C# 从BLOB转换图像后,如何调整图像大小?
我正在尝试在从数据库中的BLOB转换回图像后,调整通用处理程序中的图像服务器端的大小…这是我的处理程序代码:C# 从BLOB转换图像后,如何调整图像大小?,c#,.net,resize,blob,generic-handler,C#,.net,Resize,Blob,Generic Handler,我正在尝试在从数据库中的BLOB转换回图像后,调整通用处理程序中的图像服务器端的大小…这是我的处理程序代码: <%@ WebHandler Language="C#" Class="Image" %> using System; using System.Web; using System.Data; using System.Data.SqlClient; using System.IO; public class Image : IHttpHandler { pub
<%@ WebHandler Language="C#" Class="Image" %>
using System;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.IO;
public class Image : IHttpHandler {
public void ProcessRequest (HttpContext context) {
Guid id = new Guid(context.Request.QueryString["Id"]);
int column = 7;
if (context.Request.QueryString["img"] == "tbn")
{
column = 6;
}
context.Response.ContentType = "image/png";
MemoryStream strm = new MemoryStream(returnImage(id, column));
byte[] buffer = new byte[4096];
int byteSeq = strm.Read(buffer, 0, 4096);
while (byteSeq > 0)
{
context.Response.OutputStream.Write(buffer, 0, byteSeq);
byteSeq = strm.Read(buffer, 0, 4096);
}
}
public Byte[] returnImage(Guid id, int column)
{
SqlConnection sqlCn = new SqlConnection("Data Source=localhost;Initial Catalog=database;User ID=user;Password=password");
string qry = "SELECT * FROM Project WHERE Id=@id";
SqlCommand cmd = new SqlCommand(qry, sqlCn);
cmd.Parameters.Add("@id", SqlDbType.UniqueIdentifier).Value = id;
sqlCn.Open();
SqlDataReader dr = cmd.ExecuteReader();
dr.Read();
Byte[] ar = (Byte[])(dr[column]);
dr.Close();
cmd.Dispose();
sqlCn.Close();
return ar;
}
public bool IsReusable {
get {
return false;
}
}
}
使用制度;
使用System.Web;
使用系统数据;
使用System.Data.SqlClient;
使用System.IO;
公共类映像:IHttpHandler{
公共void ProcessRequest(HttpContext上下文){
Guid id=新Guid(context.Request.QueryString[“id”]);
int列=7;
if(context.Request.QueryString[“img”]=“tbn”)
{
列=6;
}
context.Response.ContentType=“image/png”;
MemoryStream strm=新的MemoryStream(返回图像(id,列));
字节[]缓冲区=新字节[4096];
int byteSeq=strm.Read(缓冲区,04096);
while(byteSeq>0)
{
context.Response.OutputStream.Write(缓冲区,0,字节相等);
byteSeq=strm.Read(缓冲区,04096);
}
}
公共字节[]返回图像(Guid id,int列)
{
SqlConnection sqlCn=newsqlconnection(“数据源=localhost;初始目录=database;用户ID=User;密码=Password”);
string qry=“从项目中选择*,其中Id=@Id”;
SqlCommand cmd=新的SqlCommand(qry,sqlCn);
cmd.Parameters.Add(“@id”,SqlDbType.UniqueIdentifier).Value=id;
sqlCn.Open();
SqlDataReader dr=cmd.ExecuteReader();
里德博士();
字节[]ar=(字节[])(dr[列]);
Close博士();
cmd.Dispose();
sqlCn.Close();
返回ar;
}
公共布尔可重用{
得到{
返回false;
}
}
}
它应该查看图像宽度是否高于其高度,反之亦然,并根据设置的高度或宽度以及其他值(高度/宽度)应按比例设置,以便不会拉伸
我发现的是:
但我真的不知道如何使用它…有什么建议吗?提前谢谢你的帮助 这可能有点冗长,但对我来说很有效。给定blob中的内存流,加上目标宽度和高度维度,它将返回一个新的流,其中包含图像的大小调整副本
public static Stream CreateThumbnail(Stream input, Int32 targetWidth, Int32 targetHeight)
{
output = new MemoryStream();
using (Bitmap bitmap = new Bitmap(input))
{
ImageFormat format = bitmap.RawFormat;
Boolean isJpeg = (format.Equals(ImageFormat.Jpeg));
Boolean isPng = (format.Equals(ImageFormat.Png));
Int32 width = bitmap.Width;
Int32 height = bitmap.Height;
getTargetSizes(out width, out height, bitmap, targetWidth, targetHeight);
using (Bitmap thumbnailBitmap = new Bitmap(width, height))
{
Graphics G = Graphics.FromImage(thumbnailBitmap);
G.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
G.DrawImage(bitmap, 0, 0, width, height);
thumbnailBitmap.SetResolution(72, 72);
if (isJpeg)
{
var codecParams = new EncoderParameters(1);
codecParams.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 80L);
ImageCodecInfo[] arrayICI;
ImageCodecInfo jpegICI = null;
arrayICI = ImageCodecInfo.GetImageEncoders();
for (int i = 0; i < arrayICI.Length; i++)
{
if (arrayICI[i].FormatDescription.Equals("JPEG"))
{
jpegICI = arrayICI[i];
break;
}
}
thumbnailBitmap.Save(output, jpegICI, codecParams);
}
else
{
thumbnailBitmap.Save(output, ImageFormat.Png);
}
}
}
return output;
}
private static void getTargetSizes(out Int32 targetWidth, out Int32 targetHeight, Bitmap BM, Int32 maxWidth = 150, Int32 maxHeight = 150)
{
Int32 startWidth = BM.Width;
Int32 startHeight = BM.Height;
targetWidth = startWidth;
targetHeight = startHeight;
Boolean resizeByWidth = false;
Boolean resizeByHeight = false;
if ((maxWidth > 0) && (maxHeight > 0))
{
if ((startWidth > maxWidth) || (startHeight > maxHeight))
{
if (startHeight <= startWidth)
{
if(targetWidth > maxWidth) resizeByWidth = true;
}
else
{
if(targetHeight > maxHeight) resizeByHeight = true;
}
}
}
else if (maxWidth > 0)
{
// Resize within width only
if (startWidth > maxWidth)
{
if (targetWidth > maxWidth) resizeByWidth = true;
}
}
else if (maxHeight > 0)
{
// Resize by height only
if (startHeight > maxHeight)
{
if (targetHeight > maxHeight) resizeByHeight = true;
}
}
if (resizeByWidth)
{
targetWidth = maxWidth;
targetHeight = (Int32)(startHeight * ((Decimal)targetWidth / (Decimal)startWidth));
}
if (resizeByHeight)
{
targetHeight = maxHeight;
targetWidth = (Int32)(startWidth * ((Decimal)targetHeight / (Decimal)startHeight));
}
}
}
嗯……这段代码非常庞大:)而且非常混乱……我该如何在我的代码中使用它呢?代码可以变得更紧凑,我同意你——我刚从一个旧项目中获取了它,我没有时间为你重写它。您可以通过调用第一个函数来使用它,将内存流、图像大小调整到的宽度和高度传递给它,然后将结果放回内存流。我将添加一个示例。
MemoryStream strm = new MemoryStream(returnImage(id, column));
strm = CreateThumbnail(strm, 100, 100);