Invalid parameter when retrieving image from DB

问题:

In the end I want to grab a OLE type image from an Access Database and put it into a picture box. Working with Visual Studio 2012 in C# and MS Access 2010. My solution is an app non-web related.

So this is the query code. I'm constructing an object (Equipamento) with among others an System.Drawing.Image attribute that is the focus of the issue.

OleDbConnection l = OleDbConnectionDAO.createConnection();
Equipamento eq = new Equipamento();

try
{
    OleDbDataAdapter adapter = new OleDbDataAdapter(
        "SELECT * FROM [APP_Equipamento_Geral] WHERE COD_ETIQ like '%"
           + codigo
           + " %'",
        l);
    DataSet ds = new DataSet();
    adapter.Fill(ds, "[APP_Equipamento_Geral]");
    string s = ds.Tables["[APP_Equipamento_Geral]"].Columns[16].ColumnName;
    foreach (DataRow row in ds.Tables["[APP_Equipamento_Geral]"].Rows)
    {                
        eq.NInventario = row["Codigo"].ToString();
        eq.Modelo = row["MODELO"].ToString();
        eq.Marca = row["Marca_"].ToString();
        eq.GamaMedida = row["Gama Medida"].ToString();

        if (row["FOTO"] != DBNull.Value && row["FOTO"] != null)
        {
            byte[] b = new byte[0];
            b = (byte[])row["FOTO"];

            eq.Img = getImageFromBytes(b);//Error caught here
        } 


        //if (row["FOTO"] != DBNull.Value && row["FOTO"] != null)
        //{
        //    byte[] b = (byte[])row["FOTO"];
        //    MemoryStream ms = new MemoryStream(b);
        //    eq.Img = Image.FromStream(ms);  //Error caught here
        //} 
    }
}

And here is the auxiliary method:

private Image getImageFromBytes(byte[] myByteArray)
{
    System.IO.MemoryStream newImageStream
        = new System.IO.MemoryStream(myByteArray, 0, myByteArray.Length);\

    return Image.FromStream(newImageStream, true);
}

That last commented piece of code was another of my attempts that also gave the

Invalid parameter

error. Any solutions?

Note: If I take out the image part everything works fine.

回答1:

An image stored as an OLE object has a different format from a serialized System.Drawing.Image. That's why I asked how the images were stored.

While I cannot vouch for this, never having used it personally, the following code is much recommended. Supposedly, it uses the GDI+ lib from MS (included in Win standard installation) to import/export pics to/from Access OLE.

http://www.access-im-unternehmen.de/index1.php?BeitragID=337&id=300

You can find other suggestions (including a utility to extract your images from Access) at this link:

Converting MS Access "OLE Objects" back to plain JPEGs - best way?

回答2:

You can't convert a image or string to arraybite only using the cast.

If you want convert an image to arrayBite use this function

public byte[] imageToByteArray(System.Drawing.Image imageIn)
{
    MemoryStream ms = new MemoryStream();
    imageIn.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
    return ms.ToArray();
}

to reconvert arraybite to image use this

public Image byteArrayToImage(byte[] byteArrayIn)
{
    MemoryStream ms = new MemoryStream(byteArrayIn);
    Image returnImage = Image.FromStream(ms);
    return returnImage;
}