在Python中将SVG转换为PNG

问题:在Python中将SVG转换为PNG

如何转换的svgpng,在Python?我将储存svg在的实例中StringIO。我应该使用pyCairo库吗?如何编写该代码?

How do I convert an svg to png, in Python? I am storing the svg in an instance of StringIO. Should I use the pyCairo library? How do I write that code?


回答 0

答案是“ pyrsvg ” -一个Python绑定的librsvg

有一个提供它的Ubuntu python-rsvg软件包。在Google上搜索其名称很不方便,因为其源代码似乎包含在“ gnome-python-desktop” Gnome项目GIT存储库中。

我制作了一个极简的“ hello world”,它将SVG渲染到开罗表面并将其写入磁盘:

import cairo
import rsvg

img = cairo.ImageSurface(cairo.FORMAT_ARGB32, 640,480)

ctx = cairo.Context(img)

## handle = rsvg.Handle(<svg filename>)
# or, for in memory SVG data:
handle= rsvg.Handle(None, str(<svg data>))

handle.render_cairo(ctx)

img.write_to_png("svg.png")

更新:从2014年开始,Fedora Linux发行版所需的软件包是:gnome-python2-rsvg。上面的摘录清单仍按原样工作。

The answer is “pyrsvg” – a Python binding for librsvg.

There is an Ubuntu python-rsvg package providing it. Searching Google for its name is poor because its source code seems to be contained inside the “gnome-python-desktop” Gnome project GIT repository.

I made a minimalist “hello world” that renders SVG to a cairo surface and writes it to disk:

import cairo
import rsvg

img = cairo.ImageSurface(cairo.FORMAT_ARGB32, 640,480)

ctx = cairo.Context(img)

## handle = rsvg.Handle(<svg filename>)
# or, for in memory SVG data:
handle= rsvg.Handle(None, str(<svg data>))

handle.render_cairo(ctx)

img.write_to_png("svg.png")

Update: as of 2014 the needed package for Fedora Linux distribution is: gnome-python2-rsvg. The above snippet listing still works as-is.


回答 1

这是我使用cairosvg做的事情

from cairosvg import svg2png

svg_code = """
    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#000" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
        <circle cx="12" cy="12" r="10"/>
        <line x1="12" y1="8" x2="12" y2="12"/>
        <line x1="12" y1="16" x2="12" y2="16"/>
    </svg>
"""

svg2png(bytestring=svg_code,write_to='output.png')

它就像一个魅力!

查看更多:cairosvg文档

Here is what I did using cairosvg:

from cairosvg import svg2png

svg_code = """
    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#000" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
        <circle cx="12" cy="12" r="10"/>
        <line x1="12" y1="8" x2="12" y2="12"/>
        <line x1="12" y1="16" x2="12" y2="16"/>
    </svg>
"""

svg2png(bytestring=svg_code,write_to='output.png')

And it works like a charm!

See more: cairosvg document


回答 2

安装Inkscape并将其作为命令行调用:

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -e ${dest_png}

您也可以仅使用参数捕捉特定的矩形区域-j,例如,坐标“ 0:125:451:217”

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -a ${coordinates} -e ${dest_png}

如果您只想在SVG文件中显示一个对象,则可以使用-i在SVG中已设置的对象ID 来指定参数。它隐藏了其他所有内容。

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -i ${object} -j -a ${coordinates} -e ${dest_png}

Install Inkscape and call it as command line:

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -e ${dest_png}

You can also snap specific rectangular area only using parameter -j, e.g. co-ordinate “0:125:451:217”

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -a ${coordinates} -e ${dest_png}

If you want to show only one object in the SVG file, you can specify the parameter -i with the object id that you have setup in the SVG. It hides everything else.

