Javascript 单击并拖动以使用JS在html画布上绘制字符串。可以在桌面上工作，但不能在移动设备上工作。触摸开始/结束也不工作

下面的代码使用鼠标事件侦听器在画布上绘制字符串。 然而，我无法让它在手机上工作。我尝试了触摸开始/结束/移动，并检查了多个堆栈溢出问题的答案。非常感谢你的帮助

我知道我必须使用触摸事件，并防止自动“触摸时滚动”，以便用户能够绘制，但我猜我的代码中有一部分不允许触摸事件工作

我还读到“鼠标和触摸事件”不能同时触发，或者它们不能工作。我也不知道该怎么做。如果有人能找到解决办法，我将不胜感激

// Application variables
var position = {x: 0, y: window.innerHeight/2};
var counter = 0;
var minFontSize = 3;
var angleDistortion = 0;
var letters = "Once upon a time, long, long ago a king and queen ruled over a distant land.  The queen was kind and lovely and all the people of the realm adored her.  The only sadness in the queen's life was that she wished for a child but did not have one. One winter day, the queen was doing needle work while gazing out her ebony window at the new fallen snow.  A bird flew by the window startling the queen and she pricked her finger.  A single drop of blood fell on the snow outside her window.  As she looked at the blood on the snow she said to herself, 'Oh, how I wish that I had a daughter that had skin as white as snow, lips as red as blood, and hair as black as ebony.'";

// Drawing variables
var canvas;
var context;
var mouse = {x: 0, y: 0, down: false}

function init() {
  canvas = document.getElementById( 'canvas' );
  context = canvas.getContext( '2d' );
  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;
  
  canvas.addEventListener('mousemove', mouseMove, false);
  canvas.addEventListener('mousedown', mouseDown, false);
  canvas.addEventListener('mouseup',   mouseUp,   false);
  canvas.addEventListener('mouseout',  mouseUp,  false);  
  canvas.addEventListener('dblclick', doubleClick, false);
  
  window.onresize = function(event) {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
  }
}

function mouseMove ( event ){
  mouse.x = event.pageX;
  mouse.y = event.pageY;
  draw();
}

function draw() {
 if ( mouse.down ) {
    var d = distance( position, mouse );
    var fontSize = minFontSize + d/2;
    var letter = letters[counter];
    var stepSize = textWidth( letter, fontSize );
    
    if (d > stepSize) {
      var angle = Math.atan2(mouse.y-position.y, mouse.x-position.x);
      
      context.font = fontSize + "px Great Vibes";
    
      context.save();
      context.translate( position.x, position.y);
      context.rotate( angle );
      context.fillText(letter,0,0);
      context.restore();

      counter++;
      if (counter > letters.length-1) {
        counter = 0;
      }
    
    //console.log (position.x + Math.cos( angle ) * stepSize)
      position.x = position.x + Math.cos(angle) * stepSize;
      position.y = position.y + Math.sin(angle) * stepSize;

      }
  }     
}

function distance( pt, pt2 ){
  
  var xs = 0;
  var ys = 0;
 
  xs = pt2.x - pt.x;
  xs = xs * xs;
 
  ys = pt2.y - pt.y;
  ys = ys * ys;
 
  return Math.sqrt( xs + ys );
}

function mouseDown( event ){
  mouse.down = true;
  position.x = event.pageX;
  position.y = event.pageY;
  
  document.getElementById('info').style.display = 'none';
}

function mouseUp( event ){
    mouse.down = false;
}

function doubleClick( event ) {
  canvas.width = canvas.width; 
}

function textWidth( string, size ) {
  context.font = size + "px Great Vibes";
  
  if ( context.fillText ) {
    return context.measureText( string ).width;
  } else if ( context.mozDrawText) {
    return context.mozMeasureText( string );
  }
  
 };

init();