使用 Draw2D.js 拖放菜单

Question

How would I create a Drag & Drop menu with Draw2D.js? I am making an application using React and can't find how to do it in the docs. There is something similar in this example , but I don't understand how to I would make my own.

In the example, the author uses methods that aren't in the docs .

And when I try to copy the code from that example, eslint says that it is wrong.

Answer 1

You can find the code of this example here:

shape db example

The idea is to add a ghost img to the dom following the mouse moove and to create your new element at the drop event.

The following extract of the code from this example do exactly what it is needed to perform the drag and drop:

onMouseDrag:function(canvas, dx, dy, dx2, dy2)
{
    var _this = this;

    if( !((this.mouseDraggingElement instanceof draw2d.ResizeHandle) || (this.mouseDraggingElement instanceof draw2d.Port))){
        if(this.cloneOnDrag ===true && this.mouseDraggingElement !==null){
            var tmp = this.mouseDraggingElement;

            // get the current position of the selected shape
            // cancel the current drag&drop operation
            var pos = this.mouseDraggingElement.getPosition();
            this.mouseDraggingElement.onDragEnd(pos.x, pos.y, false,false);
            this.mouseDraggingElement = null;

            // PNG snapshot's didn'T work with all kind of shapes. You can use
            // a DIV ghost as workaround if this didn't work for you
            //
            var usePNGSnapshot = true;

            // create an base64 coded image snapshoot from the figure
            // (not from the complete canvas)
            //
            if(usePNGSnapshot===true) {
                new draw2d.io.png.Writer().marshal(tmp, function (base64Image) {
                    // add the image to the DOM tree
                    //
                    var ghost = $("<img  style='position:absolute'>");
                    ghost.attr("src", base64Image);

                    _this.setupDragDropGhost(tmp, ghost);

                });
            }
            else{
                var ghost = $("<div>");
                ghost.css({
                    position: "absolute",
                    width: tmp.getWidth(),
                    height: tmp.getHeight(),
                    border:"1px dotted black",
                    borderRadius:"3",
                    backgroundColor:"rgba(128,128,200,0.3)"
                });

                _this.setupDragDropGhost(tmp, ghost);
            }
        }
    }
    this.cloneOnDrag=false;
    this._super(canvas, dx,dy,dx2,dy2);
},
setupDragDropGhost: function(figure, ghost){
    var _this = this;

    $("body").append(ghost);

    // and track mouseMove events to move the IMG element around
    //
    var offset = _this.mouseDownPos.subtract(figure.getPosition());
    var mousemoveHandler = function (e) {
        var diffX = e.pageX - offset.x;
        var diffY = e.pageY - offset.y;
        ghost.css('left', diffX + 'px').css('top', diffY + 'px');
    };
    $(document).bind('mousemove', mousemoveHandler);

    ghost.bind('mouseup', function (e) {
        try {
            // this is a drop event...determine the related canvas and add
            // the figure clone to the canvas
            //
            $(document).unbind('mousemove', mousemoveHandler);
            var r1 = new draw2d.geo.Rectangle($("#container1")[0].getBoundingClientRect());
            var r2 = new draw2d.geo.Rectangle($("#container2")[0].getBoundingClientRect());
            var canvas1Hit = r1.hitTest(e.pageX, e.pageY);
            var canvas2Hit = r2.hitTest(e.pageX, e.pageY);

            if (canvas1Hit) {
                var clone = figure.clone();
                var p = canvas1.fromDocumentToCanvasCoordinate(e.pageX, e.pageY);
                clone.setPosition(p.subtract(offset));
                canvas1.add(clone);
            }
            if (canvas2Hit) {
                var clone = figure.clone();
                var p = canvas2.fromDocumentToCanvasCoordinate(e.pageX, e.pageY);
                clone.setPosition(p.subtract(offset));
                canvas2.add(clone);
            }
        }
        finally{
            ghost.remove();
        }
    });
}