Implement side-by-side tiling

Patch by Florian Müllner for Metacity
https://bugzilla.gnome.org/show_bug.cgi?id=607694

When dragging a window over a screen edge and dropping it there,
maximize it vertically and scale it horizontally to cover the
corresponding half of the current monitor.

Whenever a "hot area" which triggers this behavior is entered, an
indication of window's target size is displayed after a short delay
to avoid distraction when moving a window between monitors.

1 files changed, 62 insertions, 3 deletions

diff --git a/src/core/constraints.c b/src/core/constraints.c
index 16d9b107..a79f858a 100644
--- a/src/core/constraints.c
+++ b/src/core/constraints.c
@@ -98,6 +98,7 @@ typedef enum
   PRIORITY_ENTIRELY_VISIBLE_ON_WORKAREA = 1,
   PRIORITY_SIZE_HINTS_INCREMENTS = 1,
   PRIORITY_MAXIMIZATION = 2,
+  PRIORITY_TILING = 2,
   PRIORITY_FULLSCREEN = 2,
   PRIORITY_SIZE_HINTS_LIMITS = 3,
   PRIORITY_TITLEBAR_VISIBLE = 4,
@@ -145,6 +146,10 @@ static gboolean constrain_maximization       (MetaWindow         *window,
                                               ConstraintInfo     *info,
                                               ConstraintPriority  priority,
                                               gboolean            check_only);
+static gboolean constrain_tiling             (MetaWindow         *window,
+                                              ConstraintInfo     *info,
+                                              ConstraintPriority  priority,
+                                              gboolean            check_only);
 static gboolean constrain_fullscreen         (MetaWindow         *window,
                                               ConstraintInfo     *info,
                                               ConstraintPriority  priority,
@@ -211,6 +216,7 @@ typedef struct {
 
 static const Constraint all_constraints[] = {
   {constrain_maximization,       "constrain_maximization"},
+  {constrain_tiling,             "constrain_tiling"},
   {constrain_fullscreen,         "constrain_fullscreen"},
   {constrain_size_increments,    "constrain_size_increments"},
   {constrain_size_limits,        "constrain_size_limits"},
@@ -731,7 +737,8 @@ constrain_maximization (MetaWindow         *window,
     return TRUE;
 
   /* Determine whether constraint applies; exit if it doesn't */
-  if (!window->maximized_horizontally && !window->maximized_vertically)
+  if ((!window->maximized_horizontally && !window->maximized_vertically) ||
+      META_WINDOW_TILED (window))
     return TRUE;
 
   /* Calculate target_size = maximized size of (window + frame) */
@@ -800,6 +807,58 @@ constrain_maximization (MetaWindow         *window,
 }
 
 static gboolean
+constrain_tiling (MetaWindow         *window,
+                  ConstraintInfo     *info,
+                  ConstraintPriority  priority,
+                  gboolean            check_only)
+{
+  MetaRectangle target_size;
+  MetaRectangle min_size, max_size;
+  gboolean hminbad, vminbad;
+  gboolean horiz_equal, vert_equal;
+  gboolean constraint_already_satisfied;
+
+  if (priority > PRIORITY_TILING)
+    return TRUE;
+
+  /* Determine whether constraint applies; exit if it doesn't */
+  if (!META_WINDOW_TILED (window))
+    return TRUE;
+
+  /* Calculate target_size - as the tile previews need this as well, we
+   * use an external function for the actual calculation
+   */
+  meta_window_get_current_tile_area (window, &target_size);
+  unextend_by_frame (&target_size, info->fgeom);
+
+  /* Check min size constraints; max size constraints are ignored as for
+   * maximized windows.
+   */
+  get_size_limits (window, info->fgeom, FALSE, &min_size, &max_size);
+  hminbad = target_size.width < min_size.width;
+  vminbad = target_size.height < min_size.height;
+  if (hminbad || vminbad)
+    return TRUE;
+
+  /* Determine whether constraint is already satisfied; exit if it is */
+  horiz_equal = target_size.x      == info->current.x &&
+                target_size.width  == info->current.width;
+  vert_equal  = target_size.y      == info->current.y &&
+                target_size.height == info->current.height;
+  constraint_already_satisfied = horiz_equal && vert_equal;
+  if (check_only || constraint_already_satisfied)
+    return constraint_already_satisfied;
+
+  /*** Enforce constraint ***/
+  info->current.x      = target_size.x;
+  info->current.width  = target_size.width;
+  info->current.y      = target_size.y;
+  info->current.height = target_size.height;
+
+  return TRUE;
+}
+
+static gboolean
 constrain_fullscreen (MetaWindow         *window,
                       ConstraintInfo     *info,
                       ConstraintPriority  priority,
@@ -850,7 +909,7 @@ constrain_size_increments (MetaWindow         *window,
 
   /* Determine whether constraint applies; exit if it doesn't */
   if (META_WINDOW_MAXIMIZED (window) || window->fullscreen || 
-      info->action_type == ACTION_MOVE)
+      META_WINDOW_TILED (window) || info->action_type == ACTION_MOVE)
     return TRUE;
 
   /* Determine whether constraint is already satisfied; exit if it is */
@@ -981,7 +1040,7 @@ constrain_aspect_ratio (MetaWindow         *window,
   constraints_are_inconsistent = minr > maxr;
   if (constraints_are_inconsistent ||
       META_WINDOW_MAXIMIZED (window) || window->fullscreen || 
-      info->action_type == ACTION_MOVE)
+      META_WINDOW_TILED (window) || info->action_type == ACTION_MOVE)
     return TRUE;
 
   /* Determine whether constraint is already satisfied; exit if it is.  We