Simplify DisplayServerWindows pos/size message handling

Replace WM_MOVE and WM_SIZE message handling with WM_POSCHANGED instead.
This is for multiple reasons:
1) Microsoft suggest using WM_POSCHANGED is more efficient
2) RectChanged callback is only called once for most window operations
3) Simplifies message handling code

2 files changed, 54 insertions, 81 deletions

diff --git a/platform/windows/display_server_windows.cpp b/platform/windows/display_server_windows.cpp
index 0e41b89c13..188d6153f8 100644
--- a/platform/windows/display_server_windows.cpp
+++ b/platform/windows/display_server_windows.cpp
@@ -2646,98 +2646,72 @@ LRESULT DisplayServerWindows::WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARA
 			}
 
 		} break;
-		case WM_MOVE: {
-			if (!IsIconic(windows[window_id].hWnd)) {
-				int x = int16_t(LOWORD(lParam));
-				int y = int16_t(HIWORD(lParam));
-				windows[window_id].last_pos = Point2(x, y);
-
-				if (!windows[window_id].rect_changed_callback.is_null()) {
-					Variant size = Rect2i(windows[window_id].last_pos.x, windows[window_id].last_pos.y, windows[window_id].width, windows[window_id].height);
-					Variant *sizep = &size;
-					Variant ret;
-					Callable::CallError ce;
-					windows[window_id].rect_changed_callback.call((const Variant **)&sizep, 1, ret, ce);
+
+		case WM_WINDOWPOSCHANGED: {
+			Rect2i window_client_rect;
+			{
+				RECT rect;
+				GetClientRect(hWnd, &rect);
+				ClientToScreen(hWnd, (POINT *)&rect.left);
+				ClientToScreen(hWnd, (POINT *)&rect.right);
+				window_client_rect = Rect2i(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
+			}
+
+			WINDOWPOS *window_pos_params = (WINDOWPOS *)lParam;
+			WindowData &window = windows[window_id];
+
+			bool rect_changed = false;
+			if (!(window_pos_params->flags & SWP_NOSIZE) || window_pos_params->flags & SWP_FRAMECHANGED) {
+				int screen_id = window_get_current_screen(window_id);
+				Size2i screen_size = screen_get_size(screen_id);
+				Point2i screen_position = screen_get_position(screen_id);
+
+				window.maximized = false;
+				window.minimized = false;
+				window.fullscreen = false;
+
+				if (IsIconic(hWnd)) {
+					window.minimized = true;
+				} else if (IsZoomed(hWnd)) {
+					window.maximized = true;
+				} else if (window_client_rect.position == screen_position && window_client_rect.size == screen_size) {
+					window.fullscreen = true;
 				}
-			}
-		} break;
-		case WM_SIZE: {
-			// Ignore window size change when a SIZE_MINIMIZED event is triggered.
-			if (wParam != SIZE_MINIMIZED) {
-				// The new width and height of the client area.
-				int window_w = LOWORD(lParam);
-				int window_h = HIWORD(lParam);
-
-				// Set new value to the size if it isn't preserved.
-				if (window_w > 0 && window_h > 0 && !windows[window_id].preserve_window_size) {
-					windows[window_id].width = window_w;
-					windows[window_id].height = window_h;
+
+				if (!window.minimized) {
+					window.width = window_client_rect.size.width;
+					window.height = window_client_rect.size.height;
 
 #if defined(VULKAN_ENABLED)
 					if (context_vulkan && window_created) {
-						context_vulkan->window_resize(window_id, windows[window_id].width, windows[window_id].height);
+						context_vulkan->window_resize(window_id, window.width, window.height);
 					}
 #endif
+					rect_changed = true;
+				}
+			}
 
-				} else { // If the size is preserved.
-					windows[window_id].preserve_window_size = false;
+			if (!window.minimized && (!(window_pos_params->flags & SWP_NOMOVE) || window_pos_params->flags & SWP_FRAMECHANGED)) {
+				window.last_pos = window_client_rect.position;
+				rect_changed = true;
+			}
 
