[PATCH wayland 1/2] protocol: replace pointer.attach with pointer.set_cursor

[Pekka Paalanen]

On Fri, 15 Jun 2012 17:27:32 +0300
Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
wrote:

> ---
>  protocol/wayland.xml |   27 +++++++++++++++++++++------
>  1 files changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/protocol/wayland.xml b/protocol/wayland.xml
> index e9c6787..23b244f 100644
> --- a/protocol/wayland.xml
> +++ b/protocol/wayland.xml
> @@ -773,15 +773,30 @@
>    </interface>
>  
>    <interface name="wl_pointer" version="1">
> -    <request name="attach">
> -      <description summary="set the pointer image">
> -	Set the pointer's image.  This request only takes effect if
> -	the pointer focus for this device is one of the requesting
> -	clients surfaces.
> +    <request name="set_cursor">
> +      <description summary="set the pointer surface">
> +	Set the pointer surface, i.e., the surface that contains the
> +	pointer image. This request only takes effect if the pointer
> +	focus for this device is one of the requesting client surfaces.
> +	If there was a previous surface set with this request it is
> +	replaced. If surface is NULL, the pointer image is hidden.
> +
> +	The parameters hotspot_x and hotspot_y define the position of
> +	the pointer surface relative to the pointer location. Its
> +	top-left corner is always at (x, y) - (hotspot_x, hotspot_y),
> +	where (x, y) are the coordinates of the pointer location.

I wonder if we could phrase this paragraph even more clearly...

"The parameters hotspot_x,hotspot_y define the cursor hotspot in the
cursor surface, given in cursor surface-local coordinates. In other
words, if x,y is the cursor position on a (window) surface, then the
top-left corner pixel of the cursor is at the window surface
coordinates (x - hotspot_x, y - hotspot_y)."

We are talking about the corner pixel, and not corner, right? There is
a half-pixel difference between the two definitions.

I've understood that integer pixel coordinates fall in the middle of a
pixel, and the border is at +-0.5 pixels from that.

(the above definition leads to the conclusion, that a 2x3 pixel sized
area has coordinate extents from (-0.5,-0.5) to (1.5, 2.5).)

> +	On surface.attach requests to the pointer surface, hotspot_x
> +	and hotspot_y are decremented by the x and y parameters
> +	passed to the request.
+ This corresponds to removing x pixels from the top, and y pixels from
+ the left in the cursor image, compared to the previous image.

Would that addition make this paragraph any clearer?

Hmm... I just realised that the surface::attach dx,dy are defined as
moving the surface more naturally than "removing pixels from top and
left sides".

> +
> +	The hotspot can also be updated by passing the current set
> +	pointer surface to this request with new values for hotspot_x
> +	and/or hotspot_y.
>        </description>
>  
>        <arg name="serial" type="uint"/>
> -      <arg name="buffer" type="object" interface="wl_buffer"/>
> +      <arg name="surface" type="object" interface="wl_surface"/>

>        <arg name="hotspot_x" type="int"/>
>        <arg name="hotspot_y" type="int"/>

Should these be wl_fixed_t? Just pondering, since all coordinates are
fixed. Or are these supposed to be pixel counts, just like in the
surface::attach request?

>      </request>


Thanks,
pq