using System;
using System.Collections.Generic;
using System.Web;
using System.Drawing.Imaging;
using System.Drawing;
/// <SUMMARY>
///MakeThum 的摘要说明
/// </SUMMARY>
public class MakeThum
{
public MakeThum()
{
//
//TODO: 在此处添加构造函数逻辑
//
}
/// <SUMMARY>
/// 生成缩略图//带压缩图片不压缩22k压缩2k
/// </SUMMARY>
/// <PARAM name="originalImagePath" />原始路径
/// <PARAM name="thumbnailPath" />生成缩略图路径
/// <PARAM name="width" />缩略图的宽
/// <PARAM name="height" />缩略图的高
//是否压缩图片质量
public void MakeThumbnail(
string originalImagePath,
string thumbnailPath,
int width,
int height,
bool Ys)
{
//获取原始图片
System.Drawing.Image originalImage =
System.Drawing.Image.FromFile(originalImagePath);
//缩略图画布宽高
int towidth =
width;
int toheight =
height;
//原始图片写入画布坐标和宽高(用来设置裁减溢出部分)
int x =
0;
int y =
0;
int ow =
originalImage.Width;
int oh =
originalImage.Height;
//原始图片画布,设置写入缩略图画布坐标和宽高(用来原始图片整体宽高缩放)
int bg_x =
0;
int bg_y =
0;
int bg_w =
towidth;
int bg_h =
toheight;
//倍数变量
double multiple =
0;
//获取宽长的或是高长与缩略图的倍数
if (originalImage.Width >=
originalImage.Height)
multiple = (
double)originalImage.Width / (
double)width;
else
multiple = (
double)originalImage.Height / (
double)height;
//上传的图片的宽和高小等于缩略图
if (ow <= width && oh <=
height)
{
//缩略图按原始宽高
bg_w =
originalImage.Width;
bg_h =
originalImage.Height;
//空白部分用背景色填充
bg_x = Convert.ToInt32(((
double)towidth - (
double)ow) /
2);
bg_y = Convert.ToInt32(((
double)toheight - (
double)oh) /
2);
}
//上传的图片的宽和高大于缩略图
else
{
//宽高按比例缩放
bg_w = Convert.ToInt32((
double)originalImage.Width /
multiple);
bg_h = Convert.ToInt32((
double)originalImage.Height /
multiple);
//空白部分用背景色填充
bg_y = Convert.ToInt32(((
double)height - (
double)bg_h) /
2);
bg_x = Convert.ToInt32(((
double)width - (
double)bg_w) /
2);
}
//新建一个bmp图片,并设置缩略图大小.
System.Drawing.Image bitmap =
new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
System.Drawing.Graphics g =
System.Drawing.Graphics.FromImage(bitmap);
//设置高质量插值法
g.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode =
System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并设置背景色
g.Clear(System.Drawing.ColorTranslator.FromHtml(
"#FFF"));
//在指定位置并且按指定大小绘制原图片的指定部分
//第一个System.Drawing.Rectangle是原图片的画布坐标和宽高,第二个是原图片写在画布上的坐标和宽高,最后一个参数是指定数值单位为像素
g.DrawImage(originalImage,
new System.Drawing.Rectangle(bg_x, bg_y, bg_w, bg_h),
new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);
if (Ys)
{
System.Drawing.Imaging.ImageCodecInfo encoder = GetEncoderInfo(
"image/jpeg");
try
{
if (encoder !=
null)
{
System.Drawing.Imaging.EncoderParameters encoderParams =
new System.Drawing.Imaging.EncoderParameters(
1);
//设置 jpeg 质量为 60
encoderParams.Param[
0] =
new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (
long)
60);
bitmap.Save(thumbnailPath, encoder, encoderParams);
encoderParams.Dispose();
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
else
{
try
{
//获取图片类型
string fileExtension =
System.IO.Path.GetExtension(originalImagePath).ToLower();
//按原图片类型保存缩略图片,不按原格式图片会出现模糊,锯齿等问题.
switch (fileExtension)
{
case ".gif": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif);
break;
case ".jpg": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case ".bmp": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp);
break;
case ".png": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png);
break;
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
}
private System.Drawing.Imaging.ImageCodecInfo GetEncoderInfo(
string mimeType)
{
//根据 mime 类型，返回编码器
System.Drawing.Imaging.ImageCodecInfo result =
null;
System.Drawing.Imaging.ImageCodecInfo[] encoders =
System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();
for (
int i =
0; i < encoders.Length; i++
)
{
if (encoders[i].MimeType ==
mimeType)
{
result =
encoders[i];
break;
}
}
return result;
}
}
if (FileUpload1.HasFile)
{
string _fileName =
FileUpload1.FileName;
string _fileExt =
System.IO.Path.GetExtension(_fileName);
string _webRoot = Server.MapPath(
"~");
string _imgOriginPath = _webRoot +
"/newimage/" + Guid.NewGuid().ToString() +
_fileExt;
FileUpload1.SaveAs(_imgOriginPath);
new MakeThum().MakeThumbnail(_imgOriginPath, _webRoot +
"/newimage/" + DateTime.Now.ToString(
"yyyyMMddHHmmssffff") +
_fileExt,
100,
100,
false);
new MakeThum().MakeThumbnail(_imgOriginPath, _webRoot +
"/newimage/ys" + DateTime.Now.ToString(
"yyyyMMddHHmmssffff") +
_fileExt,
100,
100,
true);
}
转载于:https://www.cnblogs.com/daixingqing/p/3325859.html
相关资源：android经典图片压缩算法 永不失真
