[Freetype] How to draw a bitmap

[宋仕仁]

I use ft2 version to get FT_GlyphSlot and use FT_Render_Glyph to get a
bitmap pointer.
I can read the bitmap rows,width and pitch.
It has a buffer data let me to draw it.
How should I draw the bitmap image.
I don't know how to use buffer to draw.
I use a draw a pixel function in svgalib to do this , but I can not
understand the bitmap->buffer field in FT_Bitmap struct.

Thank you for you help.