getRenderKey abstract method
Returns a key for the caches. In order to use different caches for different renderings the renderer can provide a unique key. The key should be the same if the rendering should provide the exact same image again. The key should be different if the renderer provides different images. This can be used for light/dark themes. Note that different DisplayModels also may lead to different renderings (e.g. scaleFactors) but this is currently not implemented in the default renderers. We assume that the displaymodel stays the same at one single device or the cache will be deleted if the user changes the scalieFactors.
Implementation
String getRenderKey();