NativeScript/tns-core-modules/ui/list-picker/list-picker.android.ts

import { ListPickerBase, selectedIndexProperty, itemsProperty, colorProperty, Color } from "./list-picker-common";
import { ItemsSource } from "ui/list-picker";

export * from "./list-picker-common";

@Interfaces([android.widget.NumberPicker.Formatter])
class Formatter extends java.lang.Object implements android.widget.NumberPicker.Formatter {
    constructor(private owner: WeakRef<ListPicker>) {
        super();
        return global.__native(this);
    }

    format(index: number): string {
        let owner = this.owner.get();
        if (owner) {
            return owner._getItemAsString(index);
        }

        return " ";
    }
}

@Interfaces([android.widget.NumberPicker.OnValueChangeListener])
class ValueChangeListener extends java.lang.Object implements android.widget.NumberPicker.OnValueChangeListener {
    constructor(private owner: WeakRef<ListPicker>) {
        super();
        return global.__native(this);
    }

    onValueChange(picker: android.widget.NumberPicker, oldValue: number, newValue: number): void {
        let owner = this.owner.get();
        if (owner) {
            selectedIndexProperty.nativeValueChange(owner, newValue);
        }
    }
}

function getEditText(picker: android.widget.NumberPicker): android.widget.EditText {
    for (let i = 0, count = picker.getChildCount(); i < count; i++) {
        let child = picker.getChildAt(i);
        if (child instanceof android.widget.EditText) {
            return child;
        }
    }

    return null;
}

let selectorWheelPaintField: java.lang.reflect.Field;
function getSelectorWheelPaint(picker: android.widget.NumberPicker): android.graphics.Paint {
    if (!selectorWheelPaintField) {
        selectorWheelPaintField = picker.getClass().getDeclaredField("mSelectorWheelPaint");
        selectorWheelPaintField.setAccessible(true);
    }

    return selectorWheelPaintField.get(picker);
}

export class ListPicker extends ListPickerBase {
    private _android: android.widget.NumberPicker;
    private _valueChangedListener: android.widget.NumberPicker.OnValueChangeListener;
    private _formatter: android.widget.NumberPicker.Formatter;
    private _editText: android.widget.EditText;
    private _selectorWheelPaint: android.graphics.Paint;

    get android(): android.widget.NumberPicker {
        return this._android;
    }

    public _createNativeView() {
        this._android = new android.widget.NumberPicker(this._context);
        let editText = getEditText(this._android);
        this._editText = editText;
        this._selectorWheelPaint = getSelectorWheelPaint(this._android);

        this._android.setDescendantFocusability(android.widget.NumberPicker.FOCUS_BLOCK_DESCENDANTS);

        this._android.setMinValue(0);
        this._android.setMaxValue(0);
        this._android.setValue(0);

        this._formatter = this._formatter || new Formatter(new WeakRef(this));
        this._android.setFormatter(this._formatter);

        this._valueChangedListener = this._valueChangedListener || new ValueChangeListener(new WeakRef(this));
        this._android.setOnValueChangedListener(this._valueChangedListener);

        if (editText) {
            //Fix the disappearing selected item.
            //HACK: http://stackoverflow.com/questions/17708325/android-numberpicker-with-formatter-does-not-format-on-first-rendering/26797732
            editText.setFilters([]);

            //Since the Android NumberPicker has to always have at least one item, i.e. minValue=maxValue=value=0, we don't want this zero showing up when this.items is empty.
            editText.setText(" ", android.widget.TextView.BufferType.NORMAL);
        }

        this._android.setWrapSelectorWheel(false);
        this.nativeView = this._android;
    }

    private _fixNumberPickerRendering() {
        //HACK: Force the stubborn NumberPicker to render correctly when we have 0 or 1 items.
        this._android.setFormatter(null);
        this._android.setFormatter(this._formatter); //Force the NumberPicker to call our Formatter 
        if (this._editText) {
            this._editText.setFilters([]);
            this._editText.invalidate(); //Force the EditText to redraw
        }
        this.android.invalidate();
    }

    get [selectedIndexProperty.native](): number {
        return -1;
    }
    set [selectedIndexProperty.native](value: number) {
        if (value >= 0) {
            this.android.setValue(value);
        }
    }

    get [itemsProperty.native](): any[] {
        return null;
    }
    set [itemsProperty.native](value: any[] | ItemsSource) {
        let maxValue = value && value.length > 0 ? value.length - 1 : 0;
        this.android.setMaxValue(maxValue);
        this._fixNumberPickerRendering();
    }

    get [colorProperty.native](): { wheelColor: number, textColor: number } {
        return {
            wheelColor: this._selectorWheelPaint.getColor(),
            textColor: this._editText ? this._editText.getTextColors().getDefaultColor() : -1
        }
    }

    set [colorProperty.native](value: { wheelColor: number, textColor: number } | Color) {
        let color: number;
        let wheelColor: number;
        if (value instanceof Color) {
            color = wheelColor = value.android;
        } else {
            color = value.textColor;
            wheelColor = value.wheelColor;
        }

        this._selectorWheelPaint.setColor(wheelColor);
        if (this._editText) {
            this._editText.setTextColor(color);
        }
    }
}