Merge lp:~kdub/mir/demo-stream-titlebars into lp:mir

[Kevin DuBois]

demos: transition CanonicalWindowManagerPolicy from using Surfaces to display titlebars to using Streams.

Our "Surfaces" are really more like windows (content, input, and WM), and Streams are the content. Its better to have titlebars that are merely content than to have two "Surfaces/windows" and force the WM policy to tie the two windows together to make it look like one of the windows is a titlebar to the other.

I did intentionally change behavior in the case of vertmaximized to correct behavior of the shell according to my reading of the spec.
Fixes: LP: #1569836

demos: transition CanonicalWindowManagerPolicy from using Surfaces to display titlebars to using Streams.

Our "Surfaces" are really more like windows (content, input, and WM), and Streams are the content. Its better to have titlebars that are merely content than to have two "Surfaces/windows" and force the WM policy to tie the two windows together to make it look like one of the windows is a titlebar to the other.

I did intentionally change behavior in the case of vertmaximized to correct behavior of the shell according to my reading of the spec (LP: #1569836)

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:3452
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review: Approve (continuous-integration)

[Alan Griffiths (alan-griffiths)]

This doesn't seem to get all the focus based repainting right:

$ bin/mir_demo_server
$ bin/mirrun gnome-terminal

...

in the terminal:

$ mir_demo_client_multiwin

Expected: multiwin has bright (focussed) titlebars, terminal has dim (unfocussed) titlebars
Actual .: Both the terminal and multiwin have "focus" titlebars.

review: Needs Fixing

[Cemil Azizoglu (cemil-azizoglu)]

I don't see where this is being used.
640 + SurfaceCreationParameters& with_buffer_streams(std::vector<shell::StreamSpecification> const& streams);

why is it needed? Is there a followup branch?

review: Needs Information

[Kevin DuBois (kdub)]

> I don't see where this is being used.
> 640 + SurfaceCreationParameters&
> with_buffer_streams(std::vector<shell::StreamSpecification> const& streams);
>
> why is it needed? Is there a followup branch?

It is providing a similar way to set the stream fields, eg:
ms::a_surface()
    .with_size(...)
    .with_bufer_usage(...)
    .with_buffer_streams(...);

[Cemil Azizoglu (cemil-azizoglu)]

> > I don't see where this is being used.
> > 640 + SurfaceCreationParameters&
> > with_buffer_streams(std::vector<shell::StreamSpecification> const& streams);
> >
> > why is it needed? Is there a followup branch?
>
> It is providing a similar way to set the stream fields, eg:
> ms::a_surface()
> .with_size(...)
> .with_bufer_usage(...)
> .with_buffer_streams(...);

Ok I guess it sounds useful.

review: Approve

[Daniel van Vugt (vanvugt)]

I've made a few attempts on this topic over the years. Although I feel treating the titlebar as the only type of decoration is quite wrong, simultaneously ignoring the past and not looking to the future.

Please read:
https://bugs.launchpad.net/mir/+bug/1569836/comments/1

Also consider how you would support a theme with:
  * Window borders around the sides
  * No titlebar
  * Titlebar on the side
  * Titlebar non-rectangular, or not the same length as the window
  * Titlebar on the bottom
  * A titlebar that is hidden and only pops up sometimes, maybe with floating buttons.

There is prior art for all of these. The only commonality really is that the client area is usually (but not always) rectangular. And decorations may be arbitrary.

I hesitate to disapprove, because the problem is also pre-existing. But we should be thinking about more generic solutions than this.

review: Abstain

[Chris Halse Rogers (raof)]

Looks reasonable to me, modulo Alan's needs-fixing.

This isn't code for actual Mir shell clients to use, and we don't need to implement fancy decorations in our demo server.

review: Approve

[Kevin DuBois (kdub)]

hit some difficulty with "mirrun", so branch has been lingering. Trying to fix once again.

re the various examples, the location and appearance of the titlebar are controlled by the shell, so different shell logic could control these different locations.

[Kevin DuBois (kdub)]

> Looks reasonable to me, modulo Alan's needs-fixing.
>
> This isn't code for actual Mir shell clients to use, and we don't need to
> implement fancy decorations in our demo server.

