也说 Jquery+ASP.NET 实现开心网上传头像剪裁功能

前几天博客园cnblogs里有个朋友发了一个类似的帖子（你可以点这里查看），刚刚也要做这个功能，但是原来程序稍微有点问题，特别在前台上有几处不合理的地方，所以就着开心网的代码重写一下，效果如下

Step 1 选择上传照片

 

Step2 ，点击上传一张图片，默认缩放到刚好填充画布，如果图片小于画布就不缩放了，并且将图片集中

缩放图片是，以画布中的选取框为中，向四周扩散，缩小

点击保存按钮 保存截取后的图片

 

来看下代码吧

前台：需要引用Jquery的类库和两个Ui的Js

<script type="text/javascript" src="js/jquery1.2.6.pack.js"></script>
  <script  type="text/javascript" src="js/ui.core.packed.js" ></script>
  <script type="text/javascript" src="js/ui.draggable.packed.js" ></script>

html太长就不全贴出来了，挑几个重点来说把：

1：这个我们的html片段

2：这个是开心网中的html片段

开心网中用一个table作为画布的架子，中间的一个td设置样式为选取框，把img移到table下面，就可以看到上图的效果了，但是在设置drap的时候handler设置为table（id=crop）,来看下下面开心网的代码就知道了。

因为我们点击的时候，因为table在img之上，所以点击只能点到table。但是Jquery的drap handle不能设置源以外的元素，所以上面的方法就行不通了，参考了原文中的做法，用两个图片代替，一个做成蒙层的效果（ImageDragContainer）,一个缩小放到中间的位置，变成剪切窗口（IconContainer）,只要控制好两个图片的left，top，width，height，那么可以做到看上去像一个图片那样。如前面的效果所示。

其他html就是一些布局，上传控件和几个用于存放值的textbox了，就不介绍了，来看下js把，关键的，都加上注释了。有问题可以留言交流

/// <reference path="JSintellisense/jquery-1.2.6-intellisense.js" />

//全局变量定义
var CANVAS_WIDTH = 284; //画布的宽
var CANVAS_HEIGHT = 266; //画布的高
var ICON_SIZE = 120;  //截取框的大小，正方形
var LEFT_EDGE = (CANVAS_WIDTH - ICON_SIZE) / 2; //82
var TOP_EDGE = (CANVAS_HEIGHT - ICON_SIZE) / 2; //73
var CANVAS_LEFT_MARGIN = 4;


//用document. ready事件中在上传后第一次转向时无法获取到图片的实际宽度和高度，应该是没有被下载来的缘故
$(window).load(function() {
    var $iconElement = $("#ImageIcon");
    var $imagedrag = $("#ImageDrag");

    //获取上传图片的实际高度，宽度
    var image = new Image();
    image.src = $iconElement.attr("src");
    var realWidth = image.width;
    var realHeight = image.height;  
    image = null;       
   
    //计算缩放比例开始
    var minFactor = ICON_SIZE / Math.max(realWidth, realHeight);
    if (ICON_SIZE > realWidth && ICON_SIZE > realHeight) {
        minFactor = 1;
    }
    var factor = minFactor > 0.25 ? 8.0 : 4.0 / Math.sqrt(minFactor);

    //图片缩放比例 
    var scaleFactor = 1;
    if (realWidth > CANVAS_WIDTH && realHeight > CANVAS_HEIGHT) {
        if (realWidth / CANVAS_WIDTH > realHeight / CANVAS_HEIGHT) {
            scaleFactor = CANVAS_HEIGHT / realHeight;
        }
        else {
            scaleFactor = CANVAS_WIDTH / realWidth;
        }
    }
    //计算缩放比例结束

    //设置滑动条的位置，设置滑动条的值的变化来改变缩放率是一个非线性的变化，而是幂函数类型 即类似y=factor（X）--此处x为幂指数
    //此处100 * (Math.log(scaleFactor * factor) / Math.log(factor)) 为知道y 求解x，scaleFactor 即为y  此处的100为 中间值，滑动条长度为200
    $(".child").css("left", 100 * (Math.log(scaleFactor * factor) / Math.log(factor)) + "px");

