如何在保存到数据库之前重新调整图像大小？

Question

我在使用vb.net保存为blob数据类型之前在重新调整图像大小方面存在问题。我不知道如何调整图像大小。

这里是我的代码中插入：

 Dim FileSize As UInt32 

    Dim mstream As New System.IO.MemoryStream() 
    pic_box_save.Image.Save(mstream, System.Drawing.Imaging.ImageFormat.Jpeg) 
    Dim arrImage() As Byte = mstream.GetBuffer() 
    FileSize = mstream.Length 
    mstream.Close() 
    MsgBox(FileSize) 


    Try 
     sql = "INSERT INTO clientreports(report_id, img) VALUES(@image_id, @image_data)" 
     sql_command = New MySqlCommand(SQL, sql_connection) 
     sql_command.Parameters.AddWithValue("@image_id", Nothing) 
     sql_command.Parameters.AddWithValue("@image_data", arrImage) 


     sql_command.ExecuteNonQuery() 
    Catch ex As Exception 
     MsgBox(ex.Message) 
     Exit Sub 
    End Try 

    MsgBox("Image has been saved.") 

请帮我家伙如果有人知道如何解决这个问题。谢谢！

Answer 1

要创建缩略图/调整图像：

Friend Function GetImageThumb(ByVal orgBmp As BitMap, 
        ByVal w as Int32, h as Int32) As Bitmap 

    Dim thumb As New Bitmap(w, h) 

    Using g As Graphics = Graphics.FromImage(thumb) 
     g.DrawImage(orgBmp , 0, 0, w + 1, h + 1) 
    End Using 
    Return thumb 
End Function 

对于数据存储，你可能需要将图像转换到别的东西像一个Base64字符串或字节数组。

Answer 2

您可以使用以下代码来调整具有特定要求的图像大小。如果有必要，即使您可以保持宽高比。

Public Shared Function ResizeImage(ByVal pImage As Drawing.Image, ByVal pWidth As Integer, ByVal pHeight As Integer, Optional ByVal pPreserveAspectRatio As Boolean = True, Optional ByVal pIsImageDisposeRequired As Boolean = True) As Drawing.Image 
       Dim iNewWidth As Integer 
       Dim iNewHeight As Integer 
       Dim oNewImage As System.Drawing.Image 
       Dim originalWidth As Integer 
       Dim originalHeight As Integer 
       Dim oPercentWidth As Single 
       Dim oPercentHeight As Single 
       Dim oPercent As Single 

       Try 
        If pPreserveAspectRatio Then 
         originalWidth = pImage.Width 
         originalHeight = pImage.Height 
         oPercentWidth = CSng(pWidth)/CSng(originalWidth) 
         oPercentHeight = CSng(pHeight)/CSng(originalHeight) 
         oPercent = If(oPercentHeight < oPercentWidth, oPercentHeight, oPercentWidth) 
         iNewWidth = CInt(originalWidth * oPercent) 
         iNewHeight = CInt(originalHeight * oPercent) 
        Else 
         iNewWidth = pWidth 
         iNewHeight = pHeight 
        End If 

        oNewImage = New System.Drawing.Bitmap(iNewWidth, iNewHeight) 
        Using oGraphicsHandle As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(oNewImage) 
         oGraphicsHandle.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic 
         oGraphicsHandle.DrawImage(pImage, 0, 0, iNewWidth, iNewHeight) 
        End Using 

        If pIsImageDisposeRequired Then 
         pImage.Dispose() 
        End If 

        Return oNewImage 
       Catch ex As Exception 
        eCP.Excpetion.Untility.CommonUtils.WriteExceptionToFile(ex.Message, eCP.Excpetion.Untility.CommonUtils.LogFileTypes.Host) 
        Return pImage 
       End Try 
      End Function 

随意询问是否有任何混淆。