Kineticjs dragBoundFunc for a rect in a rect

问题

i have following code to drag a smaller rect in a bigger rect.

it is almost working, but its possible to move the orange rect out of the white one. Is there any solution for this behavior?? that the bigger rect is the dragborder for the small rect??

And another question... would it be possible to do it for a rect in any polygon as border?

<!DOCTYPE HTML>
<html>
<head>
 <style>
  body {margin: 0px; padding: 20px;}
  canvas {border: 1px solid #777;}
 </style>
</head>
<body>
<div id="container"></div>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.3.2.js"></script>
<script>
    var stage = new Kinetic.Stage({
        container: 'container',
        width: 300,
        height: 300
    });
    var layer = new Kinetic.Layer();

    // White box
    var white = new Kinetic.Rect({
        x: 100,
        y: 50,
        width: 150,
        height: 100,
        fill: 'white',
        stroke: 'black',
        strokeWidth: 2
    });

    // orange box
    var orange = new Kinetic.Rect({
        x: 150,
        y: 100,
        width: 50,
        height: 30,
        fill: 'orange',
        stroke: 'black',
        strokeWidth: 2,
        draggable: true,
        // this causes orange box to be stopped if try to leave white box
        dragBoundFunc: function(pos){
            if(theyAreColliding(orange,white)){
                 // orange box is touching white box
                 // let it move ahead
                return ({ x:pos.x, y:pos.y });
            } else{
                 // orange box is not touching white box
                 // don't let orange box move outside
                if (white.getY() > orange.getY()){
                    return({x: pos.x, y: white.getY()+1});
                }
                else if (white.getY() + white.getHeight() - orange.getHeight() < orange.getY()){
                    return({x: pos.x, y: white.getY() + white.getHeight() - orange.getHeight() -1});
                }
                else if (white.getX() > orange.getX()){
                    return({x: white.getX() +1, y: pos.y})
                }
                else if (white.getX() + white.getWidth() - orange.getWidth() < orange.getX()){
                    return({x: white.getX() +white.getWidth() - orange.getWidth() -1, y: pos.y})
                }
            }
        }
    });

    function theyAreColliding(rect1, rect2) {
        return !(rect2.getX() > rect1.getX() ||
                 rect2.getX() + rect2.getWidth() - rect1.getWidth() < rect1.getX() || 
                 rect2.getY() > rect1.getY() ||
                 rect2.getY() + rect2.getHeight() - rect1.getHeight() < rect1.getY());
    }

    layer.add(white);
    layer.add(orange);
    stage.add(layer);

</script>
</body>
</html>

and also the jsfiddle link: http://jsfiddle.net/dNfjM/

回答1:

This is an improved way of setting your dragBoundFunc

The secret with dragBoundFunc is to allow it to execute fast. Remember that it is being executed with every mousemove.

So, pre-calculate all the minimum and maximum boundaries before and outside dragBoundFunc, like this:

    // pre-calc some bounds so dragBoundFunc has less calc's to do
    var height=orangeRect.getHeight();
    var minX=white.getX();
    var maxX=white.getX()+white.getWidth()-orangeRect.getWidth();
    var minY=white.getY();
    var maxY=white.getY()+white.getHeight()-orangeRect.getHeight();

That way your dragBoundFunc can just test the current position against these pre-calc’ed bounds like this:

      dragBoundFunc: function(pos) {
          var X=pos.x;
          var Y=pos.y;
          if(X<minX){X=minX;}
          if(X>maxX){X=maxX;}
          if(Y<minY){Y=minY;}
          if(Y>maxY){Y=maxY;}
          return({x:X, y:Y});
      }

Here’s code and a Fiddle: http://jsfiddle.net/m1erickson/n5xMs/

<!DOCTYPE HTML>
<html>
  <head>
    <style>
      body {
        margin: 0px;
        padding: 10px;
      }
      canvas{border:1px solid red;}
    </style>
  </head>
    <body>
      <div id="container"></div>
      <script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.4.1.min.js"></script>
      <script>
        var stage = new Kinetic.Stage({
          container: 'container',
          width: 400,
          height: 400
        });
        var layer = new Kinetic.Layer();

        var white = new Kinetic.Rect({
            x: 20,
            y: 20,
            width: 300,
            height: 300,
            fill: 'white',
            stroke: 'black',
            strokeWidth: 2
        });

        var orangeGroup = new Kinetic.Group({
          x: stage.getWidth() / 2,
          y: 70,
          draggable: true,
          dragBoundFunc: function(pos) {
              var X=pos.x;
              var Y=pos.y;
              if(X<minX){X=minX;}
              if(X>maxX){X=maxX;}
              if(Y<minY){Y=minY;}
              if(Y>maxY){Y=maxY;}
              return({x:X, y:Y});
          }
        });

        var orangeText = new Kinetic.Text({
          fontSize: 26,
          fontFamily: 'Calibri',
          text: 'boxed in',
          fill: 'black',
          padding: 10
        });

        var orangeRect = new Kinetic.Rect({
          width: orangeText.getWidth(),
          height: orangeText.getHeight(),
          fill: 'orange',
          stroke: 'blue',
          strokeWidth: 4
        });

        orangeGroup.add(orangeRect).add(orangeText);
        layer.add(white);
        layer.add(orangeGroup);
        stage.add(layer);

        // pre-calc some bounds so dragBoundFunc has less calc's to do
        var height=orangeRect.getHeight();
        var minX=white.getX();
        var maxX=white.getX()+white.getWidth()-orangeRect.getWidth();
        var minY=white.getY();
        var maxY=white.getY()+white.getHeight()-orangeRect.getHeight();

      </script>
  </body>
</html>

来源：https://stackoverflow.com/questions/15854001/kineticjs-dragboundfunc-for-a-rect-in-a-rect

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kineticjs