  # type: ignore
+
     png_data = vlc.vegalite_to_png(  # type: ignore
         spec, scale=scale_factor, format_locale=format_locale
     )
@@ -93,9 +111,8 @@ def render(spec: dict, embed_options: dict[str, Any]) -> MimeBundle:
         new_image.paste(downsided_logo, (0, pil_image.height))
     if caption:
         draw = ImageDraw.Draw(new_image)
-        if caption_font_url:
-            font_path = url_to_temp(caption_font_url)
-            font = ImageFont.truetype(str(font_path), 30)
+        if caption_font_path:
+            font = ImageFont.truetype(str(caption_font_path), 30)
         else:
             font = ImageFont.load_default(30)
         font_length = font.getlength(caption)

src/data_common/charting/theme.py

@@ -141,11 +141,14 @@ def color_scale(
     "config": {
         "padding": {"left": 5, "top": 5, "right": 20, "bottom": 5},
         "title": {
+            "align": "left",
             "font": font,
             "fontSize": 30,
             "anchor": "start",
             "subtitleFontSize": 20,
-            "subtitleFont": "Source Sans Pro",
+            "subtitleFont": font,
+            "subtitlePadding": 10,
+            "dx": -1,
         },
         "axis": {
             "labelFont": font,