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -i ${object} -j -a ${coordinates} -e ${dest_png}

回答 3

我正在使用Wand-py(围绕ImageMagick的Wand包装器的实现)导入一些非常高级的SVG,到目前为止,已经看到了不错的结果!这是所需要的全部代码:

    with wand.image.Image( blob=svg_file.read(), format="svg" ) as image:
        png_image = image.make_blob("png")

我今天才发现这个问题,觉得有必要与其他人分享这个问题,因为自从回答了大多数问题以来已经有一段时间了。

注意:从技术上讲,在测试中,我发现您甚至实际上不必传递ImageMagick的format参数,因此 with wand.image.Image( blob=svg_file.read() ) as image:真正需要的是所有这些。

编辑:通过qris的尝试编辑,这是一些有用的代码,可让您将ImageMagick与具有透明背景的SVG结合使用:

from wand.api import library
import wand.color
import wand.image

with wand.image.Image() as image:
    with wand.color.Color('transparent') as background_color:
        library.MagickSetBackgroundColor(image.wand, 
                                         background_color.resource) 
    image.read(blob=svg_file.read(), format="svg")
    png_image = image.make_blob("png32")

with open(output_filename, "wb") as out:
    out.write(png_image)

I’m using Wand-py (an implementation of the Wand wrapper around ImageMagick) to import some pretty advanced SVGs and so far have seen great results! This is all the code it takes:

    with wand.image.Image( blob=svg_file.read(), format="svg" ) as image:
        png_image = image.make_blob("png")

I just discovered this today, and felt like it was worth sharing for anyone else who might straggle across this answer as it’s been a while since most of these questions were answered.

NOTE: Technically in testing I discovered you don’t even actually have to pass in the format parameter for ImageMagick, so with wand.image.Image( blob=svg_file.read() ) as image: was all that was really needed.

EDIT: From an attempted edit by qris, here’s some helpful code that lets you use ImageMagick with an SVG that has a transparent background:

from wand.api import library
import wand.color
import wand.image

with wand.image.Image() as image:
    with wand.color.Color('transparent') as background_color:
        library.MagickSetBackgroundColor(image.wand, 
                                         background_color.resource) 
    image.read(blob=svg_file.read(), format="svg")
    png_image = image.make_blob("png32")

with open(output_filename, "wb") as out:
    out.write(png_image)

回答 4

试试这个:http : //cairosvg.org/

该网站说:

CairoSVG用纯python编写,仅取决于Pycairo。已知可以在Python 2.6和2.7上运行。

2016年11月25日更新

2.0.0是一个新的主要版本,其更改日志包括:

  • 放弃对Python 2的支持

Try this: http://cairosvg.org/

The site says:

CairoSVG is written in pure python and only depends on Pycairo. It is known to work on Python 2.6 and 2.7.

Update November 25, 2016:

2.0.0 is a new major version, its changelog includes:

  • Drop Python 2 support

回答 5

我在这里找到的另一个解决方案如何将缩放的SVG渲染到QImage?

from PySide.QtSvg import *
from PySide.QtGui import *


def convertSvgToPng(svgFilepath,pngFilepath,width):
    r=QSvgRenderer(svgFilepath)
    height=r.defaultSize().height()*width/r.defaultSize().width()
    i=QImage(width,height,QImage.Format_ARGB32)
    p=QPainter(i)
    r.render(p)
    i.save(pngFilepath)
    p.end()

PySide可以从Windows中的二进制软件包轻松安装(我将其用于其他用途,因此对我来说很容易)。

但是,从Wikimedia转换国家标记时,我注意到了一些问题,因此可能不是最可靠的svg解析器/渲染器。

Another solution I’ve just found here How to render a scaled SVG to a QImage?

from PySide.QtSvg import *
from PySide.QtGui import *


def convertSvgToPng(svgFilepath,pngFilepath,width):
    r=QSvgRenderer(svgFilepath)
    height=r.defaultSize().height()*width/r.defaultSize().width()
    i=QImage(width,height,QImage.Format_ARGB32)
    p=QPainter(i)
    r.render(p)
    i.save(pngFilepath)
    p.end()

PySide is easily installed from a binary package in Windows (and I use it for other things so is easy for me).

However, I noticed a few problems when converting country flags from Wikimedia, so perhaps not the most robust svg parser/renderer.


回答 6

关于jsbueno答案的一些扩展:

#!/usr/bin/env python

import cairo
import rsvg
from xml.dom import minidom


def convert_svg_to_png(svg_file, output_file):
    # Get the svg files content
    with open(svg_file) as f:
        svg_data = f.read()

    # Get the width / height inside of the SVG
    doc = minidom.parse(svg_file)
    width = int([path.getAttribute('width') for path
                 in doc.getElementsByTagName('svg')][0])
    height = int([path.getAttribute('height') for path
                  in doc.getElementsByTagName('svg')][0])
    doc.unlink()

