Question

我在javascript中有一组元组。是否有现有的库可以让我查看用户执行的鼠标移动？

理想情况下，我可以让我从头到尾重播捕获的数据。它看起来像一个视频播放器（即播放，暂停，调整重播速度），但您可以看到鼠标光标的移动方式，而不是视频。这种可视化将在HTML5画布上（即，一个白色像素的正方形，代表在黑色HTML画布中移动的光标）。

Answer 1

我不知道有哪些库可以执行您所描述的操作，但是创建一个位置数组然后使用它应该大致按照您的要求进行操作。

//Capture all mouse movements on the browser window.
document.onmousemove = mousePos;

//Store all previous mouse locations
var ary = [];

function mousePos (e) {

    //Log the current mouse position
    ary.push({X: e.pageX, Y: e.pageY});
}

现在，您可以遍历数组以使鼠标移动。

function replay() {

  for (var i = 0; i < ary.length; i++) {

    //Draw a point wherever the mouse moved.
    ctx.fillRect(ary[i].X, ary[i].Y, 2, 2);  
  }
}

您可以按照自己喜欢的速度添加延迟时间来播放。

Answer 2

简单到没有库就可以完成。

收听mousemove活动
在鼠标移动时，将每个鼠标位置添加到点数组
请求时，运行requestAnimationFrame循环，重新绘制点数组中的每个点。

示例代码和演示：

var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
function reOffset(){
  var BB=canvas.getBoundingClientRect();
  offsetX=BB.left;
  offsetY=BB.top;        
}
var offsetX,offsetY;
reOffset();
window.onscroll=function(e){ reOffset(); }
window.onresize=function(e){ reOffset(); }

var isDown=false;
var points=[];
var nextTime=0;
var nextN=0;
var duration=1000/60;
ctx.lineCap='round';

$("#canvas").mousedown(function(e){handleMouseDown(e);});
$("#canvas").mousemove(function(e){handleMouseMove(e);});
$("#canvas").mouseup(function(e){handleMouseUpOut(e);});
$("#canvas").mouseout(function(e){handleMouseUpOut(e);});

$('#fast').on('click',function(){ duration=1000/60; beginRedrawing(); });
$('#slow').on('click',function(){ duration=1000/15; beginRedrawing(); });

function beginRedrawing(){
  if(points.length<2){return;}
  nextN=1;
  ctx.lineWidth=3;
  ctx.strokeStyle=randomColor();
  requestAnimationFrame(redraw);
}

function handleMouseDown(e){
  // tell the browser we're handling this event
  e.preventDefault();
  e.stopPropagation();
  // get current mouse position
  ctx.lineWidth=7;
  ctx.strokeStyle='black';
  points.length=0;
  mouseX=parseInt(e.clientX-offsetX);
  mouseY=parseInt(e.clientY-offsetY);
  points.push({x:mouseX,y:mouseY});
  // Set dragging flag
  isDown=true;
}

function handleMouseUpOut(e){
  // tell the browser we're handling this event
  e.preventDefault();
  e.stopPropagation();
  // get current mouse position          
  mouseX=parseInt(e.clientX-offsetX);
  mouseY=parseInt(e.clientY-offsetY);
  // Clear dragging flag
  isDown=false;
}

function handleMouseMove(e){
  if(!isDown){return;}
  // tell the browser we're handling this event
  e.preventDefault();
  e.stopPropagation();
  // get current mouse position
  mouseX=parseInt(e.clientX-offsetX);
  mouseY=parseInt(e.clientY-offsetY);
  points.push({x:mouseX,y:mouseY});
  var n=points.length-1;
  lineSegment(points[n-1],points[n]);
}

function lineSegment(p0,p1){
  ctx.beginPath();
  ctx.moveTo(p0.x,p0.y);
  ctx.lineTo(p1.x,p1.y);
  ctx.stroke();
}

function redraw(time){
  if(nextN>points.length-1){return;}
  if(time<nextTime){requestAnimationFrame(redraw);return;}
  nextTime=time+duration;
  lineSegment(points[nextN-1],points[nextN]);
  nextN++;
  requestAnimationFrame(redraw);
}

function randomColor(){ 
  return('#'+Math.floor(Math.random()*16777215).toString(16));
}

body{ background-color: ivory; }
#canvas{border:1px solid red; }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Drag to create polyline then click a redraw button below.</h4>
<button id=fast>Fast Redraw</button>
<button id=slow>Slow Redraw</button>
<br>
<canvas id="canvas" width=512 height=512></canvas>

如何在画布上重绘鼠标移动？

2 个答案: