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Bitmap.UnlockBits Method

Unlocks this Bitmap from system memory.

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

public void UnlockBits(
	BitmapData bitmapdata
)

Parameters

bitmapdata
Type: System.Drawing.Imaging.BitmapData

A BitmapData specifying information about the lock operation.

ExceptionCondition
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 void LockUnlockBitsExample(PaintEventArgs e)
        {

            // Create a new bitmap.
            Bitmap bmp = new Bitmap("c:\\fakePhoto.jpg");

            // Lock the bitmap's bits.  
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            System.Drawing.Imaging.BitmapData bmpData =
                bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite,
                bmp.PixelFormat);

            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;

            // Declare an array to hold the bytes of the bitmap. 
            int bytes  = bmpData.Stride * bmp.Height;
���         byte[] rgbValues = new byte[bytes];

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

            // Set every third value to 255. A 24bpp bitmap will look red.   
            for (int counter = 2; counter < rgbValues.Length; counter += 3)
                rgbValues[counter] = 255;

            // 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);

        }

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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