Advice for changing symbology in QML

Question

Hi all,

I'm seeking some advice, suggestions, examples or anything else that might help me change my symbology between a 'dark' and 'light' mode. E.g., I have a map that I wish to use in a day/night configuration.

I toyed with the idea of creating two maps, with different symbology, and switching the map out (I am using a mobile map package) but that adds some complexity as I have routing on networks associated with the loaded map.

I was hoping for a way to be able to load the map, and then look up the symbology from a stylx file (maybe?) and just load a different style file based on my dark/light mode. I have looked at the dictionary style examples but they seem fixed to military type symbology.

The other option is iterating through each of the operational layers and setting a renderer.

If anyone has any other suggestions, I would be delighted to hear them.

Regards,
Sean

smithse · Answer

Hi Lucas,

Thanks for the feedback, and after much deliberation and searching following that post, I sort of came to the same conclusion.

This is the code that I ended up going with:

// Function to change the map style based on the dayNightMode variable in the app object
        function changeMapStyle() {

// Get the current dayNightMode value from the app object and convert it to uppercase
            let dayNightMode = app.dayNightMode.toUpperCase();

// Log the current mode to the console
            console.log("Mode set to: " + dayNightMode);

// Loop through all the operational layers in the map, starting from the last layer
            for (let i = mapView.map.operationalLayers.count - 1; i >= 0; i--) {

// Get the current layer
                let layer = mapView.map.operationalLayers.get(i);

// Get the name of the layer and convert it to uppercase
                let layerName = layer.name.toUpperCase();

// Check if the layer name contains "DAY" or "NIGHT"
                if (layerName.includes("DAY") || layerName.includes("NIGHT")) {
                    // Log that the layer is sensitive to day/night mode
                    //console.log("Layer is DN sensitive so check");

// If the layer name contains the current dayNightMode value, make the layer visible
                    layer.visible = layerName.indexOf(dayNightMode) !== -1;
                }
            }
        }

Note: my tendency in dev is to break apart code as much as possible...and doc it... lots of refactoring can go on later 🙂

LucasDanzinger · Answer

Your solution of toggling visibility depending on dark/light mode is pretty clean and simple in my opinion. That seems like a good option.

We do have other samples where we use dictionary symbol styles without military symbols. You could input some custom Arcade that would swap the correct colors depending on some condition, but that will be much more complicated to maintain and debug than your solution. https://github.com/Esri/arcgis-maps-sdk-samples-qt/tree/main/ArcGISRuntimeSDKQt_QMLSamples/DisplayInformation/CustomDictionaryStyle

smithse · Answer

Thanks TroyFoster,

Yes, planning to be totally offline due to remote location with no internet coverage. At the moment, I'm using a map package built in ArcGIS Pro (.mmpk). I'm really keen to look into vtpk's as you're the second person who has mentioned these to me now, on two different occasions. I don't know what the difference is between a true vtpk and the mmpk (and I say that because I only have 'shape' data in my map layers i.e. polys and points and no raster or other tilesets)  <-- still learning! From what I can gather, there is probably a whole bunch of styling and other references in the mmpk. Anyway, I digress.