Project: QGIS

Version: 3.12

Feature: Add json support to WMS GetLegendGraphic

This PR adds support for GetLegendGraphic responses encoded as JSON. It builds on previous work by @pblottiere, who added QgsLegendRenderer::exportLegendToJson for that exact purpose.

For example a GetLegendGraphic request with FORMAT=image/png producing the image

will produce the following with FORMAT=application/json

The icon image is encoded in base64, and directly displayable in a web page.

This feature was developed by Éric Lemoine