Right, this is just to stop giving an example of binding up a MirSurface to use as a titlebar, and to eliminate a use of the 'primary_buffer_stream()'

[Kevin DuBois (kdub)]

bit of bitrot while I did 0.23 testing and sync fence investigation, fixing up

[Kevin DuBois (kdub)]

back to WIP

Unmerged revisions

3452. By Kevin DuBois on 2016-04-13

make sure to expose == operator for StreamSpecification

3451. By Kevin DuBois on 2016-04-12

port over changes that transition the CanonicalWM to using streams instead of surfaces for titlebars

=== modified file 'examples/server_example_basic_window_manager.cpp'
--- examples/server_example_basic_window_manager.cpp	2015-11-27 13:58:54 +0000
+++ examples/server_example_basic_window_manager.cpp	2016-04-13 11:13:46 +0000
@@ -58,7 +58,7 @@
     auto const surface = session->surface(result);
     surface_info.emplace(surface, SurfaceInfo{session, surface, placed_params});
     policy->handle_new_surface(session, surface);
-    policy->generate_decorations_for(session, surface, surface_info, build);
+    policy->generate_decorations_for(session, surface);
     return result;
 }
 

=== modified file 'examples/server_example_basic_window_manager.h'
--- examples/server_example_basic_window_manager.h	2016-01-29 08:18:22 +0000
+++ examples/server_example_basic_window_manager.h	2016-04-13 11:13:46 +0000
@@ -104,9 +104,7 @@
     virtual int handle_set_state(std::shared_ptr<scene::Surface> const& surface, MirSurfaceState value) = 0;
 
     virtual void generate_decorations_for(
-        std::shared_ptr<scene::Session> const& session, std::shared_ptr<scene::Surface> const& surface,
-        SurfaceInfoMap& surface_info,
-        std::function<frontend::SurfaceId(std::shared_ptr<scene::Session> const&, scene::SurfaceCreationParameters const&)> const& build) = 0;
+        std::shared_ptr<scene::Session> const& session, std::shared_ptr<scene::Surface> const& surface) = 0;
 
     virtual bool handle_keyboard_event(MirKeyboardEvent const* event) = 0;
 

=== modified file 'examples/server_example_canonical_window_manager.cpp'
--- examples/server_example_canonical_window_manager.cpp	2016-04-12 14:10:00 +0000
+++ examples/server_example_canonical_window_manager.cpp	2016-04-13 11:13:46 +0000
@@ -30,6 +30,7 @@
 
 namespace me = mir::examples;
 namespace ms = mir::scene;
+namespace mg = mir::graphics;
 using namespace mir::geometry;
 
 ///\example server_example_canonical_window_manager.cpp
@@ -38,18 +39,95 @@
 namespace
 {
 int const title_bar_height = 10;
+Displacement const titlebar_displacement { 0, -10 };
+
 Size titlebar_size_for_window(Size window_size)
 {
     return {window_size.width, Height{title_bar_height}};
 }
 
-Point titlebar_position_for_window(Point window_position)
-{
-    return {
-        window_position.x,
-        window_position.y - DeltaY(title_bar_height)
-    };
-}
+void constrain_input_to(std::vector<Rectangle>& rectangles, Rectangle constraint)
+{
+    auto surface_displacement = constraint.top_left - Point{0, 0};
+    for(auto& rect : rectangles)
+    {
+        rect.top_left = rect.top_left + surface_displacement;
+        rect = rect.intersection_with(constraint);
+        rect.top_left = rect.top_left - surface_displacement;
+    }
+} 
+
+std::vector<Rectangle> input_content_area(me::SurfaceInfo& info, Rectangle surface_rect)
+{
+    std::vector<Rectangle> rectangles;
+    if (info.input_shape.is_set() && !info.input_shape.value().empty())
+        return info.input_shape.value();
+    else
+        return { { Point{0,0}, surface_rect.size } };
+}
+
+void apply_input_content_area(
+    me::SurfaceInfo& info, ms::Surface& surface, Rectangle surface_rect)
+{
+    surface.set_input_region(input_content_area(info, surface_rect));
+}
+
+void apply_input_titlebar_and_content_area(
+    me::SurfaceInfo& info, ms::Surface& surface,
+    Rectangle surface_rect)
+{
+    auto rectangles = input_content_area(info, surface_rect);
+    info.titlebar_input_shape =
+        { Point{0,0} + titlebar_displacement, titlebar_size_for_window(surface_rect.size) };
+    rectangles.emplace_back(info.titlebar_input_shape.value());
+    surface.set_input_region(rectangles);
+}
+
+void content_and_titlebar(me::SurfaceInfo& info, ms::Surface& surface, Size new_size)
+{
+    auto streams = info.streams.value();
+    auto titlebar = std::find_if(streams.begin(), streams.end(),
+        [&](mir::shell::StreamSpecification const& entry)
+        {
+            return entry.stream_id == info.titlebar_id;
+        });
+
+    if (titlebar == streams.end())
+    {
+        streams.push_back(
+            { info.titlebar_id, titlebar_displacement, {titlebar_size_for_window(new_size)}});
+    }
+    else
+    {
+        titlebar->size = titlebar_size_for_window(new_size);
+    }
+
+    if (auto session = info.session.lock())
+        session->configure_streams(surface, streams);
+
+    info.streams = streams;
+    info.visible_titlebar = true;
+}
+
+void content_only(me::SurfaceInfo& info, ms::Surface& surface)
+{
+    auto streams = info.streams.value();
+    for(auto it = streams.begin(); it != streams.end();)
+    {
+        if (it->stream_id == info.titlebar_id)
+            it = streams.erase(it);
+        else
+            it++;
+    }
+
+    if (auto session = info.session.lock())
+        session->configure_streams(surface, streams);
+
+    info.streams = streams;
+    info.visible_titlebar = false;
+}
+
+
 }
 
