JPG图片处理［已解决］ - Office中国论坛/Access中国论坛

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="originalImagePath">源图路径（物理路径）</param>
/// <param name="thumbnailPath">缩略图路径（物理路径）</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</param>
public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (mode)
{
case "HW"://指定高宽缩放（可能变形）
break;
case "W"://指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H"://指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut"://指定高宽裁减（不变形）
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else
{
ow = originalImage.Width;
oh = originalImage.Width * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
default:
break;
}
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并以透明背景色填充
g.Clear(Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow, oh),
GraphicsUnit.Pixel);
try
{
//以jpg格式保存缩略图
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}

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Imports System
Imports System.Data
Imports System.Configuration
Imports System.Collections
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports System.Drawing
'''<summary>
'''生成缩略图
'''</summary>
'''<param name="originalImagePath">源图路径（物理路径）</param>
'''<param name="thumbnailPath">缩略图路径（物理路径）</param>
'''<param name="width">缩略图宽度</param>
'''<param name="height">缩略图高度</param>
'''<param name="mode">生成缩略图的方式</param>
Sub MakeThumbnail(ByVal originalImagePath As String, ByVal thumbnailPath As String, ByVal width As Integer, ByVal height As Integer, ByVal mode As String)
Dim originalImage As System.Drawing.Image = System.Drawing.Image.FromFile(originalImagePath)
Dim towidth As Integer = width
Dim toheight As Integer = height
Dim x As Integer = 0
Dim y As Integer = 0
Dim ow As Integer = originalImage.Width
Dim oh As Integer = originalImage.Height
Select Case mode
Case "HW" '指定高宽缩放（可能变形）
Case "W" '指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width
Case "H" '指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height
Case "Cut" '指定高宽裁减（不变形）
If CDbl(originalImage.Width) / CDbl(originalImage.Height) > CDbl(towidth) / CDbl(toheight) Then
oh = originalImage.Height
ow = originalImage.Height * towidth / toheight
y = 0
x = (originalImage.Width - ow) / 2
Else
ow = originalImage.Width
oh = originalImage.Width * height / towidth
x = 0
y = (originalImage.Height - oh) / 2
End If
Case Else
End Select
'新建一个bmp图片
Dim bitmap As New System.Drawing.Bitmap(towidth, toheight)
'新建一个画板
Dim g As Graphics = System.Drawing.Graphics.FromImage(bitmap)
'设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High
'设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality
'清空画布并以透明背景色填充
g.Clear(Color.Transparent)
'在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, New Rectangle(0, 0, towidth, toheight), New Rectangle(x, y, ow, oh), GraphicsUnit.Pixel)
Try
'以jpg格式保存缩略图
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg)
Catch e As System.Exception
Throw e
Finally
originalImage.Dispose()
bitmap.Dispose()
g.Dispose()
End Try
End Sub

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