refactor(HMR): apply changes in application styles at runtime

tns-core-modules/application/application-common.ts

@@ -32,7 +32,14 @@ export function hasLaunched(): boolean {
 
 export { Observable };
 
-import { UnhandledErrorEventData, iOSApplication, AndroidApplication, CssChangedEventData, LoadAppCSSEventData } from ".";
+import {
+    AndroidApplication,
+    CssChangedEventData,
+    getRootView,
+    iOSApplication,
+    LoadAppCSSEventData,
+    UnhandledErrorEventData
+} from "./application";
 
 export { UnhandledErrorEventData, CssChangedEventData, LoadAppCSSEventData };
 
@@ -73,8 +80,19 @@ export function setApplication(instance: iOSApplication | AndroidApplication): v
 export function livesync(context?: HmrContext) {
     events.notify(<EventData>{ eventName: "livesync", object: app });
     const liveSyncCore = global.__onLiveSyncCore;
-    if (liveSyncCore) {
-        liveSyncCore(context);
+    let reapplyAppCss = false
+
+    if (context) {
+        const fullFileName = getCssFileName();
+        const fileName = fullFileName.substring(0, fullFileName.lastIndexOf(".") + 1);
+        const extensions = ["css", "scss"];
+        reapplyAppCss = extensions.some(ext => context.module === fileName.concat(ext));
+    }
+
+    if (reapplyAppCss) {
+        getRootView()._onCssStateChange();
+    } else if (liveSyncCore) {
+        liveSyncCore();
     }
 }
 

tns-core-modules/application/application.ios.ts

@@ -18,7 +18,6 @@ export * from "./application-common";
 import { createViewFromEntry } from "../ui/builder";
 import { ios as iosView, View } from "../ui/core/view";
 import { Frame, NavigationEntry } from "../ui/frame";
-import { loadCss } from "../ui/styling/style-scope";
 import * as utils from "../utils/utils";
 import { profile, level as profilingLevel, Level } from "../profiling";
 
@@ -226,23 +225,12 @@ class IOSApplication implements IOSApplicationDefinition {
         }
     }
 
-    public _onLivesync(context?: HmrContext): void {
-        let executeLivesync = true;
-        // HMR has context, livesync does not
-        if (context) {
-            if (context.module === getCssFileName()) {
-                loadCss(context.module);
-                this._rootView._onCssStateChange();
-                executeLivesync = false;
-            }
-        }
-        if (executeLivesync) {
+    public _onLivesync(): void {
         // If view can't handle livesync set window controller.
         if (!this._rootView._onLivesync()) {
             this.setWindowContent();
         }
     }
-    }
 
     public setWindowContent(view?: View): void {
         if (this._rootView) {
@@ -276,8 +264,8 @@ exports.ios = iosApp;
 setApplication(iosApp);
 
 // attach on global, so it can be overwritten in NativeScript Angular
-(<any>global).__onLiveSyncCore = function __onLiveSyncCore(context?: HmrContext) {
-    iosApp._onLivesync(context);
+(<any>global).__onLiveSyncCore = function () {
+    iosApp._onLivesync();
 }
 
 let mainEntry: NavigationEntry;

tns-core-modules/module.d.ts

@@ -52,7 +52,7 @@ declare namespace NodeJS {
         __inspector?: any;
         __extends: any;
         __onLiveSync: (context?: { type: string, module: string }) => void;
-        __onLiveSyncCore: (context?: { type: string, module: string }) => void;
+        __onLiveSyncCore: () => void;
         __onUncaughtError: (error: NativeScriptError) => void;
         TNS_WEBPACK?: boolean;
         __requireOverride?: (name: string, dir: string) => any;

tns-core-modules/ui/frame/frame.android.ts

@@ -17,7 +17,6 @@ import {
     _updateTransitions, _reverseTransitions, _clearEntry, _clearFragment, AnimationType
 } from "./fragment.transitions";
 
-import { loadCss } from "../styling/style-scope";
 import { profile } from "../../profiling";
 
 // TODO: Remove this and get it from global to decouple builder for angular
@@ -83,25 +82,14 @@ function getAttachListener(): android.view.View.OnAttachStateChangeListener {
     return attachStateChangeListener;
 }
 
-export function reloadPage(context?: HmrContext): void {
+export function reloadPage(): void {
     const activity = application.android.foregroundActivity;
     const callbacks: AndroidActivityCallbacks = activity[CALLBACKS];
     const rootView: View = callbacks.getRootView();
 
-    let executeLivesync = true;
-    // HMR has context, livesync does not
-    if (context) {
-        if (context.module === application.getCssFileName()) {
-            loadCss(context.module);
-            rootView._onCssStateChange();
-            executeLivesync = false;
-        }
-    }
-    if (executeLivesync) {
     if (!rootView || !rootView._onLivesync()) {
         callbacks.resetActivityContent(activity);
     }
-    }
 }
 
 // attach on global, so it can be overwritten in NativeScript Angular

tns-core-modules/ui/page/page-common.ts

@@ -103,9 +103,12 @@ export class PageBase extends ContentView implements PageDefinition {
     public onNavigatingTo(context: any, isBackNavigation: boolean, bindingContext?: any) {
         this._navigationContext = context;
 
+        if (isBackNavigation && this._styleScope) {
+            this._styleScope.ensureSelectors();
             if (!this._cssState.isSelectorsLatestVersionApplied()) {
                 this._onCssStateChange();
             }
+        }
 
         //https://github.com/NativeScript/NativeScript/issues/731
         if (!isBackNavigation && bindingContext !== undefined && bindingContext !== null) {

tns-core-modules/ui/styling/style-scope.ts

@@ -307,7 +307,7 @@ function onLiveSync(args: applicationCommon.CssChangedEventData): void {
     loadCss(applicationCommon.getCssFileName());
 }
 
-export const loadCss = profile(`"style-scope".loadCss`, (cssFile: string) => {
+const loadCss = profile(`"style-scope".loadCss`, (cssFile: string) => {
     if (!cssFile) {
         return undefined;
     }
@@ -369,12 +369,7 @@ export class CssState {
     }
 
     public isSelectorsLatestVersionApplied(): boolean {
-        if (this._appliedSelectorsVersion && this.view._styleScope) {
-            this.view._styleScope.ensureSelectors();
         return this.view._styleScope._getSelectorsVersion() === this._appliedSelectorsVersion;
-        } else {
-            return true;
-        }
     }
 
     public onLoaded(): void {