Bitmap.UnlockBits Method
Unlocks this Bitmap from system memory.
Assembly: System.Drawing (in System.Drawing.dll)
'Declaration Public Sub UnlockBits ( _ bitmapdata As BitmapData _ ) 'Usage Dim instance As Bitmap Dim bitmapdata As BitmapData instance.UnlockBits(bitmapdata)
Parameters
- bitmapdata
- Type: System.Drawing.Imaging.BitmapData
A BitmapData specifying information about the lock operation.
| Exception | Condition |
|---|---|
| Exception | The operation failed. |
The BitmapData specifies the attributes of the Bitmap, such as size, pixel format, the starting address of the pixel data in memory, and length of each scan line (stride).
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.