terriajs/lib/Models/NowViewing.js

Geospatial data visualization platform.

'use strict';

/*global require*/
var CesiumEvent = require('terriajs-cesium/Source/Core/Event');
var defaultValue = require('terriajs-cesium/Source/Core/defaultValue');
var defined = require('terriajs-cesium/Source/Core/defined');
var defineProperties = require('terriajs-cesium/Source/Core/defineProperties');
var DeveloperError = require('terriajs-cesium/Source/Core/DeveloperError');
var EventHelper = require('terriajs-cesium/Source/Core/EventHelper');
var knockout = require('terriajs-cesium/Source/ThirdParty/knockout');
var raiseErrorToUser = require('./raiseErrorToUser');

/**
 * The model for the "Now Viewing" pane.
 */
var NowViewing = function(terria) {
    this._terria = terria;
    this._eventSubscriptions = new EventHelper();

    /**
     * Gets the list of items that we are "now viewing".  It is recommended that you use
     * the methods on this instance instead of manipulating the list of items directly.
     * This property is observable.
     * @type {CatalogItem[]}
     */
    this.items = [];

    knockout.track(this, ['items']);

    this.showNowViewingRequested = new CesiumEvent();

    this._eventSubscriptions.add( this.terria.beforeViewerChanged, function() {
        beforeViewerChanged(this);
    }, this);

    this._eventSubscriptions.add( this.terria.afterViewerChanged, function() {
        afterViewerChanged(this);
    }, this);
};

defineProperties(NowViewing.prototype, {
    /**
      * Gets the Terria instance.
     * @memberOf NowViewing.prototype
     * @type  {Terria}
     */
    terria : {
        get : function() {
            return this._terria;
        }
    },

    /**
     * Gets a value indicating whether the "Now Viewing" pane has one or more items.
     * @memberOf NowViewing.prototype
     * @type {Boolean}
     */
    hasItems : {
        get : function() {
            return this.items.length > 0;
        }
    },

    /**
     * Gets a value indicating whether the "Now Viewing" pane has at list own data
     * source that is currently shown.
     * @memberOf NowViewing.prototype
     * @type {Boolean}
     */
    hasShownItems : {
        get : function() {
            for (var i = 0; i < this.items.length; ++i) {
                if (this.items[i].isShown) {
                    return true;
                }
            }
            return false;
        }
    },

    hasChildren : {
        get : function() {
            return this.items.length > 0;
        }
    },

});

/**
 * Destroys this instance, including unsubscribing it from any events.
 */
NowViewing.prototype.destroy = function() {
    this._eventSubscriptions.removeAll();
};

/**
 * Adds an item to the "Now Viewing" pane.
 *
 * @param {CatalogMember} item The item to add.
 */
NowViewing.prototype.add = function(item, index) {
    index = defaultValue(index, 0);

    // Keep reorderable data sources (e.g.: imagery layers) below non-orderable ones (e.g.: GeoJSON).
    if (item.supportsReordering) {
        while (index < this.items.length && !this.items[index].supportsReordering) {
            ++index;
        }
    } else {
        while (index > 0 && this.items.length > 0 && this.items[index - 1].supportsReordering) {
            --index;
        }
    }

    if (!item.keepOnTop) {
        while (index < this.items.length && this.items[index].keepOnTop && this.items[index].supportsReordering === item.supportsReordering) {
            ++index;
        }
    } else {
        while (index > 0 && this.items.length > 0 && this.items[index - 1].keepOnTop && this.items[index - 1] === item.supportsReordering) {
            --index;
        }
    }

    this.items.splice(index, 0, item);
};

/**
 * Removes an item from the "Now Viewing" pane and from the map.
 *
 * @param {CatalogMember} item The item to remove.
 */
NowViewing.prototype.remove = function(item) {
    item.isEnabled = false;
    this.items.remove(item);
};

/**
 * Removes all data sources from the "Now Viewing" pane and from the map.
 */
NowViewing.prototype.removeAll = function() {
    // Work backwards through the list of items because setting isEnabled=false
    // will usually remove the item from the list.
    for (var i = this.items.length - 1; i >= 0; --i) {
        this.items[i].isEnabled = false;
    }

    this.items.removeAll();
};

