[PATCH weston 5/6] xdg-shell: Rewrite documentation

Jason Ekstrand jason at jlekstrand.net
Sat Nov 29 18:09:10 PST 2014


I agree with Pekka's comments, I also have a couple of my own below.  (Most
of them are pretty trivial).  With Pekka's and my comments addressed, this
series looks good to me.
--Jason

On Sat, Nov 22, 2014 at 12:28 PM, Jasper St. Pierre <jstpierre at mecheye.net>
wrote:

> This rewrites basically all of the text inside xdg-shell to be up to
> date, clearer, and rid of wl_shell and X11 terminology.
> ---
>  protocol/xdg-shell.xml | 256
> ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 156 insertions(+), 100 deletions(-)
>
> diff --git a/protocol/xdg-shell.xml b/protocol/xdg-shell.xml
> index 360179d..3359cf7 100644
> --- a/protocol/xdg-shell.xml
> +++ b/protocol/xdg-shell.xml
> @@ -31,11 +31,15 @@
>
>    <interface name="xdg_shell" version="1">
>      <description summary="create desktop-style surfaces">
> -      This interface is implemented by servers that provide
> -      desktop-style user interfaces.
> -
> -      It allows clients to associate a xdg_surface with
> -      a basic surface.
> +      xdg_shell allows clients to turn a wl_surface into a "real window"
> +      which can be dragged, resized, stacked, and moved around by the
> +      user. Everything about this interface is suited towards traditional
> +      desktop environments.
> +
> +      Destroying a bound xdg_shell object while there are surfaces
> +      still alive with roles from this interface is illegal and will
> +      result in a protocol error. Make sure to destroy all surfaces
> +      before destroying this object.
>      </description>
>
>      <enum name="version">
> @@ -65,33 +69,26 @@
>
>      <request name="get_xdg_surface">
>        <description summary="create a shell surface from a surface">
> -       Create a shell surface for an existing surface.
> -
> -       This request gives the surface the role of xdg_surface. If the
> -       surface already has another role, it raises a protocol error.
> -
> -       Only one shell or popup surface can be associated with a given
> -       surface.
> +       This creates an xdg_surface for the given surface and gives it the
> +       xdg_surface role. See the documentation of xdg_surface for more
> details.
>        </description>
>        <arg name="id" type="new_id" interface="xdg_surface"/>
>        <arg name="surface" type="object" interface="wl_surface"/>
>      </request>
>
>      <request name="get_xdg_popup">
> -      <description summary="create a shell surface from a surface">
> -       Create a popup surface for an existing surface.
> -
> -       This request gives the surface the role of xdg_popup. If the
> -       surface already has another role, it raises a protocol error.
> +      <description summary="create a popup for a surface">
> +       This creates an xdg_popup for the given surface and gives it the
> +       xdg_popup role. See the documentation of xdg_surface for more
> details.
>
> -       Only one shell or popup surface can be associated with a given
> -       surface.
> +       This request must be used in response to some sort of user action
> +       like a button press, key press, or touch down event.
>        </description>
>        <arg name="id" type="new_id" interface="xdg_popup"/>
>        <arg name="surface" type="object" interface="wl_surface"/>
>        <arg name="parent" type="object" interface="wl_surface"/>
> -      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat whose pointer is used"/>
> -      <arg name="serial" type="uint" summary="serial of the implicit grab
> on the pointer"/>
> +      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat of the user event"/>
> +      <arg name="serial" type="uint" summary="the serial of the user
> event"/>
>        <arg name="x" type="int"/>
>        <arg name="y" type="int"/>
>      </request>
> @@ -107,7 +104,7 @@
>          respond to the ping request, or in what timeframe. Clients should
>          try to respond in a reasonable amount of time.
>        </description>
> -      <arg name="serial" type="uint" summary="pass this to the callback"/>
> +      <arg name="serial" type="uint" summary="pass this to the pong
> request"/>
>      </event>
>
>      <request name="pong">
> @@ -120,8 +117,7 @@
>    </interface>
>
>    <interface name="xdg_surface" version="1">
> -
> -    <description summary="desktop-style metadata interface">
> +    <description summary="A desktop window">
>        An interface that may be implemented by a wl_surface, for
>        implementations that provide a desktop-style user interface.
>
> @@ -136,20 +132,22 @@
>      </description>
>
>      <request name="destroy" type="destructor">
> -      <description summary="remove xdg_surface interface">
> -       The xdg_surface interface is removed from the wl_surface object
> -       that was turned into a xdg_surface with
> -       xdg_shell.get_xdg_surface request. The xdg_surface properties,
> -       like maximized and fullscreen, are lost. The wl_surface loses
> -       its role as a xdg_surface. The wl_surface is unmapped.
> +      <description summary="Destroy the xdg_surface">
> +       Unmap and destroy the window. The window will be effectively
> +       hidden from the user's point of view, and all state like
> +       maximization, fullscreen, and so on, will be lost.
>        </description>
>      </request>
>
>      <request name="set_parent">
> -      <description summary="surface is a child of another surface">
> -       Child surfaces are stacked above their parents, and will be
> -       unmapped if the parent is unmapped too. They should not appear
> -       on task bars and alt+tab.
> +      <description summary="set the parent of this surface">
> +       Set the "parent" of this surface. This window should be stacked
> +       above a parent. The parent surface must be mapped as long as this
> +       surface is mapped.
> +
> +       Parent windows should be set on dialogs, toolboxes, or other
> +       "auxilliary" surfaces, so that the parent is raised when the dialog
> +       is raised.
>

