NativeScript/nativescript-core/ui/core/view/view-common.ts

// Definitions.
import {
    View as ViewDefinition, Point, Size, Color, dip,
    ShownModallyData
} from ".";

import {
    booleanConverter, EventData, getEventOrGestureName, InheritedProperty, layout,
    Property, ShowModalOptions, traceCategories, traceEnabled, traceWrite, ViewBase
} from "../view-base";

import { HorizontalAlignment, VerticalAlignment, Visibility, Length, PercentLength } from "../../styling/style-properties";

import {
    observe as gestureObserve,
    GesturesObserver,
    GestureTypes,
    GestureEventData,
    fromString as gestureFromString
} from "../../gestures";

import { getModalRootViewCssClass } from "../../../css/system-classes";
import { Builder } from "../../builder";
import { sanitizeModuleName } from "../../builder/module-name-sanitizer";
import { StyleScope } from "../../styling/style-scope";
import { LinearGradient } from "../../styling/linear-gradient";
import { BackgroundRepeat } from "../../styling/style-properties";

export * from "../../styling/style-properties";
export * from "../view-base";
export { LinearGradient };

import * as am from "../../animation";

let animationModule: typeof am;
function ensureAnimationModule() {
    if (!animationModule) {
        animationModule = require("../../animation");
    }
}

export function CSSType(type: string): ClassDecorator {
    return (cls) => {
        cls.prototype.cssType = type;
    };
}

export function viewMatchesModuleContext(
    view: ViewDefinition,
    context: ModuleContext,
    types: ModuleType[]): boolean {

    return context &&
        view._moduleName &&
        context.type &&
        types.some(type => type === context.type) &&
        context.path &&
        context.path.includes(view._moduleName);
}

export function PseudoClassHandler(...pseudoClasses: string[]): MethodDecorator {
    const stateEventNames = pseudoClasses.map(s => ":" + s);
    const listeners = Symbol("listeners");

    return <T>(target: Object, propertyKey: string | symbol, descriptor: TypedPropertyDescriptor<T>) => {
        function update(change: number) {
            let prev = this[listeners] || 0;
            let next = prev + change;
            if (prev <= 0 && next > 0) {
                this[propertyKey](true);
            } else if (prev > 0 && next <= 0) {
                this[propertyKey](false);
            }
        }
        stateEventNames.forEach(s => target[s] = update);
    };
}

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";

    protected _closeModalCallback: Function;
    public _manager: any;
    public _modalParent: ViewCommon;
    private _modalContext: any;
    private _modal: ViewCommon;

    private _measuredWidth: number;
    private _measuredHeight: number;

    protected _isLayoutValid: boolean;
    private _cssType: string;

    private _localAnimations: Set<am.Animation>;

    _currentWidthMeasureSpec: number;
    _currentHeightMeasureSpec: number;

    _setMinWidthNative: (value: Length) => void;
    _setMinHeightNative: (value: Length) => void;

    public _gestureObservers = {};

    get css(): string {
        const scope = this._styleScope;

        return scope && scope.css;
    }
    set css(value: string) {
        this._updateStyleScope(undefined, undefined, value);
    }

    public addCss(cssString: string): void {
        this._updateStyleScope(undefined, cssString);
    }

    public addCssFile(cssFileName: string) {
        this._updateStyleScope(cssFileName);
    }

    public changeCssFile(cssFileName: string): void {
        const scope = this._styleScope;
        if (scope && cssFileName) {
            scope.changeCssFile(cssFileName);
            this._onCssStateChange();
        }
    }

    public _updateStyleScope(cssFileName?: string, cssString?: string, css?: string): void {
        let scope = this._styleScope;
        if (!scope) {
            scope = new StyleScope();
            this.setScopeProperty(scope, cssFileName, cssString, css);
            this._inheritStyleScope(scope);
            this._isStyleScopeHost = true;
        } else {
            this.setScopeProperty(scope, cssFileName, cssString, css);
            this._onCssStateChange();
        }
    }

    private setScopeProperty(scope: StyleScope, cssFileName?: string, cssString?: string, css?: string): void {
        if (cssFileName !== undefined) {
            scope.addCssFile(cssFileName);
        } else if (cssString !== undefined) {
            scope.addCss(cssString);
        } else if (css !== undefined) {
            scope.css = css;
        }
    }

    public _closeAllModalViewsInternal(): boolean {
        if (_rootModalViews && _rootModalViews.length > 0) {
            _rootModalViews.forEach(v => {
                v.closeModal();
            });

            return true;
        }

        return false;
    }

    public _getRootModalViews(): Array<ViewBase> {
        return _rootModalViews;
    }

    public _onLivesync(context?: ModuleContext): boolean {
        if (traceEnabled()) {
            traceWrite(`${this}._onLivesync(${JSON.stringify(context)})`, traceCategories.Livesync);
        }

        if (this._closeAllModalViewsInternal()) {
            return true;
        }

        if (this._handleLivesync(context)) {
            return true;
        }

        let handled = false;
        this.eachChildView((child) => {
            if (child._onLivesync(context)) {
                handled = true;

                return false;
            }
        });

        return handled;
    }

    public _handleLivesync(context?: ModuleContext): boolean {
        if (traceEnabled()) {
            traceWrite(`${this}._handleLivesync(${JSON.stringify(context)})`, traceCategories.Livesync);
        }

        // Handle local CSS
        if (viewMatchesModuleContext(this, context, ["style"])) {
            if (traceEnabled()) {
                traceWrite(`Change Handled: Changing CSS for ${this}`, traceCategories.Livesync);
            }

            // Always load styles with ".css" extension. Even when changes are in ".scss" ot ".less" files
            const cssModuleName = `${sanitizeModuleName(context.path)}.css`;

            this.changeCssFile(cssModuleName);

            return true;
        }

        // Handle script/markup changes in custom components by falling back to page refresh
        if (viewMatchesModuleContext(this, context, ["markup", "script"]) &&
            this.page &&
            this.page.frame) {

            if (traceEnabled()) {
                traceWrite(`Change Handled: Changing ${context.type} for ${this} inside ${this.page}`, traceCategories.Livesync);
            }

            return this.page.frame._handleLivesync({ type: context.type, path: this.page._moduleName });
        }

        return false;
    }

    _setupAsRootView(context: any): void {
        super._setupAsRootView(context);
        if (!this._styleScope) {
            this._updateStyleScope();
        }
    }

    _observe(type: GestureTypes, callback: (args: GestureEventData) => void, thisArg?: any): void {
        if (!this._gestureObservers[type]) {
            this._gestureObservers[type] = [];
        }

        this._gestureObservers[type].push(gestureObserve(this, type, callback, thisArg));
    }

    public getGestureObservers(type: GestureTypes): Array<GesturesObserver> {
        return this._gestureObservers[type];
    }

    public addEventListener(arg: string | GestureTypes, callback: (data: EventData) => void, thisArg?: any) {
        if (typeof arg === "string") {
            arg = getEventOrGestureName(arg);

            let gesture = gestureFromString(arg);
            if (gesture && !this._isEvent(arg)) {
                this._observe(gesture, callback, thisArg);
            } else {
                let events = (arg).split(",");
                if (events.length > 0) {
                    for (let i = 0; i < events.length; i++) {
                        let evt = events[i].trim();
                        let gst = gestureFromString(evt);
                        if (gst && !this._isEvent(arg)) {
                            this._observe(gst, callback, thisArg);
                        } else {
                            super.addEventListener(evt, callback, thisArg);
                        }
                    }
                } else {
                    super.addEventListener(arg, callback, thisArg);
                }
            }
        } else if (typeof arg === "number") {
            this._observe(<GestureTypes>arg, callback, thisArg);
        }
    }

    public removeEventListener(arg: string | GestureTypes, callback?: any, thisArg?: any) {
        if (typeof arg === "string") {
            let gesture = gestureFromString(arg);
            if (gesture && !this._isEvent(arg)) {
                this._disconnectGestureObservers(gesture);
            } else {
                let events = arg.split(",");
                if (events.length > 0) {
                    for (let i = 0; i < events.length; i++) {
                        let evt = events[i].trim();
                        let gst = gestureFromString(evt);
                        if (gst && !this._isEvent(arg)) {
                            this._disconnectGestureObservers(gst);
                        } else {
                            super.removeEventListener(evt, callback, thisArg);
                        }
                    }
                } else {
                    super.removeEventListener(arg, callback, thisArg);
                }

            }
        } else if (typeof arg === "number") {
            this._disconnectGestureObservers(<GestureTypes>arg);
        }
    }

    public onBackPressed(): boolean {
        return false;
    }

    public _getFragmentManager(): any {
        return undefined;
    }

    private getModalOptions(args: IArguments): { view: ViewCommon, options: ShowModalOptions } {
        if (args.length === 0) {
            throw new Error("showModal without parameters is deprecated. Please call showModal on a view instance instead.");
        } else {
            let options: ShowModalOptions = null;

            if (args.length === 2) {
                options = <ShowModalOptions>args[1];
            } else {
                if (args[0] instanceof ViewCommon) {
                    console.log("showModal(view: ViewBase, context: any, closeCallback: Function, fullscreen?: boolean, animated?: boolean, stretched?: boolean) " +
                        "is deprecated. Use showModal(view: ViewBase, modalOptions: ShowModalOptions) instead.");
                } else {
                    console.log("showModal(moduleName: string, context: any, closeCallback: Function, fullscreen?: boolean, animated?: boolean, stretched?: boolean) " +
                        "is deprecated. Use showModal(moduleName: string, modalOptions: ShowModalOptions) instead.");
                }

                options = {
                    context: args[1],
                    closeCallback: args[2],
                    fullscreen: args[3],
                    animated: args[4],
                    stretched: args[5]
                };
            }

            const firstArgument = args[0];
            const view = firstArgument instanceof ViewCommon
                ? firstArgument : <ViewCommon>Builder.createViewFromEntry({ moduleName: firstArgument });

            return { view, options };
        }
    }

    public showModal(): ViewDefinition {
        const { view, options } = this.getModalOptions(arguments);

        view._showNativeModalView(this, options);

        return view;
    }

    public closeModal(...args) {
        let closeCallback = this._closeModalCallback;
        if (closeCallback) {
            closeCallback.apply(undefined, arguments);
        } else {
            let parent = this.parent;
            if (parent) {
                parent.closeModal(...args);
            }
        }
    }

    public get modal(): ViewCommon {
        return this._modal;
    }

    protected _showNativeModalView(parent: ViewCommon, options: ShowModalOptions) {
        _rootModalViews.push(this);

        const modalRootViewCssClass = getModalRootViewCssClass();
        this.cssClasses.add(modalRootViewCssClass);

        parent._modal = this;
        this._modalParent = parent;
        this._modalContext = options.context;
        const that = this;
        this._closeModalCallback = function (...originalArgs) {
            if (that._closeModalCallback) {
                const modalIndex = _rootModalViews.indexOf(that);
                _rootModalViews.splice(modalIndex);
                that._modalParent = null;
                that._modalContext = null;
                that._closeModalCallback = null;
                that._dialogClosed();
                parent._modal = null;

                const whenClosedCallback = () => {
                    if (typeof options.closeCallback === "function") {
                        options.closeCallback.apply(undefined, originalArgs);
                    }
                };

                that._hideNativeModalView(parent, whenClosedCallback);
            }
        };
    }

    protected abstract _hideNativeModalView(parent: ViewCommon, whenClosedCallback: () => void);

    protected _raiseLayoutChangedEvent() {
        const args: EventData = {
            eventName: ViewCommon.layoutChangedEvent,
            object: this
        };
        this.notify(args);
    }

    protected _raiseShownModallyEvent() {
        const args: ShownModallyData = {
            eventName: ViewCommon.shownModallyEvent,
            object: this,
            context: this._modalContext,
            closeCallback: this._closeModalCallback
        };
        this.notify(args);
    }

    protected _raiseShowingModallyEvent() {
        const args: ShownModallyData = {
            eventName: ViewCommon.showingModallyEvent,
            object: this,
            context: this._modalContext,
            closeCallback: this._closeModalCallback
        };
        this.notify(args);
    }

    private _isEvent(name: string): boolean {
        return this.constructor && `${name}Event` in this.constructor;
    }

    private _disconnectGestureObservers(type: GestureTypes): void {
        let observers = this.getGestureObservers(type);
        if (observers) {
            for (let i = 0; i < observers.length; i++) {
                observers[i].disconnect();
            }
        }
    }

    // START Style property shortcuts
    get borderColor(): string | Color {
        return this.style.borderColor;
    }
    set borderColor(value: string | Color) {
        this.style.borderColor = value;
    }

    get borderTopColor(): Color {
        return this.style.borderTopColor;
    }
    set borderTopColor(value: Color) {
        this.style.borderTopColor = value;
    }

    get borderRightColor(): Color {
        return this.style.borderRightColor;
    }
    set borderRightColor(value: Color) {
        this.style.borderRightColor = value;
    }

    get borderBottomColor(): Color {
        return this.style.borderBottomColor;
    }
    set borderBottomColor(value: Color) {
        this.style.borderBottomColor = value;
    }

