tooltip: Implement positioning using gdk_window_move_to_rect()

In order to make tooltip positioning portable, make use of the
move_to_rect API. Some semantical changes are made, as identical
semantics cannot be implemented using the move-to-rect API.

Primarily the implemented semantics are:

Position the tooltip in the center pixels slightly below (defaults to 4
units below) the tooltipped widget. This is always the case for keyboard
driven tooltips; the case where it tries to avoid the pointer cursor is
not implemented.

For pointer position triggered tooltips, implement the following
additional semantics:

Use the current cursor size to determine the padding used to enlarge the
anchor rectangle. This is to try to avoid the cursor overlapping the
tooltip.

If the anchor rectangle is too tall (meaning if we'd be constrained
and flip on the Y axis, it'd flip too far away from the originally
intended position), rely only on the pointer position to position the
tooltip. The approximate pointer cursor rectangle is used as a anchor
rectangle. Ideally we should use the actual pointer cursor rectangle
(image used as well as hotspot coordinate), but we don't have API to
get that information.

If the anchor rectangle isn't to tall, just make sure the tooltip isn't
too far away from the pointer position on the X axis.

Closes: #134
Closes: #432
Closes: #574
Closes: #579
Closes: #878

2 files changed, 74 insertions, 221 deletions

diff --git a/gtk/gtktooltip.c b/gtk/gtktooltip.c
index 706194a538..28e84f21bc 100644
--- a/gtk/gtktooltip.c
+++ b/gtk/gtktooltip.c
@@ -107,8 +107,6 @@ struct _GtkTooltip
 
   GtkWidget *tooltip_widget;
 
-  gdouble last_x;
-  gdouble last_y;
   GdkSurface *last_surface;
 
   guint timeout_id;
@@ -601,245 +599,103 @@ gtk_tooltip_run_requery (GtkWidget  **widget,
 }
 
 static void
-get_bounding_box (GtkWidget    *widget,
-                  GdkRectangle *bounds)
-{
-  GtkWidget *toplevel;
-  GtkAllocation allocation;
-  GdkSurface *surface;
-  gint x, y;
-  gint w, h;
-  gint x1, y1;
-  gint x2, y2;
-  gint x3, y3;
-  gint x4, y4;
-
-  surface = gtk_widget_get_parent_surface (widget);
-  if (surface == NULL)
-    surface = gtk_widget_get_surface (widget);
-
-  gtk_widget_get_allocation (widget, &allocation);
-
-  x = allocation.x;
-  y = allocation.y;
-  w = allocation.width;
-  h = allocation.height;
-
-  toplevel = gtk_widget_get_toplevel (widget);
-  if (GTK_IS_WINDOW (toplevel) && !GTK_IS_WINDOW (widget))
-    {
-      GtkWidget *parent = gtk_widget_get_parent (widget);
-
-      gtk_widget_translate_coordinates (parent, toplevel,
-                                        x, y,
-                                        &x, &y);
-    }
-
-  if (GTK_IS_WINDOW (widget))
-    {
-      GtkBorder border = { 0, };
-
-      _gtk_window_get_shadow_width (GTK_WINDOW (widget), &border);
-      x += border.left;
-      y += border.right;
-      w -= border.left + border.right;
-      h -= border.top + border.bottom;
-    }
-
-  gdk_surface_get_root_coords (surface, x, y, &x1, &y1);
-  gdk_surface_get_root_coords (surface, x + w, y, &x2, &y2);
-  gdk_surface_get_root_coords (surface, x, y + h, &x3, &y3);
-  gdk_surface_get_root_coords (surface, x + w, y + h, &x4, &y4);
-
-#define MIN4(a,b,c,d) MIN(MIN(a,b),MIN(c,d))
-#define MAX4(a,b,c,d) MAX(MAX(a,b),MAX(c,d))
-
-  bounds->x = floor (MIN4 (x1, x2, x3, x4));
-  bounds->y = floor (MIN4 (y1, y2, y3, y4));
-  bounds->width = ceil (MAX4 (x1, x2, x3, x4)) - bounds->x;
-  bounds->height = ceil (MAX4 (y1, y2, y3, y4)) - bounds->y;
-}
-
-static void
 gtk_tooltip_position (GtkTooltip *tooltip,
 		      GdkDisplay *display,
-		      GtkWidget  *new_tooltip_widget)
+		      GtkWidget  *new_tooltip_widget,
+                      GdkDevice  *device)
 {
-  gint x, y, width, height;
-  GdkMonitor *monitor;
-  GdkRectangle workarea;
-  guint cursor_size;
-  GdkRectangle bounds;
-  GtkBorder border;
-
-#define MAX_DISTANCE 32
+  GtkSettings *settings;
+  GdkRectangle anchor_rect;
+  GdkSurface *surface;
+  GdkSurface *effective_toplevel;
+  GtkWidget *toplevel;
+  int rect_anchor_dx = 0;
+  int cursor_size;
+  int anchor_rect_padding;
 