As Bill said, this seems to imply that raising parents raises children and
raising children raises parents.  Did you intend this to go both ways?


>        </description>
>        <arg name="parent" type="object" interface="xdg_surface"
> allow-null="true"/>
>      </request>
> @@ -168,14 +166,19 @@
>      </request>
>
>      <request name="set_app_id">
> -      <description summary="set surface class">
> -       Set an id for the surface.
> +      <description summary="set application ID">
> +       Set an application identifier for the surface.
> +
> +       The app ID identifies the general class of applications to which
> +       the surface belongs. The compositor can use this to group multiple
> +       applications together, or to determine how to launch a new
> +       application.
>
> -       The app id identifies the general class of applications to which
> -       the surface belongs.
> +       See the desktop-entry specification [0] for more details on
> +       application identifiers and how they relate to well-known DBus
> +       names and .desktop files.
>
> -       It should be the ID that appears in the new desktop entry
> -       specification, the interface name.
> +       [0] http://standards.freedesktop.org/desktop-entry-spec/
>        </description>
>        <arg name="app_id" type="string"/>
>      </request>
> @@ -187,29 +190,32 @@
>          user a menu that they can use to maximize or minimize the window.
>
>          This request asks the compositor to pop up such a window menu at
> -        the given position, relative to the parent surface. There are
> -        no guarantees as to what the window menu contains.
> +        the given position, relative to the local surface coordinates of
> +        the parent surface. There are no guarantees as to what menu items
> +        the window menu contains.
>
> -        Your surface must have focus on the seat passed in to pop up the
> -        window menu.
> +        This request must be used in response to some sort of user action
> +        like a button press, key press, or touch down event.
>        </description>
>
> -      <arg name="seat" type="object" interface="wl_seat" summary="the
> seat to pop the window up on"/>
> -      <arg name="serial" type="uint" summary="serial of the event to pop
> up the window for"/>
> +      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat of the user event"/>
> +      <arg name="serial" type="uint" summary="the serial of the user
> event"/>
>        <arg name="x" type="int" summary="the x position to pop up the
> window menu at"/>
>        <arg name="y" type="int" summary="the y position to pop up the
> window menu at"/>
>      </request>
>
>      <request name="move">
>        <description summary="start an interactive move">
> -       Start a pointer-driven move of the surface.
> +       Start an interactive, user-driven move of the surface.
> +
> +       This request must be used in response to some sort of user action
> +       like a button press, key press, or touch down event.
>
> -       This request must be used in response to a button press event.
>         The server may ignore move requests depending on the state of
>         the surface (e.g. fullscreen or maximized).
>        </description>
> -      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat whose pointer is used"/>
> -      <arg name="serial" type="uint" summary="serial of the implicit grab
> on the pointer"/>
> +      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat of the user event"/>
> +      <arg name="serial" type="uint" summary="the serial of the user
> event"/>
>      </request>
>
>      <enum name="resize_edge">
> @@ -232,14 +238,16 @@
>
>      <request name="resize">
>        <description summary="start an interactive resize">
> -       Start a pointer-driven resizing of the surface.
> +       Start a user-driven, interactive resize of the surface.
> +
> +       This request must be used in response to some sort of user action
> +       like a button press, key press, or touch down event.
>
> -       This request must be used in response to a button press event.
>         The server may ignore resize requests depending on the state of
>         the surface (e.g. fullscreen or maximized).
>        </description>
> -      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat whose pointer is used"/>
> -      <arg name="serial" type="uint" summary="serial of the implicit grab
> on the pointer"/>
> +      <arg name="seat" type="object" interface="wl_seat" summary="the
> wl_seat of the user event"/>
> +      <arg name="serial" type="uint" summary="the serial of the user
> event"/>
>        <arg name="edges" type="uint" summary="which edge or corner is
> being dragged"/>
>      </request>
>
> @@ -287,16 +295,21 @@
>
>      <event name="configure">
>        <description summary="suggest a surface change">
> -       The configure event asks the client to resize its surface.
> +       The configure event asks the client to resize its surface or to
> +       change its state.
>
>         The width and height arguments specify a hint to the window
> -        about how its surface should be resized in window geometry
> -        coordinates. The states listed in the event specify how the
> -        width/height arguments should be interpreted.
> +       about how its surface should be resized in window geometry
> +       coordinates.
> +
> +       The states listed in the event specify how the width/height
> +       arguments should be interpreted, and possibly how it should be
> +       drawn.
>
> -        A client should arrange a new surface, and then send a
> -        ack_configure request with the serial sent in this configure
> -        event before attaching a new surface.
> +       Clients should arrange their surface for the new size and
> +       states, and then send a ack_configure request with the serial
> +       sent in this configure event at some point before committing
> +       the new surface.
>
>         If the client receives multiple configure events before it
>          can respond to one, it is free to discard all but the last
> @@ -311,14 +324,20 @@
>
>      <request name="ack_configure">
>        <description summary="ack a configure event">
> -        When a configure event is received, a client should then ack it
> -        using the ack_configure request to ensure that the compositor
> -        knows the client has seen the event.
> -
> -        By this point, the state is confirmed, and the next attach should
> -        contain the buffer drawn for the configure event you are acking.
> +        When a configure event is received, if a client is updating
> +        and redrawing its state in response to the configure event,
> +        then the client needs to make an ack_configure request before
> +        point the commit to mark this next commit as being a
> +        reaction to the configure.
>

