Bitmap.LockBits 方法

Source:

Bitmap.cs

Source:

Bitmap.cs

Source:

Bitmap.cs

public:
 System::Drawing::Imaging::BitmapData ^ LockBits(System::Drawing::Rectangle rect, System::Drawing::Imaging::ImageLockMode flags, System::Drawing::Imaging::PixelFormat format);

public System.Drawing.Imaging.BitmapData LockBits (System.Drawing.Rectangle rect, System.Drawing.Imaging.ImageLockMode flags, System.Drawing.Imaging.PixelFormat format);

member this.LockBits : System.Drawing.Rectangle * System.Drawing.Imaging.ImageLockMode * System.Drawing.Imaging.PixelFormat -> System.Drawing.Imaging.BitmapData

Public Function LockBits (rect As Rectangle, flags As ImageLockMode, format As PixelFormat) As BitmapData

参数

返回

包含有关此锁定操作信息的 BitmapData。

例外

示例

下面的代码示例演示如何使用 、、 和 属性、LockBits和 UnlockBits 方法以及 ImageLockMode 枚举。Scan0WidthHeightPixelFormat 此示例旨在与 Windows 窗体 一起使用。 此示例并非旨在正确处理所有像素格式，而是提供如何使用 LockBits 方法的示例。 若要运行此示例，请将其粘贴到窗体中，并通过调用 LockUnlockBitsExample 方法处理窗体的 Paint 事件，并e作为 PaintEventArgs传递。

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

注解

LockBits使用 方法锁定系统内存中的现有位图，以便以编程方式对其进行更改。 可以使用 方法更改图像 SetPixel 的颜色，尽管 LockBits 该方法为大规模更改提供更好的性能。

BitmapData指定 Bitmap的属性，例如大小、像素格式、内存中像素数据的起始地址以及每个扫描行的长度 (步幅) 。

调用此方法时，应使用枚举的成员 System.Drawing.Imaging.PixelFormat ，该成员包含特定的每像素位 (BPP) 值。 使用 System.Drawing.Imaging.PixelFormat 和 IndexedGdi 等值将引发 System.ArgumentException。 此外，为位图传递不正确的像素格式将引发 System.ArgumentException。

Source:

Bitmap.cs

Source:

Bitmap.cs

Source:

Bitmap.cs

public:
 System::Drawing::Imaging::BitmapData ^ LockBits(System::Drawing::Rectangle rect, System::Drawing::Imaging::ImageLockMode flags, System::Drawing::Imaging::PixelFormat format, System::Drawing::Imaging::BitmapData ^ bitmapData);

public System.Drawing.Imaging.BitmapData LockBits (System.Drawing.Rectangle rect, System.Drawing.Imaging.ImageLockMode flags, System.Drawing.Imaging.PixelFormat format, System.Drawing.Imaging.BitmapData bitmapData);

member this.LockBits : System.Drawing.Rectangle * System.Drawing.Imaging.ImageLockMode * System.Drawing.Imaging.PixelFormat * System.Drawing.Imaging.BitmapData -> System.Drawing.Imaging.BitmapData

Public Function LockBits (rect As Rectangle, flags As ImageLockMode, format As PixelFormat, bitmapData As BitmapData) As BitmapData

参数

返回

包含锁定操作信息的 BitmapData。

例外

注解

LockBits使用 方法锁定系统内存中的现有位图，以便以编程方式对其进行更改。 可以使用 方法更改图像 SetPixel 的颜色，尽管 LockBits 该方法为大规模更改提供更好的性能。

调用此方法时，应使用枚举的成员 System.Drawing.Imaging.PixelFormat ，该成员包含特定的每像素位 (BPP) 值。 使用 System.Drawing.Imaging.PixelFormat 值（如 Indexed 和 Gdi）将引发 System.ArgumentException。 此外，为位图传递不正确的像素格式将引发 System.ArgumentException。

此版本的 LockBits 方法旨在与 值ImageLockMode.UserInputBuffer一flags起使用。