feat(view): introduce LayoutChanged event on every View component (#5825)

* feat(view): introduce LayoutChanged event

* test(view): add LayoutChanged event tests

* chore(view-android): attach to onLayoutChange only if listener attached

* feat(view-android): override on/off in order to attach and detach from OnLayoutChangeListener

tests/app/testRunner.ts

@@ -141,6 +141,9 @@ allTests["FRAME"] = frameTests;
 import * as viewTests from "./ui/view/view-tests";
 allTests["VIEW"] = viewTests;
 
+import * as viewLayoutChangedEventTests from "./ui/view/view-tests-layout-event";
+allTests["VIEW-LAYOUT-EVENT"] = viewLayoutChangedEventTests;
+
 import * as styleTests from "./ui/styling/style-tests";
 allTests["STYLE"] = styleTests;
 

tests/app/ui/helper.ts

@@ -37,7 +37,7 @@ export function getColor(uiColor: UIColor): Color {
     return new Color(alpha, red, green, blue);
 }
 
-function clearPage(): void {
+export function clearPage(): void {
     let newPage = getCurrentPage();
     if (!newPage) {
         throw new Error("NO CURRENT PAGE!!!!");

tests/app/ui/view/view-tests-layout-event.ts

@@ -0,0 +1,210 @@
+import * as commonTests from "./view-tests-common";
+
+import { View } from "tns-core-modules/ui/core/view";
+import { Button } from "tns-core-modules/ui/button";
+import { StackLayout } from "tns-core-modules/ui/layouts/stack-layout/stack-layout";
+import * as helper from "../helper";
+import * as TKUnit from "../../TKUnit";
+import * as utils from "tns-core-modules/utils/utils";
+
+export function test_event_LayoutChanged_GetActualSize() {
+    const test = function (views: Array<View>) {
+        let buttonLayoutChanged = false;
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChanged = true;
+        });
+
+        TKUnit.waitUntilReady(() => buttonLayoutChanged);
+        TKUnit.assert(views[1].getActualSize().height > 0);
+        TKUnit.assert(views[1].getActualSize().width > 0);
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};
+
+export function test_event_LayoutChanged_Listeners() {
+    const test = function (views: Array<View>) {
+        let stackLayoutChanged = false;
+        let buttonLayoutChanged = false;
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChanged = true;
+        });
+
+        TKUnit.waitUntilReady(() => buttonLayoutChanged);
+        TKUnit.assertFalse(views[0].hasListeners(View.layoutChangedEvent));
+        TKUnit.assert(views[1].hasListeners(View.layoutChangedEvent));
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};
+
+export function test_event_LayoutChanged_IsRaised() {
+    helper.clearPage();
+    let newPage = helper.getCurrentPage();
+
+    let stackLayoutChanged = false;
+    let buttonLayoutChanged = false;
+
+    let stackLayout = new StackLayout();
+    let button = new Button();
+
+    stackLayout.on(View.layoutChangedEvent, (data) => {
+        stackLayoutChanged = true;
+    });
+
+    button.on(View.layoutChangedEvent, (data) => {
+        buttonLayoutChanged = true;
+    });
+
+    stackLayout.addChild(button);
+    newPage.content = stackLayout;
+
+    TKUnit.waitUntilReady(() => stackLayoutChanged && buttonLayoutChanged);
+    TKUnit.assert(stackLayoutChanged);
+    TKUnit.assert(buttonLayoutChanged);
+
+    newPage.content = null;
+};
+
+export function test_event_LayoutChanged_IsRaised_StackLayout_ChildAdded() {
+    helper.clearPage();
+    let newPage = helper.getCurrentPage();
+
+    let stackLayoutChangedCount = 0;
+    let button1LayoutChangedCount = 0;
+    let button2LayoutChanged = false;
+
+    let stackLayout = new StackLayout();
+
+    // StackLayout should not be stretched in order to layout again when new button added.
+    stackLayout.verticalAlignment = "top";
+    let button1 = new Button();
+    let button2 = new Button();
+
+    stackLayout.on(View.layoutChangedEvent, (data) => {
+        stackLayoutChangedCount++;
+    });
+
+    button1.on(View.layoutChangedEvent, (data) => {
+        button1LayoutChangedCount++;
+    });
+
+    button2.on(View.layoutChangedEvent, (data) => {
+        button2LayoutChanged = true;
+    });
+
+    stackLayout.addChild(button1);
+    newPage.content = stackLayout;
+
+    TKUnit.waitUntilReady(() => stackLayout.isLoaded);
+    stackLayout.addChild(button2);
+    
+    TKUnit.waitUntilReady(() => button2LayoutChanged);
+    TKUnit.assertEqual(stackLayoutChangedCount, 2);
+    TKUnit.assertEqual(button1LayoutChangedCount, 1);
+    TKUnit.assert(button2LayoutChanged);
+
+    newPage.content = null;
+};
+
+export function test_event_LayoutChanged_IsRaised_ChildMarginChanged() {
+    const test = function (views: Array<View>) {
+        let stackLayoutChanged = false;
+        let buttonLayoutChanged = false;
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            stackLayoutChanged = true;
+        });
+
+        views[2].on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChanged = true;
+        });
+
+        (<Button>views[2]).marginTop = 50;
+
+        TKUnit.waitUntilReady(() => buttonLayoutChanged);
+
+        TKUnit.assert(stackLayoutChanged);
+        TKUnit.assert(buttonLayoutChanged);
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};
+
+export function test_event_LayoutChanged_IsRaised_ParentMarginChanged() {
+    const test = function (views: Array<View>) {
+        let stackLayoutChanged = false;
+        let buttonLayoutChanged = false;
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            stackLayoutChanged = true;
+        });
+
+        views[2].on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChanged = true;
+        });
+
+        (<Button>views[2]).marginTop = 50;
+
+        TKUnit.waitUntilReady(() => buttonLayoutChanged);
+
+        TKUnit.assert(stackLayoutChanged);
+        TKUnit.assert(buttonLayoutChanged);
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};
+
+export function test_event_LayoutChanged_IsNotRaised_TransformChanged() {
+    const test = function (views: Array<View>) {
+        let stackLayoutChangedCount = 0;
+        let buttonLayoutChangedCount = 0;
+        const button = <Button>views[2];
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            stackLayoutChangedCount++;
+        });
+
+        button.on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChangedCount++;
+        });
+
+        button.translateX += 50;
+        button.translateY += 50;
+        button.rotate += 50;
+        button.height = 200;
+
+        TKUnit.waitUntilReady(() => button.height === 200);
+
+        TKUnit.assertEqual(stackLayoutChangedCount, 1);
+        TKUnit.assertEqual(buttonLayoutChangedCount, 1);
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};
+
+export function test_event_LayoutChanged_IsRaised_StackLayout_SizeChanged() {
+    const test = function (views: Array<View>) {
+        let stackLayoutChanged = false;
+        let buttonLayoutChanged = false;
+
+        views[1].on(View.layoutChangedEvent, (data) => {
+            stackLayoutChanged = true;
+        });
+
+        views[2].on(View.layoutChangedEvent, (data) => {
+            buttonLayoutChanged = true;
+        });
+
+        (<StackLayout>views[1]).height = 100;
+
+        TKUnit.waitUntilReady(() => buttonLayoutChanged);
+
+        TKUnit.assert(stackLayoutChanged);
+        TKUnit.assert(buttonLayoutChanged);
+    };
+
+    helper.do_PageTest_WithStackLayout_AndButton(test);
+};

