win: reshuffle code a bit

Signed-off-by: Yuhang Zhao <2546789017@qq.com>

include/FramelessHelper/Core/utils.h

@@ -118,6 +118,8 @@ FRAMELESSHELPER_CORE_API void refreshWin32ThemeResources(const WId windowId, con
 FRAMELESSHELPER_CORE_API void enableNonClientAreaDpiScalingForWindow(const WId windowId);
 [[nodiscard]] FRAMELESSHELPER_CORE_API
     Global::DpiAwareness getDpiAwarenessForCurrentProcess(bool *highest = nullptr);
+FRAMELESSHELPER_CORE_API void fixupChildWindowsDpiMessage(const WId windowId);
+FRAMELESSHELPER_CORE_API void fixupDialogsDpiScaling();
 #endif // Q_OS_WINDOWS
 
 #ifdef Q_OS_LINUX

src/core/framelesshelper_win.cpp

@@ -35,8 +35,6 @@
 #include "winverhelper_p.h"
 #include "framelesshelper_windows.h"
 
-EXTERN_C BOOL WINAPI EnableChildWindowDpiMessage2(const HWND hWnd, const BOOL fEnable);
-
 FRAMELESSHELPER_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(lcFramelessHelperWin, "wangwenx190.framelesshelper.core.impl.win")
@@ -75,7 +73,6 @@ FRAMELESSHELPER_STRING_CONSTANT(TrackMouseEvent)
 FRAMELESSHELPER_STRING_CONSTANT(FindWindowW)
 FRAMELESSHELPER_STRING_CONSTANT(UnregisterClassW)
 FRAMELESSHELPER_STRING_CONSTANT(DestroyWindow)
-FRAMELESSHELPER_STRING_CONSTANT(EnableChildWindowDpiMessage)
 [[maybe_unused]] static constexpr const char kFallbackTitleBarErrorMessage[] =
     "FramelessHelper is unable to create the fallback title bar window, and thus the snap layout feature will be disabled"
     " unconditionally. You can ignore this error and continue running your application, nothing else will be affected, "
@@ -102,12 +99,14 @@ Q_GLOBAL_STATIC(Win32Helper, g_win32Helper)
 
 [[nodiscard]] static inline QString hwnd2str(const WId windowId)
 {
+    // NULL handle is allowed here.
     return FRAMELESSHELPER_STRING_LITERAL("0x")
         + QString::number(windowId, 16).toUpper();
 }
 
 [[nodiscard]] static inline QString hwnd2str(const HWND hwnd)
 {
+    // NULL handle is allowed here.
     return hwnd2str(reinterpret_cast<WId>(hwnd));
 }
 
@@ -536,18 +535,10 @@ void FramelessHelperWin::addWindow(const SystemParameters &params)
     Utils::updateWindowFrameMargins(windowId, false);
     // Tell DWM we don't use the window icon/caption/sysmenu, don't draw them.
     Utils::hideOriginalTitleBarElements(windowId);
-    // We don't need this hack on Win10 1607 and newer, the PMv2 DPI awareness
-    // mode will take care of it for us by default.
-    if (WindowsVersionHelper::isWin10OrGreater()
-        && !WindowsVersionHelper::isWin10RS1OrGreater()) {
-        // Without this hack, child windows can't get DPI change messages,
-        // which means only top level windows can scale to the correct size.
-        if (EnableChildWindowDpiMessage2(reinterpret_cast<HWND>(windowId), TRUE) == FALSE) {
-            if (GetLastError() != ERROR_CALL_NOT_IMPLEMENTED) {
-                WARNING << Utils::getSystemErrorMessage(kEnableChildWindowDpiMessage);
-            }
-        }
-    }
+    // Without this hack, the child windows can't get DPI change messages from
+    // Windows, which means only the top level windows can be scaled to the correct
+    // size, we of course don't want such thing from happening.
+    Utils::fixupChildWindowsDpiMessage(windowId);
     if (WindowsVersionHelper::isWin10RS1OrGreater()) {
         // Tell DWM we may need dark theme non-client area (title bar & frame border).
         FramelessHelper::Core::setApplicationOSThemeAware();
@@ -649,7 +640,7 @@ bool FramelessHelperWin::nativeEventFilter(const QByteArray &eventType, void *me
         // Enable automatic DPI scaling for the non-client area of the window,
         // such as the caption bar, the scrollbars, and the menu bar. We need
         // to do this explicitly and manually here (only inside WM_NCCREATE).
-        // If we are using the PMv2 DPI awareness level, the non-client area
+        // If we are using the PMv2 DPI awareness mode, the non-client area
         // of the window will be scaled by the OS automatically, so there will
         // be no need to do this in that case.
         Utils::enableNonClientAreaDpiScalingForWindow(windowId);

