feat(title): 标题自由位置拖拽后端支持——pos_x/pos_y 注入 \pos 定位 (#1592)

packages/domain/ass_subtitle_builder.py

@@ -256,6 +256,42 @@ def _wrap_title_text(
     return "\\N".join(wrapped_segments)
 
 
+def _parse_title_position(
+    title_config: dict[str, Any],
+    video_width: int,
+    video_height: int,
+) -> tuple[int, int] | None:
+    """解析标题自由拖拽坐标 pos_x/pos_y（PlayRes 像素坐标系）。
+
+    要求两个字段同时存在、可转 int，且落在 [0, video_width] × [0, video_height]
+    闭区间内。任一条件不满足返回 None，调用方回退 position 三档逻辑。
+
+    Args:
+        title_config: 标题配置 dict
+        video_width: PlayResX（视频宽度像素）
+        video_height: PlayResY（视频高度像素）
+
+    Returns:
+        (x, y) 整数坐标，或 None 表示不使用自由位置
+    """
+    if "pos_x" not in title_config or "pos_y" not in title_config:
+        return None
+    raw_x = title_config["pos_x"]
+    raw_y = title_config["pos_y"]
+    # 坐标必须是 PlayRes 像素整数：bool 是 int 子类（isinstance(True,int)=True）
+    # 但 True/False 作坐标无意义；float 静默截断会造成拖拽位置偏差，一律按非法回退
+    if isinstance(raw_x, bool) or isinstance(raw_y, bool):
+        return None
+    if not isinstance(raw_x, int) or not isinstance(raw_y, int):
+        return None
+    x, y = raw_x, raw_y
+    if video_width <= 0 or video_height <= 0:
+        return None
+    if not (0 <= x <= video_width and 0 <= y <= video_height):
+        return None
+    return (x, y)
+
+
 def build_ass_content(
     *,
     video_width: int,
@@ -343,7 +379,16 @@ def build_ass_content(
             title_shadow.get("offset_y", 2) if title_shadow.get("enabled", False) else 0,
         )
 
-        title_alignment = position_to_ass_alignment(title_config.get("position", "top"))
+        # ── 自由位置拖拽（工单 #1405 方案 B）────────────────────────────
+        # pos_x/pos_y 为 PlayRes 坐标系像素整数（PlayResX/Y = video_width/height）。
+        # 合法时：TitleStyle Alignment 固定 5（\an5 中对齐，使 \pos 锚点为文本块中心），
+        # Dialogue 文本前注入 {\pos(x,y)}。字段缺失/非法/越界时一律回退
+        # position → alignment 三档逻辑，现有输出保持一字节不变。
+        title_pos = _parse_title_position(title_config, video_width, video_height)
+
+        title_alignment = 5 if title_pos is not None else position_to_ass_alignment(
+            title_config.get("position", "top")
+        )
 
         styles.append(
             build_ass_style(
@@ -370,6 +415,10 @@ def build_ass_content(
         safe_title_text_raw = escape_ass_text(title_text)
         safe_title_text = _wrap_title_text(safe_title_text_raw, video_width, title_font_size)
 
+        # 自由位置：在文本前注入 \pos override tag（锚点为文本块中心，配合 \an5）
+        if title_pos is not None:
+            safe_title_text = f"{{\\pos({title_pos[0]},{title_pos[1]})}}{safe_title_text}"
+
         events.append(
             "Dialogue: 0,0:00:00.00," f"{format_ass_time(video_duration)}," "TitleStyle,,0,0,0,," f"{safe_title_text}"
         )