tests/app/ui/view/view-tests.ios.ts

@@ -1,15 +1,16 @@
 import * as commonTests from "./view-tests-common";
-import * as view from "tns-core-modules/ui/core/view";
+
-import * as grid from "tns-core-modules/ui/layouts/grid-layout";
+import { View } from "tns-core-modules/ui/core/view";
-import * as color from "tns-core-modules/color";
+import { Button } from "tns-core-modules/ui/button";
+import { GridLayout } from "tns-core-modules/ui/layouts/grid-layout";
+import { Color } from "tns-core-modules/color";
 import * as helper from "../helper";
 import * as TKUnit from "../../TKUnit";
-import * as button from "tns-core-modules/ui/button";
 import * as utils from "tns-core-modules/utils/utils";
 
 global.moduleMerge(commonTests, exports);
 
-class MyGrid extends grid.GridLayout {
+class MyGrid extends GridLayout {
     public backgroundDrawCount: number = 0;
 
     _redrawNativeBackground(background: any) {
@@ -18,33 +19,33 @@ class MyGrid extends grid.GridLayout {
     }
 }
 
-export function getUniformNativeBorderWidth(v: view.View): number {
+export function getUniformNativeBorderWidth(v: View): number {
     return utils.layout.toDevicePixels((<UIView>v.ios).layer.borderWidth);
 }
 
