mxgraph示例解析(一) anchors可连接节点

anchors效果图

官方示例

// Overridden to define per-shape connection points
        mxGraph.prototype.getAllConnectionConstraints = function(terminal, source)
        {
            if (terminal != null && terminal.shape != null)
            {
                if (terminal.shape.stencil != null)
                {
                    if (terminal.shape.stencil != null)
                    {
                        return terminal.shape.stencil.constraints;
                    }
                }
                else if (terminal.shape.constraints != null)
                {
                    return terminal.shape.constraints;
                }
            }
    
            return null;
        };
    
        // Defines the default constraints for all shapes
        mxShape.prototype.constraints = [new mxConnectionConstraint(new mxPoint(0.25, 0), true),
                                         new mxConnectionConstraint(new mxPoint(0.5, 0), true),
                                         new mxConnectionConstraint(new mxPoint(0.75, 0), true),
                                         new mxConnectionConstraint(new mxPoint(0, 0.25), true),
                                         new mxConnectionConstraint(new mxPoint(0, 0.5), true),
                                         new mxConnectionConstraint(new mxPoint(0, 0.75), true),
                                         new mxConnectionConstraint(new mxPoint(1, 0.25), true),
                                         new mxConnectionConstraint(new mxPoint(1, 0.5), true),
                                         new mxConnectionConstraint(new mxPoint(1, 0.75), true),
                                         new mxConnectionConstraint(new mxPoint(0.25, 1), true),
                                         new mxConnectionConstraint(new mxPoint(0.5, 1), true),
                                         new mxConnectionConstraint(new mxPoint(0.75, 1), true)];
        
        // Edges have no connection points
        mxPolyline.prototype.constraints = null;

        // Program starts here. Creates a sample graph in the
        // DOM node with the specified ID. This function is invoked
        // from the onLoad event handler of the document (see below).
        function main(container)
        {
            // Checks if the browser is supported
            if (!mxClient.isBrowserSupported())
            {
                // Displays an error message if the browser is not supported.
                mxUtils.error('Browser is not supported!', 200, false);
            }
            else
            {
                // Disables the built-in context menu
                mxEvent.disableContextMenu(container);

                // Creates the graph inside the given container
                var graph = new mxGraph(container);
                graph.setConnectable(true);
                
                // Enables connect preview for the default edge style
                graph.connectionHandler.createEdgeState = function(me)
                {
                    var edge = graph.createEdge(null, null, null, null, null);
                    
                    return new mxCellState(this.graph.view, edge, this.graph.getCellStyle(edge));
                };
                
                // Specifies the default edge style
                graph.getStylesheet().getDefaultEdgeStyle()['edgeStyle'] = 'orthogonalEdgeStyle';
                
                // Enables rubberband selection
                new mxRubberband(graph);
                
                // Gets the default parent for inserting new cells. This
                // is normally the first child of the root (ie. layer 0).
                var parent = graph.getDefaultParent();
                                
                // Adds cells to the model in a single step
                graph.getModel().beginUpdate();
                try
                {
                    var v1 = graph.insertVertex(parent, null, 'Hello,', 20, 20, 80, 30);
                    var v2 = graph.insertVertex(parent, null, 'World!', 200, 150, 80, 30);
                    var e1 = graph.insertEdge(parent, null, '', v1, v2);
                }
                finally
                {
                    // Updates the display
                    graph.getModel().endUpdate();
                }
            }
        };

实现原理

设定可连接

graph.setConnectable(true);

设定节点位置、可编辑状态

mxShape.prototype.constraints = 
  [new mxConnectionConstraint(new mxPoint(0.25, 0), true),
   new mxConnectionConstraint(new mxPoint(0.5, 0), true),
   new mxConnectionConstraint(new mxPoint(0.75, 0), true),
   new mxConnectionConstraint(new mxPoint(0, 0.25), true),
   new mxConnectionConstraint(new mxPoint(0, 0.5), true),
   new mxConnectionConstraint(new mxPoint(0, 0.75), true),
   new mxConnectionConstraint(new mxPoint(1, 0.25), true),
   new mxConnectionConstraint(new mxPoint(1, 0.5), true),
   new mxConnectionConstraint(new mxPoint(1, 0.75), true),
   new mxConnectionConstraint(new mxPoint(0.25, 1), true),
   new mxConnectionConstraint(new mxPoint(0.5, 1), true),
   new mxConnectionConstraint(new mxPoint(0.75, 1), true)];

简化示例

mxGraph.prototype.getAllConnectionConstraints = function(terminal,source) {
    if (terminal != null && terminal.shape != null) {
        if (terminal.shape.stencil != null) {
            if (terminal.shape.stencil != null) {
                return terminal.shape.stencil.constraints;
            }
        } else if (terminal.shape.constraints != null) {
            return terminal.shape.constraints;
        }
    }

    return null;
};

//设置节点位置、数量、可编辑状态
mxShape.prototype.constraints = [
    new mxConnectionConstraint(new mxPoint(0.25, 0), true),
    new mxConnectionConstraint(new mxPoint(0.5, 0), true),
    new mxConnectionConstraint(new mxPoint(0.75, 0), true),
    new mxConnectionConstraint(new mxPoint(0, 0.25), true),
    new mxConnectionConstraint(new mxPoint(0, 0.5), true),
    new mxConnectionConstraint(new mxPoint(0, 0.75), true),
    new mxConnectionConstraint(new mxPoint(1, 0.25), true),
    new mxConnectionConstraint(new mxPoint(1, 0.5), true),
    new mxConnectionConstraint(new mxPoint(1, 0.75), true),
    new mxConnectionConstraint(new mxPoint(0.25, 1), true),
    new mxConnectionConstraint(new mxPoint(0.5, 1), true),
    new mxConnectionConstraint(new mxPoint(0.75, 1), true)
];

var graph = new mxGraph(container);
//设置可连接
graph.setConnectable(true);

var parent = graph.getDefaultParent();

graph.getModel().beginUpdate();
try {
    var v1 = graph.insertVertex(parent, null, "Hello,", 20, 20, 80, 30);
    var v2 = graph.insertVertex(parent, null, "World!", 200, 150, 80, 30);
    var e1 = graph.insertEdge(parent, null, "", v1, v2);
} finally {
    graph.getModel().endUpdate();
}