Support ttb multiline text (#8730)

Author: hugovk

Tests/images/test_combine_multiline_ttb.png

@@ -4,7 +4,11 @@
 
 from PIL import Image, ImageDraw, ImageFont
 
-from .helper import assert_image_similar_tofile, skip_unless_feature
+from .helper import (
+    assert_image_equal_tofile,
+    assert_image_similar_tofile,
+    skip_unless_feature,
+)
 
 FONT_SIZE = 20
 FONT_PATH = "Tests/fonts/DejaVuSans/DejaVuSans.ttf"
@@ -354,11 +358,27 @@ def test_combine_multiline(anchor: str, align: str) -> None:
     d.line(((200, 0), (200, 400)), "gray")
     bbox = d.multiline_textbbox((200, 200), text, anchor=anchor, font=f, align=align)
     d.rectangle(bbox, outline="red")
-    d.multiline_text((200, 200), text, fill="black", anchor=anchor, font=f, align=align)
+    d.multiline_text((200, 200), text, "black", anchor=anchor, font=f, align=align)
 
     assert_image_similar_tofile(im, path, 0.015)
 
 
+def test_combine_multiline_ttb() -> None:
+    path = "Tests/images/test_combine_multiline_ttb.png"
+    f = ImageFont.truetype("Tests/fonts/NotoSans-Regular.ttf", 48)
+    text = "te\nxt"
+
+    im = Image.new("RGB", (400, 400), "white")
+    d = ImageDraw.Draw(im)
+    d.line(((0, 200), (400, 200)), "gray")
+    d.line(((200, 0), (200, 400)), "gray")
+    bbox = d.multiline_textbbox((200, 200), text, f, direction="ttb")
+    d.rectangle(bbox, outline="red")
+    d.multiline_text((200, 200), text, "black", f, direction="ttb")
+
+    assert_image_equal_tofile(im, path)
+
+
 def test_anchor_invalid_ttb() -> None:
     font = ImageFont.truetype(FONT_PATH, FONT_SIZE)
     im = Image.new("RGB", (100, 100), "white")
@@ -378,8 +398,3 @@ def test_anchor_invalid_ttb() -> None:
             d.multiline_text((0, 0), "foo\nbar", anchor=anchor, direction="ttb")
         with pytest.raises(ValueError):
             d.multiline_textbbox((0, 0), "foo\nbar", anchor=anchor, direction="ttb")
-    # ttb multiline text does not support anchors at all
-    with pytest.raises(ValueError):
-        d.multiline_text((0, 0), "foo\nbar", anchor="mm", direction="ttb")
-    with pytest.raises(ValueError):
-        d.multiline_textbbox((0, 0), "foo\nbar", anchor="mm", direction="ttb")

Tests/test_imagefontctl.py

@@ -692,100 +692,106 @@ def _prepare_multiline_text(
         ImageFont.ImageFont | ImageFont.FreeTypeFont | ImageFont.TransposedFont,
         list[tuple[tuple[float, float], str, AnyStr]],
     ]:
-        if direction == "ttb":
-            msg = "ttb direction is unsupported for multiline text"
-            raise ValueError(msg)
-
         if anchor is None:
-            anchor = "la"
+            anchor = "lt" if direction == "ttb" else "la"
         elif len(anchor) != 2:
             msg = "anchor must be a 2 character string"
             raise ValueError(msg)
-        elif anchor[1] in "tb":
+        elif anchor[1] in "tb" and direction != "ttb":
             msg = "anchor not supported for multiline text"
             raise ValueError(msg)
 
         if font is None:
             font = self._getfont(font_size)
 
-        widths = []
-        max_width: float = 0
         lines = text.split("\n" if isinstance(text, str) else b"\n")
         line_spacing = (
             self.textbbox((0, 0), "A", font, stroke_width=stroke_width)[3]
             + stroke_width
             + spacing
         )
 
