you need to consider "view" as a diferent window.
First , in the window localize the point: middle_x , middle_y , then draw a rectangle with the size WINDOW_X_LENGTH, WINDOW_Y_LENGTH - 50 and put the center of this rectagle in middle_x , middle_y and that its your new window.
suposse this example:
window size( 800 , 650 ) ( 800 , 650 - 50 = 800 , 600 view size )
image size ( 1440 , 660 )
center of the image ( 720 , 330 ) ( center of the view )
And mi profile avatar rendered with the view. ( positionated in 0,0 )
See attachment.