-export function checkUniformNativeBorderColor(v: view.View): boolean {
+export function checkUniformNativeBorderColor(v: View): boolean {
-    if (v.borderColor instanceof color.Color) {
+    if (v.borderColor instanceof Color) {
-        return (<UIView>v.ios).layer.borderColor === (<color.Color>v.borderColor).ios.CGColor;
+        return (<UIView>v.ios).layer.borderColor === (<Color>v.borderColor).ios.CGColor;
     }
 
     return undefined;
 }
 
-export function getUniformNativeCornerRadius(v: view.View): number {
+export function getUniformNativeCornerRadius(v: View): number {
     return utils.layout.toDevicePixels((<UIView>v.ios).layer.cornerRadius);
 }
 
-export function checkNativeBackgroundColor(v: view.View): boolean {
+export function checkNativeBackgroundColor(v: View): boolean {
     if (v.ios instanceof UILabel) {
         var cgColor1 = (<UILabel>v.ios).layer.backgroundColor;
-        var cgColor2 = (<UIColor>(<color.Color>v.backgroundColor).ios).CGColor;
+        var cgColor2 = (<UIColor>(<Color>v.backgroundColor).ios).CGColor;
         return v.backgroundColor && !!CGColorEqualToColor(cgColor1, cgColor2);
     }
 
-    return v.backgroundColor && (<UIView>v.ios).backgroundColor.isEqual((<color.Color>v.backgroundColor).ios);
+    return v.backgroundColor && (<UIView>v.ios).backgroundColor.isEqual((<Color>v.backgroundColor).ios);
 }
 
-export function checkNativeBackgroundImage(v: view.View): boolean {
+export function checkNativeBackgroundImage(v: View): boolean {
     return (<UIView>v.ios).backgroundColor !== undefined;
 }
 
@@ -53,7 +54,7 @@ export function testBackgroundInternalChangedOnceOnResize() {
     let root = helper.getCurrentPage();
     let layout = new MyGrid();
     layout.className = "myClass";
-    layout.backgroundColor = new color.Color(255, 255, 0, 0);
+    layout.backgroundColor = new Color(255, 255, 0, 0);
 
     root.css = ".myClass { background-image: url('~/logo.png') }";
     root.content = layout;
@@ -82,7 +83,7 @@ export function testBackgroundInternalChangedOnceOnResize() {
 }
 
 export function test_automation_text_set_to_native() {
-    var newButton = new button.Button();
+    var newButton = new Button();
     newButton.automationText = "Button1";
     helper.getCurrentPage().content = newButton;
     TKUnit.assertEqual((<UIView>newButton.ios).accessibilityIdentifier, "Button1", "accessibilityIdentifier not set to native view.");

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

@@ -61,6 +61,7 @@ export function PseudoClassHandler(...pseudoClasses: string[]): MethodDecorator
 export const _rootModalViews = new Array<ViewBase>();
 
 export abstract class ViewCommon extends ViewBase implements ViewDefinition {
+    public static layoutChangedEvent = "layoutChanged";
     public static shownModallyEvent = "shownModally";
     public static showingModallyEvent = "showingModally";
 
@@ -277,6 +278,14 @@ export abstract class ViewCommon extends ViewBase implements ViewDefinition {
         //
     }
 
+    protected _raiseLayoutChangedEvent() {
+        const args: EventData = {
+            eventName: ViewCommon.layoutChangedEvent,
+            object: this
+        };
+        this.notify(args);
+    }
+
     protected _raiseShownModallyEvent() {
         const args: ShownModallyData = {
             eventName: ViewCommon.shownModallyEvent,

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

@@ -7,7 +7,7 @@ import {
     ViewCommon, layout, isEnabledProperty, originXProperty, originYProperty, automationTextProperty, isUserInteractionEnabledProperty,
     traceEnabled, traceWrite, traceCategories, traceNotifyEvent,
     paddingLeftProperty, paddingTopProperty, paddingRightProperty, paddingBottomProperty,
-    Color
+    Color, EventData
 } from "./view-common";
 
 import {
@@ -229,6 +229,8 @@ export class View extends ViewCommon {
     private _isClickable: boolean;
     private touchListenerIsSet: boolean;
     private touchListener: android.view.View.OnTouchListener;
+    private layoutChangeListenerIsSet: boolean;
+    private layoutChangeListener: android.view.View.OnLayoutChangeListener;
     private _manager: android.app.FragmentManager;
 
     nativeViewProtected: android.view.View;
@@ -241,6 +243,26 @@ export class View extends ViewCommon {
         }
     }
 