   gtk_widget_realize (GTK_WIDGET (tooltip->current_window));
-  gtk_widget_set_visible (GTK_WIDGET (tooltip->current_window), TRUE);
+  surface = _gtk_widget_get_surface (GTK_WIDGET (tooltip->current_window));
 
   tooltip->tooltip_widget = new_tooltip_widget;
 
-  _gtk_window_get_shadow_width (GTK_WINDOW (tooltip->current_window), &border);
+  toplevel = _gtk_widget_get_toplevel (new_tooltip_widget);
+  gtk_widget_translate_coordinates (new_tooltip_widget, toplevel,
+                                    0, 0,
+                                    &anchor_rect.x, &anchor_rect.y);
 
-  width = gtk_widget_get_allocated_width (GTK_WIDGET (tooltip->current_window)) - border.left - border.right;
-  height = gtk_widget_get_allocated_height (GTK_WIDGET (tooltip->current_window)) - border.top - border.bottom;
+  anchor_rect.width = gtk_widget_get_allocated_width (new_tooltip_widget);
+  anchor_rect.height = gtk_widget_get_allocated_height (new_tooltip_widget);
 
-  monitor = gdk_display_get_monitor_at_point (display, tooltip->last_x, tooltip->last_y);
-  gdk_monitor_get_workarea (monitor, &workarea);
-
-  get_bounding_box (new_tooltip_widget, &bounds);
-
-  /* Position the tooltip */
-
-  g_object_get (gtk_widget_get_settings (GTK_WIDGET (tooltip->current_window)),
+  settings = gtk_settings_get_for_display (display);
+  g_object_get (settings,
                 "gtk-cursor-theme-size", &cursor_size,
                 NULL);
 
-  /* Try below */
-  x = bounds.x + bounds.width / 2 - width / 2;
-  y = bounds.y + bounds.height + 4;
-
-  if (y + height <= workarea.y + workarea.height)
-    {
-      if (tooltip->keyboard_mode_enabled)
-        goto found;
-
-      if (y <= tooltip->last_y + cursor_size + MAX_DISTANCE)
-        {
-          if (tooltip->last_x + cursor_size + MAX_DISTANCE < x)
-            x = tooltip->last_x + cursor_size + MAX_DISTANCE;
-          else if (x + width < tooltip->last_x - MAX_DISTANCE)
-            x = tooltip->last_x - MAX_DISTANCE - width;
-
-          goto found;
-        }
-   }
+  if (device)
+    anchor_rect_padding = MAX (4, cursor_size - 32);
+  else
+    anchor_rect_padding = 4;
 
-  /* Try above */
-  x = bounds.x + bounds.width / 2 - width / 2;
-  y = bounds.y - height - 4;
+  anchor_rect.x -= anchor_rect_padding;
+  anchor_rect.y -= anchor_rect_padding;
+  anchor_rect.width += anchor_rect_padding * 2;
+  anchor_rect.height += anchor_rect_padding * 2;
 
