Jquery+ASP.NET 实现开心网上传头像剪裁功能

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;
}

}

转自：http://www.cnblogs.com/xuanye/archive/2008/09/25/1299091.html