window: Add lowlevel popovers API

Popovers are transient floating widgets that are confined to the
window space. These have their own GdkWindow that is set on top
of the regular window contents, so they can be used for popup menu
alike UIs with custom popup/popdown/grabs behavior.

2 files changed, 334 insertions, 0 deletions

diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 78f48f15af..1abf559368 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -123,6 +123,15 @@
 #define MNEMONICS_DELAY 300 /* ms */
 
 typedef struct _GtkDeviceGrabInfo GtkDeviceGrabInfo;
+typedef struct _GtkWindowPopover GtkWindowPopover;
+
+struct _GtkWindowPopover
+{
+  GtkWidget *widget;
+  GdkWindow *window;
+  GtkPositionType pos;
+  cairo_rectangle_int_t rect;
+};
 
 struct _GtkWindowPrivate
 {
@@ -137,6 +146,8 @@ struct _GtkWindowPrivate
   GdkScreen             *screen;
   GtkApplication        *application;
 
+  GHashTable            *popovers;
+
   GdkModifierType        mnemonic_modifier;
   GdkWindowTypeHint      gdk_type_hint;
 
@@ -1319,6 +1330,18 @@ gtk_window_close (GtkWindow *window)
 }
 
 static void
+popover_destroy (GtkWindowPopover *popover)
+{
+  if (popover->widget && gtk_widget_get_parent (popover->widget))
+    gtk_widget_unparent (popover->widget);
+
+  if (popover->window)
+    gdk_window_destroy (popover->window);
+
+  g_free (popover);
+}
+
+static void
 gtk_window_init (GtkWindow *window)
 {
   GtkStyleContext *context;
@@ -1368,6 +1391,8 @@ gtk_window_init (GtkWindow *window)
   priv->has_resize_grip = TRUE;
   priv->mnemonics_visible = TRUE;
   priv->focus_visible = TRUE;
+  priv->popovers = g_hash_table_new_full (NULL, NULL, NULL,
+                                          (GDestroyNotify) popover_destroy);
 
   g_object_ref_sink (window);
   priv->has_user_ref_count = TRUE;
@@ -5166,6 +5191,8 @@ gtk_window_finalize (GObject *object)
       priv->mnemonics_display_timeout_id = 0;
     }
 
+  g_hash_table_destroy (priv->popovers);
+
   G_OBJECT_CLASS (gtk_window_parent_class)->finalize (object);
 }
 
@@ -5399,6 +5426,19 @@ gtk_window_hide (GtkWidget *widget)
 }
 
 static void
+popover_map (GtkWidget        *widget,
+             GtkWindowPopover *popover)
+{
+  if (popover->window)
+    {
+      gdk_window_show (popover->window);
+
+      if (gtk_widget_get_visible (popover->widget))
+        gtk_widget_map (popover->widget);
+    }
+}
+
+static void
 gtk_window_map (GtkWidget *widget)
 {
   GtkWidget *child;
@@ -5511,6 +5551,8 @@ gtk_window_map (GtkWidget *widget)
 
   if (priv->application)
     gtk_application_handle_window_map (priv->application, window);
+
+  g_hash_table_foreach (priv->popovers, (GHFunc) popover_map, window);
 }
 
 static gboolean
@@ -5532,6 +5574,18 @@ gtk_window_map_event (GtkWidget   *widget,
 }
 
 static void
+popover_unmap (GtkWidget        *widget,
+               GtkWindowPopover *popover)
+{
+  if (popover->window)
+    {
+      if (gtk_widget_is_visible (popover->widget))
+        gtk_widget_unmap (popover->widget);
+      gdk_window_hide (popover->window);
+    }
+}
+
+static void
 gtk_window_unmap (GtkWidget *widget)
 {
   GtkWindow *window = GTK_WINDOW (widget);
@@ -5547,6 +5601,7 @@ gtk_window_unmap (GtkWidget *widget)
       return;
     }
 
