Adding the ability to trigger layout change (on web) explicitly. (#74)

src/common/Interfaces.ts

@@ -140,6 +140,9 @@ export abstract class UserInterface {
 
     // On-screen Keyboard
     abstract dismissKeyboard(): void;
+
+    // Explicit layout change indication
+    abstract layoutChangePending(): void;
 }
 
 export abstract class Modal {

src/native-common/UserInterface.ts

@@ -121,6 +121,10 @@ export class UserInterface extends RX.UserInterface {
     renderMainView() {
         // Nothing to do
     }
+
+    layoutChangePending() {
+        // Nothing to do
+    }
 }
 
 export default new UserInterface();

src/web/UserInterface.ts

@@ -18,6 +18,8 @@ import RX = require('../common/Interfaces');
 import Types = require('../common/Types');
 
 export class UserInterface extends RX.UserInterface {
+    private _layoutChangeAnimationFrame: number;
+
     measureLayoutRelativeToWindow(component: React.Component<any, any>) :
             SyncTasks.Promise<Types.LayoutInfo> {
 
@@ -105,6 +107,19 @@ export class UserInterface extends RX.UserInterface {
     dismissKeyboard() {
         // Nothing to do
     }
+
+    layoutChangePending() {
+        if (!this._layoutChangeAnimationFrame) {
+            // ViewBase checks for the layout changes once a second or on window resize.
+            // To avoid laggy layout updates we can indicate that there is a change pending.
+            this._layoutChangeAnimationFrame = window.requestAnimationFrame(() => {
+                this._layoutChangeAnimationFrame = undefined;
+                let event = document.createEvent('HTMLEvents');
+                event.initEvent('resize', true, false);
+                window.dispatchEvent(event);
+            });
+        }
+    }
 }
 
 export default new UserInterface();