    # create the png
    img = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
    ctx = cairo.Context(img)
    handler = rsvg.Handle(None, str(svg_data))
    handler.render_cairo(ctx)
    img.write_to_png(output_file)

if __name__ == '__main__':
    from argparse import ArgumentParser

    parser = ArgumentParser()

    parser.add_argument("-f", "--file", dest="svg_file",
                        help="SVG input file", metavar="FILE")
    parser.add_argument("-o", "--output", dest="output", default="svg.png",
                        help="PNG output file", metavar="FILE")
    args = parser.parse_args()

    convert_svg_to_png(args.svg_file, args.output)

A little extension on the answer of jsbueno:

#!/usr/bin/env python

import cairo
import rsvg
from xml.dom import minidom


def convert_svg_to_png(svg_file, output_file):
    # Get the svg files content
    with open(svg_file) as f:
        svg_data = f.read()

    # Get the width / height inside of the SVG
    doc = minidom.parse(svg_file)
    width = int([path.getAttribute('width') for path
                 in doc.getElementsByTagName('svg')][0])
    height = int([path.getAttribute('height') for path
                  in doc.getElementsByTagName('svg')][0])
    doc.unlink()

    # create the png
    img = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
    ctx = cairo.Context(img)
    handler = rsvg.Handle(None, str(svg_data))
    handler.render_cairo(ctx)
    img.write_to_png(output_file)

if __name__ == '__main__':
    from argparse import ArgumentParser

    parser = ArgumentParser()

    parser.add_argument("-f", "--file", dest="svg_file",
                        help="SVG input file", metavar="FILE")
    parser.add_argument("-o", "--output", dest="output", default="svg.png",
                        help="PNG output file", metavar="FILE")
    args = parser.parse_args()

    convert_svg_to_png(args.svg_file, args.output)

回答 7

我没有找到满意的答案。所有提到的库都存在某些问题,例如Cairo放弃了对python 3.6的支持(它们在3年前就放弃了Python 2的支持!)。另外,在Mac上安装上述库也是很痛苦的。

最后,我发现最好的解决方案是svglib + reportlab。两者都使用pip顺利安装并且首次调用将svg转换为png都工作得很好!非常满意的解决方案。

仅需2条命令即可完成操作:

from svglib.svglib import svg2rlg
from reportlab.graphics import renderPM
drawing = svg2rlg("my.svg")
renderPM.drawToFile(drawing, "my.png", fmt="PNG")

我应该注意这些限制吗?

I did not find any of the answers satisfactory. All the mentioned libraries have some problem or the other like Cairo dropping support for python 3.6 (they dropped Python 2 support some 3 years ago!). Also, installing the mentioned libraries on the Mac was a pain.

Finally, I found the best solution was svglib + reportlab. Both installed without a hitch using pip and first call to convert from svg to png worked beautifully! Very happy with the solution.

Just 2 commands do the trick:

from svglib.svglib import svg2rlg
from reportlab.graphics import renderPM
drawing = svg2rlg("my.svg")
renderPM.drawToFile(drawing, "my.png", fmt="PNG")

Are there any limitations with these I should be aware of?


回答 8

SVG缩放和PNG渲染

使用pycairolibrsvg,我能够实现SVG缩放并将其渲染为位图。假设您的SVG并非精确地为256×256像素(所需的输出),则可以使用rsvg将SVG读入Cairo上下文中,然后对其进行缩放并写入PNG。

main.py

import cairo
import rsvg

width = 256
height = 256

svg = rsvg.Handle('cool.svg')
unscaled_width = svg.props.width
unscaled_height = svg.props.height

svg_surface = cairo.SVGSurface(None, width, height)
svg_context = cairo.Context(svg_surface)
svg_context.save()
svg_context.scale(width/unscaled_width, height/unscaled_height)
svg.render_cairo(svg_context)
svg_context.restore()

svg_surface.write_to_png('cool.png')

