Add overlay layer possibility, fix #515

Models/ThemeConfig/TilesourceConfig.ts

@@ -0,0 +1,38 @@
+import TilesourceConfigJson from "./Json/TilesourceConfigJson";
+import Translations from "../../UI/i18n/Translations";
+import {Translation} from "../../UI/i18n/Translation";
+
+export default class TilesourceConfig {
+    public readonly source: string
+    public readonly isOverlay: boolean
+    public readonly name: Translation
+    public readonly minzoom: number
+    public readonly maxzoom: number
+    public readonly defaultState: boolean;
+
+    constructor(config: TilesourceConfigJson, ctx: string = "") {
+
+        this.source = config.source;
+        this.isOverlay = config.isOverlay ?? false;
+        this.name = Translations.T(config.name)
+        this.minzoom = config.minZoom ?? 0
+        this.maxzoom = config.maxZoom ?? 999
+        this.defaultState = config.defaultState ?? true;
+        if (this.minzoom > this.maxzoom) {
+            throw "Invalid tilesourceConfig: minzoom should be smaller then maxzoom (at " + ctx + ")"
+        }
+        if (this.minzoom < 0) {
+            throw "minzoom should be > 0 (at " + ctx + ")"
+        }
+        if (this.maxzoom < 0) {
+            throw "maxzoom should be > 0 (at " + ctx + ")"
+        }
+        if (this.source.indexOf("{zoom}") >= 0) {
+            throw "Invalid source url: use {z} instead of {zoom}  (at " + ctx + ".source)"
+        }
+        if(!this.defaultState && config.name === undefined){
+            throw "Disabling an overlay without a name is not possible"
+        }
+    }
+
+}