Added type declarations

types/layout.d.ts

@@ -0,0 +1,48 @@
+import Contents from "./contents";
+
+interface LayoutSettings {
+  layout: string,
+  spread: string,
+  minSpreadWidth: number,
+  evenSpreads: boolean
+}
+
+export default class Layout {
+  constructor(settings: LayoutSettings);
+
+  settings: LayoutSettings;
+  name: string;
+  props: {
+    name: string,
+    spread: string,
+    flow: string,
+    width: number,
+    height: number,
+    spreadWidth: number,
+    delta: number,
+    columnWidth: number,
+    gap: number,
+    divisor: number
+  };
+
+  flow(flow: string): string;
+
+  spread(spread: string, min: number): boolean;
+
+  calculate(_width:number, _height:number, _gap?:number): void;
+
+  format(contents: Contents): void | Promise<void>;
+
+  count(totalLength: number, pageLength: number): {spreads: Number, pages: Number};
+
+  // Event emitters
+  emit(type: any, ...args: any[]): void;
+
+  off(type: any, listener: any): any;
+
+  on(type: any, listener: any): any;
+
+  once(type: any, listener: any, ...args: any[]): any;
+
+  private update(props: object): void;
+}