Left align text when center_text is false

barcode/writer.py

@@ -140,6 +140,7 @@ def __init__(
         self.text_distance = 5
         self.text_line_distance = 1
         self.center_text = True
+        self._left_align_text = False
         self.guard_height_factor = 1.1
         self.margin_top = 1
         self.margin_bottom = 1
@@ -275,6 +276,8 @@ def render(self, code: list[str]) -> bytes | T_Image:
         ypos += self.module_height
 
         if self.text and self._callbacks["paint_text"] is not None:
+            # Text blocks between guards are always positioned by their center.
+            self._left_align_text = not (self.center_text or text["start"])
             if not text["start"]:
                 # If we don't have any start value, print the entire ean
                 ypos += self.text_distance
@@ -378,14 +381,15 @@ def _create_text(self, xpos: float, ypos: float) -> None:
         # check option to override self.text with self.human (barcode as
         # human readable data, can be used to print own formats)
         barcodetext = self.human if self.human != "" else self.text
+        anchor = "start" if self._left_align_text else "middle"
         for subtext in barcodetext.split("\n"):
             element = self._document.createElement("text")
             attributes = {
                 "x": SIZE.format(xpos),
                 "y": SIZE.format(ypos),
                 "style": (
                     f"fill:{self.foreground};"
-                    f"font-size:{self.font_size}pt;text-anchor:middle;"
+                    f"font-size:{self.font_size}pt;text-anchor:{anchor};"
                 ),
             }
             _set_attributes(element, **attributes)
@@ -494,13 +498,14 @@ def _paint_text(self, xpos: float, ypos: float) -> None:
             if font_size <= 0:
                 return
             font = ImageFont.truetype(self.font_path, font_size)
+            anchor = "ld" if self._left_align_text else "md"
             for subtext in barcodetext.split("\n"):
                 pos = (
                     mm2px(xpos, self.dpi),
                     mm2px(ypos, self.dpi),
                 )
                 self._draw.text(
-                    pos, subtext, font=font, fill=self.foreground, anchor="md"
+                    pos, subtext, font=font, fill=self.foreground, anchor=anchor
                 )
                 ypos += pt2mm(self.font_size) / 2 + self.text_line_distance
 

docs/changelog.rst

@@ -9,6 +9,8 @@ v0.17.0
   barcodes. (#251)
 * Fix ISBN-10 and ISSN barcodes being truncated to 10 and 8 digits.
 * Fix Code128 emitting different (but valid) output depending on invocation.
+* Fix ``center_text=False`` centering the text on the left edge of the barcode
+  instead of left aligning it, which cut off the text. (#145)
 
 v0.16.1
 ~~~~~~~

tests/test_writers.py

@@ -2,15 +2,19 @@
 
 import os
 from io import BytesIO
+from xml.dom.minidom import Element
+from xml.dom.minidom import parseString
 
 from barcode import EAN13
 from barcode.writer import ImageWriter
 from barcode.writer import SVGWriter
+from barcode.writer import mm2px
 
 PATH = os.path.dirname(os.path.abspath(__file__))
 TESTPATH = os.path.join(PATH, "test_outputs")
 
 if ImageWriter is not None:
+    from PIL import ImageOps
 
     def test_saving_image_to_byteio() -> None:
         assert ImageWriter is not None  # workaround for mypy
@@ -34,6 +38,20 @@ def test_saving_rgba_image() -> None:
                 f, options={"background": "rgba(255,0,0,0)"}
             )
 
+    def test_image_center_text_false_left_aligns_text() -> None:
+        assert ImageWriter is not None  # workaround for mypy
+
+        writer = ImageWriter()
+        image = EAN13("100000902922", writer=writer).render(
+            {"center_text": False, "quiet_zone": 6.5, "module_height": 15.0}
+        )
+        assert not isinstance(image, bytes)  # workaround for mypy
+
+        below_bars = (0, int(mm2px(17, writer.dpi)), image.width, image.height)
+        text_box = ImageOps.invert(image.convert("L")).crop(below_bars).getbbox()
+        assert text_box is not None
+        assert text_box[0] >= int(mm2px(6.5, writer.dpi))
+
 
 def test_saving_svg_to_byteio() -> None:
     rv = BytesIO()
@@ -49,3 +67,31 @@ def test_saving_svg_to_byteio_with_guardbar() -> None:
 
     with open(f"{TESTPATH}/somefile_guardbar.svg", "wb") as f:
         EAN13("100000011111", writer=SVGWriter(), guardbar=True).write(f)
+
+
+def _svg_texts(barcode: EAN13, **options: object) -> list[Element]:
+    rv = BytesIO()
+    barcode.write(rv, options=options)
+    return parseString(rv.getvalue()).getElementsByTagName("text")
+
+
+def test_svg_text_is_centered_by_default() -> None:
+    [text] = _svg_texts(EAN13("100000902922", writer=SVGWriter()))
+
+    assert "text-anchor:middle;" in text.getAttribute("style")
+
+
+def test_svg_center_text_false_left_aligns_text() -> None:
+    [text] = _svg_texts(EAN13("100000902922", writer=SVGWriter()), center_text=False)
+
+    assert "text-anchor:start;" in text.getAttribute("style")
+    assert text.getAttribute("x") == "6.500mm"
+
+
+def test_svg_center_text_false_keeps_guardbar_blocks_centered() -> None:
+    texts = _svg_texts(
+        EAN13("100000902922", writer=SVGWriter(), guardbar=True), center_text=False
+    )
+
+    assert len(texts) > 1
+    assert all("text-anchor:middle;" in text.getAttribute("style") for text in texts)