 me::CanonicalWindowManagerPolicyCopy::CanonicalWindowManagerPolicyCopy(
@@ -83,7 +161,7 @@
 
             display_layout->place_in_output(info.output_id.value(), rect);
             surface->move_to(rect.top_left);
-            surface->resize(rect.size);
+            apply_resize(surface, rect.top_left, rect.size); 
         }
     }
 }
@@ -103,9 +181,6 @@
     auto surf_type = parameters.type.is_set() ? parameters.type.value() : mir_surface_type_normal;
     bool const needs_titlebar = SurfaceInfo::needs_titlebar(surf_type);
 
-    if (needs_titlebar)
-        parameters.size.height = parameters.size.height + DeltaY{title_bar_height};
-
     if (!parameters.state.is_set())
         parameters.state = mir_surface_state_restored;
 
@@ -238,45 +313,34 @@
         parameters.size.height = parameters.size.height - DeltaY{title_bar_height};
     }
 
+    if (parameters.input_shape.is_set())
+    {
+        auto rect = parameters.input_shape.value();
+        constrain_input_to(rect, {parameters.top_left, parameters.size});
+        parameters.input_shape = rect;
+    }
+
     return parameters;
 }
 
 void me::CanonicalWindowManagerPolicyCopy::generate_decorations_for(
     std::shared_ptr<scene::Session> const& session,
-    std::shared_ptr<scene::Surface> const& surface,
-    SurfaceInfoMap& surface_map,
-    std::function<frontend::SurfaceId(std::shared_ptr<scene::Session> const& session, scene::SurfaceCreationParameters const& params)> const& build)
+    std::shared_ptr<scene::Surface> const& surface)
 {
     if (!SurfaceInfo::needs_titlebar(surface->type()))
         return;
 
     auto format = mir_pixel_format_xrgb_8888;
-    mir::graphics::BufferProperties properties(titlebar_size_for_window(surface->size()),
-        format, mir::graphics::BufferUsage::software);
-    auto stream_id = session->create_buffer_stream(properties);
-    auto params = ms::a_surface()
-        .of_size(titlebar_size_for_window(surface->size()))
-        .of_name("decoration")
-        .of_pixel_format(format)
-        .of_buffer_usage(mir::graphics::BufferUsage::software)
-        .of_position(titlebar_position_for_window(surface->top_left()))
-        .of_type(mir_surface_type_gloss)
-        .with_buffer_stream(stream_id);
-    auto id = build(session, params);
-    auto titlebar = session->surface(id);
-    titlebar->set_alpha(0.9);
-
+    auto size = titlebar_size_for_window(surface->size());
+    auto usage = mir::graphics::BufferUsage::software;
     auto& surface_info = tools->info_for(surface);
-    surface_info.titlebar = titlebar;
-    surface_info.titlebar_id = id;
-    surface_info.titlebar_stream_id = stream_id;
-    surface_info.children.push_back(titlebar);
+    surface_info.has_titlebar = true;
+    surface_info.titlebar_id = session->create_buffer_stream(mg::BufferProperties{size, format, usage});
+    surface_info.init_titlebar(size);
+    surface_info.paint_titlebar(0xFF);
 
-    SurfaceInfo& titlebar_info =
-            surface_map.emplace(titlebar, SurfaceInfo{session, titlebar, {}}).first->second;
-    titlebar_info.is_titlebar = true;
-    titlebar_info.parent = surface;
-    titlebar_info.init_titlebar(titlebar);
+    content_and_titlebar(surface_info, *surface, size);
+    apply_input_titlebar_and_content_area(surface_info, *surface, {surface->top_left(), surface->size()});
 }
 
 void me::CanonicalWindowManagerPolicyCopy::handle_new_surface(std::shared_ptr<ms::Session> const& session, std::shared_ptr<ms::Surface> const& surface)
@@ -289,18 +353,6 @@
 
     tools->info_for(session).surfaces.push_back(surface);
 
-    if (surface_info.can_be_active())
-    {
-        surface->add_observer(std::make_shared<shell::SurfaceReadyObserver>(
-            [this](std::shared_ptr<scene::Session> const& /*session*/,
-                   std::shared_ptr<scene::Surface> const& surface)
-                {
-                    select_active_surface(surface);
-                },
-            session,
-            surface));
-    }
-
     if (surface_info.state == mir_surface_state_fullscreen)
         fullscreen_surfaces.insert(surface);
 }
@@ -362,6 +414,19 @@
 