+  g_hash_table_foreach (priv->popovers, (GHFunc) popover_unmap, window);
   gdk_window = gtk_widget_get_window (widget);
 
   gtk_widget_set_mapped (widget, FALSE);
@@ -5677,6 +5732,117 @@ gtk_window_get_remembered_size (GtkWindow *window,
 }
 
 static void
+popover_get_rect (GtkWindowPopover      *popover,
+                  GtkWindow             *window,
+                  cairo_rectangle_int_t *rect)
+{
+  GtkAllocation win_alloc;
+  GtkRequisition req;
+
+  gtk_widget_get_preferred_size (popover->widget, NULL, &req);
+  gtk_widget_get_allocation (GTK_WIDGET (window), &win_alloc);
+  rect->width = req.width;
+  rect->height = req.height;
+
+  if (popover->pos == GTK_POS_LEFT || popover->pos == GTK_POS_RIGHT)
+    {
+      if (req.height < win_alloc.height &&
+          gtk_widget_get_vexpand (popover->widget))
+        {
+          rect->y = 0;
+          rect->height = win_alloc.height;
+        }
+      else
+        rect->y = CLAMP (popover->rect.y + (popover->rect.height / 2) -
+                         (req.height / 2), 0, win_alloc.height - req.height);
+
+      if (popover->pos == GTK_POS_LEFT)
+        {
+          rect->x = popover->rect.x - req.width;
+
+          if (rect->x > 0 && gtk_widget_get_hexpand (popover->widget))
+            {
+              rect->x = 0;
+              rect->width = popover->rect.x;
+            }
+        }
+      else
+        {
+          rect->x = popover->rect.x + popover->rect.width;
+
+          if (rect->x + rect->width < win_alloc.width &&
+              gtk_widget_get_hexpand (popover->widget))
+            rect->width = win_alloc.width - rect->x;
+        }
+    }
+  else if (popover->pos == GTK_POS_TOP || popover->pos == GTK_POS_BOTTOM)
+    {
+      if (req.width < win_alloc.width &&
+          gtk_widget_get_hexpand (popover->widget))
+        {
+          rect->x = 0;
+          rect->width = win_alloc.width;
+        }
+      else
+        rect->x = CLAMP (popover->rect.x + (popover->rect.width / 2) -
+                         (req.width / 2), 0, win_alloc.width - req.width);
+
+      if (popover->pos == GTK_POS_TOP)
+        {
+          rect->y = popover->rect.y - req.height;
+
+          if (rect->y > 0 && gtk_widget_get_vexpand (popover->widget))
+            {
+              rect->y = 0;
+              rect->height = popover->rect.y;
+            }
+        }
+      else
+        {
+          rect->y = popover->rect.y + popover->rect.height;
+
+          if (rect->y + rect->height < win_alloc.height &&
+              gtk_widget_get_vexpand (popover->widget))
+            rect->height = win_alloc.height - rect->y;
+        }
+    }
+}
+
+static void
+popover_realize (GtkWidget        *widget,
+                 GtkWindowPopover *popover,
+                 GtkWindow        *window)
+{
+  cairo_rectangle_int_t rect;
+  GdkWindow *parent_window;
+  GdkWindowAttr attributes;
+  gint attributes_mask;
+
+  if (popover->window)
+    return;
+
+  popover_get_rect (popover, window, &rect);
+
+  attributes.window_type = GDK_WINDOW_CHILD;
+  attributes.wclass = GDK_INPUT_OUTPUT;
+  attributes.x = rect.x;
+  attributes.y = rect.y;
+  attributes.width = rect.width;
+  attributes.height = rect.height;
+  attributes.visual = gtk_widget_get_visual (widget);
+  attributes.event_mask = gtk_widget_get_events (popover->widget) |
+    GDK_EXPOSURE_MASK;
+  attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL;
+
+  parent_window = gtk_widget_get_window (GTK_WIDGET (window));
+  popover->window =
+    gdk_window_new (parent_window, &attributes, attributes_mask);
+  gtk_widget_register_window (GTK_WIDGET (window), popover->window);
+
+  gtk_widget_set_parent_window (popover->widget, popover->window);
+}
+
+static void
 gtk_window_realize (GtkWidget *widget)
 {
   GtkAllocation allocation;
@@ -5926,6 +6092,8 @@ gtk_window_realize (GtkWidget *widget)
   if (priv->has_resize_grip)
     resize_grip_create_window (window);
 
