Allow generating multi-line QR codes in batch mode

Author: jgoerzen

README.md

@@ -191,18 +191,20 @@ commands are:
   first.
 * `TEXTADD`: Adds an additional line to the current block of text.  Used to
   create multiline text blocks.
-* `QR`: Creates a QR code block
+* `QRSTART`: Creates a QR code block
+* `QRADD`: Adds additional lines to the text that will be encoded to form the QR
+  code (rarely used)
 
 For instance, this input:
 
 ```text
 TEXTSTART:FD12
 TEXTADD:2013
-QR:1234
+QRSTART:1234
 TEXTSTART:BIG
 TEXTSTART:LINE1
 TEXTADD:LINE2
-QR:12345
+QRSTART:12345
 ```
 
 Creates a label with:

src/labelle/cli/cli.py

@@ -506,24 +506,44 @@ def render_text(lines):
 
     if batch:
         text_accumulator: List[str] = []
+        qr_accumulator: List[str] = []
+
+        def flush_text():
+            nonlocal text_accumulator
+            if len(text_accumulator) > 0:
+                render_text(text_accumulator)
+                text_accumulator = []
+
+        def flush_qr():
+            nonlocal qr_accumulator
+            if len(qr_accumulator) > 0:
+                render_engines.append(
+                    QrRenderEngine(qr_callback("\n".join(qr_accumulator)))
+                )
+                qr_accumulator = []
+
+        def flush_both():
+            flush_text()
+            flush_qr()
+
         for line in sys.stdin:
             line = line.rstrip("\r\n")
             parts = line.split(":", 1)
             if parts[0] == "TEXTSTART":
-                if len(text_accumulator) > 0:
-                    render_text(text_accumulator)
-                text_accumulator = [parts[1]]
+                flush_both()
+                text_accumulator.append(parts[1])
             elif parts[0] == "TEXTADD":
+                flush_qr()
                 text_accumulator.append(parts[1])
-            elif parts[0] == "QR":
-                if len(text_accumulator) > 0:
-                    render_text(text_accumulator)
-                    text_accumulator = []
-                render_engines.append(QrRenderEngine(qr_callback(parts[1])))
+            elif parts[0] == "QRSTART":
+                flush_both()
+                qr_accumulator.append(parts[1])
+            elif parts[0] == "QRADD":
+                flush_text()
+                qr_accumulator.append(parts[1])
             else:
                 print("WARNING: invalid command", line)
-        if len(text_accumulator) > 0:
-            render_text(text_accumulator)
+        flush_both()
 
     if fixed_length is None:
         min_label_mm_len = min_length