/**
 * Raises an item, making it displayed on top of the item that is currently above it.  If it
 * is nonsensical to move this item up (e.g. it is already at the top), this method does nothing.
 *
 * @param {CatalogMember} item The item to raise.
 * @param {Number} [index] The index of the item of the list, if it is already known.
 */
NowViewing.prototype.raise = function(item, index) {
    if (defined(index)) {
        if (this.items[index] !== item) {
            throw new DeveloperError('The provided index is not correct.');
        }
    } else {
        index = this.items.indexOf(item);
        if (index < 0) {
            return;
        }
    }

    if (index === 0) {
        return;
    }

    // Don't allow reorderable data sources to move above non-reorderable ones.
    if (item.supportsReordering && !this.items[index - 1].supportsReordering) {
        return;
    }

    var terria =  this.terria;

    terria.currentViewer.raise(index);

    this.items.splice(index, 1);
    this.items.splice(index - 1, 0, item);

    terria.currentViewer.updateLayerOrderAfterReorder();

    terria.currentViewer.notifyRepaintRequired();
};

/**
 * Lowers an item, making it displayed below the item that is currently below it.  If it
 * is nonsensical to move this item down (e.g. it is already at the bottom), this method does nothing.
 *
 * @param {CatalogMember} item The item to lower.
 * @param {Number} [index] The index of the item of the list, if it is already known.
 */
NowViewing.prototype.lower = function(item, index) {
    if (defined(index)) {
        if (this.items[index] !== item) {
            throw new DeveloperError('The provided index is not correct.');
        }
    } else {
        index = this.items.indexOf(item);
        if (index < 0) {
            return;
        }
    }

    if (index === this.items.length - 1) {
        return;
    }

    var itemBelow = this.items[index + 1];

    // Don't allow non-reorderable data sources to move below reorderable ones.
    if (!item.supportsReordering && itemBelow.supportsReordering) {
        return;
    }

    var terria =  this.terria;

    terria.currentViewer.lower(index);

    this.items.splice(index, 1);
    this.items.splice(index + 1, 0, item);

    terria.currentViewer.updateLayerOrderAfterReorder();

    terria.currentViewer.notifyRepaintRequired();
};

/**
 * Toggles the {@link NowViewing#isOpen} flag.  If it's open, it is closed.  If it's closed, it is opened.
 */
NowViewing.prototype.toggleOpen = function() {
    this.isOpen = !this.isOpen;
};

/**
 * Records the the index of each data source in the Now Viewing list in a {@link CatalogItem#nowViewingIndex} property
 * on the data source.  This is used to save the state of the Now Viewing list and is not intended for general
 * use.
 * @private
 */
NowViewing.prototype.recordNowViewingIndices = function() {
    for (var i = 0; i < this.items.length; ++i) {
        this.items[i].nowViewingIndex = i;
    }
};

/**
 * Sorts the data sources in the Now Viewing list by their {@link CatalogItem#nowViewingIndex} properties.  This is used
 * to restore the state of the Now Viewing list and is not intended for general use.
 * @private
 */
NowViewing.prototype.sortByNowViewingIndices = function() {
    var sortedItems = this.items.slice();
    sortedItems.sort(function(a, b) {
        return a.nowViewingIndex - b.nowViewingIndex;
    });

    for (var i = 0; i < sortedItems.length; ++i) {
        var item = sortedItems[i];
        var existingIndex = this.items.indexOf(item);
        var lastIndex;
        // Check if raise didn't succeed (ie. item's index didn't change), and quit the loop if so.
        while (existingIndex > i && existingIndex !== lastIndex) {
            lastIndex = existingIndex;
            this.raise(item, lastIndex);
            existingIndex = this.items.indexOf(item);
        }
    }

    if (defined( this.terria.currentViewer)) {
         this.terria.currentViewer.notifyRepaintRequired();
    }
};

function beforeViewerChanged(nowViewing) {
    // Hide and disable all data sources, without actually changing
    // their isEnabled and isShown flags.

    var dataSources = nowViewing.items;

    for (var i = 0; i < dataSources.length; ++i) {
        var dataSource = dataSources[i];
        if (defined(dataSource._loadForEnablePromise)) {
            continue;
        }

        if (dataSource.isShown) {
            dataSource._hide();
        }

        if (dataSource.isEnabled) {
            dataSource._disable();
        }
    }
}

function afterViewerChanged(nowViewing) {
    // Re-enable and re-show all data sources that were previously enabled or shown.
    // Work from the bottom data source up so that the correct order is created.

    var dataSources = nowViewing.items;

    for (var i = dataSources.length - 1; i >= 0; --i) {
        var dataSource = dataSources[i];
        if (defined(dataSource._loadForEnablePromise)) {
            continue;
        }

        if (dataSource.isEnabled) {
            try {
                dataSource._enable();
            } catch(e) {
                raiseErrorToUser(nowViewing.terria, e);
            }
            //Re-enable attribution
            nowViewing.terria.currentViewer.addAttribution(dataSource.attribution);
        }

        if (dataSource.isShown) {
            try {
                dataSource._show();
            } catch(e) {
                raiseErrorToUser(nowViewing.terria, e);
            }
        }
    }
}

module.exports = NowViewing;