-					// Restore the old size.
-					window_set_size(Size2(windows[window_id].width, windows[window_id].height), window_id);
+			if (rect_changed) {
+				if (!window.rect_changed_callback.is_null()) {
+					Variant size = Rect2i(window.last_pos.x, window.last_pos.y, window.width, window.height);
+					const Variant *args[] = { &size };
+					Variant ret;
+					Callable::CallError ce;
+					window.rect_changed_callback.call(args, 1, ret, ce);
 				}
-			} else { // When the window has been minimized, preserve its size.
-				windows[window_id].preserve_window_size = true;
 			}
 
-			// Call windows rect change callback.
-			if (!windows[window_id].rect_changed_callback.is_null()) {
-				Variant size = Rect2i(windows[window_id].last_pos.x, windows[window_id].last_pos.y, windows[window_id].width, windows[window_id].height);
-				Variant *size_ptr = &size;
-				Variant ret;
-				Callable::CallError ce;
-				windows[window_id].rect_changed_callback.call((const Variant **)&size_ptr, 1, ret, ce);
-			}
-
-			// The window has been maximized.
-			if (wParam == SIZE_MAXIMIZED) {
-				windows[window_id].maximized = true;
-				windows[window_id].minimized = false;
-			}
-			// The window has been minimized.
-			else if (wParam == SIZE_MINIMIZED) {
-				windows[window_id].maximized = false;
-				windows[window_id].minimized = true;
-				windows[window_id].preserve_window_size = false;
-			}
-			// The window has been resized, but neither the SIZE_MINIMIZED nor SIZE_MAXIMIZED value applies.
-			else if (wParam == SIZE_RESTORED) {
-				windows[window_id].maximized = false;
-				windows[window_id].minimized = false;
-			}
-#if 0
-			if (is_layered_allowed() && layered_window) {
-				DeleteObject(hBitmap);
-
-				RECT r;
-				GetWindowRect(hWnd, &r);
-				dib_size = Size2i(r.right - r.left, r.bottom - r.top);
-
-				BITMAPINFO bmi;
-				ZeroMemory(&bmi, sizeof(BITMAPINFO));
-				bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
-				bmi.bmiHeader.biWidth = dib_size.x;
-				bmi.bmiHeader.biHeight = dib_size.y;
-				bmi.bmiHeader.biPlanes = 1;
-				bmi.bmiHeader.biBitCount = 32;
-				bmi.bmiHeader.biCompression = BI_RGB;
-				bmi.bmiHeader.biSizeImage = dib_size.x * dib_size.y * 4;
-				hBitmap = CreateDIBSection(hDC_dib, &bmi, DIB_RGB_COLORS, (void **)&dib_data, nullptr, 0x0);
-				SelectObject(hDC_dib, hBitmap);
-
-				ZeroMemory(dib_data, dib_size.x * dib_size.y * 4);
-			}
-#endif
+			// Return here to prevent WM_MOVE and WM_SIZE from being sent
+			// See: https://docs.microsoft.com/en-us/windows/win32/winmsg/wm-windowposchanged#remarks
+			return 0;
+
 		} break;
+
 		case WM_ENTERSIZEMOVE: {
 			Input::get_singleton()->release_pressed_events();
 			windows[window_id].move_timer_id = SetTimer(windows[window_id].hWnd, 1, USER_TIMER_MINIMUM, (TIMERPROC) nullptr);
diff --git a/platform/windows/display_server_windows.h b/platform/windows/display_server_windows.h
index 803c2d4836..42506db29e 100644
--- a/platform/windows/display_server_windows.h
+++ b/platform/windows/display_server_windows.h
@@ -326,7 +326,6 @@ class DisplayServerWindows : public DisplayServer {
 
 		Vector<Vector2> mpath;
 
-		bool preserve_window_size = false;
 		bool pre_fs_valid = false;
 		RECT pre_fs_rect;
 		bool maximized = false;