c - Draw RGB888 image to an X11 window

Question

I am working on refactoring some code in a project that requires me to read a PNG image and draw it into an X11 window. I have been able successfully read the image file using libpng, but I am not able to figure out how to convert these raw bytes into a Pixmap, so that the rest of the code can use the Pixmap.

The png image is RGB888 format, I tried using XCreatePixmapFromBitmapData as follows

Pixmap theLogo = XCreatePixmapFromBitmapData(
                                       display,
                                       rootWindow,
                                       reinterpret_cast<char*>(png_image_data) ,
                                       png_width,
                                       png_height,
                                       BlackPixel,
                                       WhitePixel,
                                       DefaultDepth(display, screen)
                                       );

The resultant Pixmap seems to be a garbage image. It is probably because the screen depth is 16 and my png image is 24bit RGB.

Could anyone please suggest what is the best way to create a Pixmap out of raw bytes of an image.

Thanks, Abhinay