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| void LockUnlockBitsExample( PaintEventArgs^ e )
{
// Create a new bitmap.
Bitmap^ bmp = gcnew Bitmap( "c:\\1.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 = bmp->Width * bmp->Height * 3;
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 red value to 255.
for ( int counter = 0; 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 );
} |