    //图片实际尺寸，并近似到整数
    var currentWidth = Math.round(scaleFactor * realWidth);
    var currentHeight = Math.round(scaleFactor * realHeight);


    //图片相对CANVAS的初始位置，图片相对画布居中
    var originLeft = Math.round((CANVAS_WIDTH - currentWidth) / 2) ;
    var originTop = Math.round((CANVAS_HEIGHT - currentHeight) / 2);
    //计算截取框中的图片的位置
    var dragleft = originLeft - LEFT_EDGE;
    var dragtop = originTop - TOP_EDGE;


    //设置图片当前尺寸和位置
    $iconElement.css({ width: currentWidth + "px", height: currentHeight + "px", left: originLeft + "px", top: originTop + "px" });
    $imagedrag.css({ width: currentWidth + "px", height: currentHeight + "px", left: dragleft + "px", top: dragtop + "px" });

    //初始化默认值
    $("#txt_width").val(currentWidth);
    $("#txt_height").val(currentHeight);
    $("#txt_top").val(0-dragtop);
    $("#txt_left").val(0-dragleft);
    $("#txt_Zoom").val(scaleFactor);

    var oldWidth = currentWidth;
    var oldHeight = currentHeight;

    //设置图片可拖拽，并且拖拽一张图片时，同时移动另外一张图片
    $imagedrag.draggable(
    {
        cursor: 'move',
        drag: function(e, ui) {
            var self = $(this).data("draggable");
            var drop_img = $("#ImageIcon");
            var top = drop_img.css("top").replace(/px/, ""); //取出截取框到顶部的距离
            var left = drop_img.css("left").replace(/px/, ""); //取出截取框到左边的距离
            drop_img.css({ left: (parseInt(self.position.left) + LEFT_EDGE) + "px", top: (parseInt(self.position.top) + TOP_EDGE) + "px" }); //同时移动内部的图片
            $("#txt_left").val(0 - parseInt(self.position.left));
            $("#txt_top").val(0 - parseInt(self.position.top));
        }
    }
    );
    //设置图片可拖拽，并且拖拽一张图片时，同时移动另外一张图片
    $iconElement.draggable(
    {
        cursor: 'move',
        drag: function(e, ui) {
            var self = $(this).data("draggable");
            var drop_img = $("#ImageDrag");
            var top = drop_img.css("top").replace(/px/, ""); //取出截取框到顶部的距离
            var left = drop_img.css("left").replace(/px/, ""); //取出截取框到左边的距离
            drop_img.css({ left: (parseInt(self.position.left) - LEFT_EDGE) + "px", top: (parseInt(self.position.top) - TOP_EDGE) + "px" }); //同时移动内部的图片
            $("#txt_left").val(0 - (parseInt(self.position.left) - LEFT_EDGE));
            $("#txt_top").val(0 - (parseInt(self.position.top) - TOP_EDGE));
        }

    }
    );

    //缩放的代码，要缩放以截取框为中心，所以要重新计算图片的left和top
    $(".child").draggable(
  {
      cursor: "move", containment: $("#bar"),
      drag: function(e, ui) {
      var left = parseInt($(this).css("left"));
          //前面讲过了y=factor（x），此处是知道x求y的值，即知道滑动条的位置，获取缩放率
          scaleFactor = Math.pow(factor, (left / 100 - 1));
          if (scaleFactor < minFactor) {
              scaleFactor = minFactor;
          }
          if (scaleFactor > factor) {
              scaleFactor = factor;
          }
          //以下代码同初始化过程，因为用到局部变量所以没有
          var iconElement = $("#ImageIcon");
          var imagedrag = $("#ImageDrag");

          var image = new Image();
          image.src = iconElement.attr("src");
          var realWidth = image.width;
          var realHeight = image.height;
          image = null;

          //图片实际尺寸
          var currentWidth = Math.round(scaleFactor * realWidth);
          var currentHeight = Math.round(scaleFactor * realHeight);

          //图片相对CANVAS的初始位置
          var originLeft = parseInt(iconElement.css("left"));
          var originTop = parseInt(iconElement.css("top"));

          originLeft -= Math.round((currentWidth - oldWidth) / 2);
          originTop -= Math.round((currentHeight - oldHeight) / 2);
          dragleft = originLeft - LEFT_EDGE;
          dragtop = originTop - TOP_EDGE;