+  g_hash_table_foreach (priv->popovers, (GHFunc) popover_realize, window);
+
   old_scale = priv->scale;
   priv->scale = gtk_widget_get_scale_factor (widget);
   if (old_scale != priv->scale)
@@ -5933,6 +6101,15 @@ gtk_window_realize (GtkWidget *widget)
 }
 
 static void
+popover_unrealize (GtkWidget        *widget,
+                   GtkWindowPopover *popover)
+{
+  gtk_widget_unrealize (popover->widget);
+  gdk_window_destroy (popover->window);
+  popover->window = NULL;
+}
+
+static void
 gtk_window_unrealize (GtkWidget *widget)
 {
   GtkWindow *window = GTK_WINDOW (widget);
@@ -5982,6 +6159,8 @@ gtk_window_unrealize (GtkWidget *widget)
         }
     }
 
+  g_hash_table_foreach (priv->popovers, (GHFunc) popover_unrealize, window);
+
   GTK_WIDGET_CLASS (gtk_window_parent_class)->unrealize (widget);
 }
 
@@ -6698,6 +6877,32 @@ _gtk_window_set_allocation (GtkWindow           *window,
 }
 
 static void
+popover_size_allocate (GtkWidget        *widget,
+                       GtkWindowPopover *popover,
+                       GtkWindow        *window)
+{
+  cairo_rectangle_int_t rect;
+
+  if (!popover->window)
+    return;
+
+  popover_get_rect (popover, window, &rect);
+  gdk_window_move_resize (popover->window, rect.x, rect.y,
+                          rect.width, rect.height);
+  rect.x = rect.y = 0;
+  gtk_widget_size_allocate (widget, &rect);
+
+  if (gtk_widget_is_drawable (GTK_WIDGET (window)) &&
+      gtk_widget_is_visible (widget))
+    {
+      if (!gdk_window_is_visible (popover->window))
+        gdk_window_show (popover->window);
+    }
+  else if (gdk_window_is_visible (popover->window))
+    gdk_window_hide (popover->window);
+}
+
+static void
 gtk_window_size_allocate (GtkWidget     *widget,
                           GtkAllocation *allocation)
 {
@@ -6710,6 +6915,9 @@ gtk_window_size_allocate (GtkWidget     *widget,
   child = gtk_bin_get_child (GTK_BIN (window));
   if (child && gtk_widget_get_visible (child))
     gtk_widget_size_allocate (child, &child_allocation);
+
+  g_hash_table_foreach (window->priv->popovers,
+                        (GHFunc) popover_size_allocate, widget);
 }
 
 static gint
@@ -7619,8 +7827,11 @@ gtk_window_remove (GtkContainer *container,
                   GtkWidget     *widget)
 {
   GtkWindow *window = GTK_WINDOW (container);
+
   if (widget == window->priv->title_box)
     unset_titlebar (window);
+  else if (g_hash_table_contains (window->priv->popovers, widget))
+    gtk_window_remove_popover (window, widget);
   else
     GTK_CONTAINER_CLASS (gtk_window_parent_class)->remove (container, widget);
 }
@@ -9395,10 +9606,12 @@ gtk_window_draw (GtkWidget *widget,
 		 cairo_t   *cr)
 {
   GtkWindowPrivate *priv = GTK_WINDOW (widget)->priv;
+  GtkWindowPopover *popover;
   GtkStyleContext *context;
   gboolean ret = FALSE;
   GtkAllocation allocation;
   GtkBorder window_border;
+  GHashTableIter iter;
   gint title_height;
 
   context = gtk_widget_get_style_context (widget);
@@ -9483,6 +9696,16 @@ gtk_window_draw (GtkWidget *widget,
       gtk_style_context_restore (context);
     }
 
+  g_hash_table_iter_init (&iter, priv->popovers);
+
+  while (g_hash_table_iter_next (&iter, NULL, (gpointer*) &popover))
+    {
+      if (popover->window && gtk_widget_is_visible (popover->widget) &&
+          gtk_cairo_should_draw_window (cr, popover->window))
+        gtk_container_propagate_draw (GTK_CONTAINER (widget),
+                                      popover->widget, cr);
+    }
+
   return ret;
 }
 
