将裁剪的图像缩放到屏幕宽度

// 裁剪图像
function cropImage(image, x, y, width, height) {
  var canvas = document.createElement('canvas');
  canvas.width = width;
  canvas.height = height;
  var ctx = canvas.getContext('2d');
  ctx.drawImage(image, x, y, width, height, 0, 0, width, height);
  return canvas.toDataURL(); // 返回裁剪后的图像数据URL
}

// 获取屏幕宽度
var screenWidth = window.innerWidth || document.documentElement.clientWidth;

// 缩放图像
function scaleImageToScreenWidth(imageUrl) {
  var image = new Image();
  image.src = imageUrl;
  image.onload = function() {
    var imageWidth = image.width;
    var imageHeight = image.height;
    var scale = screenWidth / imageWidth;
    var scaledWidth = screenWidth;
    var scaledHeight = imageHeight * scale;
    image.style.width = scaledWidth + 'px';
    image.style.height = scaledHeight + 'px';
  };
}

// 使用示例
var croppedImageUrl = cropImage(image, x, y, width, height);
scaleImageToScreenWidth(croppedImageUrl);