          //图片当前尺寸和位置
          iconElement.css({ width: currentWidth + "px", height: currentHeight + "px", left: originLeft + "px", top: originTop + "px" });
          imagedrag.css({ width: currentWidth + "px", height: currentHeight + "px", left: dragleft + "px", top: dragtop + "px" });

          $("#txt_Zoom").val(scaleFactor);
          $("#txt_left").val(0 - dragleft);
          $("#txt_top").val(0 - dragtop);
          $("#txt_width").val(currentWidth);
          $("#txt_height").val(currentHeight);
          oldWidth = currentWidth;
          oldHeight = currentHeight;

      }
  });
    var SilderSetValue = function(i) {
        var left = parseInt($(".child").css("left"));
        left += i;

        if (left < 0) {
            left = 0;
        }
        if (left > 200) {
            left = 200;
        }

        scaleFactor = Math.pow(factor, (left / 100 - 1)); 
        if (scaleFactor < minFactor) {
            scaleFactor = minFactor;
        }
        if (scaleFactor > factor) {
            scaleFactor = factor;
        }
        var iconElement = $("#ImageIcon");
        var imagedrag = $("#ImageDrag");

        var image = new Image();
        image.src = iconElement.attr("src");
        var realWidth = image.width;
        var realHeight = image.height;
        image = null;

        //图片实际尺寸
        var currentWidth = Math.round(scaleFactor * realWidth);
        var currentHeight = Math.round(scaleFactor * realHeight);

        //图片相对CANVAS的初始位置
        var originLeft = parseInt(iconElement.css("left"));
        var originTop = parseInt(iconElement.css("top"));

        originLeft -= Math.round((currentWidth - oldWidth) / 2);
        originTop -= Math.round((currentHeight - oldHeight) / 2);
        dragleft = originLeft - LEFT_EDGE;
        dragtop = originTop - TOP_EDGE;

        //图片当前尺寸和位置
        $(".child").css("left", left + "px");
        iconElement.css({ width: currentWidth + "px", height: currentHeight + "px", left: originLeft + "px", top: originTop + "px" });
        imagedrag.css({ width: currentWidth + "px", height: currentHeight + "px", left: dragleft + "px", top: dragtop + "px" });

        $("#txt_Zoom").val(scaleFactor);
        $("#txt_left").val(0 - dragleft);
        $("#txt_top").val(0 - dragtop);
        $("#txt_width").val(currentWidth);
        $("#txt_height").val(currentHeight);

        oldWidth = currentWidth;
        oldHeight = currentHeight;
    }
    //点击加减号的事件 ，滑动条一共200px，点击一下+-20px
    $("#moresmall").click(function() {
        SilderSetValue(-20);
    });
    $("#morebig").click(function() {
        SilderSetValue(20);
    });

});

 

后台的代码相对简单，上传保存，通过textbox中的参数进行图片切割，也比较简单，来看下分为两个，一个是缩放裁剪，一个原图裁剪，代码参考原文。

 public static string SaveCutPic(string pPath, string pSavedPath, int pPartStartPointX, int pPartStartPointY, int pPartWidth, int pPartHeight, int pOrigStartPointX, int pOrigStartPointY, int imageWidth, int imageHeight)
        {
             using (Image originalImg = Image.FromFile(pPath))
             {
                 if (originalImg.Width == imageWidth && originalImg.Height == imageHeight)
                 {
                     return SaveCutPic(pPath, pSavedPath, pPartStartPointX, pPartStartPointY, pPartWidth, pPartHeight,
                             pOrigStartPointX, pOrigStartPointY);
                      
                 }
                 string filename = DateTime.Now.ToString("yyyyMMddHHmmss") + ".jpg";
                 string filePath = pSavedPath + "\\" + filename;

                 Bitmap thumimg =MakeThumbnail(originalImg, imageWidth, imageHeight);
               
                 Bitmap partImg = new Bitmap(pPartWidth, pPartHeight);