This sentence needs to be reworded.  The last half, in particular, makes no
sense.  You and I both know what it means, but it's not very clear.


> +
> +        The compositor might use this information to move a surface
> +        to the top left only when the client has drawn itself for
> +        the maximized or fullscreen state.
> +
> +        If the client receives multiple configure events before it
> +        can respond to one, it only has to ack the last configure event.
>        </description>
> -      <arg name="serial" type="uint" summary="a serial to configure for"/>
> +      <arg name="serial" type="uint" summary="the serial from the
> configure event"/>
>      </request>
>
>      <request name="set_window_geometry">
> @@ -328,15 +347,20 @@
>          portions like drop-shadows which should be ignored for the
>          purposes of aligning, placing and constraining windows.
>
> -        The default value is the full bounds of the surface, including any
> -        subsurfaces. Once the window geometry of the surface is set once,
> -        it is not possible to unset it, and it will remain the same until
> +        Once the window geometry of the surface is set once, it is not
> +        possible to unset it, and it will remain the same until
>          set_window_geometry is called again, even if a new subsurface or
>          buffer is attached.
>
> +        If never set, the value is the full bounds of the surface,
> +        including any subsurfaces. This updates dynamically on every
> +        commit. This unset mode is meant for extremely simple clients.
> +
>          If responding to a configure event, the window geometry in here
>          must respect the sizing negotiations specified by the states in
>          the configure event.
> +
> +        The width and height must be greater than zero.
>        </description>
>        <arg name="x" type="int"/>
>        <arg name="y" type="int"/>
> @@ -359,7 +383,18 @@
>      </request>
>      <request name="unset_fullscreen" />
>
> -    <request name="set_minimized" />
> +    <request name="set_minimized">
> +      <description summary="set the window as minimized">
> +       Request that the compositor minimize your surface. There is no
> +       way to know if the surface is currently minimized, nor is there
> +       any way to unset minimization on this surface.
> +
> +       If you are looking to throttle redrawing when minimized, please
> +       instead use the wl_surface.frame event for this, as this will
> +       also work with live previews on windows in Alt-Tab, Expose or
> +       similar compositor features.
> +      </description>
> +    </request>
>
>      <event name="close">
>        <description summary="surface wants to be closed">
> @@ -376,26 +411,48 @@
>    </interface>
>
>    <interface name="xdg_popup" version="1">
> -    <description summary="desktop-style metadata interface">
> -      An interface that may be implemented by a wl_surface, for
> -      implementations that provide a desktop-style popups/menus. A popup
> -      surface is a transient surface with an added pointer grab.
> -
> -      An existing implicit grab will be changed to owner-events mode,
> -      and the popup grab will continue after the implicit grab ends
> -      (i.e. releasing the mouse button does not cause the popup to be
> -      unmapped).
> -
> -      The popup grab continues until the window is destroyed or a mouse
> -      button is pressed in any other clients window. A click in any of
> -      the clients surfaces is reported as normal, however, clicks in
> -      other clients surfaces will be discarded and trigger the callback.
> -
> -      The x and y arguments specify the locations of the upper left
> -      corner of the surface relative to the upper left corner of the
