app.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
SVG → PNG 批量转换（rsvg-convert ▸ Inkscape ▸ CairoSVG 三层保险版）
作者: ChatGPT 示例
"""

import shutil, subprocess, tempfile, zipfile, gradio as gr
from pathlib import Path
from typing import List, Tuple
import cairosvg   # 兜底

DEFAULT_DPI = 300  # 默认分辨率

# ───────────────────────── 工具检测 ─────────────────────────
def which(cmd: str) -> str | None:
    """返回可执行文件完整路径，找不到则 None"""
    return shutil.which(cmd)

RSVG = which("rsvg-convert")
INKSCAPE = which("inkscape")

# ──────────────────────── 渲染核心函数 ───────────────────────
def svg_to_png(svg: Path, png: Path, dpi: int = DEFAULT_DPI):
    """
    依次尝试 rsvg-convert → Inkscape → CairoSVG。
    任一成功即返回；全部失败则抛 RuntimeError。
    """
    errs = []

    # 1) rsvg-convert（最快最稳，支持大部分特性）
    if RSVG:
        cmd = [RSVG, "-d", str(dpi), "-p", str(dpi), "-f", "png",
               "-o", str(png), str(svg)]
        try:
            subprocess.run(cmd, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            if png.stat().st_size > 2048:    # 简单判空
                return
        except subprocess.CalledProcessError as e:
            errs.append(f"[rsvg-convert] {e.stderr.decode(errors='ignore')}")

    # 2) Inkscape CLI（加 export-area-drawing 防止空白）
    if INKSCAPE:
        cmd_new = [INKSCAPE, str(svg),
                   "--export-type=png",
                   f"--export-filename={png}",
                   f"--export-dpi={dpi}",
                   "--export-area-drawing"]     # 关键参数
        try:
            subprocess.run(cmd_new, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            if png.stat().st_size > 2048:
                return
        except subprocess.CalledProcessError as e_new:
            # 极老版本 Inkscape (<1.0) 回退旧参数
            cmd_old = [INKSCAPE, str(svg),
                       f"--export-png={png}",
                       f"-d={dpi}",
                       "--export-area-drawing"]
            try:
                subprocess.run(cmd_old, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                if png.stat().st_size > 2048:
                    return
            except subprocess.CalledProcessError as e_old:
                errs.append(f"[Inkscape] {e_new.stderr.decode(errors='ignore')}\n"
                            f"[Inkscape-old] {e_old.stderr.decode(errors='ignore')}")

    # 3) CairoSVG 兜底
    try:
        cairosvg.svg2png(url=str(svg), write_to=str(png), dpi=dpi)
        if png.stat().st_size > 2048:
            return
    except Exception as cs_err:
        errs.append(f"[CairoSVG] {cs_err}")

    raise RuntimeError("三种渲染器均失败：\n" + "\n".join(errs))

# ───────────────────────── Gradio 回调 ───────────────────────
def batch_convert(files: List[gr.File], dpi: int = DEFAULT_DPI
                  ) -> Tuple[List[Tuple[str, str]], str]:
    if not files:
        raise gr.Error("请先上传至少一个 SVG 文件！")

    tmp = Path(tempfile.mkdtemp(prefix="svg2png_"))
    out_dir = tmp / "png"; out_dir.mkdir()

    gallery, errs = [], []
    for f in files:
        svg = Path(f.name)
        out = out_dir / f"{svg.stem}.png"
        try:
            svg_to_png(svg, out, dpi)
            gallery.append((out.name, str(out)))
        except Exception as e:
            errs.append(f"{svg.name} 转换失败：{e}")

    # 打包 zip
    zip_path = tmp / "result.zip"
    with zipfile.ZipFile(zip_path, "w", zipfile.ZIP_DEFLATED) as zf:
        for p in out_dir.iterdir():
            zf.write(p, p.name)

    if errs:
        # 收敛为单条 Warning，避免打断流程
        gr.Warning("\n".join(errs))

    return gallery, str(zip_path)

# ────────────────────────── Gradio UI ────────────────────────
with gr.Blocks(title="SVG → PNG 在线转换", theme="soft") as demo:
    gr.Markdown("""
# 🖼️ SVG → PNG 转换器  
- **rsvg-convert ▸ Inkscape ▸ CairoSVG** 三层保险  
- 支持批量上传，DPI 可调，默认导出实际绘图区域  
""")
    with gr.Row():
        uploader = gr.File(file_count="multiple", file_types=[".svg"],
                           label="上传 SVG 文件（可多选）")
        dpi_slider = gr.Slider(72, 600, value=DEFAULT_DPI, step=1,
                               label="输出 DPI", info="分辨率越高越清晰")
    btn = gr.Button("🚀 开始转换")
    gallery = gr.Gallery(label="PNG 预览")
    zip_out = gr.File(label="下载全部 PNG (ZIP)")

    btn.click(batch_convert, [uploader, dpi_slider], [gallery, zip_out],
              api_name="convert", queue=True)

if __name__ == "__main__":
    demo.launch(share=False)   # 本地调试可改 True