.net 实现修改图片大小

做了个在上传图片的时候,自动修改图片大小的功能,其实一开始是想做类似京东商城的放大镜,然后发现做那样的需要相同的图片大小不同的的三张,于是想到是不是可以再上传图片的时候只上传一张,自动生成三张大小的图片,最后就做了这个功能!

#region 图片上传

/// <summary>
/// 图片上传0
/// </summary>
/// <returns></returns>
private string Upload_Images0()
{
Boolean fileOK = false;
string imageFile = "";
String path = Server.MapPath("~/adpic/"); //设置服务器上传的路径,即文件上传的位置
if (fulImage.PostedFile.ContentLength / 1024 < 2000)
{
if (fulImage.HasFile)
{
//获取上传文件类型
String fileExtension = System.IO.Path.GetExtension(fulImage.FileName).ToLower();
//判断允许上传图片类型
String[] allowedExtensions = { ".gif", ".png", ".jpeg", ".jpg" };
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (fileExtension == allowedExtensions[i])
{
fileOK = true;
break;
}
}

if (fileOK)
{
try
{
//把当前时间取出,组成字符串,加入文件名称,防止重复命名
string fileName = DateTime.Now.ToString().Replace("-", "").Replace(" ", "").Replace(":", "").Replace("/", "") + fulImage.FileName;
fulImage.PostedFile.SaveAs(path + fileName);
imageFile = "adpic/" + fileName;

//自动生成小图
MakeThumNail(path + fileName, Server.MapPath("~/imagess/") + fileName, 600, 500, "W");

//自动生成小图
MakeThumNail(path + fileName, Server.MapPath("~/image/") + fileName, 100, 50, "W");
//自动生成中图
MakeThumNail(path + fileName, Server.MapPath("~/images/") + fileName, 200, 50, "W");

//删除原图
System.IO.File.Delete(path + fileName);
}
catch (Exception e)
{
Response.Write("<script>alert('对不起,图片不能上传!')</script>");
}
}
else
{
Response.Write("<script>alert('对不起,不能接受这种文件类型!')</script>");
}
}

}
else
{
Response.Write("<script>alert('对不起,图片过大不能上传!')</script>");
}
return imageFile;
}

#endregion

# region 图片处理

/// <summary>
/// 缩放图像
/// </summary>
/// <param name="originalImagePath">图片原始路径</param>
/// <param name="thumNailPath">保存路径</param>
/// <param name="width">缩放图的宽</param>
/// <param name="height">缩放图的高</param>
/// <param name="model">缩放模式</param>
public static void MakeThumNail(string originalImagePath, string thumNailPath, int width, int height, string model)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

int thumWidth = width; //缩略图的宽度
int thumHeight = height; //缩略图的高度

int x = 0;
int y = 0;

int originalWidth = originalImage.Width; //原始图片的宽度
int originalHeight = originalImage.Height; //原始图片的高度

switch (model)
{
case "HW": //指定高宽缩放,可能变形
break;
case "W": //指定宽度,高度按照比例缩放
thumHeight = originalImage.Height * width / originalImage.Width;
break;
case "H": //指定高度,宽度按照等比例缩放
thumWidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut":
if ((double)originalImage.Width / (double)originalImage.Height > (double)thumWidth / (double)thumHeight)
{
originalHeight = originalImage.Height;
originalWidth = originalImage.Height * thumWidth / thumHeight;
y = 0;
x = (originalImage.Width - originalWidth) / 2;
}
else
{
originalWidth = originalImage.Width;
originalHeight = originalWidth * height / thumWidth;
x = 0;
y = (originalImage.Height - originalHeight) / 2;
}
break;
default:
break;
}

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(thumWidth, thumHeight);

//新建一个画板
System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量查值法
graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
graphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
graphic.Clear(System.Drawing.Color.Transparent);

//在指定位置并且按指定大小绘制原图片的指定部分
graphic.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, thumWidth, thumHeight), new System.Drawing.Rectangle(x, y, originalWidth, originalHeight), System.Drawing.GraphicsUnit.Pixel);

try
{
bitmap.Save(thumNailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (Exception ex)
{
throw ex;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
graphic.Dispose();
}
}

# endregion

 

posted @ 2011-12-26 16:18  日月当空  阅读(4926)  评论(0编辑  收藏  举报