update at 2026-02-08 18:28:39

apiserver/renderer.py

@@ -0,0 +1,275 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""服务端字体渲染核心：输入文本和字体文件，输出 SVG。"""
+
+import os
+import re
+
+HB = None
+BoundsPen = None
+SVGPathPen = None
+TTFont = None
+
+MAX_CHARS_PER_LINE = 45
+HEX_COLOR_RE = re.compile(r"^#[0-9a-fA-F]{6}$")
+
+
+def _ensure_deps():
+    global HB, BoundsPen, SVGPathPen, TTFont
+    if HB is not None:
+        return
+
+    try:
+        import uharfbuzz as hb  # type: ignore[import-not-found]
+        from fontTools.pens.boundsPen import BoundsPen as BP  # type: ignore[import-not-found]
+        from fontTools.pens.svgPathPen import SVGPathPen as SP  # type: ignore[import-not-found]
+        from fontTools.ttLib import TTFont as FT  # type: ignore[import-not-found]
+    except ModuleNotFoundError as error:
+        raise RuntimeError("缺少依赖，请先安装: fonttools uharfbuzz") from error
+
+    HB = hb
+    BoundsPen = BP
+    SVGPathPen = SP
+    TTFont = FT
+
+
+def _normalize_line_breaks(text):
+    return str(text or "").replace("\r\n", "\n").replace("\r", "\n")
+
+
+def wrap_text_by_chars(text, max_chars_per_line=MAX_CHARS_PER_LINE):
+    if max_chars_per_line <= 0:
+        return _normalize_line_breaks(text)
+
+    normalized = _normalize_line_breaks(text)
+    lines = normalized.split("\n")
+    wrapped_lines = []
+
+    for line in lines:
+        chars = list(line)
+        if not chars:
+            wrapped_lines.append("")
+            continue
+        for i in range(0, len(chars), max_chars_per_line):
+            wrapped_lines.append("".join(chars[i : i + max_chars_per_line]))
+
+    return "\n".join(wrapped_lines)
+
+
+def _normalize_hex_color(color, fallback="#000000"):
+    value = str(color or "").strip()
+    if HEX_COLOR_RE.match(value):
+        return value
+    return fallback
+
+
+def _format_number(value):
+    text = f"{value:.2f}".rstrip("0").rstrip(".")
+    return text if text else "0"
+
+
+def _shape_line(hb_font, line):
+    buf = HB.Buffer()
+    buf.add_str(line)
+    buf.guess_segment_properties()
+    HB.shape(hb_font, buf)
+    return buf.glyph_infos, buf.glyph_positions
+
+
+def _positions_scale(positions, upem):
+    sample = 0
+    for pos in positions:
+        if pos.x_advance:
+            sample = abs(pos.x_advance)
+            break
+    if sample > upem * 4:
+        return 1 / 64.0
+    return 1.0
+
+
+def _compute_bounds(glyph_set, runs):
+    min_x = None
+    min_y = None
+    max_x = None
+    max_y = None
+
+    for glyph_name, x_pos, y_pos in runs:
+        glyph = glyph_set[glyph_name]
+        pen = BoundsPen(glyph_set)
+        glyph.draw(pen)
+        if pen.bounds is None:
+            continue
+
+        xmin, ymin, xmax, ymax = pen.bounds
+        xmin += x_pos
+        xmax += x_pos
+        ymin += y_pos
+        ymax += y_pos
+
+        min_x = xmin if min_x is None else min(min_x, xmin)
+        min_y = ymin if min_y is None else min(min_y, ymin)
+        max_x = xmax if max_x is None else max(max_x, xmax)
+        max_y = ymax if max_y is None else max(max_y, ymax)
+
+    return min_x, min_y, max_x, max_y
+
+
+def _font_name(ttfont):
+    name_table = ttfont.get("name")
+    if not name_table:
+        return "Unknown"
+
+    for name_id in (1, 4):
+        for record in name_table.names:
+            if record.nameID != name_id:
+                continue
+            try:
+                value = record.toUnicode().strip()
+            except Exception:
+                continue
+            if value:
+                return value
+
+    return "Unknown"
+
+
+def _compose_svg(
+    glyph_set,
+    runs,
+    bounds,
+    *,
+    fill_color="#000000",
+    width_override=None,
+    height_override=None,
+):
+    min_x, min_y, max_x, max_y = bounds
+    if min_x is None or min_y is None or max_x is None or max_y is None:
+        raise ValueError("未生成有效字形轮廓。")
+
+    width = max_x - min_x
+    height = max_y - min_y
