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ImageLockMode Enumeration

Specifies flags that are passed to the flags parameter of the LockBits method. The LockBits method locks a portion of an image so that you can read or write the pixel data.

Namespace:  System.Drawing.Imaging
Assembly:  System.Drawing (in System.Drawing.dll)

'Declaration
Public Enumeration ImageLockMode
'Usage
Dim instance As ImageLockMode

Member nameDescription
Supported by the .NET Compact FrameworkReadOnlySpecifies that a portion of the image is locked for reading.
Supported by the .NET Compact FrameworkWriteOnlySpecifies that a portion of the image is locked for writing.
Supported by the .NET Compact FrameworkReadWriteSpecifies that a portion of the image is locked for reading or writing.
UserInputBufferSpecifies that the buffer used for reading or writing pixel data is allocated by the user. If this flag is set, the flags parameter of the LockBits method serves as an input parameter (and possibly as an output parameter). If this flag is cleared, then the flags parameter serves only as an output parameter.

The following code example demonstrates how to use the PixelFormat, Height, Width, and Scan0 properties; the LockBits and UnlockBits methods; and the ImageLockMode enumeration. This example is designed to be used with Windows Forms. To run this example, paste it into a form and handle the form's Paint event by calling the LockUnlockBitsExample method, passing e as PaintEventArgs.

Private Sub LockUnlockBitsExample(ByVal e As PaintEventArgs)

    ' Create a new bitmap. 
    Dim bmp As New Bitmap("c:\fakePhoto.jpg")

    ' Lock the bitmap's bits.   
    Dim rect As New Rectangle(0, 0, bmp.Width, bmp.Height)
    Dim bmpData As System.Drawing.Imaging.BitmapData = bmp.LockBits(rect, _
        Drawing.Imaging.ImageLockMode.ReadWrite, bmp.PixelFormat)

    ' Get the address of the first line. 
    Dim ptr As IntPtr = bmpData.Scan0

    ' Declare an array to hold the bytes of the bitmap. 
    ' This code is specific to a bitmap with 24 bits per pixels. 
    Dim bytes As Integer = bmpData.Stride * bmp.Height
    Dim rgbValues(bytes - 1) As Byte

    ' Copy the RGB values into the array.
    System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes)

    ' Set every third value to 255. A 24bpp image will look red. 
    For counter As Integer = 2 To rgbValues.Length - 1 Step 3
        rgbValues(counter) = 255
    Next 

    ' Copy the RGB values back to the bitmap
    System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes)

    ' Unlock the bits.
    bmp.UnlockBits(bmpData)

    ' Draw the modified image.
    e.Graphics.DrawImage(bmp, 0, 150)

End Sub

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0
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