Parse and generate style for SVG

[TonyCrane]

Motivation

Before, SVGMobject will remove all styles from a svg file.
This pull request parse the style for SVG by refering to ManimCommunity/manim.
In order to prevent the style generated layer by layer in init_points from being globally overwritten by the init_colors after it. I added a parameter override to init_colors, which is set to True by default (that is, consistent with the original performance), but when override = False, it will recurse layer by layer and set the color to the currently generated color.

Proposed changes

• M manimlib/mobject/svg/svg_mobject.py: add SVG style parser and fix some bugs of path string
• M manimlib/mobject/types/vectorized_mobject.py: add override parameter to init_colors
• M manimlib/mobject/mobject.py: synchronously update the parameters of init_colors
• M manimlib/mobject/geometry.py: synchronously update the parameters of init_colors
• M manimlib/mobject/types/surface.py: synchronously update the parameters of init_colors
• M manimlib/mobject/svg/tex_mobject.py: synchronously update the parameters of init_colors and synchronize SingleStringTex's stroke_width to SVGMobject
• M manimlib/mobject/svg/tex_mobject.py: cache color in tex_string_to_mob_map together with tex_string
• M manimlib/mobject/svg/text_mobject.py: replace warnings.warn with log.warning

Test

I tested all the svg files used in ManimCE for testing and each file renders correctly with color and stroke.
And Tex TexText can correctly generate texts with color according to the corresponding LaTeX expression (\color{})

Code:

class Code(Scene):
    def construct(self):
        svg = VGroup(
            TexText(r"test {\color{red}and} {\color{blue}test}").set_width(10),
            TexText(r"test {\color{red}and} {\color{blue}test}").set_width(10).set_color(WHITE),
            TexText(r"test {\color{red}and} {\color{blue}test}", color=BLACK).set_width(10),
        ).arrange(DOWN)
        self.add(svg)

Result:

As can be seen from the above example, the color parameter is only the default color, and this color will be overwritten as long as a color is included in the SVG. If you want to ignore the color in SVG, you can directly .set_color again.

[3b1b]

This looks great, thanks for doing it

[3b1b]

There are a few examples I can find, like the one attached, where due to how the style is represented in the SVG it does not quite work, but it's certainly better than current functionality so worth the merge.

.

[TonyCrane]

Yes, it's because the styles are defined by the css in the <style> tag, which is not handled yet (nor is ManimCommunity). I'll try my best to handle this situation when I have time :)

[3b1b]

I agree it seems a little tricky. I mostly just wanted to keep track of an edge case here, don't feel like it's something you have to do.

Also, just FYI, I made a few quick fixes based on its behavior with Text and MTex