+    on(eventNames: string, callback: (data: EventData) => void, thisArg?: any) {
+        super.on(eventNames, callback, thisArg);
+        const isLayoutEvent = typeof eventNames === "string" ? eventNames.indexOf(ViewCommon.layoutChangedEvent) !== -1 : false;
+
+        if (this.isLoaded && !this.layoutChangeListenerIsSet && isLayoutEvent) {
+            this.setOnLayoutChangeListener();
+        }
+    }
+
+    off(eventNames: string, callback?: any, thisArg?: any) {
+        super.off(eventNames, callback, thisArg);
+        const isLayoutEvent = typeof eventNames === "string" ? eventNames.indexOf(ViewCommon.layoutChangedEvent) !== -1 : false;
+
+        // Remove native listener only if there are no more user listeners for LayoutChanged event
+        if (this.isLoaded && this.layoutChangeListenerIsSet && isLayoutEvent && !this.hasListeners(ViewCommon.layoutChangedEvent)) {
+            this.nativeViewProtected.removeOnLayoutChangeListener(this.layoutChangeListener);
+            this.layoutChangeListenerIsSet = false;
+        }
+    }
+
     public _getFragmentManager(): android.app.FragmentManager {
         let manager = this._manager;
         if (!manager) {
@@ -305,6 +327,19 @@ export class View extends ViewCommon {
     public initNativeView(): void {
         super.initNativeView();
         this._isClickable = this.nativeViewProtected.isClickable();
+
+        if (this.hasListeners(ViewCommon.layoutChangedEvent)) {
+            this.setOnLayoutChangeListener();
+        }
+    }
+
+    public disposeNativeView(): void {
+        super.disposeNativeView();
+
+        if (this.layoutChangeListenerIsSet) {
+            this.layoutChangeListenerIsSet = false;
+            this.nativeViewProtected.removeOnLayoutChangeListener(this.layoutChangeListener);
+        }
     }
 
     private setOnTouchListener() {
@@ -320,6 +355,25 @@ export class View extends ViewCommon {
         }
     }
 
+    private setOnLayoutChangeListener() {
+        if (this.nativeViewProtected) {
+            const owner = this;
+            this.layoutChangeListenerIsSet = true;
+            this.layoutChangeListener = this.layoutChangeListener || new android.view.View.OnLayoutChangeListener({
+                onLayoutChange(
+                    v: android.view.View,
+                    left: number, top: number, right: number, bottom: number,
+                    oldLeft: number, oldTop: number, oldRight: number, oldBottom: number): void {
+                    if (left !== oldLeft || top !== oldTop || right !== oldRight || bottom !== oldBottom) {
+                        owner._raiseLayoutChangedEvent();
+                    }
+                }
+            });
+
+            this.nativeViewProtected.addOnLayoutChangeListener(this.layoutChangeListener);
+        }
+    }
+
     get isLayoutRequired(): boolean {
         return !this.isLayoutValid;
     }

tns-core-modules/ui/core/view/view.d.ts

@@ -103,6 +103,10 @@ export interface ShownModallyData extends EventData {
  * A View occupies a rectangular area on the screen and is responsible for drawing and layouting of all UI components within. 
  */
 export abstract class View extends ViewBase {
+    /**
+     * String value used when hooking to layoutChanged event.
+     */
+    public static layoutChangedEvent: string;
     /**
      * String value used when hooking to showingModally event.
      */

tns-core-modules/ui/core/view/view.ios.ts

@@ -28,6 +28,7 @@ export class View extends ViewCommon {
     nativeViewProtected: UIView;
     viewController: UIViewController;
 
+    private _isLaidOut = false;
     private _hasTransfrom = false;
     private _privateFlags: number = PFLAG_LAYOUT_REQUIRED | PFLAG_FORCE_LAYOUT;
     private _cachedFrame: CGRect;
@@ -160,6 +161,11 @@ export class View extends ViewCommon {
 
             const boundsOrigin = nativeView.bounds.origin;
             nativeView.bounds = CGRectMake(boundsOrigin.x, boundsOrigin.y, frame.size.width, frame.size.height);
+            this._raiseLayoutChangedEvent();
+            this._isLaidOut = true;
+        } else if (!this._isLaidOut) {
+            // Rects could be equal on the first layout and an event should be raised.
+            this._raiseLayoutChangedEvent();
         }
     }