chart;leafletqgis
I have created a web map to show some sales information using QGIS with Leaflet library.
Is there a way to show pie charts in the same web map as a separate layer?
Although pie charts are visible in the QGIS desktop version, it disappears when it converts to a web map.
I guess there should be a way to edit the HTML file to make pie charts visible.
QGIS uses the PAL library to determine the "best" diagram position, which places diagrams, based on render context information such as DPI, zoom level...
To get diagrams to render at the same place every time, you can either use the placement method "Over Point" which will always put the diagrams over the centroid of the polygon.
Or you can specify the place, where you want to put the diagram yourself with "Data defined position" using attributes.
I don't think there is a way to dynamically intercept the (PAL-calculated) diagram position before they are drawn in order to adjust your line nodes.
Hint: To manually define x and y attributes for placement, you can first "prepare" them with labels. Label your layer with whatever attribute and enable data defined placement. Then use the "move label" tool to position your labels, wherever you would like to have the diagrams placed. Now disable labeling and enable diagrams with data defined placement.
I had the same problem after initial installation. Just in case it can help someone else, my solution was to edit the project properties (Project > Project Properties), check "Service capabilities", in WMS check "CRS restrictions" and add EPSG:4326 (CRS I use for map layers) and check "Advertised extent" and set extent with "Use Current Canvas Extent". Note that for the latter I did set project CRS to EPSG:3857 to be able to have the project opened within the right extent.
Best Answer
You don't mention how you create web map. For example using NextGIS Connect plugin for QGIS 2.18.x you can create such pie charts. This is done using nextgis.com cloud web client, based on OpenLayers. But you can do the same using leaflet. See an example of such integration.
Disclaimer: I'm developer at NextGIS.