[PATCH weston] protocol,compositor: wl_viewport destination 1x1 min

[Bill Spitzak]

I think this is a good argument for having source size of zero mean 
"unset", just like it does for the destination size. Then you don't have 
to worry about this at all.

Pekka Paalanen wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> Ensure, that the resulting surface size is at least 1x1, even when
> destination size is not set and source size is zero. Previously this
> lead to zero surface size.
> 
> Tested by hacking clients/scaler.c to set src_width and src_height to 0.
> 
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> ---
> 
> There is something wrong in the Pixman renderer, when using 0 or 1/256
> as the source width and height, but I can't investigate right now.
> ---
>  protocol/scaler.xml | 8 +++++---
>  src/compositor.c    | 7 ++++---
>  2 files changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/protocol/scaler.xml b/protocol/scaler.xml
> index 5094616..580b026 100644
> --- a/protocol/scaler.xml
> +++ b/protocol/scaler.xml
> @@ -86,13 +86,15 @@
>        dst_width, dst_height. The source (rectangle) is scaled to exactly
>        this size. This overrides whatever the attached wl_buffer size is,
>        unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface
> -      has no content and therefore no size.
> +      has no content and therefore no size. Otherwise, the size is always
> +      at least 1x1 in surface coordinates.
>  
>        If the source rectangle is set, it defines what area of the
>        wl_buffer is taken as the source. If the source rectangle is set and
>        the destination size is not set, the surface size becomes the source
> -      rectangle size rounded up to the nearest integer. If the source size
> -      is already exactly integers, this results in cropping without scaling.
> +      rectangle size rounded up to the nearest integer (note: 0
> +      destination width or height becomes 1). If the source size is
> +      already exactly integers, this results in cropping without scaling.
>  
>        The coordinate transformations from buffer pixel coordinates up to
>        the surface-local coordinates happen in the following order:
> diff --git a/src/compositor.c b/src/compositor.c
> index 016f514..a80fde9 100644
> --- a/src/compositor.c
> +++ b/src/compositor.c
> @@ -1245,9 +1245,10 @@ weston_surface_set_size_from_buffer(struct weston_surface *surface)
>  	}
>  
>  	if (vp->buffer.src_width != wl_fixed_from_int(-1)) {
> -		surface_set_size(surface,
> -				 fixed_round_up_to_int(vp->buffer.src_width),
> -				 fixed_round_up_to_int(vp->buffer.src_height));
> +		int32_t w = fixed_round_up_to_int(vp->buffer.src_width);
> +		int32_t h = fixed_round_up_to_int(vp->buffer.src_height);
> +
> +		surface_set_size(surface, w ?: 1, h ?: 1);
>  		return;
>  	}
>