tests/unit/test_ass_subtitle_builder.py

@@ -602,3 +602,148 @@ class TestFontsizeCompensation:
         result = build_ass_style("S", font_size=0)
         parts = result.split(",")
         assert int(parts[2]) >= 1
+
+
+# ── 标题自由位置拖拽（工单 #1405 方案 B）──────────────────────────────────────
+
+
+def _title_style_line(content: str) -> str:
+    return [line for line in content.splitlines() if line.startswith("Style: TitleStyle")][0]
+
+
+def _title_dialogue_line(content: str) -> str:
+    return [line for line in content.splitlines() if line.startswith("Dialogue:") and "TitleStyle" in line][0]
+
+
+class TestTitleFreePosition:
+    """pos_x/pos_y 合法时注入 \\pos 且 Alignment=5；非法/缺失时回退原逻辑。"""
+
+    def _base_kwargs(self):
+        return dict(
+            video_width=1080,
+            video_height=1920,
+            video_duration=8.0,
+            title_text="测试标题",
+        )
+
+    def test_valid_position_injects_pos_tag_and_alignment_5(self):
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36, "pos_x": 540, "pos_y": 300},
+        )
+        # Dialogue 文本前注入 {\pos(540,300)}
+        dialogue = _title_dialogue_line(content)
+        assert "{\\pos(540,300)}" in dialogue
+        # TitleStyle Alignment 固定 5（\an5 中对齐，\pos 锚点为文本块中心）
+        fields = [f.strip() for f in _title_style_line(content).split(",")]
+        assert fields[18] == "5"
+
+    def test_boundary_coordinates_zero_and_max_accepted(self):
+        """边界值 0 和 video_width/video_height 合法（闭区间）。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 0, "pos_y": 1920},
+        )
+        assert "{\\pos(0,1920)}" in _title_dialogue_line(content)
+
+        content2 = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 1080, "pos_y": 0},
+        )
+        assert "{\\pos(1080,0)}" in _title_dialogue_line(content2)
+
+    def test_no_coords_output_identical_to_before(self):
+        """不传坐标 → 输出与现有断言完全一致（回归保护）。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        # 无 \pos 注入
+        assert "\\pos(" not in content
+        # Alignment 走 position 映射（top → 8）
+        fields = [f.strip() for f in _title_style_line(content).split(",")]
+        assert fields[18] == "8"
+
+    def test_out_of_bounds_falls_back(self):
+        """越界坐标 → 回退 position 三档逻辑，输出与无坐标一致。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        for pos_x, pos_y in [(-1, 300), (540, -1), (1081, 300), (540, 1921), (99999, 99999)]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": "top", "size": 36, "pos_x": pos_x, "pos_y": pos_y},
+            )
+            assert "\\pos(" not in content, f"({pos_x},{pos_y}) should be rejected"
+            assert content == base, f"({pos_x},{pos_y}) output differs from fallback"
+
+    def test_invalid_coords_falls_back(self):
+        """非法类型坐标 → 回退原逻辑。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        for pos_x, pos_y in [("abc", 300), (540, None), (None, None), (True, 300), (540, False), (540.5, 300.9)]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": "top", "size": 36, "pos_x": pos_x, "pos_y": pos_y},
+            )
+            assert "\\pos(" not in content, f"({pos_x!r},{pos_y!r}) should be rejected"
+            assert content == base, f"({pos_x!r},{pos_y!r}) output differs from fallback"
+
+    def test_only_one_coord_falls_back(self):
+        """只传 pos_x 或 pos_y → 回退原逻辑。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36},
+        )
+        content_x = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36, "pos_x": 540},
+        )
+        content_y = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36, "pos_y": 300},
+        )
+        assert content_x == base
+        assert content_y == base
+        assert "\\pos(" not in content_x
+        assert "\\pos(" not in content_y
+
+    def test_position_three_levels_unchanged_without_coords(self):
+        """无坐标时 top/center/bottom 三档 Alignment 输出不变。"""
+        for position, expected_align in [("top", "8"), ("center", "5"), ("bottom", "2")]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": position, "size": 36},
+            )
+            fields = [f.strip() for f in _title_style_line(content).split(",")]
+            assert fields[18] == expected_align
+
+    def test_pos_overrides_position_alignment(self):
+        """有合法坐标时，无论 position 是什么，Alignment 都固定为 5。"""
+        for position in ["top", "center", "bottom"]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": position, "size": 36, "pos_x": 100, "pos_y": 200},
+            )
+            fields = [f.strip() for f in _title_style_line(content).split(",")]
+            assert fields[18] == "5"
+            assert "{\\pos(100,200)}" in _title_dialogue_line(content)
+
+    def test_subtitle_not_affected_by_pos(self):
+        """pos_x/pos_y 只影响 Title，Subtitle 输出不变。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 540, "pos_y": 300},
+            subtitle_text="配音字幕",
+            subtitle_config={"position": "bottom", "size": 24},
+        )
+        sub_style = [line for line in content.splitlines() if line.startswith("Style: SubtitleStyle")][0]
+        sub_fields = [f.strip() for f in sub_style.split(",")]
+        assert sub_fields[18] == "2"  # bottom
+        sub_dialogue = [
+            line for line in content.splitlines() if line.startswith("Dialogue:") and "SubtitleStyle" in line
+        ][0]
+        assert "\\pos(" not in sub_dialogue