     #undef COPY_IF_SET
 
+    if (modifications.input_shape.is_set())
+    {
+        auto rects = modifications.input_shape.value();
+        constrain_input_to(rects, {surface->top_left(), surface->size()} );
+        surface_info.input_shape = rects;
+
+        std::vector<Rectangle> input_area;
+        if (surface_info.visible_titlebar)
+            apply_input_titlebar_and_content_area(surface_info, *surface, {surface->top_left(), surface->size()});
+        else
+            apply_input_content_area(surface_info, *surface, {surface->top_left(), surface->size()});
+    }
+
     std::swap(surface_info, surface_info_old);
 
     if (modifications.name.is_set())
@@ -394,7 +459,7 @@
             false,
             display_area);
 
-        apply_resize(surface, surface_info.titlebar, top_left, new_size);
+        apply_resize(surface, top_left, new_size);
     }
 
     if (modifications.input_shape.is_set())
@@ -439,12 +504,8 @@
     }
 
     session->destroy_surface(surface);
-    if (info.titlebar)
-    {
-        session->destroy_surface(info.titlebar_id);
-        session->destroy_buffer_stream(info.titlebar_stream_id);
-        tools->forget(info.titlebar);
-    }
+    if (info.has_titlebar)
+        session->destroy_buffer_stream(info.titlebar_id);
 
     auto& surfaces = tools->info_for(session).surfaces;
 
@@ -511,36 +572,28 @@
     {
     case mir_surface_state_restored:
         movement = info.restore_rect.top_left - old_pos;
-        surface->resize(info.restore_rect.size);
-        if (info.titlebar)
-        {
-            info.titlebar->resize(titlebar_size_for_window(info.restore_rect.size));
-            info.titlebar->show();
-        }
+        info.visible_titlebar = true;
+        apply_resize(surface, surface->top_left() + movement, info.restore_rect.size);
         break;
 
     case mir_surface_state_maximized:
         movement = display_area.top_left - old_pos;
-        surface->resize(display_area.size);
-        if (info.titlebar)
-            info.titlebar->hide();
+        movement.dy = movement.dy - titlebar_displacement.dy;
+        info.visible_titlebar = true;
+        apply_resize(surface, surface->top_left() + movement, display_area.size);
         break;
 
     case mir_surface_state_horizmaximized:
         movement = Point{display_area.top_left.x, info.restore_rect.top_left.y} - old_pos;
-        surface->resize({display_area.size.width, info.restore_rect.size.height});
-        if (info.titlebar)
-        {
-            info.titlebar->resize(titlebar_size_for_window({display_area.size.width, info.restore_rect.size.height}));
-            info.titlebar->show();
-        }
+        info.visible_titlebar = true;
+        apply_resize(surface, surface->top_left() + movement, {display_area.size.width, info.restore_rect.size.height});
         break;
 
     case mir_surface_state_vertmaximized:
         movement = Point{info.restore_rect.top_left.x, display_area.top_left.y} - old_pos;
-        surface->resize({info.restore_rect.size.width, display_area.size.height});
-        if (info.titlebar)
-            info.titlebar->hide();
+        movement.dy = movement.dy - titlebar_displacement.dy;
+        info.visible_titlebar = true;
+        apply_resize(surface, surface->top_left() + movement, {info.restore_rect.size.width, display_area.size.height});
         break;
 
     case mir_surface_state_fullscreen:
@@ -557,14 +610,15 @@
         }
 
         movement = rect.top_left - old_pos;
-        surface->resize(rect.size);
+
+        //needs to be content only
+        info.visible_titlebar = false;
+        apply_resize(surface, surface->top_left() + movement, rect.size);
         break;
     }
 
     case mir_surface_state_hidden:
     case mir_surface_state_minimized:
-        if (info.titlebar)
-            info.titlebar->hide();
         surface->hide();
         return info.state = value;
 
@@ -572,11 +626,6 @@
         break;
     }
 
-    // TODO It is rather simplistic to move a tree WRT the top_left of the root
-    // TODO when resizing. But for more sophistication we would need to encode
-    // TODO some sensible layout rules.
-    move_tree(surface, movement);
-
     info.state = value;
 
     if (info.is_visible())
@@ -757,9 +806,9 @@
     {
         if (mir_pointer_event_button_state(event, mir_pointer_button_primary))
         {
-            if (auto const possible_titlebar = tools->surface_at(old_cursor))
+            if (auto const surface = tools->surface_at(old_cursor))
             {
-                if (tools->info_for(possible_titlebar).is_titlebar)
+                if (old_cursor.y < surface->top_left().y)
                 {
                     drag(cursor);
                     consumes_event = true;
@@ -783,6 +832,7 @@
 
         auto const value = handle_set_state(surface, MirSurfaceState(state));
         surface->configure(mir_surface_attrib_state, value);
+        handle_set_state(surface, state);
     }
 }
 
