Legend with continuous gradient

[filonico]

Hello! Thank you for the very useful tool! I was plotting bootstrap data on my phylogenetic tree as points on nodes color-coded with a continuous gradient. Here is the code to produce this:

static Gradient gradient = new Gradient(
new List<TreeViewer.GradientStop>()
{
    new TreeViewer.GradientStop(0, Colour.FromRgba(0.996078431372549d, 0.2901960784313726d, 0.28627450980392155d, 1d)),
    new TreeViewer.GradientStop(0.5, Colour.FromRgba(0.996078431372549d, 0.8431372549019608d, 0.4d, 1d)),
    new TreeViewer.GradientStop(1, Colour.FromRgba(0d, 0.6235294117647059d, 0.7176470588235294d, 1d))
});

public static Colour? Format(object attribute)
{
    if (attribute is double attributeValue &&
    !double.IsNaN(attributeValue))
    {
        double position = (attributeValue - 0) / 100;
        position = Math.Max(Math.Min(position, 1), 0);
        return gradient.GetColour(position);
    }
    else
    {
        return null;
    }
}

On the manual, you show how to create a legend using binned categories, and that works fine. Though, I was wondering if you know of any way in which I can create an actual gradient also in the legend. Something like this:

Thank you very much for helping!

[arklumpus]

Hi! It is currently not possible to do this directly from within TreeViewer, so the easiest option would probably be to generate the legend figure separately (e.g., in Inkscape) and the include it in the tree plot.

If you attach the legend image (e.g., in SVG or PNG format), you can either draw it directly using the Draw image Plot action module, or use the Legend module to include it in a Markdown document, e.g.:

**Bootstrap values**: ![](attachment://attachment_name)