Auto-select digit template font

README.md

@@ -29,6 +29,8 @@ make
 
 No sudo install is required for the default Portal/PipeWire capture path.
 
+The digit matcher uses ImageMagick to render reference digits. By default it auto-selects an installed font, preferring Roboto Condensed when present and falling back to common system fonts such as DejaVu Sans.
+
 ## Use
 
 Preferred command:
@@ -61,6 +63,12 @@ Save the captured input image while debugging:
 uv run reforger_queue_read.py --portal-window --save-input /tmp/apt-portal-window.png --show-crop --debug
 ```
 
+If font matching is weird on a specific machine, pass an installed ImageMagick font explicitly:
+
+```bash
+uv run reforger_queue_read.py --portal-window --font DejaVu-Sans-Condensed --show-crop --debug
+```
+
 ## Optional KDE/KWin Mode
 
 KWin mode can automatically find the Arma window by KWin metadata and can rebind after the game restarts. It is KDE-specific and requires installing an authorized helper.

reforger_queue_read.py

@@ -16,8 +16,20 @@ import uuid
 
 DEFAULT_REFERENCE_SIZE = (2560, 1440)
 DEFAULT_REFERENCE_CROP = (1050, 620, 100, 60)
-DEFAULT_FONT = "Roboto-Condensed"
+DEFAULT_FONT = "auto"
 DEFAULT_POINTSIZE = 43
+AUTO_FONT_CANDIDATES = (
+    "Roboto-Condensed",
+    "RobotoCondensed-Regular",
+    "Roboto-Condensed-Regular",
+    "Noto-Sans-Condensed",
+    "NotoSans-Condensed",
+    "Liberation-Sans-Narrow",
+    "DejaVu-Sans-Condensed",
+    "DejaVu-Sans",
+    "Arial",
+    "Helvetica",
+)
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 SYSTEM_KWIN_HELPER = "/usr/local/bin/reforger-kwin-capture"
 DEFAULT_PORTAL_RESTORE_TOKEN = os.path.expanduser(
@@ -507,8 +519,7 @@ def save_obs_scene_screenshot_with_setup(
             time.sleep(0.5)
 
 
-def ppm_from_magick(args):
-    data = run_bytes(["magick", *args, "-alpha", "off", "-depth", "8", "ppm:-"])
+def parse_ppm(data):
     idx = 0
 
     def next_token():
@@ -540,6 +551,44 @@ def ppm_from_magick(args):
     return width, height, data[idx:]
 
 
+def ppm_from_magick(args):
+    return parse_ppm(run_bytes(["magick", *args, "-alpha", "off", "-depth", "8", "ppm:-"]))
+
+
+def try_ppm_from_magick(args):
+    command = ["magick", *args, "-alpha", "off", "-depth", "8", "ppm:-"]
+    try:
+        result = subprocess.run(command, check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    except FileNotFoundError:
+        sys.exit("missing required command: magick")
+
+    if result.returncode != 0:
+        return None, result.stderr.decode("utf-8", "replace").strip()
+
+    try:
+        return parse_ppm(result.stdout), ""
+    except Exception as exc:
+        return None, str(exc)
+
+
+def magick_fonts():
+    fonts = set()
+    for line in run_text(["magick", "-list", "font"]).splitlines():
+        match = re.match(r"\s*Font:\s*(\S+)", line)
+        if match:
+            fonts.add(match.group(1))
+    return fonts
+
+
+def template_font_candidates(font):
+    if font != "auto":
+        return [font]
+
+    available = magick_fonts()
+    candidates = [candidate for candidate in AUTO_FONT_CANDIDATES if candidate in available]
+    return [*candidates, None]
+
+
 def image_size(image_path):
     output = run_bytes(["magick", "identify", "-format", "%w %h", image_path]).decode("ascii")
     width, height = output.split()
@@ -657,24 +706,46 @@ def template_distance(left, right):
     return hamming, iou
 
 
-def build_templates(font, pointsize):
-    width, height, raw = ppm_from_magick(
+def build_template_args(font, pointsize):
+    args = [
+        "-background",
+        "black",
+        "-fill",
+        "white",
+    ]
+    if font:
+        args.extend(["-font", font])
+    args.extend(
         [
-            "-background",
-            "black",
-            "-fill",
-            "white",
-            "-font",
-            font,
             "-pointsize",
             str(pointsize),
             "label:0123456789",
         ]
     )
-    components = connected_components(white_mask(width, height, raw))
-    if len(components) < 10:
-        sys.exit(f"template rendering produced only {len(components)} digit components")
-    return {str(index): normalize(component) for index, component in enumerate(components[:10])}
+    return args
+
+
+def build_templates(font, pointsize):
+    errors = []
+    for candidate in template_font_candidates(font):
+        ppm, error = try_ppm_from_magick(build_template_args(candidate, pointsize))
+        if ppm is None:
+            errors.append(f"{candidate or 'ImageMagick default'}: {error}")
+            continue
+
+        width, height, raw = ppm
+        components = connected_components(white_mask(width, height, raw))
+        if len(components) < 10:
+            errors.append(f"{candidate or 'ImageMagick default'}: rendered only {len(components)} digit components")
+            continue
+        return {str(index): normalize(component) for index, component in enumerate(components[:10])}
+
+    if font == "auto":
+        sys.exit("could not render digit templates with any available ImageMagick font:\n  " + "\n  ".join(errors))
+    sys.exit(
+        f"could not render digit templates with font {font!r}. "
+        "Install that font, use --font auto, or pass another ImageMagick font name."
+    )
 
 
 def classify(component, templates):