panel: Constrain the candidate area to the current monitor bounds

If the second monitor has the different size, lookup window on
the second monitor could not get the right size.

BUG=https://github.com/ibus/ibus/issues/1594

Review URL: https://codereview.appspot.com/267710043

Patch from Alexey Kotlyarov <a@koterpillar.com>.

2 files changed, 40 insertions, 21 deletions

diff --git a/ui/gtk2/candidatepanel.py b/ui/gtk2/candidatepanel.py
index 374f9649..a105faa9 100644
--- a/ui/gtk2/candidatepanel.py
+++ b/ui/gtk2/candidatepanel.py
@@ -487,15 +487,20 @@ class CandidatePanel(gtk.VBox):
         window_right = cursor_right + self.__toplevel.allocation.width
         window_bottom = cursor_bottom + self.__toplevel.allocation.height
 
-        root_window = gdk.get_default_root_window()
-        sx, sy = root_window.get_size()
+        screen = gdk.screen_get_default()
+        monitor_num = screen.get_monitor_at_point(cursor_location[0],
+                                                  cursor_location[1])
+        monitor_area = screen.get_monitor_geometry(monitor_num)
 
-        if window_right > sx:
-            x = sx - self.__toplevel.allocation.width
+        monitor_right = monitor_area.x + monitor_area.width
+        monitor_bottom = monitor_area.y + monitor_area.height
+
+        if window_right > monitor_right:
+            x = monitor_right - self.__toplevel.allocation.width
         else:
             x = cursor_right
 
-        if window_bottom > sy:
+        if window_bottom > monitor_bottom:
             # move the window just above the cursor so the window and a preedit string do not overlap.
             y = cursor_location[1] - self.__toplevel.allocation.height
         else:
diff --git a/ui/gtk3/candidatepanel.vala b/ui/gtk3/candidatepanel.vala
index 823c54af..06ed0c9d 100644
--- a/ui/gtk3/candidatepanel.vala
+++ b/ui/gtk3/candidatepanel.vala
@@ -306,19 +306,26 @@ public class CandidatePanel : Gtk.Box{
             cursor_right_bottom.y + allocation.height
         };
 
-        Gdk.Window root = Gdk.get_default_root_window();
-        int root_width = root.get_width();
-        int root_height = root.get_height();
+        Gdk.Screen screen = Gdk.Screen.get_default();
+        int monitor_num = screen.get_monitor_at_point(m_cursor_location.x,
+                                                      m_cursor_location.y);
+        // Use get_monitor_geometry() instead of get_monitor_area().
+        // get_monitor_area() excludes docks, but the lookup window should be
+        // shown over them.
+        Gdk.Rectangle monitor_area;
+        screen.get_monitor_geometry(monitor_num, out monitor_area);
+        int monitor_right = monitor_area.x + monitor_area.width;
+        int monitor_bottom = monitor_area.y + monitor_area.height;
 
         int x, y;
-        if (window_right_bottom.x > root_width)
-            x = root_width - allocation.width;
+        if (window_right_bottom.x > monitor_right)
+            x = monitor_right - allocation.width;
         else
             x = cursor_right_bottom.x;
         if (x < 0)
             x = 0;
 
-        if (window_right_bottom.y > root_height)
+        if (window_right_bottom.y > monitor_bottom)
             y = m_cursor_location.y - allocation.height;
         else
             y = cursor_right_bottom.y;
@@ -352,31 +359,38 @@ public class CandidatePanel : Gtk.Box{
             m_cursor_location.y + allocation.height
         };
 
-        Gdk.Window root = Gdk.get_default_root_window();
-        int root_width = root.get_width();
-        int root_height = root.get_height();
+        Gdk.Screen screen = Gdk.Screen.get_default();
+        int monitor_num = screen.get_monitor_at_point(m_cursor_location.x,
+                                                      m_cursor_location.y);
+        // Use get_monitor_geometry() instead of get_monitor_area().
+        // get_monitor_area() excludes docks, but the lookup window should be
+        // shown over them.
+        Gdk.Rectangle monitor_area;
+        screen.get_monitor_geometry(monitor_num, out monitor_area);
+        int monitor_right = monitor_area.x + monitor_area.width;
+        int monitor_bottom = monitor_area.y + monitor_area.height;
 
         int x, y;
         if (!m_candidate_area.get_vertical()) {
-            if (hwindow_right_bottom.x > root_width)
-                x = root_width - allocation.width;
+            if (hwindow_right_bottom.x > monitor_right)
+                x = monitor_right - allocation.width;
             else
                 x = m_cursor_location.x;
 
-            if (hwindow_right_bottom.y > root_height)
+            if (hwindow_right_bottom.y > monitor_bottom)
                 y = m_cursor_location.y - allocation.height;
             else
                 y = cursor_right_bottom.y;
         } else {
-            if (vwindow_left_bottom.x > root_width)
-                x = root_width - allocation.width;
+            if (vwindow_left_bottom.x > monitor_right)
+                x = monitor_right - allocation.width;
             else if (vwindow_left_bottom.x < 0)
                 x = cursor_right_bottom.x;
             else
                 x = vwindow_left_bottom.x;
 
-            if (vwindow_left_bottom.y > root_height)
-                y = root_height - allocation.height;
+            if (vwindow_left_bottom.y > monitor_bottom)
+                y = monitor_bottom - allocation.height;
             else
                 y = m_cursor_location.y;
         }