Fix bidirectional text processing on get_string_width

CHANGELOG.md

@@ -40,6 +40,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 * default values for `top_margin` and `bottom_margin` in `HTML2FPDF._new_paragraph()` calls are now correctly converted into chosen document units.
 * In [text_columns()](https://py-pdf.github.io/fpdf2/extColumns.html), paragraph top/bottom margins didn't correctly trigger column breaks; [issue #1214](https://github.com/py-pdf/fpdf2/issues/1214)
 * [`fpdf.drawing.color_from_hex_string`](https://py-pdf.github.io/fpdf2/fpdf/drawing.html#fpdf.drawing.color_from_hex_string) did not test or mention accepting lowercase hex values.
+* handling of bidirectional text on `FPDF.get_string_width()` [issue #1231]
 ### Removed
 * an obscure and undocumented [feature](https://github.com/py-pdf/fpdf2/issues/1198) of [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html), which used to magically pass instance attributes as arguments.
 ### Deprecated

fpdf/fpdf.py

@@ -1073,7 +1073,7 @@ def get_string_width(self, s, normalized=False, markdown=False):
         # normalized is parameter for internal use
         s = s if normalized else self.normalize_text(s)
         w = 0
-        for frag in self._parse_chars(s, markdown):
+        for frag in self._preload_bidirectional_text(s, markdown):
             w += frag.get_width()
         return w
 

test/text_shaping/test_bidirectional.py

@@ -234,3 +234,36 @@ def test_bidi_paragraph_direction(tmp_path):
         HERE / "bidi_paragraph_direction.pdf",
         tmp_path,
     )
+
+
+def test_bidi_get_string_width(tmp_path):
+    # issue 1231
+    teststrings = [
+        "الملوك",
+        "الملوك",
+        "test",
+        "الملوك",
+        "الملوك",
+        "الملوك",
+        "test",
+        "الملوك",
+        "test",
+    ]
+    pdf = FPDF()
+    pdf.add_page()
+    pdf.c_margin = 0
+    pdf.add_font("noto", style="", fname=HERE / "NotoNaskhArabic-Regular.ttf")
+    pdf.set_text_shaping(use_shaping_engine=True)
+
+    pdf.set_font("noto", size=24)
+    pdf.set_draw_color(160)
+    pdf.set_line_width(0.3)
+    for string in teststrings:
+        pdf.set_x(110 - pdf.get_string_width(string))
+        pdf.rect(
+            pdf.get_x(), pdf.get_y() + 2, pdf.get_string_width(string), 13, style="D"
+        )
+        pdf.cell(h=17, text=string)
+        pdf.ln()
+    pdf.ln()
+    assert_pdf_equal(pdf, HERE / "bidi_get_string_width.pdf", tmp_path)