public PDFBitmap(int width, int height, bool useAlphaChannel)
{
PDFLibrary.AddRef("PDFBitmap");
m_Width = width;
m_Height = height;
m_UseAlphaChannel = useAlphaChannel;
m_NativePointer = FPDFBitmap_Create(m_Width, m_Height, useAlphaChannel);
}