[PATCH v8 xdg-shell-unstable-v6] xdg-shell: Add min/max size requests

[Olivier Fourdan]

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.
 v7: Specify that width/height values must be greater than or equal to
     zero as discussed with Mike.
 v8: Explicitely state that the compositor may ignore the mix/max size.

 unstable/xdg-shell/xdg-shell-unstable-v6.xml | 88 ++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/unstable/xdg-shell/xdg-shell-unstable-v6.xml b/unstable/xdg-shell/xdg-shell-unstable-v6.xml
index 3fc7d42..1448c2c 100644
--- a/unstable/xdg-shell/xdg-shell-unstable-v6.xml
+++ b/unstable/xdg-shell/xdg-shell-unstable-v6.xml
@@ -489,6 +489,94 @@
       <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.
+
+	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.
+
+	The client should not rely on the compositor to obey the maximum
+	size. The compositor may decide to ignore the values set by the
+	client and request a larger size. In such a case, the client can
+	either adapt to the requested size or refuse to acknowledge the
+	configure event sent by the compositor. See xdg_surface.configure
+	and xdg_surface.ack_configure for details.
+
+	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.
+
+	The client should not rely on the compositor to obey the minimum
+	size. The compositor may decide to ignore the values set by the
+	client and request a smaller size. In such a case, the client can
+	either adapt to the requested size or refuse to acknowledge the
+	configure event sent by the compositor. See xdg_surface.configure
+	and xdg_surface.ack_configure for details.
+
+	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