-  if (y >= workarea.y)
+  if (device)
     {
-      if (tooltip->keyboard_mode_enabled)
-        goto found;
+      const int max_x_distance = 32;
+      /* Max 48x48 icon + default padding */
+      const int max_anchor_rect_height = 48 + 8;
+      int pointer_x, pointer_y;
+
+      /*
+       * For pointer position triggered tooltips, implement the following
+       * semantics:
+       *
+       * If the anchor rectangle is too tall (meaning if we'd be constrained
+       * and flip, it'd flip too far away), rely only on the pointer position
+       * to position the tooltip. The approximate pointer cursorrectangle is
+       * used as a anchor rectantgle.
+       *
+       * If the anchor rectangle isn't to tall, make sure the tooltip isn't too
+       * far away from the pointer position.
+       */
+      effective_toplevel = _gtk_widget_get_surface (new_tooltip_widget);
+      gdk_surface_get_device_position (effective_toplevel,
+                                       device,
+                                       &pointer_x, &pointer_y, NULL);
 
-      if (y + height >= tooltip->last_y - MAX_DISTANCE)
+      if (anchor_rect.height > max_anchor_rect_height)
         {
-          if (tooltip->last_x + cursor_size + MAX_DISTANCE < x)
-            x = tooltip->last_x + cursor_size + MAX_DISTANCE;
-          else if (x + width < tooltip->last_x - MAX_DISTANCE)
-            x = tooltip->last_x - MAX_DISTANCE - width;
-
-          goto found;
+          anchor_rect.x = pointer_x - 4;
+          anchor_rect.y = pointer_y - 4;
+          anchor_rect.width = cursor_size;
+          anchor_rect.height = cursor_size;
         }
-    }
-
-  /* Try right FIXME: flip on rtl ? */
-  x = bounds.x + bounds.width + 4;
-  y = bounds.y + bounds.height / 2 - height / 2;
-
-  if (x + width <= workarea.x + workarea.width)
-    {
-      if (tooltip->keyboard_mode_enabled)
-        goto found;
-
-      if (x <= tooltip->last_x + cursor_size + MAX_DISTANCE)
+      else
         {
-          if (tooltip->last_y + cursor_size + MAX_DISTANCE < y)
-            y = tooltip->last_y + cursor_size + MAX_DISTANCE;
-          else if (y + height < tooltip->last_y - MAX_DISTANCE)
-            y = tooltip->last_y - MAX_DISTANCE - height;
-
-          goto found;
-        }
-    }
+          int anchor_point_x;
+          int x_distance;
 
-  /* Try left FIXME: flip on rtl ? */
-  x = bounds.x - width - 4;
-  y = bounds.y + bounds.height / 2 - height / 2;
+          anchor_point_x = anchor_rect.x + anchor_rect.width / 2;
+          x_distance = pointer_x - anchor_point_x;
 
-  if (x >= workarea.x)
-    {
-      if (tooltip->keyboard_mode_enabled)
-        goto found;
-
-      if (x + width >= tooltip->last_x - MAX_DISTANCE)
-        {
-          if (tooltip->last_y + cursor_size + MAX_DISTANCE < y)
-            y = tooltip->last_y + cursor_size + MAX_DISTANCE;
-          else if (y + height < tooltip->last_y - MAX_DISTANCE)
-            y = tooltip->last_y - MAX_DISTANCE - height;
-
-          goto found;
+          if (x_distance > max_x_distance)
+            rect_anchor_dx = x_distance - max_x_distance;
+          else if (x_distance < -max_x_distance)
+            rect_anchor_dx = x_distance + max_x_distance;
         }
     }
 
-   /* Fallback */
-  if (tooltip->keyboard_mode_enabled)
-    {
-      x = bounds.x + bounds.width / 2 - width / 2;
-      y = bounds.y + bounds.height + 4;
-    }
-  else
-    {
-      /* At cursor */
-      x = tooltip->last_x + cursor_size * 3 / 4;
-      y = tooltip->last_y + cursor_size * 3 / 4;
-    }
-
-found:
-  /* Show it */
-  if (x + width > workarea.x + workarea.width)
-    x -= x - (workarea.x + workarea.width) + width;
-  else if (x < workarea.x)
-    x = workarea.x;
-
-  if (y + height > workarea.y + workarea.height)
-    y -= y - (workarea.y + workarea.height) + height;
-  else if (y < workarea.y)
-    y = workarea.y;
-
-  if (!tooltip->keyboard_mode_enabled)
-    {
-      /* don't pop up under the pointer */
-      if (x <= tooltip->last_x && tooltip->last_x < x + width &&
-          y <= tooltip->last_y && tooltip->last_y < y + height)
-        y = tooltip->last_y - height - 2;
-    }
-
-#ifdef GDK_WINDOWING_WAYLAND
-  /* set the transient parent on the tooltip when running with the Wayland
-   * backend to allow correct positioning of the tooltip windows
-   */
-  if (GDK_IS_WAYLAND_DISPLAY (display))
-    {
-      GtkWidget *toplevel;
+  gtk_window_set_transient_for (GTK_WINDOW (tooltip->current_window),
+                                GTK_WINDOW (toplevel));
 
