win: add a little delay to some operations

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

src/core/framelesshelper_win.cpp

@@ -27,6 +27,7 @@
 #include <QtCore/qmutex.h>
 #include <QtCore/qvariant.h>
 #include <QtCore/qcoreapplication.h>
+#include <QtCore/qtimer.h>
 #include <QtGui/qwindow.h>
 #include "framelessmanager.h"
 #include "framelessmanager_p.h"
@@ -639,7 +640,7 @@ bool FramelessHelperWin::nativeEventFilter(const QByteArray &eventType, void *me
     const WPARAM wParam = msg->wParam;
     const LPARAM lParam = msg->lParam;
     switch (uMsg) {
-#if (QT_VERSION < QT_VERSION_CHECK(5, 9, 0))
+#if (QT_VERSION < QT_VERSION_CHECK(5, 9, 0)) // Qt has done this for us since 5.9.0
     case WM_NCCREATE: {
         // 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
@@ -1112,7 +1113,7 @@ bool FramelessHelperWin::nativeEventFilter(const QByteArray &eventType, void *me
             return true;
         }
     }
-#if (QT_VERSION < QT_VERSION_CHECK(6, 2, 2))
+#if (QT_VERSION < QT_VERSION_CHECK(6, 2, 2)) // I contributed this to Qt since 6.2.2
     case WM_WINDOWPOSCHANGING: {
         // Tell Windows to discard the entire contents of the client area, as re-using
         // parts of the client area would lead to jitter during resize.
@@ -1127,13 +1128,17 @@ bool FramelessHelperWin::nativeEventFilter(const QByteArray &eventType, void *me
             << hwnd2str(hWnd) << ": QDpi(" << dpiX << ", " << dpiY << ").";
         // Sync the internal window frame margins with the latest DPI.
         Utils::updateInternalWindowFrameMargins(data.params.getWindowHandle(), true);
-        // For some unknown reason, Qt sometimes won't re-paint the window contents after
+        // Here we need a little delay because event filters are processed before
-        // the DPI changes, and in my experiments the controls should be moved to our
+        // Qt's own window message handlers.
-        // desired geometry already, the only issue is we don't get the updated appearance
+        QTimer::singleShot(50, [data](){ // Copy "data" intentionally, otherwise it'll go out of scope when Qt finally use it.
-        // of our window. And we can workaround this issue by simply triggering a resize
+            // For some unknown reason, Qt sometimes won't re-paint the window contents after
-        // event manually. There's no need to increase/decrease the window size and then
+            // the DPI changes, and in my experiments the controls should be moved to our
-        // change it back, just give Qt our current window size is sufficient enough.
+            // desired geometry already, the only issue is we don't get the updated appearance
-        data.params.setWindowSize(data.params.getWindowSize());
+            // of our window. And we can workaround this issue by simply triggering a resize
+            // event manually. There's no need to increase/decrease the window size and then
+            // change it back, just give Qt our current window size is sufficient enough.
+            data.params.setWindowSize(data.params.getWindowSize());
+        });
     } break;
     case WM_DWMCOMPOSITIONCHANGED: {
         // Re-apply the custom window frame if recovered from the basic theme.

src/core/framelessmanager.cpp

@@ -25,6 +25,7 @@
 #include "framelessmanager_p.h"
 #include <QtCore/qmutex.h>
 #include <QtCore/qcoreapplication.h>
+#include <QtCore/qtimer.h>
 #include <QtGui/qscreen.h>
 #include <QtGui/qwindow.h>
 #include <QtGui/qfontdatabase.h>
@@ -217,14 +218,18 @@ void FramelessManagerPrivate::addWindow(const SystemParameters &params)
             g_helper()->data[windowId].screenChangeConnection =
                 connect(window, &QWindow::screenChanged, window, [windowId, window](QScreen *screen){
                     Q_UNUSED(screen);
-                    // Force a WM_NCCALCSIZE event to inform Windows about our custom window frame,
+                    // Add a little delay here, make sure it happens after Qt has processed the window
-                    // this is only necessary when the window is being moved cross monitors.
+                    // messages.
-                    Utils::triggerFrameChange(windowId);
+                    QTimer::singleShot(50, window, [windowId, window](){
-                    // For some reason the window is not repainted correctly when moving cross monitors,
+                        // Force a WM_NCCALCSIZE event to inform Windows about our custom window frame,
-                    // we workaround this issue by force a re-paint and re-layout of the window by triggering
+                        // this is only necessary when the window is being moved cross monitors.
-                    // a resize event manually. Although the actual size does not change, the issue we
+                        Utils::triggerFrameChange(windowId);
-                    // observed disappeared indeed, amazingly.
+                        // For some reason the window is not repainted correctly when moving cross monitors,
-                    window->resize(window->size());
+                        // we workaround this issue by force a re-paint and re-layout of the window by triggering
+                        // a resize event manually. Although the actual size does not change, the issue we
+                        // observed disappeared indeed, amazingly.
+                        window->resize(window->size());
+                    });
                 });
             g_helper()->mutex.unlock();
         }