compositor-xrender.c: Make sure tooltips are visible when the source

widget is close to the edge of the work area.

See inline comments - as of 3.24 tooltip positioning is handled
differently, and under certain conditions in hidpi, tooltips for the
bottom panel applets can end up off the bottom of the work area.

To reproduce, in hidpi, set the bottom panel to approximately 30px
tall and try to activate a tooltip for an applet on that panel.

1 files changed, 89 insertions, 0 deletions

diff --git a/src/compositor/compositor-xrender.c b/src/compositor/compositor-xrender.c
index 37440a79..13e8e620 100644
--- a/src/compositor/compositor-xrender.c
+++ b/src/compositor/compositor-xrender.c
@@ -42,6 +42,8 @@
 
 #include "display.h"
 #include "../core/display-private.h"
+#include "../core/screen-private.h"
+#include "../core/workspace.h"
 #include "screen.h"
 #include "frame.h"
 #include "errors.h"
@@ -49,6 +51,7 @@
 #include "compositor-private.h"
 #include "compositor-xrender.h"
 #include "xprops.h"
+#include "core.h"
 #include <X11/Xatom.h>
 #include <X11/extensions/shape.h>
 #include <X11/extensions/Xcomposite.h>
@@ -1856,6 +1859,87 @@ free_win (MetaCompWindow *cw,
 }
 
 static void
+constrain_tooltip_onscreen (MetaDisplay    *display,
+                            MetaScreen     *screen,
+                            MetaCompWindow *cw,
+                            Window          id)
+{
+  MetaWorkspace *workspace;
+  MetaRectangle work_area, win_rect;
+  const MetaXineramaScreenInfo* xinerama;
+  gint new_x, new_y;
+  gint active_workspace_num;
+
+  /* Why this is here:
+   * As of gtk 3.24, tooltips are positioned differently, and can end up off the
+   * screen in certain situations in hidpi.
+   *
+   * See: https://github.com/GNOME/gtk/commit/14d22cb3233e
+   *
+   * If the panel is too tall (around > 25 or so), tooltip positioning fails both
+   * tests in gdkwindowimpl.c (maybe_flip_position()) skipping repositioning of the
+   * tooltip inside the workarea. This only occurs on bottom panels.
+   *
+   * Since the calculations are based upon the monitor's workarea and the 'attach'
+   * (gdk) window's rectangle, there's no way to compensate for or fool gtk into
+   * displaying it correctly.  So here, we do our own check and adjustment. */
+
+  active_workspace_num = meta_core_get_active_workspace (cw->attrs.screen);
+
+  workspace = meta_screen_get_workspace_by_index (screen,
+                                                  active_workspace_num);
+
+  win_rect.x = cw->attrs.x;
+  win_rect.y = cw->attrs.y;
+  win_rect.width = cw->attrs.width;
+  win_rect.height = cw->attrs.height;
+
+  xinerama = meta_screen_get_xinerama_for_rect (screen,
+                                                &win_rect);
+
+  meta_workspace_get_work_area_for_xinerama (workspace,
+                                             xinerama->number,
+                                             &work_area);
+
+  new_x = win_rect.x;
+  new_y = win_rect.y;
+
+  /* Valid tooltip positions seem to cheat into the panel by a few pixels - maybe
+   * accounting for shadow margin.  There's no reason the fix these, but they'd
+   * be caught here otherwise, so 10px of overshoot in the direction of the panel
+   * is allowed. The tooltips we're out to catch are the ones on the complete other
+   * side of the panel (off screren), so there won't be any confusion. */
+  if (win_rect.y < work_area.y - 10)
+    {
+      new_y = work_area.y;
+    }
+  else if (win_rect.y + win_rect.height > work_area.y + work_area.height + 10)
+    {
+      new_y = (work_area.y + work_area.height - win_rect.height);
+    }
+
+  if (win_rect.x < work_area.x - 10)
+    {
+      new_x = work_area.x;
+    }
+  else if (win_rect.x + win_rect.width > work_area.x + work_area.width + 10)
+    {
+      new_x = (work_area.x + work_area.width - win_rect.width);
+    }
+
+  if (new_x != win_rect.x || new_y != win_rect.y)
+    {
+      if (DISPLAY_COMPOSITOR (display)->debug)
+        {
+          fprintf(stderr, "Constraining tooltip onscreen   x:%d -> %d, y:%d -> %d\n",
+                win_rect.x,new_x, win_rect.y,new_y);
+        }
+
+      XMoveWindow (display->xdisplay, cw->id, new_x, new_y);
+    }
+}
+
+static void
 map_win (MetaDisplay *display,
          MetaScreen  *screen,
          Window       id)
@@ -1866,6 +1950,11 @@ map_win (MetaDisplay *display,
   if (cw == NULL)
     return;
 
+  if (cw->type == META_COMP_WINDOW_TOOLTIP)
+    {
+      constrain_tooltip_onscreen (display, screen, cw, id);
+    }
+
   /* The reason we deallocate this here and not in unmap
      is so that we will still have a valid pixmap for
      whenever the window is unmapped */