Bitmap.UnlockBits(BitmapData) 方法

定義

從系統記憶體解除鎖定這個 BitmapUnlocks this Bitmap from system memory.

public:
 void UnlockBits(System::Drawing::Imaging::BitmapData ^ bitmapdata);
public void UnlockBits (System.Drawing.Imaging.BitmapData bitmapdata);
member this.UnlockBits : System.Drawing.Imaging.BitmapData -> unit

參數

bitmapdata
BitmapData

BitmapData,指定鎖定作業的相關資訊。A BitmapData that specifies information about the lock operation.

例外狀況

作業失敗。The operation failed.

範例

下列程式碼範例示範如何使用 PixelFormatHeightWidthScan0 屬性;LockBits 和 @no__t 5 方法;和 ImageLockMode 列舉。The following code example demonstrates how to use the PixelFormat, Height, Width, and Scan0 properties; the LockBits and UnlockBits methods; and the ImageLockMode enumeration. 這個範例的設計目的並不是要搭配所有像素格式正常運作,而是提供如何使用 LockBits 方法的範例。This example is not designed to work correctly with all pixel formats, but to provide an example of how to use the LockBits method. 這個範例是設計來與 Windows Forms 搭配使用。This example is designed to be used with Windows Forms. 若要執行此範例,請將它貼到表單中,並藉由呼叫 LockUnlockBitsExample 方法來處理表單的 Paint 事件,並將 e 傳遞為 PaintEventArgsTo run this example, paste it into a form and handle the form's Paint event by calling the LockUnlockBitsExample method, passing e as PaintEventArgs.

void LockUnlockBitsExample( PaintEventArgs^ e )
{
   // Create a new bitmap.
   Bitmap^ bmp = gcnew Bitmap( "c:\\fakePhoto.jpg" );

   // Lock the bitmap's bits.  
   Rectangle rect = 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.
   // This code is specific to a bitmap with 24 bits per pixels.
   int bytes = Math::Abs(bmpData->Stride) * bmp->Height;
   array<Byte>^rgbValues = gcnew array<Byte>(bytes);

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

   // Set every third value to 255.  
   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 );
}
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  = Math.Abs(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);

    }

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 = Math.Abs(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

備註

@No__t-0 會指定 Bitmap 的屬性,例如大小、像素格式、記憶體中圖元資料的起始位址,以及每個掃描線(stride)的長度。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).

適用於