genode/repos/os/src/server/nit_fb/README
Norman Feske f3988a27d4 nit_fb: support 'origin' attribute
This patch makes the specification of screen coordinates more flexible.
First, the 'origin' attribute allows one to refer to either of the four
screen corners without knowing the screen size. Second, the 'width'
and 'height' values now accept negative values, which are relative to
the screen size.
2017-11-06 13:57:18 +01:00

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The 'nit_fb' server provides a single session of the 'Input' and 'Framebuffer'
services by presenting a Nitpicker view at a predefined screen position. If
instantiated multiple times, it can be used to statically arrange multiple
virtual frame buffers on one physical screen. The size and screen position
of each 'nit_fb' instance can be defined via Genode's configuration mechansim
using the following attributes of the 'nit_fb' config node:
! <config xpos="100" ypos="150" width="300" height="200" origin="top_left"/>
The 'origin' attribute denotes the coordinate origin of the values specified
in the 'xpos' and 'ypos' attributes. Supported origins are "top_left",
"top_right", "bottom_left", and "bottom_right". This attribute allows one to
align the nitpicker view at any of the four screen boundaries.
The 'width' and 'height' attribute values can be negative. If so, they are
relative to the physical screen size. E.g., when using a screen size of
640x480, the effective width for a 'width' attribute value of "-100" would
be 640 - 100 = 540.