如何从选择查询中检索保存的图像作为缩略图？ [英] How to retrieve saved image as thumbnail from select query ?

问题描述

DataTable dt3 = dbo.GetRecordsWithQuery（选择id，'''作为url，图像，''''作为拇指从图像顺序通过id desc）;



for（int i = 0; i< dt3.Rows.Count; i ++）

{

byte [] val =（byte []）dt3 .Rows [i] [2];

MemoryStream ms = new MemoryStream（val）;



System.Drawing.Image newImage = System .Drawing.Image.FromStream（ms）;

newImage.Save（Server.MapPath（〜/ Images / temp / img+ i.ToString（）+.jpg））;

dt3.Rows [i] [1] =Images / temp / img+ i.ToString（）+.jpg;











}





在这里，我将保存的图像检索为图像网址。但我不知道如何检索缩略图..任何人都可以帮助我吗？



提前谢谢：）

DataTable dt3 = dbo.GetRecordsWithQuery("select id,'''' as url,image,'''' as thumb from Image order by id desc");

for (int i = 0; i < dt3.Rows.Count; i++)
{
byte[] val = (byte[])dt3.Rows[i][2];
MemoryStream ms = new MemoryStream(val);

System.Drawing.Image newImage = System.Drawing.Image.FromStream(ms);
newImage.Save(Server.MapPath("~/Images/temp/img" + i.ToString() + ".jpg"));
dt3.Rows[i][1] = "Images/temp/img" + i.ToString() + ".jpg";





}


Here i retrieve saved image as image url. But i didnt know how to retrieve as thumbnail.. Can anyone help me ?

Thanks in advance :)

推荐答案

就我所知，你可以'通过SQL查询将其转换为缩略图，您必须在保存它时将其转换为应用程序代码（例如，除了完整大小之外还保存缩略图版本）或从数据库中检索它之后。对于这些类型的任务我找到 ImageMagick [ ^ ]很有用。具体来说，这是一个关于生成缩略图的页面 [ ^ ]。

As far as I''m aware, you can''t convert it to a thumbnail via SQL query, you have to convert it your application code either when you save it (e.g. save it with a thumbnail version in addition to the full size) or after you retrieve it from the database. For these sorts of tasks I find ImageMagick[^] to be useful. And specifically, here''s a page on generating thumbails[^].

Hello。



您可以使用

Hello.

you can use

Image.GetThumbnailImage Method

来执行此任务。

请参阅MSDN：

http://msdn.microsoft.com/en-us/library/system.drawing.image.getthumbnailimage.aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-2 [ ^ ]



这是你可以做的代码示例：

to perform this task.
see MSDN here:
http://msdn.microsoft.com/en-us/library/system.drawing.image.getthumbnailimage.aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-2[^]

that''s a code example of what you could do:

public bool ThumbnailCallback()
{
    return false;
}

//your code below...

DataTable dt3 = dbo.GetRecordsWithQuery("select id,'''' as url,image,'''' as thumb from Image order by id desc");
 
for (int i = 0; i < dt3.Rows.Count; i++)
{
    byte[] val = (byte[])dt3.Rows[i][2];
    MemoryStream ms = new MemoryStream(val);
 
    System.Drawing.Image newImage = System.Drawing.Image.FromStream(ms);

    newImage.Save(Server.MapPath("~/Images/temp/img" + i.ToString() + ".jpg"));
    dt3.Rows[i][1] = "Images/temp/img" + i.ToString() + ".jpg";

    // get thumbnail
    Image.GetThumbnailImageAbort myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
    Image myThumbnail = newImage.GetThumbnailImage(40, 40, myCallback, IntPtr.Zero);
    e.Graphics.DrawImage(myThumbnail, 150, 75);

    // save thumbnail
    myThumbnail .Save(Server.MapPath("~/Images/temp/thumb" + i.ToString() + ".jpg"));
}

Valery。

Valery.

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