support ime in fullscreen dx mode

panda/src/dxgsg/dxGraphicsStateGuardian.cxx

@@ -366,6 +366,7 @@ DXGraphicsStateGuardian(GraphicsWindow *win) : GraphicsStateGuardian(win) {
     _fpsmeter_verts=NULL;
     _fpsmeter_font_surf=NULL;
     _dx_ready = false;
+    _overlay_windows_supported = false;
 
 //    scrn.pddsPrimary = scrn.pddsZBuf = scrn.pddsBack = NULL;
 //    _pDD = NULL;
@@ -6466,6 +6467,50 @@ void DXGraphicsStateGuardian::show_frame(void) {
   }
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: dxGraphicsStateGuardian::support_overlay_window
+//       Access: Public
+//  Description: Specifies whether dialog windows placed on top of the
+//               dx rendering window should be supported.  This
+//               requires a bit of extra overhead, so it should only
+//               be activated when necessary; however, if it is not
+//               activated, a window that pops up over the fullscreen
+//               DX window (like a dialog box, or particularly like
+//               the IME composition or candidate windows) may not be
+//               visible.
+//
+//               This is not necessary when running in windowed mode,
+//               but it does no harm.
+////////////////////////////////////////////////////////////////////
+void DXGraphicsStateGuardian::
+support_overlay_window(bool flag) {
+  if (_overlay_windows_supported && !flag) {
+    // Disable support for overlay windows.
+    _overlay_windows_supported = false;
+    
+    if (dx_full_screen) {
+      scrn.pddsPrimary->SetClipper(NULL);
+    }
+
+  } else if (!_overlay_windows_supported && flag) {
+    // Enable support for overlay windows.
+    _overlay_windows_supported = true;
+
+    if (dx_full_screen) {
+      // Create a Clipper object to blt the whole screen.
+      LPDIRECTDRAWCLIPPER Clipper;
+      
+      if (scrn.pDD->CreateClipper(0, &Clipper, NULL) == DD_OK) {
+        Clipper->SetHWnd(0, scrn.hWnd);
+        scrn.pddsPrimary->SetClipper(Clipper);
+      }
+      scrn.pDD->FlipToGDISurface();
+      Clipper->Release();
+    }
+  }
+}
+
+
 ////////////////////////////////////////////////////////////////////
 //     Function: show_full_screen_frame
 //       Access:
@@ -6477,6 +6522,13 @@ void DXGraphicsStateGuardian::show_full_screen_frame(void) {
   // Flip the front and back buffers, to make what we just rendered
   // visible.
 
+  if (_overlay_windows_supported) {
+    // If we're asking for overlay windows, we have to blt instead of
+    // flip, so we don't lose the window.
+    hr = scrn.pddsPrimary->Blt( NULL, scrn.pddsBack,  NULL, DDBLT_WAIT, NULL );
+
+  } else {
+    // Normally, we can just do the fast flip operation.
     DWORD dwFlipFlags = DDFLIP_WAIT;
 
     if (!dx_sync_video) {
@@ -6501,6 +6553,7 @@ void DXGraphicsStateGuardian::show_full_screen_frame(void) {
         exit(1);
       }
     }
+  }
 
 }
 

panda/src/dxgsg/dxGraphicsStateGuardian.h

@@ -460,6 +460,7 @@ protected:
   LMatrix4f _current_color_mat;
   float _current_alpha_offset;
   float _current_alpha_scale;
+  bool _overlay_windows_supported;
 
   // vars for frames/sec meter
   DWORD _start_time;
@@ -503,6 +504,10 @@ public:
   void  show_frame();
   void  show_full_screen_frame();
   void  show_windowed_frame();
+
+  void support_overlay_window(bool flag);
+
+
 /*  void  dx_init(  LPDIRECTDRAW7     context,
           LPDIRECTDRAWSURFACE7  pri,
           LPDIRECTDRAWSURFACE7  back,

panda/src/wdxdisplay/wdxGraphicsWindow.cxx

@@ -354,6 +354,19 @@ window_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
       }
       break;
 
+    case WM_IME_STARTCOMPOSITION:
+      // In case we're running fullscreen mode, we have to turn on
+      // explicit DX support for overlay windows now, so we'll be able
+      // to see the IME window.
+      _dxgsg->support_overlay_window(true);
+      break;
+
+    case WM_IME_ENDCOMPOSITION:
+      // Turn off the support for overlay windows, since we're done
+      // with the IME window for now and it just slows things down.
+      _dxgsg->support_overlay_window(false);
+      break;
+
     case WM_IME_COMPOSITION:
       if (lparam & GCS_RESULTSTR) {
         if (!_input_devices.empty()) {