From 389b24e69522f986296817818f2f2ab1803fc1bb Mon Sep 17 00:00:00 2001
From: rdb <git@rdb.name>
Date: Mon, 13 Mar 2023 10:36:55 +0100
Subject: [PATCH] windisplay: Fix issues switching fullscreen while maximized

Fixes #1469
---
 panda/src/windisplay/winGraphicsWindow.cxx | 79 +++++++++++++++-------
 panda/src/windisplay/winGraphicsWindow.h   |  2 +
 2 files changed, 55 insertions(+), 26 deletions(-)

diff --git a/panda/src/windisplay/winGraphicsWindow.cxx b/panda/src/windisplay/winGraphicsWindow.cxx
index 1ca0425273..7878484a79 100644
--- a/panda/src/windisplay/winGraphicsWindow.cxx
+++ b/panda/src/windisplay/winGraphicsWindow.cxx
@@ -283,15 +283,34 @@ process_events() {
  */
 void WinGraphicsWindow::
 set_properties_now(WindowProperties &properties) {
-  if (properties.has_fullscreen() && !properties.get_fullscreen() &&
-      is_fullscreen()) {
-    if (do_windowed_switch()) {
-      _properties.set_fullscreen(false);
-      properties.clear_fullscreen();
-    } else {
-      windisplay_cat.warning()
-        << "Switching to windowed mode failed!\n";
+  if (properties.has_fullscreen()) {
+    if (!properties.get_fullscreen() && is_fullscreen()) {
+      if (do_windowed_switch()) {
+        _properties.set_fullscreen(false);
+      } else {
+        windisplay_cat.warning()
+          << "Switching to windowed mode failed!\n";
+      }
     }
+    else if (properties.get_fullscreen() && !is_fullscreen()) {
+      int x_size;
+      int y_size;
+      if (properties.has_size()) {
+        x_size = properties.get_x_size();
+        y_size = properties.get_y_size();
+      } else {
+        x_size = _properties.get_x_size();
+        y_size = _properties.get_y_size();
+      }
+      if (do_fullscreen_switch(x_size, y_size)) {
+        _properties.set_fullscreen(true);
+        properties.clear_size();
+      } else {
+        windisplay_cat.warning()
+          << "Switching to fullscreen mode failed!\n";
+      }
+    }
+    properties.clear_fullscreen();
   }
 
   GraphicsWindow::set_properties_now(properties);
@@ -917,8 +936,8 @@ do_fullscreen_resize(int x_size, int y_size) {
  * Called in the set_properties_now function to switch to fullscreen.
  */
 bool WinGraphicsWindow::
-do_fullscreen_switch() {
-  if (!do_fullscreen_enable()) {
+do_fullscreen_switch(int x_size, int y_size) {
+  if (!do_fullscreen_enable(x_size, y_size)) {
     // Couldn't get fullscreen.
     return false;
   }
@@ -928,17 +947,21 @@ do_fullscreen_switch() {
   DWORD window_style = make_style(props);
   SetWindowLong(_hWnd, GWL_STYLE, window_style);
 
-  WINDOW_METRICS metrics;
-  bool has_origin;
-  if (!calculate_metrics(true, window_style, metrics, has_origin)){
-    return false;
-  }
-
-  SetWindowPos(_hWnd, HWND_NOTOPMOST, 0, 0, metrics.width, metrics.height,
+  SetWindowPos(_hWnd, HWND_NOTOPMOST, 0, 0, x_size, y_size,
     SWP_FRAMECHANGED | SWP_SHOWWINDOW);
+
+  handle_reshape();
   return true;
 }
 
+/**
+ * Called in the set_properties_now function to switch to fullscreen.
+ */
+bool WinGraphicsWindow::
+do_fullscreen_switch() {
+  return do_fullscreen_switch(_properties.get_x_size(), _properties.get_y_size());
+}
+
 /**
  * Called in the set_properties_now function to switch to windowed mode.
  */
@@ -1188,8 +1211,8 @@ open_graphic_window() {
   // somehow, but I need the window's black background to cover up the desktop
   // during the mode change.
 
-  if (fullscreen){
-    if (!do_fullscreen_enable()){
+  if (fullscreen) {
+    if (!do_fullscreen_enable()) {
       return false;
     }
   }
@@ -1202,7 +1225,7 @@ open_graphic_window() {
  * Not to confuse with do_fullscreen_switch().
  */
 bool WinGraphicsWindow::
-do_fullscreen_enable() {
+do_fullscreen_enable(int x_size, int y_size) {
 
   HWND hDesktopWindow = GetDesktopWindow();
   HDC scrnDC = GetDC(hDesktopWindow);
@@ -1212,8 +1235,8 @@ do_fullscreen_enable() {
   // GetDeviceCaps(scrnDC, VERTRES);
   ReleaseDC(hDesktopWindow, scrnDC);
 
-  DWORD dwWidth = _properties.get_x_size();
-  DWORD dwHeight = _properties.get_y_size();
+  DWORD dwWidth = x_size;
+  DWORD dwHeight = y_size;
   DWORD dwFullScreenBitDepth = cur_bitdepth;
 
   DEVMODE dm;
@@ -1241,12 +1264,16 @@ do_fullscreen_enable() {
   }
 
   _fullscreen_display_mode = dm;
-
-  _properties.set_origin(0, 0);
-  _properties.set_size(dwWidth, dwHeight);
-
   return true;
+}
 
+/**
+ * This is a low-level function that just puts Windows in fullscreen mode.
+ * Not to confuse with do_fullscreen_switch().
+ */
+bool WinGraphicsWindow::
+do_fullscreen_enable() {
+  return do_fullscreen_enable(_properties.get_x_size(), _properties.get_y_size());
 }
 
 /**
diff --git a/panda/src/windisplay/winGraphicsWindow.h b/panda/src/windisplay/winGraphicsWindow.h
index 083508087b..a0416a873f 100644
--- a/panda/src/windisplay/winGraphicsWindow.h
+++ b/panda/src/windisplay/winGraphicsWindow.h
@@ -111,8 +111,10 @@ protected:
   virtual void handle_reshape();
   virtual bool do_fullscreen_resize(int x_size, int y_size);
 
+  bool do_fullscreen_switch(int x_size, int y_size);
   virtual bool do_fullscreen_switch();
   virtual bool do_windowed_switch();
+  bool do_fullscreen_enable(int x_size, int y_size);
   virtual bool do_fullscreen_enable();
   virtual bool do_fullscreen_disable();