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Detect Image is Upside Down

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2 Jun 2014 1  
Check image is upside down in VisualBasic.NET

Introduction

The following function may used to detect if an image is upside down or not.
The function will check the BitmapData.Stride value and returned value is of a Boolean type and if the returned value of BitmapData.Stride is greater than zero...then the bitmap is upside down. For further details about BitmapData class, please check this link.

Function

//   ''' <summary>
   ''' Check image is upside down 
    ''' </summary>
    ''' <param name="originalBitmap">bitmap</param> 
    ''' <returns>True, if the image is upside dwn</returns> 
    ''' <remarks></remarks> 
    Private Function IsUpSideDownBitmap(originalBitmap As Bitmap) As Boolean 
        Dim bmp As Bitmap = CType(originalBitmap.Clone(), Bitmap) 
        Dim rect As Rectangle = New Rectangle(0, 0, bmp.Width, bmp.Height) 
        Dim bmpData As Imaging.BitmapData = bmp.LockBits
        (rect, Imaging.ImageLockMode.ReadOnly, Imaging.PixelFormat.Format32bppArgb) 
        Return originalBitmap IsNot Nothing AndAlso bmpData.Stride > 0 
    End Function 

Using the Code

        ' Define any image
        Dim bmp As New Bitmap(My.Resources._29322)
       ' check image, the function shall return true if the image is upside down
        If IsUpSideDownBitmap(bmp) Then
            ' do something like rotate the image or do not draw it
            ' the image will drawn becuase the function return True
            e.Graphics.DrawImage(bmp, 0, 0)
        End If

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