add roll printer support via PRINTER_MAX_LINES=0

A continuous-feed printer has no fixed page length, so photobooth.py
now sizes captures to the carriage width (PRINTER_MAX_COLS) and lets
height follow the image's own aspect ratio instead of cropping to a
row count, and txt2printr.sh always feeds the paper out at the end of
a print since there's no page to auto-advance past.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

photobooth.py

@@ -110,8 +110,12 @@ class Config:
 
 
 def convert_to_ascii(jpg_bytes, width, height, flags):
+    # height=None means "roll printer": only the width is fixed, so let the
+    # converter derive height from the image's own aspect ratio instead of
+    # forcing both dimensions and distorting or cropping the art.
+    dim_flags = ["-W", str(width)] if height is None else ["-d", f"{width},{height}"]
     proc = subprocess.run(
-        ["ascii-image-converter", "-", "-d", f"{width},{height}", *flags],
+        ["ascii-image-converter", "-", *dim_flags, *flags],
         input=jpg_bytes,
         stdout=subprocess.PIPE,
         stderr=subprocess.DEVNULL,
@@ -206,7 +210,16 @@ def prepare_print_frame(frame, cfg, inner_cols, inner_rows):
     first and mangling already-rendered ascii text, which doesn't account
     for non-square character cells and reads as visibly distorted.
     """
+    if cfg.printer_max_lines == 0:
+        # Roll printer: paper feeds continuously, so there's no page height
+        # to crop to - only the carriage width (PRINTER_MAX_COLS) limits the
+        # print. Leave the frame uncropped and pass rows=None downstream so
+        # ascii-image-converter derives height from the image's own aspect
+        # ratio instead of forcing a row count.
+        cols, rows = cfg.printer_max_cols, None
         if cfg.printer_a4:
+            frame = cv2.rotate(frame, cv2.ROTATE_90_CLOCKWISE)
+    elif cfg.printer_a4:
         cols, rows = cfg.printer_max_cols, cfg.printer_max_lines
         # Cropping happens before the 90-degree rotation below, which swaps
         # width and height, so crop to the inverse of the final aspect ratio.
@@ -338,7 +351,7 @@ def main(stdscr):
                 )
                 print_jpg_bytes = print_buf.tobytes()
                 print_width = cfg.width or str(print_cols)
-                print_height = cfg.height or str(print_rows)
+                print_height = cfg.height or (str(print_rows) if print_rows is not None else None)
                 print_ascii_lines = convert_to_ascii(
                     print_jpg_bytes, print_width, print_height, conv_flags
                 )

printer.conf

@@ -21,5 +21,12 @@ PRINTER_A4=false
 # then read off the last line number on page 1 (-> PRINTER_MAX_LINES) and
 # how many characters of the 64-wide test lines actually printed before
 # being cut off (-> PRINTER_MAX_COLS).
+#
+# Set PRINTER_MAX_LINES=0 for a roll/continuous-feed printer that has no
+# fixed page length. In that mode photobooth.py sizes captures to fill
+# PRINTER_MAX_COLS width and lets height follow the image's own aspect
+# ratio instead of cropping to a row count, and txt2printr.sh always feeds
+# the paper out at the end of a print instead of skipping the feed when a
+# page is already full (there's no page to fill).
 PRINTER_MAX_LINES=64
 PRINTER_MAX_COLS=54

txt2printr.sh

@@ -9,7 +9,8 @@
 #                            converting it to ascii (photobooth.py does this
 #                            for better quality; set by it automatically)
 # Reads printer.conf for PRINTER_A4 (landscape rotation) and PRINTER_MAX_LINES
-# (per-page line capacity, measured with pagetest.sh).
+# (per-page line capacity, measured with pagetest.sh; 0 means a roll/
+# continuous-feed printer with no fixed page length).
 
 dir="$(dirname "$0")"
 [ -f "$dir/printer.conf" ] && source "$dir/printer.conf"
@@ -84,7 +85,9 @@ line_count=$(body | wc -l)
     # Skip the form feed once the page is already full: printers commonly
     # auto-advance to a new page as soon as content hits the bottom margin,
     # so an explicit form feed on top of that just ejects a blank extra page.
-    if [ "$line_count" -lt "$PRINTER_MAX_LINES" ]; then
+    # A roll printer (PRINTER_MAX_LINES=0) has no page to fill or auto-advance
-        printf '\x0c'                # form feed - eject the page
+    # past, so always feed the paper out to clear the printed art for tear-off.
+    if [ "$PRINTER_MAX_LINES" -eq 0 ] || [ "$line_count" -lt "$PRINTER_MAX_LINES" ]; then
+        printf '\x0c'                # form feed - eject the page / advance the roll
     fi
 } > "$dev"