dwmapi: Fallback to 60Hz if the display frequency is invalid in get_display_frequency().

DwmGetCompositionTimingInfo() may throw a zero division exception if the display reports a 0Hz frequency, which can happen when testing under Xephyr without -fakescreenfps option.

dwmapi: Fallback to 60Hz if the display frequency is invalid in get_display_frequency().
6a57ed80 · Zhiyi Zhang · Alexandre Julliard · 2fde0a3f · 6a57ed80
Commit 6a57ed80 authored Nov 17, 2022 by Zhiyi Zhang Committed by Alexandre Julliard Nov 17, 2022
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dwmapi_main.c dlls/dwmapi/dwmapi_main.c +6 -2

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--- a/dlls/dwmapi/dwmapi_main.c
+++ b/dlls/dwmapi/dwmapi_main.c
@@ -213,12 +213,16 @@ HRESULT WINAPI DwmRegisterThumbnail(HWND dest, HWND src, PHTHUMBNAIL thumbnail_i

 static int get_display_frequency(void)
 {
-    DEVMODEA mode;
+    DEVMODEW mode;
+    BOOL ret;

    memset(&mode, 0, sizeof(mode));
    mode.dmSize = sizeof(mode);
-    if (EnumDisplaySettingsA(NULL, ENUM_CURRENT_SETTINGS, &mode))
+    ret = EnumDisplaySettingsExW(NULL, ENUM_CURRENT_SETTINGS, &mode, 0);
+    if (ret && mode.dmFields & DM_DISPLAYFREQUENCY && mode.dmDisplayFrequency)
+    {
        return mode.dmDisplayFrequency;
+    }
    else
    {
        WARN("Failed to query display frequency, returning a fallback value.\n");