如何截图并在窗口中显示(不保存文件)？

<canvas id="screenshotCanvas"></canvas>
<button onclick="captureScreenshot()">截图</button>

function captureScreenshot() {
  // 获取Canvas元素
  var canvas = document.getElementById("screenshotCanvas");
  
  // 获取窗口的宽度和高度
  var width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
  var height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
  
  // 设置Canvas的宽度和高度
  canvas.width = width;
  canvas.height = height;
  
  // 获取Canvas的绘图上下文
  var context = canvas.getContext("2d");
  
  // 在Canvas上绘制整个窗口的截图
  context.drawImage(window, 0, 0, width, height);
}