> -      parent surface, in surface local coordinates.
> -
> -      xdg_popup surfaces are always transient for another surface.
> +    <description summary="short-lived, popup surfaces for menus">
> +      A popup surface is a short-lived, temporary surface that can be
> +      used to implement menus. It takes an explicit grab on the surface
> +      that will be dismissed when the user dismisses the popup. This can
> +      be done by the user clicking outside the surface, using the
> keyboard,
> +      or even locking the screen through closing the lid or a timeout.
> +
> +      When the popup is dismissed, a popup_done event will be sent out,
> +      and at the same time the surface will be unmapped. The xdg_popup
> +      object is now inert and cannot be reactivated, so clients should
> +      destroy it. Explicitly destroying the xdg_popup object will also
> +      dismiss the popup, and unmap the surface.
>

no comma


> +
> +      Clients will receive events for all their surfaces during this
> +      grab (which is an "owner-events" grab in X11 parlance). This is
> +      done so that users can navigate through submenus and other
> +      "nested" popup windows without having to dismiss the topmost
> +      popup.
> +
> +      Clients that want to dismiss the popup when another surface of
> +      their own is clicked should dismiss the popup using the destroy
> +      request.
> +
> +      The parent surface must have either an xdg_surface or xdg_popup
> +      role.
> +
> +      Specifying an xdg_popup for the parent means that the popups are
> +      nested, with this popup now being the topmost popup. Nested
> +      popups must be destroyed in the reverse order they were created
> +      in, e.g. the only popup you are allowed to destroy at all times
> +      is the topmost one.
> +
> +      If there is an existing popup when creating a new popup, the
> +      parent must be the current topmost popup.
> +
> +      When compositors choose to dismiss a popup if the user clicks
> +      outside the window, they will likely dismiss every nested popup
> +      as well.
>

No need to specify clicking outside a window.  I would expect that to
happen for hotkeys screen locks, etc. as well.


> +
> +      The x and y arguments specify where the top left of the popup
> +      should be placed, relative to the local surface coordinates of the
> +      parent surface.
>      </description>
>
>      <enum name="error">
> @@ -407,19 +464,18 @@
>
>      <request name="destroy" type="destructor">
>        <description summary="remove xdg_surface interface">
>

I believe you mean "xdg_popup" here.


> -       The xdg_surface interface is removed from the wl_surface object
> -       that was turned into a xdg_surface with
> -       xdg_shell.get_xdg_surface request. The xdg_surface properties,
> -       like maximized and fullscreen, are lost. The wl_surface loses
> -       its role as a xdg_surface. The wl_surface is unmapped.
> +       This destroys the popup. Explicitly destroying the xdg_popup
> +       object will also dismiss the popup, and unmap the surface.
> +
> +       If this xdg_popup is not the "topmost" popup, a protocol error
> +       will be sent.
>        </description>
>      </request>
>
>      <event name="popup_done">
>        <description summary="popup interaction is done">
> -       The popup_done event is sent out when a popup grab is broken,
> -       that is, when the users clicks a surface that doesn't belong
> -       to the client owning the popup surface.
> +       The popup_done event is sent out when a popup is dismissed
> +       by the compositor.
>        </description>
>      </event>
>
> --
> 2.1.0
>
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