New positioning algorithm.(#116649)

Tue Aug  5 00:24:13 2003  Soeren Sandmann  <sandmann@daimi.au.dk>

	* gtk/gtkmenu.c (gtk_menu_position): New positioning
	algorithm.(#116649)

1 files changed, 112 insertions, 2 deletions

diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index 81907cfd06..81c518ea59 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -2750,8 +2750,118 @@ gtk_menu_position (GtkMenu *menu)
     (* menu->position_func) (menu, &x, &y, &push_in, menu->position_func_data);
   else
     {
-      x = CLAMP (x - 2, monitor.x, MAX (monitor.x, monitor.x + monitor.width - requisition.width));
-      y = CLAMP (y - 2, monitor.y, MAX (monitor.y, monitor.y + monitor.height - requisition.height));      
+      gint space_left, space_right, space_above, space_below;
+      gint needed_width;
+      gint needed_height;
+      gint xthickness = widget->style->xthickness;
+      gint ythickness = widget->style->ythickness;
+      gboolean rtl = (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL);
+
+      /* The placement of popup menus horizontally works like this (with
+       * RTL in parentheses)
+       *
+       * - If there is enough room to the right (left) of the mouse cursor,
+       *   position the menu there.
+       * 
+       * - Otherwise, if if there is enough room to the left (right) of the 
+       *   mouse cursor, position the menu there.
+       * 
+       * - Otherwise if the menu is smaller than the monitor, position it
+       *   on the side of the mouse cursor that has the most space available
+       *
+       * - Otherwise (if there is simply not enough room for the menu on the
+       *   monitor), position it as far left (right) as possible.
+       *
+       * Positioning in the vertical direction is similar: first try below
+       * mouse cursor, then above.
+       */
+      space_left = x - monitor.x;
+      space_right = monitor.x + monitor.width - x - 1;
+      space_above = y - monitor.y;
+      space_below = monitor.y + monitor.height - y - 1;
+
+      /* position horizontally */
+
+      /* the amount of space we need to position the menu. Note the
+       * menu is offset "xthickness" pixels 
+       */
+      needed_width = requisition.width - xthickness;
+
+      if (needed_width <= space_left ||
+	  needed_width <= space_right)
+	{
+	  if ((rtl  && needed_width <= space_left) ||
+	      (!rtl && needed_width >  space_right))
+	    {
+	      /* position left */
+	      x = x + xthickness - requisition.width + 1;
+	    }
+	  else
+	    {
+	      /* position right */
+	      x = x - xthickness;
+	    }
+
+	  /* x is clamped on-screen further down */
+	}
+      else if (requisition.width <= monitor.width)
+	{
+	  /* the menu is too big to fit on either side of the mouse
+	   * cursor, but smaller than the monitor. Position it on
+	   * the side that has the most space
+	   */
+	  if (space_left > space_right)
+	    {
+	      /* left justify */
+	      x = monitor.x;
+	    }
+	  else
+	    {
+	      /* right justify */
+	      x = monitor.x + monitor.width - requisition.width;
+	    }
+	}
+      else /* menu is simply too big for the monitor */
+	{
+	  if (rtl)
+	    {
+	      /* right justify */
+	      x = monitor.x + monitor.width - requisition.width;
+	    }
+	  else
+	    {
+	      /* left justify */
+	      x = monitor.x;
+	    }
+	}
+
+      /* Position vertically. The algorithm is the same as above, but
+       * simpler because we don't have to take RTL into account.
+       */
+      needed_height = requisition.height - ythickness;
+
+      if (needed_height <= space_above ||
+	  needed_height <= space_below)
+	{
+	  if (needed_height <= space_below)
+	    y = y - ythickness;
+	  else
+	    y = y + ythickness - requisition.height + 1;
+	  
+	  y = CLAMP (y, monitor.y,
+		     monitor.y + monitor.height - requisition.height);
+	}
+      else if (needed_height > space_below && needed_height > space_above)
+	{
+	  if (space_below >= space_above)
+	    y = monitor.y + monitor.height - requisition.height;
+	  else
+	    y = monitor.y;
+	}
+      else
+	{
+	  y = monitor.y;
+	}
     }
 
   scroll_offset = 0;