    get borderLeftColor(): Color {
        return this.style.borderLeftColor;
    }
    set borderLeftColor(value: Color) {
        this.style.borderLeftColor = value;
    }

    get borderWidth(): string | Length {
        return this.style.borderWidth;
    }
    set borderWidth(value: string | Length) {
        this.style.borderWidth = value;
    }

    get borderTopWidth(): Length {
        return this.style.borderTopWidth;
    }
    set borderTopWidth(value: Length) {
        this.style.borderTopWidth = value;
    }

    get borderRightWidth(): Length {
        return this.style.borderRightWidth;
    }
    set borderRightWidth(value: Length) {
        this.style.borderRightWidth = value;
    }

    get borderBottomWidth(): Length {
        return this.style.borderBottomWidth;
    }
    set borderBottomWidth(value: Length) {
        this.style.borderBottomWidth = value;
    }

    get borderLeftWidth(): Length {
        return this.style.borderLeftWidth;
    }
    set borderLeftWidth(value: Length) {
        this.style.borderLeftWidth = value;
    }

    get borderRadius(): string | Length {
        return this.style.borderRadius;
    }
    set borderRadius(value: string | Length) {
        this.style.borderRadius = value;
    }

    get borderTopLeftRadius(): Length {
        return this.style.borderTopLeftRadius;
    }
    set borderTopLeftRadius(value: Length) {
        this.style.borderTopLeftRadius = value;
    }

    get borderTopRightRadius(): Length {
        return this.style.borderTopRightRadius;
    }
    set borderTopRightRadius(value: Length) {
        this.style.borderTopRightRadius = value;
    }

    get borderBottomRightRadius(): Length {
        return this.style.borderBottomRightRadius;
    }
    set borderBottomRightRadius(value: Length) {
        this.style.borderBottomRightRadius = value;
    }

    get borderBottomLeftRadius(): Length {
        return this.style.borderBottomLeftRadius;
    }
    set borderBottomLeftRadius(value: Length) {
        this.style.borderBottomLeftRadius = value;
    }

    get color(): Color {
        return this.style.color;
    }
    set color(value: Color) {
        this.style.color = value;
    }

    get background(): string {
        return this.style.background;
    }
    set background(value: string) {
        this.style.background = value;
    }

    get backgroundColor(): Color {
        return this.style.backgroundColor;
    }
    set backgroundColor(value: Color) {
        this.style.backgroundColor = value;
    }

    get backgroundImage(): string | LinearGradient {
        return this.style.backgroundImage;
    }
    set backgroundImage(value: string | LinearGradient) {
        this.style.backgroundImage = value;
    }

    get backgroundSize(): string {
        return this.style.backgroundSize;
    }
    set backgroundSize(value: string) {
        this.style.backgroundSize = value;
    }

    get backgroundPosition(): string {
        return this.style.backgroundPosition;
    }
    set backgroundPosition(value: string) {
        this.style.backgroundPosition = value;
    }

    get backgroundRepeat(): BackgroundRepeat {
        return this.style.backgroundRepeat;
    }
    set backgroundRepeat(value: BackgroundRepeat) {
        this.style.backgroundRepeat = value;
    }

    get minWidth(): Length {
        return this.style.minWidth;
    }
    set minWidth(value: Length) {
        this.style.minWidth = value;
    }

    get minHeight(): Length {
        return this.style.minHeight;
    }
    set minHeight(value: Length) {
        this.style.minHeight = value;
    }

    get width(): PercentLength {
        return this.style.width;
    }
    set width(value: PercentLength) {
        this.style.width = value;
    }

    get height(): PercentLength {
        return this.style.height;
    }
    set height(value: PercentLength) {
        this.style.height = value;
    }

    get margin(): string | PercentLength {
        return this.style.margin;
    }
    set margin(value: string | PercentLength) {
        this.style.margin = value;
    }

    get marginLeft(): PercentLength {
        return this.style.marginLeft;
    }
    set marginLeft(value: PercentLength) {
        this.style.marginLeft = value;
    }

    get marginTop(): PercentLength {
        return this.style.marginTop;
    }
    set marginTop(value: PercentLength) {
        this.style.marginTop = value;
    }

    get marginRight(): PercentLength {
        return this.style.marginRight;
    }
    set marginRight(value: PercentLength) {
        this.style.marginRight = value;
    }

    get marginBottom(): PercentLength {
        return this.style.marginBottom;
    }
    set marginBottom(value: PercentLength) {
        this.style.marginBottom = value;
    }

