如何将平移限制到画布边缘？

// 获取画布元素
var canvas = document.getElementById("canvas");

// 获取画布边界坐标
var canvasLeft = canvas.offsetLeft;
var canvasTop = canvas.offsetTop;
var canvasRight = canvasLeft + canvas.offsetWidth;
var canvasBottom = canvasTop + canvas.offsetHeight;

// 监听平移操作
canvas.addEventListener("mousemove", function(event) {
  // 获取平移距离和方向
  var deltaX = event.movementX || event.webkitMovementX || event.mozMovementX || 0;
  var deltaY = event.movementY || event.webkitMovementY || event.mozMovementY || 0;

  // 判断是否超出边界
  var newX = canvas.offsetLeft + deltaX;
  var newY = canvas.offsetTop + deltaY;
  if (newX < canvasLeft) {
    deltaX = canvasLeft - canvas.offsetLeft;
  } else if (newX + canvas.offsetWidth > canvasRight) {
    deltaX = canvasRight - canvas.offsetLeft - canvas.offsetWidth;
  }
  if (newY < canvasTop) {
    deltaY = canvasTop - canvas.offsetTop;
  } else if (newY + canvas.offsetHeight > canvasBottom) {
    deltaY = canvasBottom - canvas.offsetTop - canvas.offsetHeight;
  }

  // 更新平移后的位置
  canvas.style.left = canvas.offsetLeft + deltaX + "px";
  canvas.style.top = canvas.offsetTop + deltaY + "px";
});