问绘制连接的线

EN

function handleMouseDown(e){
// tell the browser we're handling this event
e.preventDefault();
e.stopPropagation();

startX=parseInt(e.clientX-offsetX);
startY=parseInt(e.clientY-offsetY);

draggingIndex=-1;
for(var i=0;i<anchors.length;i++){
    var a=anchors[i];
    var dx=startX-a.x;
    var dy=startY-a.y;
    if(dx*dx+dy*dy<radius*radius){
        draggingIndex=i;
        break;
    }
}

//Detect if we're on a line:
fullDrag = mouseOnLine({x:startX, y: startY});

// If a drag hasn't started, add another anchor here
if(draggingIndex==-1 && fullDrag == null){
    addAnchor(startX,startY);
    var al = anchors.length-1;
    var almod4 = al%2;
    if(almod4==1){
        connectors.push({start:al-1,end:al});
    }
    if(almod4==2){
        connectors.push({start:al-2,end:al});
        connectors.push({start:al-1,end:al});
    }
    draw();
}
}