    get horizontalAlignment(): HorizontalAlignment {
        return this.style.horizontalAlignment;
    }
    set horizontalAlignment(value: HorizontalAlignment) {
        this.style.horizontalAlignment = value;
    }

    get verticalAlignment(): VerticalAlignment {
        return this.style.verticalAlignment;
    }
    set verticalAlignment(value: VerticalAlignment) {
        this.style.verticalAlignment = value;
    }

    get visibility(): Visibility {
        return this.style.visibility;
    }
    set visibility(value: Visibility) {
        this.style.visibility = value;
    }

    get opacity(): number {
        return this.style.opacity;
    }
    set opacity(value: number) {
        this.style.opacity = value;
    }

    get rotate(): number {
        return this.style.rotate;
    }
    set rotate(value: number) {
        this.style.rotate = value;
    }

    get translateX(): dip {
        return this.style.translateX;
    }
    set translateX(value: dip) {
        this.style.translateX = value;
    }

    get translateY(): dip {
        return this.style.translateY;
    }
    set translateY(value: dip) {
        this.style.translateY = value;
    }

    get scaleX(): number {
        return this.style.scaleX;
    }
    set scaleX(value: number) {
        this.style.scaleX = value;
    }

    get scaleY(): number {
        return this.style.scaleY;
    }
    set scaleY(value: number) {
        this.style.scaleY = value;
    }

    get androidElevation(): number {
        return this.style.androidElevation;
    }
    set androidElevation(value: number) {
        this.style.androidElevation = value;
    }

    get androidDynamicElevationOffset(): number {
        return this.style.androidDynamicElevationOffset;
    }
    set androidDynamicElevationOffset(value: number) {
        this.style.androidDynamicElevationOffset = value;
    }

    //END Style property shortcuts

    public automationText: string;
    public originX: number;
    public originY: number;
    public isEnabled: boolean;
    public isUserInteractionEnabled: boolean;
    public iosOverflowSafeArea: boolean;
    public iosOverflowSafeAreaEnabled: boolean;

    get isLayoutValid(): boolean {
        return this._isLayoutValid;
    }

    get cssType(): string {
        if (!this._cssType) {
            this._cssType = this.typeName.toLowerCase();
        }

        return this._cssType;
    }
    set cssType(type: string) {
        this._cssType = type.toLowerCase();
    }

    get isLayoutRequired(): boolean {
        return true;
    }

    public measure(widthMeasureSpec: number, heightMeasureSpec: number): void {
        this._setCurrentMeasureSpecs(widthMeasureSpec, heightMeasureSpec);
    }

    public layout(left: number, top: number, right: number, bottom: number): void {
        this._setCurrentLayoutBounds(left, top, right, bottom);
    }

    public getMeasuredWidth(): number {
        return this._measuredWidth & layout.MEASURED_SIZE_MASK || 0;
    }

    public getMeasuredHeight(): number {
        return this._measuredHeight & layout.MEASURED_SIZE_MASK || 0;
    }

    public getMeasuredState(): number {
        return (this._measuredWidth & layout.MEASURED_STATE_MASK)
            | ((this._measuredHeight >> layout.MEASURED_HEIGHT_STATE_SHIFT)
                & (layout.MEASURED_STATE_MASK >> layout.MEASURED_HEIGHT_STATE_SHIFT));
    }

    public setMeasuredDimension(measuredWidth: number, measuredHeight: number): void {
        this._measuredWidth = measuredWidth;
        this._measuredHeight = measuredHeight;
        if (traceEnabled()) {
            traceWrite(this + " :setMeasuredDimension: " + measuredWidth + ", " + measuredHeight, traceCategories.Layout);
        }
    }

    public requestLayout(): void {
        this._isLayoutValid = false;
        super.requestLayout();
    }

    public abstract onMeasure(widthMeasureSpec: number, heightMeasureSpec: number): void;
    public abstract onLayout(left: number, top: number, right: number, bottom: number): void;
    public abstract layoutNativeView(left: number, top: number, right: number, bottom: number): void;

    public static resolveSizeAndState(size: number, specSize: number, specMode: number, childMeasuredState: number): number {
        let result = size;
        switch (specMode) {
            case layout.UNSPECIFIED:
                result = Math.ceil(size);
                break;

            case layout.AT_MOST:
                if (specSize < size) {
                    result = Math.ceil(specSize) | layout.MEASURED_STATE_TOO_SMALL;
                }
                break;

            case layout.EXACTLY:
                result = Math.ceil(specSize);
                break;
        }

