Connect canvas with lines

2020-02-04 22:31发布

站内问答 / 后端开发
2017 1 5

I need to connect two canvas with a line to create a dynamic workflow.

I'll generate the canvas rectangle dynamic (amount of steps I have at DB) but I need to connect the steps with lines.

Anybody have some ideas?

1条回答
你好瞎i
2楼-- · 2020-02-04 22:56

Here’s how to automatically connect 2 draggable canvas rectangles with a line

enter image description hereenter image description here

First, define some boxes and connectors:

    // define any boxes that will be drawn
    var boxes=[];
    boxes.push({x:50,y:25,w:75,h:50});    // x,y,width,height
    boxes.push({x:200,y:100,w:50,h:50});

    // define any connectors between any boxes
    var connectors=[];
    connectors.push({box1:0,box2:1});

Draw the boxes and automatically draw their connectors:

    function draw(){

        // clear the canvas
        ctx.clearRect(0,0,canvas.width,canvas.height);

        for(var i=0;i<boxes.length;i++){
            var box=boxes[i];
            ctx.fillRect(box.x,box.y,box.w,box.h);
        }
        for(var i=0;i<connectors.length;i++){
            var connector=connectors[i];
            var box1=boxes[connector.box1];
            var box2=boxes[connector.box2];
            ctx.beginPath();
            ctx.moveTo(box1.x+box1.w/2,box1.y+box1.h/2);
            ctx.lineTo(box2.x+box2.w/2,box2.y+box2.h/2);
            ctx.stroke();
        }

    }

The code below allows any box to be dragged and remain connected.

Here is code and a Fiddle: http://jsfiddle.net/m1erickson/GX6HS/

<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>

<style>
    body{ background-color: ivory; padding:20px;}
    #canvas{border:1px solid red;}
</style>

<script>
$(function(){

    var canvas=document.getElementById("canvas");
    var ctx=canvas.getContext("2d");

    var canvasOffset=$("#canvas").offset();
    var offsetX=canvasOffset.left;
    var offsetY=canvasOffset.top;

    var startX;
    var startY;
    var isDown=false;
    var dragTarget;

    var boxes=[];
    boxes.push({x:50,y:25,w:75,h:50});    // x,y,width,height
    boxes.push({x:200,y:100,w:50,h:50});


    var connectors=[];
    connectors.push({box1:0,box2:1});

    draw();

    function draw(){

        // clear the canvas
        ctx.clearRect(0,0,canvas.width,canvas.height);

        for(var i=0;i<boxes.length;i++){
            var box=boxes[i];
            ctx.fillRect(box.x,box.y,box.w,box.h);
        }
        for(var i=0;i<connectors.length;i++){
            var connector=connectors[i];
            var box1=boxes[connector.box1];
            var box2=boxes[connector.box2];
            ctx.beginPath();
            ctx.moveTo(box1.x+box1.w/2,box1.y+box1.h/2);
            ctx.lineTo(box2.x+box2.w/2,box2.y+box2.h/2);
            ctx.stroke();
        }

    }

    function hit(x,y){
        for(var i=0;i<boxes.length;i++){
            var box=boxes[i];
            if(x>=box.x && x<=box.x+box.w && y>=box.y && y<=box.y+box.h){
                dragTarget=box;
                return(true);
            }
        }
        return(false);
    }

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

      // Put your mousedown stuff here
      isDown=hit(startX,startY);
    }

    function handleMouseUp(e){
      // Put your mouseup stuff here
      dragTarget=null;
      isDown=false;
    }

    function handleMouseOut(e){
        handleMouseUp(e);
    }

    function handleMouseMove(e){
      if(!isDown){return;}

      mouseX=parseInt(e.clientX-offsetX);
      mouseY=parseInt(e.clientY-offsetY);

      // Put your mousemove stuff here
      var dx=mouseX-startX;
      var dy=mouseY-startY;
      startX=mouseX;
      startY=mouseY;
      dragTarget.x+=dx;
      dragTarget.y+=dy;
      draw();
    }

    $("#canvas").mousedown(function(e){handleMouseDown(e);});
    $("#canvas").mousemove(function(e){handleMouseMove(e);});
    $("#canvas").mouseup(function(e){handleMouseUp(e);});
    $("#canvas").mouseout(function(e){handleMouseOut(e);});

}); // end $(function(){});
</script>

</head>

<body>
    <p>Drag boxes--they remain connected</p>
    <canvas id="canvas" width=300 height=300></canvas>
</body>
</html>
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