Method Cairo.ImageSurface()->write_to_png()
- Method
write_to_png
 voidwrite_to_png(string|Stdio.OutputStreamMixinpng_file)- Description
 Writes the contents of this ImageSurface as a PNG image.
- Parameter 
png_file the name of a file to write to, or a Stdio.OutputStreamMixin to write the PNG data to