        return result | (childMeasuredState & layout.MEASURED_STATE_MASK);
    }

    public static combineMeasuredStates(curState: number, newState): number {
        return curState | newState;
    }

    public static layoutChild(parent: ViewDefinition, child: ViewDefinition, left: number, top: number, right: number, bottom: number, setFrame: boolean = true): void {
        if (!child || child.isCollapsed) {
            return;
        }

        let childStyle = child.style;

        let childTop: number;
        let childLeft: number;

        let childWidth = child.getMeasuredWidth();
        let childHeight = child.getMeasuredHeight();

        let effectiveMarginTop = child.effectiveMarginTop;
        let effectiveMarginBottom = child.effectiveMarginBottom;

        let vAlignment: VerticalAlignment;
        if (child.effectiveHeight >= 0 && childStyle.verticalAlignment === "stretch") {
            vAlignment = "middle";
        }
        else {
            vAlignment = childStyle.verticalAlignment;
        }

        switch (vAlignment) {
            case "top":
                childTop = top + effectiveMarginTop;
                break;

            case "middle":
                childTop = top + (bottom - top - childHeight + (effectiveMarginTop - effectiveMarginBottom)) / 2;
                break;

            case "bottom":
                childTop = bottom - childHeight - effectiveMarginBottom;
                break;

            case "stretch":
            default:
                childTop = top + effectiveMarginTop;
                childHeight = bottom - top - (effectiveMarginTop + effectiveMarginBottom);
                break;
        }

        let effectiveMarginLeft = child.effectiveMarginLeft;
        let effectiveMarginRight = child.effectiveMarginRight;

        let hAlignment: HorizontalAlignment;
        if (child.effectiveWidth >= 0 && childStyle.horizontalAlignment === "stretch") {
            hAlignment = "center";
        }
        else {
            hAlignment = childStyle.horizontalAlignment;
        }

        switch (hAlignment) {
            case "left":
                childLeft = left + effectiveMarginLeft;
                break;

            case "center":
                childLeft = left + (right - left - childWidth + (effectiveMarginLeft - effectiveMarginRight)) / 2;
                break;

            case "right":
                childLeft = right - childWidth - effectiveMarginRight;
                break;

            case "stretch":
            default:
                childLeft = left + effectiveMarginLeft;
                childWidth = right - left - (effectiveMarginLeft + effectiveMarginRight);
                break;
        }

        let childRight = Math.round(childLeft + childWidth);
        let childBottom = Math.round(childTop + childHeight);
        childLeft = Math.round(childLeft);
        childTop = Math.round(childTop);

        if (traceEnabled()) {
            traceWrite(child.parent + " :layoutChild: " + child + " " + childLeft + ", " + childTop + ", " + childRight + ", " + childBottom, traceCategories.Layout);
        }

        child.layout(childLeft, childTop, childRight, childBottom, setFrame);
    }

    public static measureChild(parent: ViewCommon, child: ViewCommon, widthMeasureSpec: number, heightMeasureSpec: number): { measuredWidth: number; measuredHeight: number } {
        let measureWidth = 0;
        let measureHeight = 0;

        if (child && !child.isCollapsed) {

            const widthSpec = parent ? parent._currentWidthMeasureSpec : widthMeasureSpec;
            const heightSpec = parent ? parent._currentHeightMeasureSpec : heightMeasureSpec;

            const width = layout.getMeasureSpecSize(widthSpec);
            const widthMode = layout.getMeasureSpecMode(widthSpec);

            const height = layout.getMeasureSpecSize(heightSpec);
            const heightMode = layout.getMeasureSpecMode(heightSpec);

            child._updateEffectiveLayoutValues(width, widthMode, height, heightMode);

            const style = child.style;
            const horizontalMargins = child.effectiveMarginLeft + child.effectiveMarginRight;
            const verticalMargins = child.effectiveMarginTop + child.effectiveMarginBottom;

            const childWidthMeasureSpec = ViewCommon.getMeasureSpec(widthMeasureSpec, horizontalMargins, child.effectiveWidth, style.horizontalAlignment === "stretch");
            const childHeightMeasureSpec = ViewCommon.getMeasureSpec(heightMeasureSpec, verticalMargins, child.effectiveHeight, style.verticalAlignment === "stretch");

            if (traceEnabled()) {
                traceWrite(`${child.parent} :measureChild: ${child} ${layout.measureSpecToString(childWidthMeasureSpec)}, ${layout.measureSpecToString(childHeightMeasureSpec)}}`, traceCategories.Layout);
            }

            child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
            measureWidth = Math.round(child.getMeasuredWidth() + horizontalMargins);
            measureHeight = Math.round(child.getMeasuredHeight() + verticalMargins);
        }

        return { measuredWidth: measureWidth, measuredHeight: measureHeight };
    }

    private static getMeasureSpec(parentSpec: number, margins: number, childLength: number, stretched: boolean): number {
        const parentLength = layout.getMeasureSpecSize(parentSpec);
        const parentSpecMode = layout.getMeasureSpecMode(parentSpec);

        let resultSize: number;
        let resultMode: number;