RSVG C绑定

从Cario网站进行一些小的修改。也是如何从Python调用C库的一个很好的例子

from ctypes import CDLL, POINTER, Structure, byref, util
from ctypes import c_bool, c_byte, c_void_p, c_int, c_double, c_uint32, c_char_p


class _PycairoContext(Structure):
    _fields_ = [("PyObject_HEAD", c_byte * object.__basicsize__),
                ("ctx", c_void_p),
                ("base", c_void_p)]


class _RsvgProps(Structure):
    _fields_ = [("width", c_int), ("height", c_int),
                ("em", c_double), ("ex", c_double)]


class _GError(Structure):
    _fields_ = [("domain", c_uint32), ("code", c_int), ("message", c_char_p)]


def _load_rsvg(rsvg_lib_path=None, gobject_lib_path=None):
    if rsvg_lib_path is None:
        rsvg_lib_path = util.find_library('rsvg-2')
    if gobject_lib_path is None:
        gobject_lib_path = util.find_library('gobject-2.0')
    l = CDLL(rsvg_lib_path)
    g = CDLL(gobject_lib_path)
    g.g_type_init()

    l.rsvg_handle_new_from_file.argtypes = [c_char_p, POINTER(POINTER(_GError))]
    l.rsvg_handle_new_from_file.restype = c_void_p
    l.rsvg_handle_render_cairo.argtypes = [c_void_p, c_void_p]
    l.rsvg_handle_render_cairo.restype = c_bool
    l.rsvg_handle_get_dimensions.argtypes = [c_void_p, POINTER(_RsvgProps)]

    return l


_librsvg = _load_rsvg()


class Handle(object):
    def __init__(self, path):
        lib = _librsvg
        err = POINTER(_GError)()
        self.handle = lib.rsvg_handle_new_from_file(path.encode(), byref(err))
        if self.handle is None:
            gerr = err.contents
            raise Exception(gerr.message)
        self.props = _RsvgProps()
        lib.rsvg_handle_get_dimensions(self.handle, byref(self.props))

    def get_dimension_data(self):
        svgDim = self.RsvgDimensionData()
        _librsvg.rsvg_handle_get_dimensions(self.handle, byref(svgDim))
        return (svgDim.width, svgDim.height)

    def render_cairo(self, ctx):
        """Returns True is drawing succeeded."""
        z = _PycairoContext.from_address(id(ctx))
        return _librsvg.rsvg_handle_render_cairo(self.handle, z.ctx)

SVG scaling and PNG rendering

Using pycairo and librsvg I was able to achieve SVG scaling and rendering to a bitmap. Assuming your SVG is not exactly 256×256 pixels, the desired output, you can read in the SVG to a Cairo context using rsvg and then scale it and write to a PNG.

main.py

import cairo
import rsvg

width = 256
height = 256

svg = rsvg.Handle('cool.svg')
unscaled_width = svg.props.width
unscaled_height = svg.props.height

svg_surface = cairo.SVGSurface(None, width, height)
svg_context = cairo.Context(svg_surface)
svg_context.save()
svg_context.scale(width/unscaled_width, height/unscaled_height)
svg.render_cairo(svg_context)
svg_context.restore()

svg_surface.write_to_png('cool.png')

RSVG C binding

From the Cario website with some minor modification. Also a good example of how to call a C-library from Python

from ctypes import CDLL, POINTER, Structure, byref, util
from ctypes import c_bool, c_byte, c_void_p, c_int, c_double, c_uint32, c_char_p


class _PycairoContext(Structure):
    _fields_ = [("PyObject_HEAD", c_byte * object.__basicsize__),
                ("ctx", c_void_p),
                ("base", c_void_p)]


class _RsvgProps(Structure):
    _fields_ = [("width", c_int), ("height", c_int),
                ("em", c_double), ("ex", c_double)]


class _GError(Structure):
    _fields_ = [("domain", c_uint32), ("code", c_int), ("message", c_char_p)]


def _load_rsvg(rsvg_lib_path=None, gobject_lib_path=None):
    if rsvg_lib_path is None:
        rsvg_lib_path = util.find_library('rsvg-2')
    if gobject_lib_path is None:
        gobject_lib_path = util.find_library('gobject-2.0')
    l = CDLL(rsvg_lib_path)
    g = CDLL(gobject_lib_path)
    g.g_type_init()

    l.rsvg_handle_new_from_file.argtypes = [c_char_p, POINTER(POINTER(_GError))]
    l.rsvg_handle_new_from_file.restype = c_void_p
    l.rsvg_handle_render_cairo.argtypes = [c_void_p, c_void_p]
    l.rsvg_handle_render_cairo.restype = c_bool
    l.rsvg_handle_get_dimensions.argtypes = [c_void_p, POINTER(_RsvgProps)]

    return l


_librsvg = _load_rsvg()