src/core/framelesshelpercore_global.cpp

@@ -169,12 +169,17 @@ void initialize()
 #ifdef Q_OS_WINDOWS
     // This is equivalent to set the "dpiAware" and "dpiAwareness" field in
     // your manifest file. It works through out Windows Vista to Windows 11.
-    // It's highly recommended to enable the highest DPI awareness level
+    // It's highly recommended to enable the highest DPI awareness mode
     // (currently it's PerMonitor Version 2, or PMv2 for short) for any GUI
     // applications, to allow your user interface scale to an appropriate
     // size and still stay sharp, though you will have to do the calculation
     // and resize by yourself.
     Utils::tryToEnableHighestDpiAwarenessLevel();
+    // This function need to be called before any dialogs are created, so
+    // to be safe we call it here.
+    // Without this hack, our native dialogs won't be able to respond to
+    // DPI change messages correctly, especially the non-client area.
+    Utils::fixupDialogsDpiScaling();
 #endif
 
     // This attribute is known to be __NOT__ compatible with QGLWidget.

src/core/utils_win.cpp

@@ -1850,18 +1850,6 @@ void Utils::setAeroSnappingEnabled(const WId windowId, const bool enable)
 
 void Utils::tryToEnableHighestDpiAwarenessLevel()
 {
-    // We don't need this hack when running on Win10 1607 and newer, the PMv2
-    // DPI awareness mode will take care of it for us by default.
-    if (WindowsVersionHelper::isWin10OrGreater()
-        && !WindowsVersionHelper::isWin10RS1OrGreater()) {
-        // This function need to be called before any dialogs are created, so
-        // to be safe we call it here.
-        if (EnablePerMonitorDialogScaling2() == FALSE) {
-            if (GetLastError() != ERROR_CALL_NOT_IMPLEMENTED) {
-                WARNING << getSystemErrorMessage(kEnablePerMonitorDialogScaling);
-            }
-        }
-    }
     bool isHighestAlready = false;
     const DpiAwareness currentAwareness = getDpiAwarenessForCurrentProcess(&isHighestAlready);
     DEBUG << "Current DPI awareness mode:" << currentAwareness;
@@ -2490,8 +2478,7 @@ void Utils::enableNonClientAreaDpiScalingForWindow(const WId windowId)
     if (!API_USER_AVAILABLE(EnableNonClientDpiScaling)) {
         return;
     }
-    // There's no need to enable automatic non-client area DPI scaling for PMv2,
-    // PMv2 will enable it for us by default.
+    // The PMv2 DPI awareness mode will take care of it for us.
     if (getDpiAwarenessForCurrentProcess() == DpiAwareness::PerMonitorVersion2) {
         return;
     }
@@ -2607,4 +2594,49 @@ DpiAwareness Utils::getDpiAwarenessForCurrentProcess(bool *highest)
     return DpiAwareness::Unknown;
 }
 
+void Utils::fixupChildWindowsDpiMessage(const WId windowId)
+{
+    Q_ASSERT(windowId);
+    if (!windowId) {
+        return;
+    }
+    // This hack is only available on Windows 10 and newer, and starting from
+    // Win10 1607 it become useless due to the PMv2 DPI awareness mode already
+    // takes care of it for us.
+    if (!WindowsVersionHelper::isWin10OrGreater()
+        || (WindowsVersionHelper::isWin10RS1OrGreater()
+            && (getDpiAwarenessForCurrentProcess() == DpiAwareness::PerMonitorVersion2))) {
+        return;
+    }
+    const auto hwnd = reinterpret_cast<HWND>(windowId);
+    if (EnableChildWindowDpiMessage2(hwnd, TRUE) != FALSE) {
+        return;
+    }
+    // This API is not available on current platform, it's fine.
+    if (GetLastError() == ERROR_CALL_NOT_IMPLEMENTED) {
+        return;
+    }
+    WARNING << getSystemErrorMessage(kEnableChildWindowDpiMessage);
+}
+
+void Utils::fixupDialogsDpiScaling()
+{
+    // This hack is only available on Windows 10 and newer, and starting from
+    // Win10 1607 it become useless due to the PMv2 DPI awareness mode already
+    // takes care of it for us.
+    if (!WindowsVersionHelper::isWin10OrGreater()
+        || (WindowsVersionHelper::isWin10RS1OrGreater()
+            && (getDpiAwarenessForCurrentProcess() == DpiAwareness::PerMonitorVersion2))) {
+        return;
+    }
+    if (EnablePerMonitorDialogScaling2() != FALSE) {
+        return;
+    }
+    // This API is not available on current platform, it's fine.
+    if (GetLastError() == ERROR_CALL_NOT_IMPLEMENTED) {
+        return;
+    }
+    WARNING << getSystemErrorMessage(kEnablePerMonitorDialogScaling);
+}
+
 FRAMELESSHELPER_END_NAMESPACE