        // We want a specific size... let be it.
        if (childLength >= 0) {
            // If mode !== UNSPECIFIED we take the smaller of parentLength and childLength
            // Otherwise we will need to clip the view but this is not possible in all Android API levels.
            // TODO: remove Math.min(parentLength, childLength)
            resultSize = parentSpecMode === layout.UNSPECIFIED ? childLength : Math.min(parentLength, childLength);
            resultMode = layout.EXACTLY;
        }
        else {
            switch (parentSpecMode) {
                // Parent has imposed an exact size on us
                case layout.EXACTLY:
                    resultSize = Math.max(0, parentLength - margins);
                    // if stretched - nativeView wants to be our size. So be it.
                    // else - nativeView wants to determine its own size. It can't be bigger than us.
                    resultMode = stretched ? layout.EXACTLY : layout.AT_MOST;
                    break;

                // Parent has imposed a maximum size on us
                case layout.AT_MOST:
                    resultSize = Math.max(0, parentLength - margins);
                    resultMode = layout.AT_MOST;
                    break;

                // Equivalent to measure with Infinity.
                case layout.UNSPECIFIED:
                    resultSize = 0;
                    resultMode = layout.UNSPECIFIED;
                    break;
            }
        }

        return layout.makeMeasureSpec(resultSize, resultMode);
    }

    _setCurrentMeasureSpecs(widthMeasureSpec: number, heightMeasureSpec: number): boolean {
        let changed: boolean = this._currentWidthMeasureSpec !== widthMeasureSpec || this._currentHeightMeasureSpec !== heightMeasureSpec;
        this._currentWidthMeasureSpec = widthMeasureSpec;
        this._currentHeightMeasureSpec = heightMeasureSpec;

        return changed;
    }

    _getCurrentLayoutBounds(): { left: number; top: number; right: number; bottom: number } {
        return { left: 0, top: 0, right: 0, bottom: 0 };
    }

    /**
     * Returns two booleans - the first if "boundsChanged" the second is "sizeChanged".
     */
    _setCurrentLayoutBounds(left: number, top: number, right: number, bottom: number): { boundsChanged: boolean, sizeChanged: boolean } {
        this._isLayoutValid = true;
        let boundsChanged: boolean = this._oldLeft !== left || this._oldTop !== top || this._oldRight !== right || this._oldBottom !== bottom;
        let sizeChanged: boolean = (this._oldRight - this._oldLeft !== right - left) || (this._oldBottom - this._oldTop !== bottom - top);
        this._oldLeft = left;
        this._oldTop = top;
        this._oldRight = right;
        this._oldBottom = bottom;

        return { boundsChanged, sizeChanged };
    }

    public eachChild(callback: (child: ViewBase) => boolean): void {
        this.eachChildView(<any>callback);
    }

    public eachChildView(callback: (view: ViewDefinition) => boolean) {
        //
    }

    _getNativeViewsCount(): number {
        return this._isAddedToNativeVisualTree ? 1 : 0;
    }

    _eachLayoutView(callback: (View) => void): void {
        return callback(this);
    }

    public focus(): boolean {
        return undefined;
    }

    public getSafeAreaInsets(): { left, top, right, bottom } {
        return { left: 0, top: 0, right: 0, bottom: 0 };
    }

    public getLocationInWindow(): Point {
        return undefined;
    }

    public getLocationOnScreen(): Point {
        return undefined;
    }

    public getLocationRelativeTo(otherView: ViewDefinition): Point {
        return undefined;
    }

    public getActualSize(): Size {
        let currentBounds = this._getCurrentLayoutBounds();
        if (!currentBounds) {
            return undefined;
        }

        return {
            width: layout.toDeviceIndependentPixels(currentBounds.right - currentBounds.left),
            height: layout.toDeviceIndependentPixels(currentBounds.bottom - currentBounds.top),
        };
    }

    public animate(animation: any): am.AnimationPromise {
        return this.createAnimation(animation).play();
    }

    public createAnimation(animation: any): am.Animation {
        ensureAnimationModule();
        if (!this._localAnimations) {
            this._localAnimations = new Set();
        }
        animation.target = this;
        const anim = new animationModule.Animation([animation]);
        this._localAnimations.add(anim);

        return anim;
    }

    public _removeAnimation(animation: am.Animation): boolean {
        const localAnimations = this._localAnimations;
        if (localAnimations && localAnimations.has(animation)) {
            localAnimations.delete(animation);
            if (animation.isPlaying) {
                animation.cancel();
            }

            return true;
        }

        return false;
    }

    public resetNativeView(): void {
        if (this._localAnimations) {
            this._localAnimations.forEach(a => this._removeAnimation(a));
        }

        super.resetNativeView();
    }

    public _setNativeViewFrame(nativeView: any, frame: any) {
        //
    }

    public _getValue(): never {
        throw new Error("The View._getValue is obsolete. There is a new property system.");
    }

    public _setValue(): never {
        throw new Error("The View._setValue is obsolete. There is a new property system.");
    }

    _updateEffectiveLayoutValues(
        parentWidthMeasureSize: number,
        parentWidthMeasureMode: number,
        parentHeightMeasureSize: number,
        parentHeightMeasureMode: number): void {
        const style = this.style;

        const availableWidth = parentWidthMeasureMode === layout.UNSPECIFIED ? -1 : parentWidthMeasureSize;

        this.effectiveWidth = PercentLength.toDevicePixels(style.width, -2, availableWidth);
        this.effectiveMarginLeft = PercentLength.toDevicePixels(style.marginLeft, 0, availableWidth);
        this.effectiveMarginRight = PercentLength.toDevicePixels(style.marginRight, 0, availableWidth);

        const availableHeight = parentHeightMeasureMode === layout.UNSPECIFIED ? -1 : parentHeightMeasureSize;

        this.effectiveHeight = PercentLength.toDevicePixels(style.height, -2, availableHeight);
        this.effectiveMarginTop = PercentLength.toDevicePixels(style.marginTop, 0, availableHeight);
        this.effectiveMarginBottom = PercentLength.toDevicePixels(style.marginBottom, 0, availableHeight);
    }

    public _setNativeClipToBounds() {
        //
    }

    public _redrawNativeBackground(value: any): void {
        //
    }

    _onAttachedToWindow(): void {
        //
    }

    _onDetachedFromWindow(): void {
        //
    }

    _hasAncestorView(ancestorView: ViewDefinition): boolean {
        let matcher = (view: ViewDefinition) => view === ancestorView;

        for (let parent = this.parent; parent != null; parent = parent.parent) {
            if (matcher(<ViewDefinition>parent)) {
                return true;
            }
        }

        return false;
    }
}

export const automationTextProperty = new Property<ViewCommon, string>({ name: "automationText" });
automationTextProperty.register(ViewCommon);

export const originXProperty = new Property<ViewCommon, number>({ name: "originX", defaultValue: 0.5, valueConverter: (v) => parseFloat(v) });
originXProperty.register(ViewCommon);

export const originYProperty = new Property<ViewCommon, number>({ name: "originY", defaultValue: 0.5, valueConverter: (v) => parseFloat(v) });
originYProperty.register(ViewCommon);

export const isEnabledProperty = new Property<ViewCommon, boolean>({
    name: "isEnabled",
    defaultValue: true,
    valueConverter: booleanConverter,
    valueChanged(this: void, target, oldValue, newValue): void {
        target._goToVisualState(newValue ? "normal" : "disabled");
    }
});
isEnabledProperty.register(ViewCommon);

export const isUserInteractionEnabledProperty = new Property<ViewCommon, boolean>({ name: "isUserInteractionEnabled", defaultValue: true, valueConverter: booleanConverter });
isUserInteractionEnabledProperty.register(ViewCommon);

export const iosOverflowSafeAreaProperty = new Property<ViewCommon, boolean>({ name: "iosOverflowSafeArea", defaultValue: false, valueConverter: booleanConverter });
iosOverflowSafeAreaProperty.register(ViewCommon);

export const iosOverflowSafeAreaEnabledProperty = new InheritedProperty<ViewCommon, boolean>({ name: "iosOverflowSafeAreaEnabled", defaultValue: true, valueConverter: booleanConverter });
iosOverflowSafeAreaEnabledProperty.register(ViewCommon);