Zooming in steps of 8 (the width will be a multiple of 8 ) and with a relatively low speed can be achieved by pxl-Testing the sprite (directly from the program or from the backbuffer) and drawing a black square in the corresponding size at scaled coordinates.
Example:
Pic1 ... sprite you want to zoom in
F ... zooming factor (1 or greater)
Pt-Off(0,0,Pic1)r //draw it on the backbuffer
For(Y,0,7)
For(X,0,7)
If (pxl-Test(X,Y)r) //read a pixel from backbuffer
Rect(X*F,Y*F,F,) //draw a square on frontbuffer
End
End
End