From 6a586dedb794c48aedab49a1667b89f5434b0668 Mon Sep 17 00:00:00 2001
From: Mina Brown <wcbrow02@gmail.com>
Date: Sat, 9 Aug 2025 13:14:10 -0400
Subject: [PATCH] Only change video mode if the current video mode matches one
 of the preferences.

This avoids the program resetting the video mode if you're doing something like testing different resolutions or playing a game in fullscreen.
---
 WinPowerDMS/WinPowerDMS.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/WinPowerDMS/WinPowerDMS.c b/WinPowerDMS/WinPowerDMS.c
index a7b5c6d..64d017a 100644
--- a/WinPowerDMS/WinPowerDMS.c
+++ b/WinPowerDMS/WinPowerDMS.c
@@ -168,6 +168,16 @@ static BOOL LoadPrefs(void) {
     else return FALSE;
 }
 
+static DISPLAY_MODE GetCurrentDisplayMode(void) {
+    DEVMODE currentMode = { .dmSize = sizeof(currentMode) };
+    EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &currentMode);
+    return (DISPLAY_MODE) {
+        .width = currentMode.dmPelsWidth,
+        .height = currentMode.dmPelsHeight,
+        .refresh = currentMode.dmDisplayFrequency
+    };
+}
+
 static INT_PTR CALLBACK PrefsDialogProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) {
     switch (message) {
     case WM_INITDIALOG: {
@@ -284,8 +294,12 @@ static LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM l
     case WM_POWERBROADCAST:
         if (LOWORD(wParam) == PBT_POWERSETTINGCHANGE) {
             OutputDebugString(L"Power status changed\n");
+            DISPLAY_MODE currentMode = GetCurrentDisplayMode();
             SYSTEM_POWER_STATUS powerStatus;
-            if (GetSystemPowerStatus(&powerStatus)) {
+            // Change display mode only if there is a battery present and the current display mode is one of the configured options.
+            if (GetSystemPowerStatus(&powerStatus) && powerStatus.BatteryFlag != 128 &&
+                (DisplayModeEquals(&currentMode, &userPrefs.modeBatt) || DisplayModeEquals(&currentMode, &userPrefs.modeAC)))
+            {
                 ChangeDisplayMode(powerStatus.ACLineStatus ? &userPrefs.modeAC : &userPrefs.modeBatt, CDS_UPDATEREGISTRY);
             }
         }
@@ -296,15 +310,9 @@ static LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM l
 
 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
     if (!LoadPrefs()) { // set both battery and AC to current display mode if there are no preferences set
-        DEVMODE currentMode = { .dmSize = sizeof(currentMode) };
-        EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &currentMode);
-        DISPLAY_MODE mode = {
-            .width = currentMode.dmPelsWidth,
-            .height = currentMode.dmPelsHeight,
-            .refresh = currentMode.dmDisplayFrequency
-        };
-        userPrefs.modeAC = mode;
-        userPrefs.modeBatt = mode;
+        DISPLAY_MODE currentMode = GetCurrentDisplayMode();
+        userPrefs.modeAC = currentMode;
+        userPrefs.modeBatt = currentMode;
     }
 
     InitCommonControls(); // Initialize modern controls