@@ -11697,3 +11920,102 @@ _gtk_window_get_shadow_width (GtkWindow *window,
 {
   get_shadow_width (GTK_WIDGET (window), border);
 }
+
+void
+gtk_window_add_popover (GtkWindow *window,
+                        GtkWidget *popover)
+{
+  GtkWindowPrivate *priv;
+  GtkWindowPopover *data;
+
+  g_return_if_fail (GTK_IS_WINDOW (window));
+  g_return_if_fail (GTK_IS_WIDGET (popover));
+  g_return_if_fail (gtk_widget_get_parent (popover) == NULL);
+
+  priv = window->priv;
+
+  if (g_hash_table_contains (priv->popovers, popover))
+    return;
+
+  data = g_new0 (GtkWindowPopover, 1);
+  data->widget = popover;
+  g_hash_table_insert (priv->popovers, popover, data);
+
+  if (gtk_widget_get_realized (GTK_WIDGET (window)))
+    popover_realize (popover, data, window);
+
+  gtk_widget_set_parent (popover, GTK_WIDGET (window));
+}
+
+void
+gtk_window_remove_popover (GtkWindow *window,
+                           GtkWidget *popover)
+{
+  GtkWindowPrivate *priv;
+
+  g_return_if_fail (GTK_IS_WINDOW (window));
+  g_return_if_fail (GTK_IS_WIDGET (popover));
+
+  priv = window->priv;
+  g_hash_table_remove (priv->popovers, popover);
+}
+
+/**
+ * gtk_window_set_popover_position:
+ * @window: a #GtkWindow
+ * @popover: #GtkWidget to be positioned on top of window contents
+ * @pos: Position of the popover, relative of the contents it's related to
+ * @rect: Disclosure rectangle, in @window coordinates
+ *
+ * Positions @popover so it is at the side given by @pos of the rectangle @rect.
+ * If @popover is set to expand horizontally or vertically, the position given
+ * by @pos will be used to determine how the popover is allowed to expand
+ * without covering the content it's logically attached to.
+ *
+ * Since: 3.12
+ **/
+void
+gtk_window_set_popover_position (GtkWindow                   *window,
+                                 GtkWidget                   *popover,
+                                 GtkPositionType              pos,
+                                 const cairo_rectangle_int_t *rect)
+{
+  GtkWindowPopover *data;
+  GtkWindowPrivate *priv;
+
+  g_return_if_fail (GTK_IS_WINDOW (window));
+  g_return_if_fail (GTK_IS_WIDGET (popover));
+
+  priv = window->priv;
+  data = g_hash_table_lookup (priv->popovers, popover);
+
+  if (!data)
+    {
+      g_warning ("Widget %s(%p) is not a popover of window %s",
+                 gtk_widget_get_name (popover), popover,
+                 gtk_widget_get_name (GTK_WIDGET (window)));
+      return;
+    }
+  else
+    {
+      if (data->pos == pos &&
+          memcmp (&data->rect, rect, sizeof (cairo_rectangle_int_t)) == 0)
+        return;
+    }
+
+  data->rect = *rect;
+  data->pos = pos;
+
+  if (gtk_widget_is_visible (popover))
+    {
+      if (!data->window)
+        {
+          popover_realize (popover, data, window);
+          popover_map (popover, data);
+        }
+      else
+        gdk_window_raise (data->window);
+    }
+
+  gtk_widget_queue_resize (popover);
+}
diff --git a/gtk/gtkwindow.h b/gtk/gtkwindow.h
index dce09f11fd..31ced6f926 100644
--- a/gtk/gtkwindow.h
+++ b/gtk/gtkwindow.h
@@ -483,6 +483,18 @@ void     gtk_window_set_titlebar           (GtkWindow    *window,
 GDK_AVAILABLE_IN_3_12
 gboolean gtk_window_is_maximized           (GtkWindow    *window);
 
+GDK_AVAILABLE_IN_3_12
+void     gtk_window_add_popover            (GtkWindow     *window,
+                                            GtkWidget     *popover);
+GDK_AVAILABLE_IN_3_12
+void     gtk_window_remove_popover         (GtkWindow     *window,
+                                            GtkWidget     *popover);
+GDK_AVAILABLE_IN_3_12
+void     gtk_window_set_popover_position   (GtkWindow                   *window,
+                                            GtkWidget                   *popover,
+                                            GtkPositionType              pos,
+                                            const cairo_rectangle_int_t *rect);
+
 G_END_DECLS
 
 #endif /* __GTK_WINDOW_H__ */