用画布进行Javascript触摸事件

嘿,所以我的触摸事件偏移量有问题,可以用鼠标在画布上绘制,但是用触摸板偏移量在角落很远,当我触摸画布时,它会“绘制”触摸板,但就像我说的那样。我知道我的偏移量不见了,但是我是一个JavaScript新手,并且一直在尝试调试几个小时

$( document ).ready(function() {

  var container = document.getElementById('canvas');
  init(container,200,'#ddd');


  function init(container,width,height,fillColor) {
    var canvas = createCanvas(container,height);
    var ctx = canvas.getcontext('2d');


    var mouse = {x: 0,y: 0};
    var touch = {x: 0,y: 0};
    var last_mouse = {x: 0,y: 0};
    var last_touch = {x: 0,y: 0};


    canvas.addEventListener('mousemove',function(e) {
      last_mouse.x = mouse.x;
      last_mouse.y = mouse.y;


      if (e.offsetX) {
        mouse.x = e.offsetX;
        mouse.y = e.offsetY;
      }
    });    

    canvas.addEventListener('touchmove',function(e) {
      var touch = e.touches[0];
      last_touch.x = e.pageX - touch.offsetLeft;
      last_touch.y = e.pageY - touch.offsetTop;


      if (e.offsetX) {
        touch.x = e.offsetX;
        touch.y = e.offsetY;
      }
    });  

    canvas.onmousemove = function(e) {

      var x = e.pageX - this.offsetLeft;
      var y = e.pageY - this.offsetTop;
    };

    canvas.addEventListener('touchstart',function(e) {
      canvas.addEventListener('touchmove',onTouchPaint,false);
    },false);

    canvas.addEventListener('mousedown',function(e) {
      canvas.addEventListener('mousemove',onPaint,false);
    canvas.addEventListener('mouseup',function() {
      canvas.removeEventListener('mousemove',false);
    });

    var onPaint = function() {
      ctx.beginPath();
      ctx.moveTo(last_mouse.x,last_mouse.y);
      ctx.lineTo(mouse.x,mouse.y);
      ctx.closePath();
      ctx.stroke();

      ctx.lineWidth = 15 ;
      ctx.lineJoin = 'round';
      ctx.lineCap = 'round';
      ctx.strokeStyle = 'black';
    };

    var onTouchPaint = function() {
      ctx.beginPath();
      ctx.moveTo(last_touch.x,last_touch.y);
      ctx.lineTo(touch.x,touch.y);
      ctx.closePath();
      ctx.stroke();

      ctx.lineWidth = 15 ;
      ctx.lineJoin = 'round';
      ctx.lineCap = 'round';
      ctx.strokeStyle = 'black';
    };
  } 
});

onTouchPaint还是touchmove,它正在杀死我。任何帮助都可以申请。

hahahaha548 回答:用画布进行Javascript触摸事件

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