drop-down-common.ts

/*! *****************************************************************************
Copyright (c) 2018 Tangra Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***************************************************************************** */
import {
  CSSType,
  CoercibleProperty,
  EventData,
  ItemsSource,
  ObservableArray,
  Property,
  Utils,
  View,
  addWeakEventListener,
  makeParser,
  makeValidator,
  removeWeakEventListener
} from "@nativescript/core";
import { TextAlignment } from "@nativescript/core/ui/text-base";
import { DropDown as DropDownDefinition, SelectedIndexChangedEventData, ValueItem, ValueList as ValueListDefinition } from ".";
export {
  Length,
  Utils,
  backgroundColorProperty,
  colorProperty,
  fontInternalProperty,
  paddingBottomProperty,
  paddingLeftProperty,
  paddingRightProperty,
  paddingTopProperty
} from "@nativescript/core";

@CSSType("DropDown")
export abstract class DropDownBase extends View implements DropDownDefinition {
    public static openedEvent = "opened";
    public static closedEvent = "closed";
    public static selectedIndexChangedEvent = "selectedIndexChanged";

    public hint: string;
    public itemsTextAlignment: TextAlignment;
    public itemsPadding: string;
    public selectedIndex: number;
    public items: any[] | ItemsSource;
    public accessoryViewVisible: boolean;
    public isItemsSourceIn: boolean;
    public isValueListIn: boolean;

    public abstract open();
    public abstract close();
    public abstract refresh();

    public _getItemAsString(index: number) {
        const items = this.items;

        if (!items) {
            return " ";
        }

        if (Utils.isNullOrUndefined(index)) {
            return null;
        }

        if (this.isValueListIn) {
            return (items as ValueList<any>).getDisplay(index);
        }

        const item = this.isItemsSourceIn ? (this.items as ItemsSource).getItem(index) : this.items[index];
        return (item === undefined || item === null) ? index + "" : item + "";
    }
}

export interface DropDownBase {
    on(eventNames: string, callback: (data: EventData) => void, thisArg?: any);
    on(event: "selectedIndexChanged", callback: (args: SelectedIndexChangedEventData) => void, thisArg?: any);
}

// @ts-ignore
export class ValueList<T> extends ObservableArray<ValueItem<T>> implements ValueListDefinition<T> {
    private _array: Array<ValueItem<T>>;

    public getDisplay(index: number): string {
        if (Utils.isNullOrUndefined(index)) {
            return null;
        }

        if (index < 0 || index >= this.length) {
            return "";
        }

        return this._array[index].display;
    }

    public getValue(index: number): T {
        if (Utils.isNullOrUndefined(index) || index < 0 || index >= this.length) {
            return null;
        }

        return this._array[index].value;
    }

    public getIndex(value: T): number {
        let loop: number;

        for (loop = 0; loop < this.length; loop++) {
            if (this.getValue(loop) === value) {
                return loop;
            }
        }

        return null;
    }
}

export const selectedIndexProperty = new CoercibleProperty<DropDownBase, number>({
    name: "selectedIndex",
    defaultValue: null,
    valueConverter: (v) => {
        if (v === undefined || v === null) {
            return null;
        }

        return parseInt(v, 10);
    },
    coerceValue: (target, value) => {
        const items = target.items;
        if (items && items.length !== 0) {
            const max = items.length - 1;
            if (value < 0) {
                value = 0;
            }
            if (value > max) {
                value = max;
            }
        }
        else {
            value = null;
        }

        return value;
    }
});
selectedIndexProperty.register(DropDownBase);

export const itemsProperty = new Property<DropDownBase, any[] | ItemsSource>({
    name: "items",
    valueChanged: (target, oldValue, newValue) => {
        const getItem = newValue && (newValue as ItemsSource).getItem;
        const getDisplay = newValue && (newValue as ValueList<any>).getDisplay;

        target.isItemsSourceIn = typeof getItem === "function";
        target.isValueListIn = typeof getDisplay === "function";

        if (oldValue instanceof ObservableArray) {
            removeWeakEventListener(oldValue, ObservableArray.changeEvent, target.refresh, target);
        }

        if (newValue instanceof ObservableArray) {
            addWeakEventListener(newValue, ObservableArray.changeEvent, target.refresh, target);
        }
    }
});
itemsProperty.register(DropDownBase);

export const hintProperty = new Property<DropDownBase, string>({
    name: "hint",
    defaultValue: ""
});
hintProperty.register(DropDownBase);

const textAlignmentConverter = makeParser<TextAlignment>(makeValidator<TextAlignment>("initial", "left", "center", "right"));
export const itemsTextAlignmentProperty = new Property<DropDownBase, TextAlignment>({ 
    name: "itemsTextAlignment", 
    defaultValue: "initial", 
    valueConverter: textAlignmentConverter 
});
itemsTextAlignmentProperty.register(DropDownBase);

export const itemsPaddingProperty = new Property<DropDownBase, string>({
    name: "itemsPadding",
    defaultValue: ""
});
itemsPaddingProperty.register(DropDownBase);