Question

我正在尝试在我的通用处理程序中将图像服务器端调整为从数据库中的BLOB转换回图像... ...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 {

    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;
        }
    }

}

应该看图像宽度高于其高度而相反，根据设置高度或宽度，另一个值（高度/宽度）应按比例设置，以免拉伸。

我发现的是：http://www.codeproject.com/Articles/25838/A-Simple-Image-Handler

但我真的不知道如何使用它...有什么建议吗？感谢您提前获得所有帮助！

Answer 1

这可能有点啰嗦，但它对我有用。给定来自blob的内存流，加上目标宽度和高度尺寸，它将返回一个带有调整大小的图像副本的新流。

 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));
        }
    }
}

并用以下内容称呼它：

MemoryStream strm = new MemoryStream(returnImage(id, column));
strm = CreateThumbnail(strm, 100, 100);

如何从BLOB转换图像后调整图像大小？

1 个答案: