How can I change the color of an SVG string using colorMapper

[Marlenfranto]

I want to change the color of an SVG before converting it to an image. Here's the code I'm currently using—how can I modify it to achieve this?

PictureInfo pictureInfo = await vg.loadPicture(SvgStringLoader(svgString), null);
image = await pictureInfo.picture.toImage(150, 150);