Question

我必须根据需要在mousemove事件的图层上绘制一个弧。如何根据当前的鼠标位置修复函数context.arc(x,y,startAngel,endAngle,Counterclockwise)中的参数？我的代码如下：

var newarc;
ui.stage.on("mousedown", function () {
    var arc = new Kinetic.Shape({
        drawFunc: function (canvas) {
            var context = canvas.getContext();
            var pos = ui.stage.getMousePosition();

            var sx = Math.floor(pos.x / ui.scale - ui.stage.getAbsolutePosition().x / ui.scale + ui.stage.getOffset().x);
            var sy = Math.floor(pos.y / ui.scale - ui.stage.getAbsolutePosition().y / ui.scale + ui.stage.getOffset().y);
            var x = sx;
            var y = sy;
            var radius = 100;
            var startAngle = 1 * Math.PI;
            var endAngle = 0.5 * Math.PI;
            var context = canvas.getContext('2d');
            context.beginPath();
            context.arc(x, y, radius, startAngle, endAngle, false);
            canvas.stroke(this);
        },
        fill: '#00D2FF',
        stroke: 'red',
        strokeWidth: 2,
        // draggable: false
    });
    newarc = arc;
    moving = true;
    ui.myLayer.add(newarc );
});

ui.stage.on("mouseup", function () {
    moving = false;
})

ui.stage.on("mousemove", function () {
    if (!moving) {
        return;
    }

    var dx = x - startX;
    var dy = y - startY
    var aradius = Math.sqrt(dx * dx + dy * dy)
    newarc.radius = aradius;
    ui.myLayer.drawScene();
    ui.myLayer.add(newarc);
    ui.stage.add(ui.myLayer);
});

Answer 1

以下是如何通过拖动鼠标来创建圆圈。

Mousedown：

创建一个新中心，其中心位于鼠标位置。

MOUSEMOVE：

将圆的半径更改为中心圆与鼠标之间的距离。

的MouseUp：

结束调整圆圈的大小

enter image description here

这是代码和小提琴：http://jsfiddle.net/m1erickson/NQDdE/

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Prototype</title>
    <script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
    <script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.7.2.min.js"></script>

<style>
body{padding:20px;}
#container{
  border:solid 1px #ccc;
  margin-top: 10px;
  width:350px;
  height:350px;
}
</style>        
<script>
$(function(){

    var stage = new Kinetic.Stage({
        container: 'container',
        width: 350,
        height: 350
    });
    var layer = new Kinetic.Layer();
    stage.add(layer);

    var newArc;
    var isDown=false;

    stage.on("contentMousedown",function(){
        var mouse=stage.getMousePosition();
        newArc=new Kinetic.Circle({
            x:mouse.x,
            y:mouse.y,
            radius:.25,
            fill:randomColor(),
            stroke:"lightgray",
            strokeWidth:3
        });
        layer.add(newArc);
        layer.draw();
        isDown=true;
    });

    stage.on("contentMousemove",function(){
        if(!isDown){return;}
        var mouse=stage.getMousePosition();
        var dx=mouse.x-newArc.getX();
        var dy=mouse.y-newArc.getY();
        var radius=Math.sqrt(dx*dx+dy*dy);
        newArc.setRadius(radius);
        layer.draw();
    });


    $(stage.getContent()).on('mouseup', function () {
        isDown=false;
        newArc=null;
    });



    function randomColor(){ 
        return('#'+Math.floor(Math.random()*16777215).toString(16));
    }

    layer.draw();



}); // end $(function(){});

</script>       
</head>

<body>
    <div id="container"></div>
</body>
</html>

使用Kineticjs在mousemove事件上绘制弧

1 个答案: