Python converting SVG

試用了一下 svglib，功能都正常，滿好的，唯一的缺點就是在處理大量的檔案時，就可以看的出來效能沒有很好，呵呵。跑了好久，檔案都還沒有轉完，似乎使用其他原生系統的轉換程式效果會好一點。

svglib：
https://pypi.org/project/svglib/

github：
https://github.com/deeplook/svglib

看了一下github 的 issue，似乎還是有一些異常的情況會發生。

使用方法：

from svglib.svglib import svg2rlg
from reportlab.graphics import renderPDF, renderPM

drawing = svg2rlg("file.svg")
renderPM.drawToFile(drawing, "file.png", fmt="PNG")

---

有挑戰使用 imagemagick 來換，可是試出來的結果，svg 轉出來是純白的，不知為何？

ImageMagick convert a SVG file results a blank image

The problem here is that I don’t know how ImageMagick uses the librsvg interface in detail. But a few things stand out in the latest librsvg doc. While the paragraphs were only added in the v2.42 doc, I think they apply also to older versions, according to what I have observed in Gnome systems.

When processing an SVG, librsvg will only load referenced files if they are in the same directory as the base file, or in a subdirectory of it…This is so that malicious SVG files cannot include files that are in a directory above.

If you already have SVG data in memory, you can create a memory input stream…Note that in this case, it is important that you specify the base_file for the in-memory SVG data. Librsvg uses the base_file to resolve links to external content, like raster images.

Depending on the ImageMagick implementation, that leads to two possible solutions:

1. Load the SVG directly from a file with$im->readImage('src.svg');
2. Use the string, but set the second file argument in$im->readImageBlob('<?xml version="1.0"?>' . $svg, 'src.svg')

Only as an aside, $im->setFormat('RSVG') doesn’t make any sense, since “RSVG” is only the name of the library and not a file format.

---

服用下面的指令，一樣無效：

magick MSVG:test.svg test2.png

---

改用這個 svgexport 看看：
https://github.com/shakiba/svgexport

Installation

npm install svgexport -g

Usage

svgexport <input file> <output file> <options>
svgexport <datafile>

<options>        [<format>] [<quality>] [<input viewbox>] [<output size>] [<resize mode>] [<styles>]

<format>         png|jpeg|jpg
                 If not specified, it will be inferred from output file extension or defaults to "png".
                 
<quality>        1%-100%

<input viewbox>  <left>:<top>:<width>:<height>|<width>:<height>
                 If input viewbox is not specified it will be inferred from input file.
                 
<output size>    <scale>x|<width>:<height>|<width>:|:<height>
                 If output size is specified as width:height, <viewbox mode> is used.

<viewbox mode>   crop|pad
                 Crop (slice) or pad (extend) input to match output aspect ratio, default mode is "crop".

<datafile>       Path of a JSON file with following content:
                 [ {
                   "input" : ["<input file>", "<option>", "<option>", ...],
                   "output": [ ["<output file>", "<option>", "<option>", ...] ]
                 }, ...]
                 Input file options are merged with and overridden by output file options.
                 Instead of a JSON file, a Node module which exports same content can be provided.

---

也可以使用 brew install svg2png

Usage: svg2png [OPTIONS] [<SVG_file> [<PNG_file>]]
svg2png - svg2png - Render an SVG image to a PNG image

  -w, --width=WIDTH	Width of output image in pixels
  -h, --height=HEIGHT	Height of output image in pixels
  -s, --scale=FACTOR	Scale image by FACTOR

  --flipx		Flip X coordinates of image
  --flipy		Flip Y coordinates of image

  --help		Give this help list
  -V, --version		Print program version

---

如果是使用 macOS 也可以使用：

Or without installing anything:

qlmanage -t -s 1000 -o . picture.svg 

It will produce picture.svg.png that is 1000 pixels wide.

I have tested it only on OS X 10.6.3.

處理多個檔案，可以試看看這個指令：

find . -name "*.svg" -exec qlmanage -t -s 1000 -o . {} \;