@@ -795,10 +845,7 @@
     {
         if (auto const active_surface = active_surface_.lock())
         {
-            if (auto const titlebar = tools->info_for(active_surface).titlebar)
-            {
-                tools->info_for(titlebar).paint_titlebar(0x3F);
-            }
+            tools->info_for(active_surface).paint_titlebar(0x3F);
         }
 
         if (active_surface_.lock())
@@ -814,15 +861,9 @@
     {
         if (auto const active_surface = active_surface_.lock())
         {
-            if (auto const titlebar = tools->info_for(active_surface).titlebar)
-            {
-                tools->info_for(titlebar).paint_titlebar(0x3F);
-            }
-        }
-        if (auto const titlebar = tools->info_for(surface).titlebar)
-        {
-            tools->info_for(titlebar).paint_titlebar(0xFF);
-        }
+            tools->info_for(active_surface).paint_titlebar(0x3F);
+        }
+        tools->info_for(surface).paint_titlebar(0xFF);
         tools->set_focus_to(info_for.session.lock(), surface);
         tools->raise_tree(surface);
         active_surface_ = surface;
@@ -852,7 +893,7 @@
 
 bool me::CanonicalWindowManagerPolicyCopy::resize(std::shared_ptr<ms::Surface> const& surface, Point cursor, Point old_cursor, Rectangle bounds)
 {
-    if (!surface || !surface->input_area_contains(old_cursor))
+    if (!surface)
         return false;
 
     auto const top_left = surface->top_left();
@@ -883,27 +924,38 @@
 
     Point new_pos = top_left + left_resize*delta.dx + top_resize*delta.dy;
 
-
     auto const& surface_info = tools->info_for(surface);
 
     surface_info.constrain_resize(surface, new_pos, new_size, left_resize, top_resize, bounds);
 
-    apply_resize(surface, surface_info.titlebar, new_pos, new_size);
+    apply_resize(surface, new_pos, new_size);
 
     return true;
 }
 
 void me::CanonicalWindowManagerPolicyCopy::apply_resize(
     std::shared_ptr<ms::Surface> const& surface,
-    std::shared_ptr<ms::Surface> const& titlebar,
     Point const& new_pos,
     Size const& new_size) const
 {
-    if (titlebar)
-        titlebar->resize({new_size.width, Height{title_bar_height}});
+    auto& surface_info = tools->info_for(surface);
+
+    if (surface_info.visible_titlebar)
+    {
+        apply_input_titlebar_and_content_area(surface_info, *surface, {new_pos, new_size}); 
+        content_and_titlebar(surface_info, *surface, new_size);
+    }
+    else
+    {
+        apply_input_content_area(surface_info, *surface, {new_pos, new_size});
+        content_only(surface_info, *surface);
+    }
 
     surface->resize(new_size);
 
+    // TODO It is rather simplistic to move a tree WRT the top_left of the root
+    // TODO when resizing. But for more sophistication we would need to encode
+    // TODO some sensible layout rules.
     move_tree(surface, new_pos-surface->top_left());
 }
 
@@ -912,7 +964,7 @@
     if (!surface)
         return false;
 
-    if (!surface->input_area_contains(from) && !tools->info_for(surface).titlebar)
+    if (!surface->input_area_contains(from))
         return false;
 
     auto movement = to - from;

=== modified file 'examples/server_example_canonical_window_manager.h'
--- examples/server_example_canonical_window_manager.h	2016-01-29 08:18:22 +0000
+++ examples/server_example_canonical_window_manager.h	2016-04-13 11:13:46 +0000
@@ -88,9 +88,7 @@
 
     void generate_decorations_for(
         std::shared_ptr<scene::Session> const& session,
-        std::shared_ptr<scene::Surface> const& surface,
-        SurfaceInfoMap& surface_map,
-        std::function<frontend::SurfaceId(std::shared_ptr<scene::Session> const& session, scene::SurfaceCreationParameters const& params)> const& build);
+        std::shared_ptr<scene::Surface> const& surface);
 
 private:
     static const int modifier_mask =
@@ -112,7 +110,6 @@
     void move_tree(std::shared_ptr<scene::Surface> const& root, geometry::Displacement movement) const;
     void apply_resize(
         std::shared_ptr<mir::scene::Surface> const& surface,
-        std::shared_ptr<mir::scene::Surface> const& titlebar,
         geometry::Point const& new_pos,
         geometry::Size const& new_size) const;
 

=== modified file 'examples/server_example_tiling_window_manager.cpp'
--- examples/server_example_tiling_window_manager.cpp	2016-01-29 08:18:22 +0000
+++ examples/server_example_tiling_window_manager.cpp	2016-04-13 11:13:46 +0000
@@ -138,9 +138,7 @@
 
 void me::TilingWindowManagerPolicy::generate_decorations_for(
     std::shared_ptr<ms::Session> const&,
-    std::shared_ptr<ms::Surface> const&,
-    SurfaceInfoMap&,
-    std::function<mf::SurfaceId(std::shared_ptr<ms::Session> const&, ms::SurfaceCreationParameters const&)> const&)
+    std::shared_ptr<ms::Surface> const&)
 {
 }
 

=== modified file 'examples/server_example_tiling_window_manager.h'
--- examples/server_example_tiling_window_manager.h	2016-01-29 08:18:22 +0000
+++ examples/server_example_tiling_window_manager.h	2016-04-13 11:13:46 +0000
@@ -78,9 +78,7 @@
         std::shared_ptr<scene::Surface> const& surface);
 
     void generate_decorations_for(
-        std::shared_ptr<scene::Session> const& session, std::shared_ptr<scene::Surface> const& surface,
-        SurfaceInfoMap& surface_info,
-        std::function<frontend::SurfaceId(std::shared_ptr<scene::Session> const&, scene::SurfaceCreationParameters const&)> const& build);
+        std::shared_ptr<scene::Session> const& session, std::shared_ptr<scene::Surface> const& surface);
 
 private:
     static const int modifier_mask =

=== modified file 'examples/server_example_window_management.cpp'
--- examples/server_example_window_management.cpp	2016-03-23 06:39:56 +0000
+++ examples/server_example_window_management.cpp	2016-04-13 11:13:46 +0000
@@ -105,10 +105,7 @@
     }
 
     void generate_decorations_for(
-        std::shared_ptr<ms::Session> const&,
-        std::shared_ptr<ms::Surface> const&,
-        SurfaceInfoMap&,
-        std::function<mf::SurfaceId(std::shared_ptr<ms::Session> const&, ms::SurfaceCreationParameters const&)> const&) override
+        std::shared_ptr<ms::Session> const&, std::shared_ptr<ms::Surface> const&) override
     {
     }
 private:

=== modified file 'examples/server_example_window_management_info.cpp'
--- examples/server_example_window_management_info.cpp	2016-01-29 08:18:22 +0000
+++ examples/server_example_window_management_info.cpp	2016-04-13 11:13:46 +0000
@@ -19,6 +19,7 @@
 #include "server_example_window_management_info.h"
 
 #include "mir/scene/surface.h"
+#include "mir/scene/session.h"
 #include "mir/scene/surface_creation_parameters.h"
 
 #include "mir/graphics/buffer.h"
@@ -46,7 +47,9 @@
     width_inc{params.width_inc},
     height_inc{params.height_inc},
     min_aspect{params.min_aspect},
-    max_aspect{params.max_aspect}
+    max_aspect{params.max_aspect},
+    input_shape{params.input_shape.is_set() ? params.input_shape.value() : std::vector<Rectangle>{}},
+    streams{params.streams.is_set() ? params.streams.value() : std::vector<shell::StreamSpecification>{}}
 {
     if (params.output_id != mir::graphics::DisplayConfigurationOutputId{0})
         output_id = params.output_id;
@@ -243,16 +246,19 @@
     mg::BufferID back_buffer; 
 };
 
-void mir::examples::SurfaceInfo::init_titlebar(std::shared_ptr<scene::Surface> const& surface)
+void mir::examples::SurfaceInfo::init_titlebar(Size titlebar_size)
 {
-    auto stream = surface->primary_buffer_stream();
-    try
-    {
-        stream_painter = std::make_shared<AllocatingPainter>(stream, surface->size());
-    }
-    catch (...)
-    {
-        stream_painter = std::make_shared<SwappingPainter>(stream);
+    if (auto s = session.lock())
+    {
+        auto stream = s->get_buffer_stream(titlebar_id);
+        try
+        {
+            stream_painter = std::make_shared<AllocatingPainter>(stream, titlebar_size);
+        }
+        catch (...)
+        {
+            stream_painter = std::make_shared<SwappingPainter>(stream);
+        }
     }
 }
 