+    if width <= 0 or height <= 0:
+        raise ValueError("计算得到的SVG尺寸无效。")
+
+    paths = []
+    for glyph_name, x_pos, y_pos in runs:
+        glyph = glyph_set[glyph_name]
+        pen = SVGPathPen(glyph_set)
+        glyph.draw(pen)
+        d = pen.getCommands()
+        if not d:
+            continue
+
+        transform = f"translate({_format_number(x_pos)} {_format_number(y_pos)})"
+        paths.append(f'  <path d="{d}" transform="{transform}"/>')
+
+    if not paths:
+        raise ValueError("未生成任何路径。")
+
+    view_box = f"{_format_number(min_x)} 0 {_format_number(width)} {_format_number(height)}"
+    group_transform = f"translate(0 {_format_number(max_y)}) scale(1 -1)"
+
+    svg_content = (
+        '<?xml version="1.0" encoding="UTF-8" standalone="no"?>\n'
+        '<svg xmlns="http://www.w3.org/2000/svg" '
+        f'width="{_format_number(width_override if width_override is not None else width)}" '
+        f'height="{_format_number(height_override if height_override is not None else height)}" '
+        f'viewBox="{view_box}">\n'
+        f'  <g transform="{group_transform}" fill="{_normalize_hex_color(fill_color)}" stroke="none">\n'
+        f"{chr(10).join(paths)}\n"
+        "  </g>\n"
+        "</svg>\n"
+    )
+
+    return svg_content, width, height
+
+
+def render_svg_from_font_file(
+    font_path,
+    text,
+    *,
+    font_size=120,
+    fill_color="#000000",
+    letter_spacing=0.0,
+    max_chars_per_line=MAX_CHARS_PER_LINE,
+):
+    if not os.path.isfile(font_path):
+        raise FileNotFoundError(f"字体文件不存在: {font_path}")
+
+    raw_text = str(text or "")
+    if not raw_text.strip():
+        raise ValueError("文本内容不能为空")
+
+    _ensure_deps()
+
+    ttfont = TTFont(font_path)
+    glyph_set = ttfont.getGlyphSet()
+    upem = ttfont["head"].unitsPerEm
+
+    hb_blob = HB.Blob.from_file_path(font_path)
+    hb_face = HB.Face(hb_blob, 0)
+    hb_font = HB.Font(hb_face)
+    hb_font.scale = (upem, upem)
+    HB.ot_font_set_funcs(hb_font)
+
+    normalized_text = wrap_text_by_chars(raw_text, int(max_chars_per_line or 0))
+    lines = normalized_text.split("\n")
+
+    ascender = upem * 0.8
+    descender = -upem * 0.2
+    if "hhea" in ttfont:
+        hhea = ttfont["hhea"]
+        if hasattr(hhea, "ascent"):
+            ascender = float(hhea.ascent)
+        if hasattr(hhea, "descent"):
+            descender = float(hhea.descent)
+    line_advance = max(upem * 1.2, ascender - descender)
+
+    letter_spacing_raw = float(letter_spacing or 0.0) * upem
+    runs = []
+
+    for line_index, line in enumerate(lines):
+        if line == "":
+            continue
+
+        infos, positions = _shape_line(hb_font, line)
+        scale = _positions_scale(positions, upem)
+        spacing_raw = letter_spacing_raw / scale
+        x = 0.0
+        y = 0.0
+        y_base = -line_index * line_advance
+
+        for info, pos in zip(infos, positions):
+            glyph_name = ttfont.getGlyphName(info.codepoint)
+            x_pos = (x + pos.x_offset) * scale
+            y_pos = (y + pos.y_offset) * scale
+            runs.append((glyph_name, x_pos, y_pos + y_base))
+            x += float(pos.x_advance) + spacing_raw
+            y += float(pos.y_advance)
+
+    bounds = _compute_bounds(glyph_set, runs)
+    min_x, min_y, max_x, max_y = bounds
+    if min_x is None or min_y is None or max_x is None or max_y is None:
+        raise ValueError("未生成有效字形轮廓。")
+
+    scale = float(font_size) / float(upem)
+    width = (max_x - min_x) * scale
+    height = (max_y - min_y) * scale
+    if width <= 0 or height <= 0:
+        raise ValueError("计算得到的SVG尺寸无效。")
+
+    svg_content, _, _ = _compose_svg(
+        glyph_set,
+        runs,
+        bounds,
+        fill_color=fill_color,
+        width_override=width,
+        height_override=height,
+    )
+
+    return {
+        "svg": svg_content,
+        "width": width,
+        "height": height,
+        "fontName": _font_name(ttfont),
+    }