class Handle(object):
    def __init__(self, path):
        lib = _librsvg
        err = POINTER(_GError)()
        self.handle = lib.rsvg_handle_new_from_file(path.encode(), byref(err))
        if self.handle is None:
            gerr = err.contents
            raise Exception(gerr.message)
        self.props = _RsvgProps()
        lib.rsvg_handle_get_dimensions(self.handle, byref(self.props))

    def get_dimension_data(self):
        svgDim = self.RsvgDimensionData()
        _librsvg.rsvg_handle_get_dimensions(self.handle, byref(svgDim))
        return (svgDim.width, svgDim.height)

    def render_cairo(self, ctx):
        """Returns True is drawing succeeded."""
        z = _PycairoContext.from_address(id(ctx))
        return _librsvg.rsvg_handle_render_cairo(self.handle, z.ctx)

回答 9

这是Python调用Inkscape的一种方法。

请注意,它可以抑制Inkscape在正常无错误操作期间写到控制台的特定输出(特别是stderr和stdout)。输出被捕获到两个字符串变量out和中err

import subprocess               # May want to use subprocess32 instead

cmd_list = [ '/full/path/to/inkscape', '-z', 
             '--export-png', '/path/to/output.png',
             '--export-width', 100,
             '--export-height', 100,
             '/path/to/input.svg' ]

# Invoke the command.  Divert output that normally goes to stdout or stderr.
p = subprocess.Popen( cmd_list, stdout=subprocess.PIPE, stderr=subprocess.PIPE )

# Below, < out > and < err > are strings or < None >, derived from stdout and stderr.
out, err = p.communicate()      # Waits for process to terminate

# Maybe do something with stdout output that is in < out >
# Maybe do something with stderr output that is in < err >

if p.returncode:
    raise Exception( 'Inkscape error: ' + (err or '?')  )

例如,在我的Mac OS系统上运行特定作业时,out最终导致:

Background RRGGBBAA: ffffff00
Area 0:0:339:339 exported to 100 x 100 pixels (72.4584 dpi)
Bitmap saved as: /path/to/output.png

(输入的svg文件的大小为339 x 339像素。)

Here is an approach where Inkscape is called by Python.

Note that it suppresses certain crufty output that Inkscape writes to the console (specifically, stderr and stdout) during normal error-free operation. The output is captured in two string variables, out and err.

import subprocess               # May want to use subprocess32 instead

cmd_list = [ '/full/path/to/inkscape', '-z', 
             '--export-png', '/path/to/output.png',
             '--export-width', 100,
             '--export-height', 100,
             '/path/to/input.svg' ]

# Invoke the command.  Divert output that normally goes to stdout or stderr.
p = subprocess.Popen( cmd_list, stdout=subprocess.PIPE, stderr=subprocess.PIPE )

# Below, < out > and < err > are strings or < None >, derived from stdout and stderr.
out, err = p.communicate()      # Waits for process to terminate

# Maybe do something with stdout output that is in < out >
# Maybe do something with stderr output that is in < err >

if p.returncode:
    raise Exception( 'Inkscape error: ' + (err or '?')  )

For example, when running a particular job on my Mac OS system, out ended up being:

Background RRGGBBAA: ffffff00
Area 0:0:339:339 exported to 100 x 100 pixels (72.4584 dpi)
Bitmap saved as: /path/to/output.png

(The input svg file had a size of 339 by 339 pixels.)


回答 10

实际上,除了Python(Cairo,Ink ..等)之外,我不想依赖于其他任何东西。我的要求是尽可能地简单,最多只需要一个简单的pip install "savior"就够了,这就是上述任何原因都不是的原因。不适合我。

我经历了这一点(在研究上比Stackoverflow还要深入)。 https://www.tutorialexample.com/best-practice-to-python-convert-svg-to-png-with-svglib-python-tutorial/

到目前为止看起来不错。因此,如果有人遇到相同的情况,我会分享。

Actually, I did not want to be dependent of anything else but Python (Cairo, Ink.., etc.) My requirements were to be as simple as possible, at most, a simple pip install "savior" would suffice, that’s why any of those above didn’t suit for me.

I came through this (going further than Stackoverflow on the research). https://www.tutorialexample.com/best-practice-to-python-convert-svg-to-png-with-svglib-python-tutorial/

Looks good, so far. So I share it in case anyone in the same situation.