=== modified file 'examples/server_example_window_management_info.h'
--- examples/server_example_window_management_info.h	2016-03-30 14:08:54 +0000
+++ examples/server_example_window_management_info.h	2016-04-13 11:13:46 +0000
@@ -63,10 +63,6 @@
     std::weak_ptr <scene::Session> session;
     std::weak_ptr <scene::Surface> parent;
     std::vector <std::weak_ptr<scene::Surface>> children;
-    std::shared_ptr <scene::Surface> titlebar;
-    frontend::SurfaceId titlebar_id;
-    frontend::BufferStreamId titlebar_stream_id;
-    bool is_titlebar = false;
     geometry::Width min_width;
     geometry::Height min_height;
     geometry::Width max_width;
@@ -76,8 +72,15 @@
     mir::optional_value<shell::SurfaceAspectRatio> min_aspect;
     mir::optional_value<shell::SurfaceAspectRatio> max_aspect;
     mir::optional_value<graphics::DisplayConfigurationOutputId> output_id;
-
-    void init_titlebar(std::shared_ptr <scene::Surface> const& surface);
+    mir::optional_value<std::vector<geometry::Rectangle>> input_shape;
+    mir::optional_value<geometry::Rectangle> titlebar_input_shape;
+
+    mir::optional_value<std::vector<shell::StreamSpecification>> streams;
+    frontend::BufferStreamId titlebar_id;
+    bool has_titlebar = false;
+    bool visible_titlebar = false;
+
+    void init_titlebar(geometry::Size titlebar_size);
 
     void paint_titlebar(int intensity);
 

=== modified file 'include/server/mir/scene/surface_creation_parameters.h'
--- include/server/mir/scene/surface_creation_parameters.h	2016-03-29 16:30:22 +0000
+++ include/server/mir/scene/surface_creation_parameters.h	2016-04-13 11:13:46 +0000
@@ -72,6 +72,8 @@
 
     SurfaceCreationParameters& with_buffer_stream(frontend::BufferStreamId const& id);
 
+    SurfaceCreationParameters& with_buffer_streams(std::vector<shell::StreamSpecification> const& streams);
+
     std::string name;
     geometry::Size size;
     geometry::Point top_left;
@@ -84,7 +86,6 @@
     mir::optional_value<MirSurfaceType> type;
     mir::optional_value<MirOrientationMode> preferred_orientation;
     mir::optional_value<frontend::SurfaceId> parent_id;
-    mir::optional_value<frontend::BufferStreamId> content_id;
     mir::optional_value<geometry::Rectangle> aux_rect;
     mir::optional_value<MirEdgeAttachment> edge_attachment;
 

=== modified file 'include/server/mir/shell/surface_specification.h'
--- include/server/mir/shell/surface_specification.h	2016-03-23 06:39:56 +0000
+++ include/server/mir/shell/surface_specification.h	2016-04-13 11:13:46 +0000
@@ -45,6 +45,7 @@
     geometry::Displacement displacement;
     optional_value<geometry::Size> size;
 };
+bool operator==(StreamSpecification const& lhs, StreamSpecification const& rhs);
 
 /// Specification of surface properties requested by client
 struct SurfaceSpecification

=== modified file 'src/server/frontend/session_mediator.cpp'
--- src/server/frontend/session_mediator.cpp	2016-04-12 14:10:00 +0000
+++ src/server/frontend/session_mediator.cpp	2016-04-13 11:13:46 +0000
@@ -287,10 +287,10 @@
     #undef COPY_IF_SET
 
     mf::BufferStreamId buffer_stream_id;
-    std::shared_ptr<mf::BufferStream> legacy_stream = nullptr;
+    std::shared_ptr<mf::BufferStream> legacy_stream;
+    std::vector<msh::StreamSpecification> stream_spec;
     if (request->stream_size() > 0)
     {
-        std::vector<msh::StreamSpecification> stream_spec;
         for (auto& stream : request->stream())
         {
             if (stream.has_width() && stream.has_height())
@@ -310,16 +310,17 @@
                         {}});
             }
         }
-        params.streams = std::move(stream_spec);
     }
     else
     {
         buffer_stream_id = session->create_buffer_stream(
             {params.size, params.pixel_format, params.buffer_usage});
         legacy_stream = session->get_buffer_stream(buffer_stream_id);
-        params.content_id = buffer_stream_id;
+        stream_spec.emplace_back(msh::StreamSpecification{ {buffer_stream_id}, {0, 0}, {}});
     }
 
+    params.streams = std::move(stream_spec);
+
     if (request->has_min_aspect())
         params.min_aspect = { request->min_aspect().width(), request->min_aspect().height()};
 
@@ -334,17 +335,16 @@
     auto const surf_id = shell->create_surface(session, params, sink);
 
     auto surface = session->get_surface(surf_id);
-    auto stream = session->get_buffer_stream(buffer_stream_id);
     auto const& client_size = surface->client_size();
     response->mutable_id()->set_value(surf_id.as_value());
     response->set_width(client_size.width.as_uint32_t());
     response->set_height(client_size.height.as_uint32_t());
 
