[GIS] How to create point symbols with smooth color gradient fill and associated legend

Question

I like the feature heatmap as a layer style, but it doesn't have any symbolism in the legend at the compose manager. So I took a print screen from a characteristic part of the heatmap and now I am pasting it in the legend near the Text of the heatmap reference. But for every new project I have to make the same job, or move it if I move the legend…is there a simpler way for it?

I am using heatmap for stand alone trees instead of svg symbols or simple points. I think it makes the map prettier. So the heatmap has small radius circles and white area. A green square is not what I am looking for. Mostly I made this question, if there is somewhere a parameter for editing the point layer with the heatmap style and I haven't seen it.

Answer 1

edit: Due to question was improved here is exact solution:

1. Go to symbology properties of point layer Layer Properties -> Style
2. In the symbol layer list choose Simple marker and change the Symbol layer type from Sipmle marker to Filled marker

3. Same way in the properites of Simple fill change Symbol layer type from Simple fill to Shapeburst fill and set colors or color ramp that you want

Result:

old answer: Using Heatmap plugin you can generate new heatmap raster file. Use this raster itself for output map or you can use only symbology from this raster for specific radius.

Heatmap plugin:

Heatmap plugin output raster: