Bitmap.UnlockBits(BitmapData) 方法
定義
重要
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從系統記憶體解除鎖定這個 Bitmap。
public:
void UnlockBits(System::Drawing::Imaging::BitmapData ^ bitmapdata);
public void UnlockBits (System.Drawing.Imaging.BitmapData bitmapdata);
member this.UnlockBits : System.Drawing.Imaging.BitmapData -> unit
Public Sub UnlockBits (bitmapdata As BitmapData)
參數
- bitmapdata
- BitmapData
BitmapData,指定鎖定作業的相關資訊。
例外狀況
作業失敗。
範例
下列程式碼範例示範如何使用 、、 和 屬性、 LockBits 和 UnlockBits 方法,以及 ImageLockMode 列舉。 Scan0WidthHeightPixelFormat 此範例並非設計來正確處理所有像素格式,而是提供如何使用 方法的 LockBits 範例。 此範例的設計目的是要與Windows Forms搭配使用。 若要執行此範例,請將它貼到表單中,並藉由呼叫 方法來處理表單 Paint 的 事件,並 e
傳遞為 PaintEventArgs 。 LockUnlockBitsExample
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
BitmapData指定 的屬性 Bitmap ,例如大小、像素格式、記憶體中圖元資料的起始位址,以及每個掃描線的長度 () 。
適用於
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