[PATCH v6 xdg-shell-unstable-v6] xdg-shell: Add min/max size requests

[Jonas Ådahl]

On Wed, Apr 13, 2016 at 08:15:57PM +0200, Olivier Fourdan wrote:
> Some application may wish to restrict their window in size, but
> xdg-shell has no mechanism for the client to specify a maximum or
> minimum size.
> 
> As a result, the compositor may try to maximize or fullscreen a window
> while the client would not allow for the requested size.
> 
> Add new requests "set_max_size" and "set_min_size" to xdg-shell so that
> the client can tell the compositor what would be its smallest/largest
> acceptable size, and that the compositor can decide if maximize or
> fullscreen is achievable, draw an accurate animation, etc.
> 
> Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
> Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=764413
> ---
>  v2: Rename the request to "set_preferred_max_size",
>      add "set_preferred_min_size" as well
>  v3: Rebase above patch 72427 in branch xdg-shell-unstable-v6
>      Rephrase description to clarify the unscaled size and using 0 to
>      reset back the preferred size to an unspecified state
>  v4: Patch the correct xml file (v6, not v5 <facepalm>)
>      Fix multiple mismatch of min/max in the description
>      Remove mention of "unscaled", specify window geometry coordinates
>      and refer to set_window_geometry.
>  v5: Fix typos and remove "preferred" from the name and description as
>      requested by several people on the ML and irc.
>  v6: Specify the requests are double-buffered and require a commit,
>      rephrase the values never set as suggested by Jasper, state
>      that min > max is an invalid state and result in a protocol error
>      as suggested by Bill, Yong and Jonas.
>      Specify that width/height values must be greater than or equal to
>      zero as discussed with Mike.
> 
>  unstable/xdg-shell/xdg-shell-unstable-v6.xml | 74 ++++++++++++++++++++++++++++
>  1 file changed, 74 insertions(+)
> 
> diff --git a/unstable/xdg-shell/xdg-shell-unstable-v6.xml b/unstable/xdg-shell/xdg-shell-unstable-v6.xml
> index 3fc7d42..eba31ce 100644
> --- a/unstable/xdg-shell/xdg-shell-unstable-v6.xml
> +++ b/unstable/xdg-shell/xdg-shell-unstable-v6.xml
> @@ -489,6 +489,80 @@
>        <arg name="states" type="array"/>
>      </event>
>  
> +    <request name="set_max_size">
> +      <description summary="set the maximum size">
> +	Set a maximum size for the window.
> +
> +	The client can specify a maximum size so that the compositor does
> +	not try to configure the window beyond this size.

This makes it sound like the compositor will have to obay the limits.
Did we end up with requiring that a correctly working compositor never
tries to configure a size that is not within the set bounds? I think it
should be cleared out anyhow, what the client can rely upon here anyhow.

Another (minor) issue is the lack of error code for when the min/max are
conflicting. I think we can leave that unfixed and rely on
https://lists.freedesktop.org/archives/wayland-devel/2016-April/028091.html
for that though.

Other than that part, this patch is Reviewed-by: Jonas Ådahl
<jadahl at gmail.com>


Jonas

> +
> +	The width and height arguments are in window geometry coordinates.
> +	See set_window_geometry.
> +
> +	Values set in this way are double-buffered. They will get applied
> +	on the next commit.
> +
> +	The compositor can use this information to allow or disallow
> +	different states like maximize or fullscreen and draw accurate
> +	animations.
> +
> +	Similarly, a tiling window manager may use this information to
> +	place and resize client windows in a more effective way.
> +
> +	If never set, or a value of zero in the request, means that the
> +	client has no expected maximum size in the given dimension.
> +	As a result, a client wishing to reset the maximum size
> +	to an unspecified state can use zero for width and height in the
> +	request.
> +
> +	Requesting a maximum size to be smaller than the minimum size of
> +	a surface is illegal and will result in a protocol error.
> +
> +	The width and height must be greater than or equal to zero. Using
> +	strictly negative values for width and height will result in a
> +	protocol error.
> +      </description>
> +      <arg name="width" type="int"/>
> +      <arg name="height" type="int"/>
> +    </request>
> +
> +    <request name="set_min_size">
> +      <description summary="set the minimum size">
> +	Set a minimum size for the window.
> +
> +	The client can specify a minimum size so that the compositor does
> +	not try to configure the window below this size.
> +
> +	The width and height arguments are in window geometry coordinates.
> +	See set_window_geometry.
> +
> +	Values set in this way are double-buffered. They will get applied
> +	on the next commit.
> +
> +	The compositor can use this information to allow or disallow
> +	different states like maximize or fullscreen and draw accurate
> +	animations.
> +
> +	Similarly, a tiling window manager may use this information to
> +	place and resize client windows in a more effective way.
> +
> +	If never set, or a value of zero in the request, means that the
> +	client has no expected minimum size in the given dimension.
> +	As a result, a client wishing to reset the minimum size
> +	to an unspecified state can use zero for width and height in the
> +	request.
> +
> +	Requesting a minimum size to be larger than the maximum size of
> +	a surface is illegal and will result in a protocol error.
> +
> +	The width and height must be greater than or equal to zero. Using
> +	strictly negative values for width and height will result in a
> +	protocol error.
> +      </description>
> +      <arg name="width" type="int"/>
> +      <arg name="height" type="int"/>
> +    </request>
> +
>      <request name="set_maximized">
>        <description summary="maximize the window">
>  	Maximize the surface.
> -- 
> 2.5.5
>