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自己根据实际需要更改一下:
C#
- 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();
- }
- }
复制代码
VB.Net
- 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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