image-swipe-common.ts

/*! *****************************************************************************
Copyright (c) 2019 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 { ObservableArray } from "data/observable-array";
import { CSSType, CoercibleProperty, Property } from "ui/core/view";
import { addWeakEventListener, removeWeakEventListener } from "ui/core/weak-event-listener";
import { Cache } from "ui/image-cache";
import { ItemsSource } from "ui/list-picker";
import { ScrollView } from "ui/scroll-view";

import { ImageSwipe as ImageSwipeDefinition } from ".";

export * from "ui/scroll-view";

@CSSType("ImageSwipe")
export abstract class ImageSwipeBase extends ScrollView implements ImageSwipeDefinition {
    public static pageChangedEvent: string = "pageChanged";

    public static _imageCache: Cache;

    public items: any[] | ItemsSource;
    public pageNumber: number;
    public imageUrlProperty: string;
    public isItemsSourceIn: boolean;
    public allowZoom: boolean;

    constructor() {
        super();
        if (!ImageSwipeBase._imageCache) {
            ImageSwipeBase._imageCache = new Cache();
            ImageSwipeBase._imageCache.maxRequests = 3;
        }    
    }

    public _getDataItem(index: number): any {
        return this.isItemsSourceIn ? (this.items as ItemsSource).getItem(index) : this.items[index];
    }

    public abstract refresh(): void;
}

export const pageNumberProperty = new CoercibleProperty<ImageSwipeBase, number>({
    name: "pageNumber",
    defaultValue: 0,
    valueConverter: (v) => 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;
    }
});
pageNumberProperty.register(ImageSwipeBase);

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

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

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

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

        target.refresh();
    }
});
itemsProperty.register(ImageSwipeBase);

export const imageUrlPropertyProperty = new Property<ImageSwipeBase, string>({
    name: "imageUrlProperty",
    defaultValue: ""
});
imageUrlPropertyProperty.register(ImageSwipeBase);

export const allowZoomProperty = new Property<ImageSwipeBase, boolean>({
    name: "allowZoom",
    defaultValue: true
});
allowZoomProperty.register(ImageSwipeBase);