                 Graphics graphics = Graphics.FromImage(partImg);
                 Rectangle destRect = new Rectangle(new Point(pPartStartPointX, pPartStartPointY), new Size(pPartWidth, pPartHeight));//目标位置
                 Rectangle origRect = new Rectangle(new Point(pOrigStartPointX, pOrigStartPointY), new Size(pPartWidth, pPartHeight));//原图位置（默认从原图中截取的图片大小等于目标图片的大小）

                 ///文字水印  
                 Graphics G = Graphics.FromImage(partImg);
                 //Font f = new Font("Lucida Grande", 6);
                 //Brush b = new SolidBrush(Color.Gray);
                 G.Clear(Color.White);
                 // 指定高质量的双三次插值法。执行预筛选以确保高质量的收缩。此模式可产生质量最高的转换图像。 
                 G.InterpolationMode = InterpolationMode.HighQualityBicubic; 
                // 指定高质量、低速度呈现。 
                 G.SmoothingMode = SmoothingMode.HighQuality;

                 graphics.DrawImage(thumimg, destRect, origRect, GraphicsUnit.Pixel);
                 //G.DrawString("Xuanye", f, b, 0, 0);
                 G.Dispose();

                 originalImg.Dispose();
                 if (File.Exists(filePath))
                 {
                     File.SetAttributes(filePath, FileAttributes.Normal);
                     File.Delete(filePath);
                 }
                 partImg.Save(filePath, ImageFormat.Jpeg);

                 partImg.Dispose();
                 thumimg.Dispose();
                 return filename;
             }
        }

        public static Bitmap MakeThumbnail(Image fromImg, int width, int height)
        {
            Bitmap bmp = new Bitmap(width, height);
            int ow = fromImg.Width;
            int oh = fromImg.Height; 

            //新建一个画板
            Graphics g = Graphics.FromImage(bmp);
         
            //设置高质量插值法
            g.InterpolationMode = InterpolationMode.High;
            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode =SmoothingMode.HighQuality;
            //清空画布并以透明背景色填充
            g.Clear(Color.Transparent);

            g.DrawImage(fromImg, new Rectangle(0, 0, width, height),
                new Rectangle(0, 0, ow, oh),
                GraphicsUnit.Pixel);

            return bmp;

       }

        public static string SaveCutPic(string pPath, string pSavedPath, int pPartStartPointX, int pPartStartPointY, int pPartWidth, int pPartHeight, int pOrigStartPointX, int pOrigStartPointY)
        {
           string filename = DateTime.Now.ToString("yyyyMMddHHmmss") + ".jpg";
           string filePath = pSavedPath + "\\" + filename;

            using (Image originalImg = Image.FromFile(pPath))
            {
                Bitmap partImg = new Bitmap(pPartWidth, pPartHeight);
                Graphics graphics = Graphics.FromImage(partImg);
                Rectangle destRect = new Rectangle(new Point(pPartStartPointX, pPartStartPointY), new Size(pPartWidth, pPartHeight));//目标位置
                Rectangle origRect = new Rectangle(new Point(pOrigStartPointX, pOrigStartPointY), new Size(pPartWidth, pPartHeight));//原图位置（默认从原图中截取的图片大小等于目标图片的大小）
                
                ///注释 文字水印  
                Graphics G = Graphics.FromImage(partImg);
                //Font f = new Font("Lucida Grande", 6);
                //Brush b = new SolidBrush(Color.Gray);
                G.Clear(Color.White);
                // 指定高质量的双三次插值法。执行预筛选以确保高质量的收缩。此模式可产生质量最高的转换图像。 
                G.InterpolationMode = InterpolationMode.HighQualityBicubic;
                // 指定高质量、低速度呈现。 
                G.SmoothingMode = SmoothingMode.HighQuality; 

                graphics.DrawImage(originalImg, destRect, origRect, GraphicsUnit.Pixel);
                //G.DrawString("Xuanye", f, b, 0, 0);
                G.Dispose();

                originalImg.Dispose();
                if (File.Exists(filePath))
                {
                    File.SetAttributes(filePath, FileAttributes.Normal);
                    File.Delete(filePath);
                }
                partImg.Save(filePath, ImageFormat.Jpeg);
                partImg.Dispose();
            }
            return filename;
        }
       
    }

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