-      toplevel = gtk_widget_get_toplevel (tooltip->tooltip_widget);
-      if (GTK_IS_WINDOW (toplevel))
-        gtk_window_set_transient_for (GTK_WINDOW (tooltip->current_window),
-                                      GTK_WINDOW (toplevel));
-    }
-#endif
-#ifdef GDK_WINDOWING_MIR
-      /* Set the transient parent on the tooltip when running with the Mir
-       * backend to allow correct positioning of the tooltip windows */
-      if (GDK_IS_MIR_DISPLAY (display))
-        {
-          GtkWidget *toplevel;
-
-          toplevel = gtk_widget_get_toplevel (tooltip->tooltip_widget);
-          if (GTK_IS_WINDOW (toplevel))
-            gtk_window_set_transient_for (GTK_WINDOW (tooltip->current_window),
-                                          GTK_WINDOW (toplevel));
-        }
-#endif
-
-  x -= border.left;
-  y -= border.top;
-
-  gtk_window_move (GTK_WINDOW (tooltip->current_window), x, y);
+  gdk_surface_move_to_rect (surface,
+                            &anchor_rect,
+                            GDK_GRAVITY_SOUTH,
+                            GDK_GRAVITY_NORTH,
+                            GDK_ANCHOR_FLIP_Y | GDK_ANCHOR_SLIDE_X,
+                            rect_anchor_dx, 0);
   gtk_widget_show (GTK_WIDGET (tooltip->current_window));
 }
 
@@ -849,6 +705,7 @@ gtk_tooltip_show_tooltip (GdkDisplay *display)
   gint x, y;
   GdkSurface *surface;
   GtkWidget *tooltip_widget;
+  GdkDevice *device;
   GtkTooltip *tooltip;
   gboolean return_value = FALSE;
 
@@ -858,10 +715,10 @@ gtk_tooltip_show_tooltip (GdkDisplay *display)
     {
       x = y = -1;
       tooltip_widget = tooltip->keyboard_widget;
+      device = NULL;
     }
   else
     {
-      GdkDevice *device;
       gint tx, ty;
 
       surface = tooltip->last_surface;
@@ -874,9 +731,6 @@ gtk_tooltip_show_tooltip (GdkDisplay *display)
       gdk_surface_get_device_position (surface, device, &x, &y, NULL);
 
       gdk_surface_get_root_coords (surface, x, y, &tx, &ty);
-      tooltip->last_x = tx;
-      tooltip->last_y = ty;
-
       tooltip_widget = _gtk_widget_find_at_coords (surface, x, y, &x, &y);
     }
 
@@ -908,7 +762,7 @@ gtk_tooltip_show_tooltip (GdkDisplay *display)
                         G_CALLBACK (gtk_tooltip_display_closed), tooltip);
     }
 
-  gtk_tooltip_position (tooltip, display, tooltip_widget);
+  gtk_tooltip_position (tooltip, display, tooltip_widget, device);
 
   /* Now a tooltip is visible again on the display, make sure browse
    * mode is enabled.
diff --git a/gtk/gtktooltipwindow.c b/gtk/gtktooltipwindow.c
index 8fcb2a44a6..f614acb60e 100644
--- a/gtk/gtktooltipwindow.c
+++ b/gtk/gtktooltipwindow.c
@@ -77,7 +77,6 @@ gtk_tooltip_window_init (GtkTooltipWindow *self)
 
   gtk_widget_init_template (GTK_WIDGET (self));
 
-  gtk_window_set_use_subsurface (window, TRUE);
   _gtk_window_request_csd (window);
 }