     // TODO: Deprecate
-    response->set_pixel_format(stream->pixel_format());
+    response->set_pixel_format(params.pixel_format);
     response->set_buffer_usage(request->buffer_usage());
 
-    response->mutable_buffer_stream()->set_pixel_format(stream->pixel_format());
+    response->mutable_buffer_stream()->set_pixel_format(params.pixel_format);
     response->mutable_buffer_stream()->set_buffer_usage(request->buffer_usage());
 
     if (surface->supports_input())

=== modified file 'src/server/scene/application_session.cpp'
--- src/server/scene/application_session.cpp	2016-04-13 11:13:46 +0000
+++ src/server/scene/application_session.cpp	2016-04-13 11:13:46 +0000
@@ -94,19 +94,12 @@
     //TODO: we take either the content_id or the first streams content for now.
     //      Once the surface factory interface takes more than one stream,
     //      we can take all the streams as content.
-    if (!((the_params.content_id.is_set()) ||
-          (the_params.streams.is_set() && the_params.streams.value().size() > 0)))
-    {
+    if (!(the_params.streams.is_set() && the_params.streams.value().size() > 0))
         BOOST_THROW_EXCEPTION(std::logic_error("surface must have content"));
-    }
 
     auto params = the_params;
 
-    mf::BufferStreamId stream_id;
-    if (params.content_id.is_set())
-        stream_id = params.content_id.value();
-    else
-        stream_id = params.streams.value()[0].stream_id;
+    mf::BufferStreamId stream_id = params.streams.value()[0].stream_id;
 
     if (params.parent_id.is_set())
         params.parent = checked_find(the_params.parent_id.value())->second;
@@ -116,15 +109,8 @@
         buffer_stream->resize(params.size);
 
     std::list<StreamInfo> streams;
-    if (the_params.content_id.is_set())
-    {
-        streams.push_back({checked_find(the_params.content_id.value())->second, {0,0}, {}});
-    }
-    else
-    {
-        for (auto& stream : params.streams.value())
-            streams.push_back({checked_find(stream.stream_id)->second, stream.displacement, stream.size});
-    }
+    for (auto& stream : params.streams.value())
+        streams.push_back({checked_find(stream.stream_id)->second, stream.displacement, stream.size});
 
     auto surface = surface_factory->create_surface(streams, params);
 

=== modified file 'src/server/scene/surface_creation_parameters.cpp'
--- src/server/scene/surface_creation_parameters.cpp	2016-01-29 08:18:22 +0000
+++ src/server/scene/surface_creation_parameters.cpp	2016-04-13 11:13:46 +0000
@@ -130,7 +130,14 @@
 
 ms::SurfaceCreationParameters& ms::SurfaceCreationParameters::with_buffer_stream(mf::BufferStreamId const& id)
 {
-    content_id = id;
+    streams = std::vector<shell::StreamSpecification>{ {id, {}, {}} };
+    return *this;
+}
+
+ms::SurfaceCreationParameters& ms::SurfaceCreationParameters::with_buffer_streams(
+    std::vector<shell::StreamSpecification> const& s)
+{
+    streams = s;
     return *this;
 }
 
@@ -149,7 +156,7 @@
         lhs.type == rhs.type &&
         lhs.preferred_orientation == rhs.preferred_orientation &&
         lhs.parent_id == rhs.parent_id &&
-        lhs.content_id == rhs.content_id;
+        lhs.streams == rhs.streams;
 }
 
 bool ms::operator!=(

=== modified file 'src/server/shell/surface_specification.cpp'
--- src/server/shell/surface_specification.cpp	2015-10-15 04:20:44 +0000
+++ src/server/shell/surface_specification.cpp	2016-04-13 11:13:46 +0000
@@ -47,3 +47,10 @@
         !parent.is_set() &&
         !input_shape.is_set();
 }
+
+bool msh::operator==(StreamSpecification const& lhs, StreamSpecification const& rhs)
+{
+    return lhs.stream_id == rhs.stream_id &&
+        lhs.displacement == rhs.displacement && 
+        lhs.size == rhs.size;
+}

=== modified file 'src/server/symbols.map'
--- src/server/symbols.map	2016-03-28 23:15:00 +0000
+++ src/server/symbols.map	2016-04-13 11:13:46 +0000
@@ -290,6 +290,7 @@
     mir::shell::ShellWrapper::start_prompt_session_for*;
     mir::shell::ShellWrapper::stop_prompt_session*;
     mir::shell::ShellWrapper::surface_at*;
+    mir::shell::StreamSpecification::operator*;
     mir::shell::SurfaceReadyObserver::frame_posted*;
     mir::shell::SurfaceReadyObserver::?SurfaceReadyObserver*;
     mir::shell::SurfaceReadyObserver::SurfaceReadyObserver*;