SetTransparentColor — Designate one color to be transparent
$plot->SetTransparentColor($color
)
SetTransparentColor
designates one color in the image
to be transparent. The designated color will not be visible (assuming the
image is viewed with a program which supports transparency) - instead,
everything drawn in that color will be transparent.
By default, no color is transparent.
$color
Name of the color in the current color map (see SetRGBArray) which should become transparent.
This will only work if both the selected image file format (see SetFileFormat) and the user's browser or viewer support transparency. GIF format supports transparency. PNG format also supports transparency, but viewer support is more limited.