all files / src/src/mixins/ DraggableElement.js

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/**
 * DraggableElement is a mixin class used to create elements that can be clicked
 * and dragged by a mouse to a new position within a group. This class must be used
 * in conjunction with OO.ui.mixin.DraggableGroupElement, which provides a container for
 * the draggable elements.
 *
 * @abstract
 * @class
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {jQuery} [$handle] The part of the element which can be used for dragging, defaults to
 *  the whole element
 * @cfg {boolean} [draggable] The items are draggable. This can change with #toggleDraggable
 *  but the draggable state should be called from the DraggableGroupElement, which updates
 *  the whole group
 */
OO.ui.mixin.DraggableElement = function OoUiMixinDraggableElement( config ) {
	config = config || {};
 
	// Properties
	this.index = null;
	this.$handle = config.$handle || this.$element;
	this.wasHandleUsed = null;
 
	// Initialize and events
	this.$element
		.addClass( 'oo-ui-draggableElement' )
		.on( {
			mousedown: this.onDragMouseDown.bind( this ),
			dragstart: this.onDragStart.bind( this ),
			dragover: this.onDragOver.bind( this ),
			dragend: this.onDragEnd.bind( this ),
			drop: this.onDrop.bind( this )
		} );
	this.$handle.addClass( 'oo-ui-draggableElement-handle' );
	this.toggleDraggable( config.draggable === undefined ? true : !!config.draggable );
};
 
OO.initClass( OO.ui.mixin.DraggableElement );
 
/* Events */
 
/**
 * @event dragstart
 *
 * A dragstart event is emitted when the user clicks and begins dragging an item.
 * @param {OO.ui.mixin.DraggableElement} item The item the user has clicked and is dragging with
 *  the mouse.
 */
 
/**
 * @event dragend
 * A dragend event is emitted when the user drags an item and releases the mouse,
 * thus terminating the drag operation.
 */
 
/**
 * @event drop
 * A drop event is emitted when the user drags an item and then releases the mouse button
 * over a valid target.
 */
 
/* Static Properties */
 
/**
 * @inheritdoc OO.ui.mixin.ButtonElement
 */
OO.ui.mixin.DraggableElement.static.cancelButtonMouseDownEvents = false;
 
/* Methods */
 
/**
 * Change the draggable state of this widget.
 * This allows users to temporarily halt the dragging operations.
 *
 * @param {boolean} isDraggable Widget supports draggable operations
 * @fires draggable
 */
OO.ui.mixin.DraggableElement.prototype.toggleDraggable = function ( isDraggable ) {
	isDraggable = isDraggable !== undefined ? !!isDraggable : !this.draggable;
 
	Eif ( this.draggable !== isDraggable ) {
		this.draggable = isDraggable;
 
		this.$handle.toggleClass( 'oo-ui-draggableElement-undraggable', !this.draggable );
 
		// We make the entire element draggable, not just the handle, so that
		// the whole element appears to move. wasHandleUsed prevents drags from
		// starting outside the handle
		this.$element.prop( 'draggable', this.draggable );
	}
};
 
/**
 * Check the draggable state of this widget.
 *
 * @return {boolean} Widget supports draggable operations
 */
OO.ui.mixin.DraggableElement.prototype.isDraggable = function () {
	return this.draggable;
};
 
/**
 * Respond to mousedown event.
 *
 * @private
 * @param {jQuery.Event} e Drag event
 */
OO.ui.mixin.DraggableElement.prototype.onDragMouseDown = function ( e ) {
	if ( !this.isDraggable() ) {
		return;
	}
 
	this.wasHandleUsed =
		// Optimization: if the handle is the whole element this is always true
		this.$handle[ 0 ] === this.$element[ 0 ] ||
		// Check the mousedown occurred inside the handle
		OO.ui.contains( this.$handle[ 0 ], e.target, true );
};
 
/**
 * Respond to dragstart event.
 *
 * @private
 * @param {jQuery.Event} e Drag event
 * @return {boolean} False if the event is cancelled
 * @fires dragstart
 */
OO.ui.mixin.DraggableElement.prototype.onDragStart = function ( e ) {
	var element = this,
		dataTransfer = e.originalEvent.dataTransfer;
 
	if ( !this.wasHandleUsed || !this.isDraggable() ) {
		return false;
	}
 
	// Define drop effect
	dataTransfer.dropEffect = 'none';
	dataTransfer.effectAllowed = 'move';
	// Support: Firefox
	// We must set up a dataTransfer data property or Firefox seems to
	// ignore the fact the element is draggable.
	try {
		dataTransfer.setData( 'application-x/OOUI-draggable', this.getIndex() );
	} catch ( err ) {
		// The above is only for Firefox. Move on if it fails.
	}
	// Briefly add a 'clone' class to style the browser's native drag image
	this.$element.addClass( 'oo-ui-draggableElement-clone' );
	// Add placeholder class after the browser has rendered the clone
	setTimeout( function () {
		element.$element
			.removeClass( 'oo-ui-draggableElement-clone' )
			.addClass( 'oo-ui-draggableElement-placeholder' );
	} );
	// Emit event
	this.emit( 'dragstart', this );
	return true;
};
 
/**
 * Respond to dragend event.
 *
 * @private
 * @fires dragend
 */
OO.ui.mixin.DraggableElement.prototype.onDragEnd = function () {
	this.$element.removeClass( 'oo-ui-draggableElement-placeholder' );
	this.emit( 'dragend' );
};
 
/**
 * Handle drop event.
 *
 * @private
 * @param {jQuery.Event} e Drop event
 * @fires drop
 */
OO.ui.mixin.DraggableElement.prototype.onDrop = function ( e ) {
	e.preventDefault();
	this.emit( 'drop', e );
};
 
/**
 * In order for drag/drop to work, the dragover event must
 * return false and stop propogation.
 *
 * @param {jQuery.Event} e Drag event
 * @private
 */
OO.ui.mixin.DraggableElement.prototype.onDragOver = function ( e ) {
	e.preventDefault();
};
 
/**
 * Set item index.
 * Store it in the DOM so we can access from the widget drag event.
 *
 * @private
 * @param {number} index Item index
 */
OO.ui.mixin.DraggableElement.prototype.setIndex = function ( index ) {
	if ( this.index !== index ) {
		this.index = index;
		this.$element.data( 'index', index );
	}
};
 
/**
 * Get item index.
 *
 * @private
 * @return {number} Item index
 */
OO.ui.mixin.DraggableElement.prototype.getIndex = function () {
	return this.index;
};