[gtk/ime-preedit-hidpi-3] gtkimcontextime.c: Fix preedit window placement on HiDPI

[Chun-wei Fan <fanchunwei src gnome org>]

commit c073a062b6ad0dfccdd83282fd7ac5e0f8870a19
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Thu Apr 25 12:13:21 2019 +0800

    gtkimcontextime.c: Fix preedit window placement on HiDPI
    
    We must also take the scaling factor into account for placing the IME
    preedit window that is often used for Chinese and Japanese input on
    Windows.

 modules/input/gtkimcontextime.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
---
diff --git a/modules/input/gtkimcontextime.c b/modules/input/gtkimcontextime.c
index 2b165e9fcd..5bc31c42db 100644
--- a/modules/input/gtkimcontextime.c
+++ b/modules/input/gtkimcontextime.c
@@ -845,6 +845,7 @@ gtk_im_context_ime_set_cursor_location (GtkIMContext *context,
   COMPOSITIONFORM cf;
   HWND hwnd;
   HIMC himc;
+  guint scale;
 
   g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context));
 
@@ -860,10 +861,11 @@ gtk_im_context_ime_set_cursor_location (GtkIMContext *context,
   if (!himc)
     return;
 
+  scale = gdk_window_get_scale_factor (context_ime->client_window);
   get_window_position (context_ime->client_window, &wx, &wy);
   cf.dwStyle = CFS_POINT;
-  cf.ptCurrentPos.x = wx + context_ime->cursor_location.x;
-  cf.ptCurrentPos.y = wy + context_ime->cursor_location.y;
+  cf.ptCurrentPos.x = (wx + context_ime->cursor_location.x) * scale;
+  cf.ptCurrentPos.y = (wy + context_ime->cursor_location.y) * scale;
   ImmSetCompositionWindow (himc, &cf);
 
   ImmReleaseContext (hwnd, himc);
@@ -1050,6 +1052,7 @@ gtk_im_context_ime_message_filter (GdkXEvent *xevent,
       {
         gint wx = 0, wy = 0;
         CANDIDATEFORM cf;
+        guint scale = gdk_window_get_scale_factor (context_ime->client_window);
 
         get_window_position (context_ime->client_window, &wx, &wy);
         /* FIXME! */
@@ -1062,17 +1065,17 @@ gtk_im_context_ime_message_filter (GdkXEvent *xevent,
             gdk_win32_window_get_impl_hwnd (gdk_window_get_toplevel
                                             (context_ime->client_window));
           GetWindowRect (hwnd_top, &rc);
-          pt.x = wx;
-          pt.y = wy;
+          pt.x = wx * scale;
+          pt.y = wy * scale;
           ClientToScreen (hwnd_top, &pt);
-          wx = pt.x - rc.left;
-          wy = pt.y - rc.top;
+          wx = (pt.x - rc.left) / scale;
+          wy = (pt.y - rc.top) / scale;
         }
         cf.dwIndex = 0;
         cf.dwStyle = CFS_CANDIDATEPOS;
-        cf.ptCurrentPos.x = wx + context_ime->cursor_location.x;
-        cf.ptCurrentPos.y = wy + context_ime->cursor_location.y
-          + context_ime->cursor_location.height;
+        cf.ptCurrentPos.x = (wx + context_ime->cursor_location.x) * scale;
+        cf.ptCurrentPos.y = (wy + context_ime->cursor_location.y
+          + context_ime->cursor_location.height) * scale;
         ImmSetCandidateWindow (himc, &cf);
 
         if ((msg->lParam & GCS_COMPSTR))