Raphaeljs: Copy element or set to another paper

问题:

Is there a possibility of adding an element or set that exists within a paper to another paper, without creating each element twice from scratch?

Background for this: I visualize a large node graph and want to create an "overview map" in a separate paper.

回答1:

Raphael don't allow to move element from one paper to another directly. So it is better to create a new element with same property in the target paper. I have created following sample method. you can add the code in your page and use cloneToPaper function to clone a element or a set to another paper.

function extractJSON(element) {
    var attr = element.attr(),
    newNodeJSON = {type: element.type},
    key;
    for (key in attr) {
        newNodeJSON[key] = attr[key];
    }
    return newNodeJSON;
}
/*
 * @param {Object} element: raphael element or set
 * @param {Object} paper: Target paper where to clone
 * @return {object}: newly created set or element
 */
function cloneToPaper(element, paper) {
    var isSet = element.type === 'set',
    elementJSONArr = [],
    i, ln, newSet;

    if (isSet) {
        ln = element.items.length;
        for (i = 0; i < ln; i += 1) {
            elementJSONArr.push(extractJSON(element.items[i]));
        }
    }
    else {
        elementJSONArr.push(extractJSON(element));
    }
    newSet = paper.add(elementJSONArr);
    return isSet ? newSet : newSet[0];
}

回答2:

The following set of codes adds a nw function to Raphael Set and Raphael Elements. The usage is to simply call .cloneToPaper(targetPaper) on any set or element.

(function (R) {
    var cloneSet; // to cache set cloning function for optimisation

    /**
     * Clones Raphael element from one paper to another
     *     
     * @param {Paper} targetPaper is the paper to which this element 
     * has to be cloned
     *
     * @return RaphaelElement
     */
    R.el.cloneToPaper = function (targetPaper) {
        return (!this.removed &&
            targetPaper[this.type]().attr(this.attr()));
    };

    /**
     * Clones Raphael Set from one paper to another
     *     
     * @param {Paper} targetPaper is the paper to which this element 
     * has to be cloned
     *
     * @return RaphaelSet
     */
    R.st.cloneToPaper = function (targetPaper) {
        targetPaper.setStart();
        this.forEach(cloneSet || (cloneSet = function (el) {
            el.cloneToPaper(targetPaper);
        }));
        return targetPaper.setFinish();
    };
}(Raphael));

For a sample implementation, you may check out this fiddle: http://jsfiddle.net/shamasis/39yTS/

Note that if you have events on the source elements, they will not be cloned to the target paper.