-        for line in lines:
-            line_width = self.textlength(
-                line,
-                font,
-                direction=direction,
-                features=features,
-                language=language,
-                embedded_color=embedded_color,
-            )
-            widths.append(line_width)
-            max_width = max(max_width, line_width)
-
         top = xy[1]
-        if anchor[1] == "m":
-            top -= (len(lines) - 1) * line_spacing / 2.0
-        elif anchor[1] == "d":
-            top -= (len(lines) - 1) * line_spacing
-
         parts = []
-        for idx, line in enumerate(lines):
+        if direction == "ttb":
             left = xy[0]
-            width_difference = max_width - widths[idx]
-
-            # align by align parameter
-            if align in ("left", "justify"):
-                pass
-            elif align == "center":
-                left += width_difference / 2.0
-            elif align == "right":
-                left += width_difference
-            else:
-                msg = 'align must be "left", "center", "right" or "justify"'
-                raise ValueError(msg)
+            for line in lines:
+                parts.append(((left, top), anchor, line))
+                left += line_spacing
+        else:
+            widths = []
+            max_width: float = 0
+            for line in lines:
+                line_width = self.textlength(
+                    line,
+                    font,
+                    direction=direction,
+                    features=features,
+                    language=language,
+                    embedded_color=embedded_color,
+                )
+                widths.append(line_width)
+                max_width = max(max_width, line_width)
 
-            if align == "justify" and width_difference != 0 and idx != len(lines) - 1:
-                words = line.split(" " if isinstance(text, str) else b" ")
-                if len(words) > 1:
-                    # align left by anchor
-                    if anchor[0] == "m":
-                        left -= max_width / 2.0
-                    elif anchor[0] == "r":
-                        left -= max_width
-
-                    word_widths = [
-                        self.textlength(
-                            word,
-                            font,
-                            direction=direction,
-                            features=features,
-                            language=language,
-                            embedded_color=embedded_color,
-                        )
-                        for word in words
-                    ]
-                    word_anchor = "l" + anchor[1]
-                    width_difference = max_width - sum(word_widths)
-                    for i, word in enumerate(words):
-                        parts.append(((left, top), word_anchor, word))
-                        left += word_widths[i] + width_difference / (len(words) - 1)
-                    top += line_spacing
-                    continue
+            if anchor[1] == "m":
+                top -= (len(lines) - 1) * line_spacing / 2.0
+            elif anchor[1] == "d":
+                top -= (len(lines) - 1) * line_spacing
+
+            for idx, line in enumerate(lines):
+                left = xy[0]
+                width_difference = max_width - widths[idx]
+
+                # align by align parameter
+                if align in ("left", "justify"):
+                    pass
+                elif align == "center":
+                    left += width_difference / 2.0
+                elif align == "right":
+                    left += width_difference
+                else:
+                    msg = 'align must be "left", "center", "right" or "justify"'
+                    raise ValueError(msg)
+
+                if (
+                    align == "justify"
+                    and width_difference != 0
+                    and idx != len(lines) - 1
+                ):
+                    words = line.split(" " if isinstance(text, str) else b" ")
+                    if len(words) > 1:
+                        # align left by anchor
+                        if anchor[0] == "m":
+                            left -= max_width / 2.0
+                        elif anchor[0] == "r":
+                            left -= max_width
+
+                        word_widths = [
+                            self.textlength(
+                                word,
+                                font,
+                                direction=direction,
+                                features=features,
+                                language=language,
+                                embedded_color=embedded_color,
+                            )
+                            for word in words
+                        ]
+                        word_anchor = "l" + anchor[1]
+                        width_difference = max_width - sum(word_widths)
+                        for i, word in enumerate(words):
+                            parts.append(((left, top), word_anchor, word))
+                            left += word_widths[i] + width_difference / (len(words) - 1)
+                        top += line_spacing
+                        continue
 
-            # align left by anchor
-            if anchor[0] == "m":
-                left -= width_difference / 2.0
-            elif anchor[0] == "r":
-                left -= width_difference
-            parts.append(((left, top), anchor, line))
-            top += line_spacing
+                # align left by anchor
+                if anchor[0] == "m":
+                    left -= width_difference / 2.0
+                elif anchor[0] == "r":
+                    left -= width_difference
+                parts.append(((left, top), anchor, line))
+                top += line_spacing
 
         return font, parts