From 46285db399f75154ad6c451e12f2cae2e59ace25 Mon Sep 17 00:00:00 2001
From: Sine Striker <trueful@163.com>
Date: 周日, 24 12月 2023 23:52:03 +0800
Subject: [PATCH] Use brilliant workaround to show Windows 10 top border

---
 src/widgets/widgetwindowagent_win.cpp |   98 +++++++++++++++++++++++++++++++++----------------
 1 files changed, 66 insertions(+), 32 deletions(-)

diff --git a/src/widgets/widgetwindowagent_win.cpp b/src/widgets/widgetwindowagent_win.cpp
index d2a49a2..173304f 100644
--- a/src/widgets/widgetwindowagent_win.cpp
+++ b/src/widgets/widgetwindowagent_win.cpp
@@ -2,46 +2,79 @@
 
 #include <QtGui/QPainter>
 
-#include <QWKCore/private/eventobserver_p.h>
+#include <QWKCore/qwindowkit_windows.h>
+#include <QWKCore/qwkconfig.h>
+#include <QWKCore/private/nativeeventfilter_p.h>
 
 namespace QWK {
 
-    class WidgetBorderHandler : public QObject, public EventObserver {
-        Q_OBJECT
+#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDER)
+
+    class WidgetBorderHandler;
+
+    class WidgetBorderHandler : public QObject, public NativeEventFilter {
     public:
-        explicit WidgetBorderHandler(QWidget *widget, AbstractWindowContext *ctx,
-                                     QObject *parent = nullptr)
-            : QObject(parent), widget(widget), ctx(ctx) {
+        explicit WidgetBorderHandler(QWidget *widget, AbstractWindowContext *ctx)
+            : QObject(ctx), widget(widget), ctx(ctx) {
             widget->installEventFilter(this);
 
-            ctx->addObserver(this);
+            ctx->installNativeEventFilter(this);
             updateGeometry();
         }
 
+        inline bool isNormalWindow() const {
+            return widget->windowState() &
+                   (Qt::WindowMinimized | Qt::WindowMaximized | Qt::WindowFullScreen);
+        }
+
         void updateGeometry() {
-            if (widget->windowState() & (Qt::WindowMaximized | Qt::WindowFullScreen)) {
-                widget->setContentsMargins({});
-            } else {
+            if (isNormalWindow()) {
                 widget->setContentsMargins({
                     0,
                     ctx->property("borderThickness").toInt(),
                     0,
                     0,
                 });
+            } else {
+                widget->setContentsMargins({});
             }
         }
 
     protected:
-        bool observe(QEvent *event) override {
-            switch (event->type()) {
-                case QEvent::UpdateLater: {
+        bool nativeEventFilter(const QByteArray &eventType, void *message,
+                               QT_NATIVE_EVENT_RESULT_TYPE *result) override {
+            Q_UNUSED(eventType)
+            const auto msg = static_cast<const MSG *>(message);
+            switch (msg->message) {
+                case WM_DPICHANGED: {
+                    updateGeometry();
+                    break;
+                }
+
+                case WM_THEMECHANGED:
+                case WM_SYSCOLORCHANGE:
+                case WM_DWMCOLORIZATIONCOLORCHANGED: {
                     widget->update();
                     break;
                 }
 
-                case QEvent::ScreenChangeInternal: {
-                    updateGeometry();
+                case WM_SETTINGCHANGE: {
+                    if (!msg->wParam && msg->lParam &&
+                        std::wcscmp(reinterpret_cast<LPCWSTR>(msg->lParam), L"ImmersiveColorSet") ==
+                            0) {
+                        widget->update();
+                    }
                     break;
+                }
+
+                case WM_PAINT: {
+                    // Let Qt paint first
+                    m_dispatcher->resume(eventType, message, result);
+
+                    // Upon receiving the WM_PAINT message, Qt will redraw the entire view, and we
+                    // must wait for it to finish redrawing before drawing this top border area
+                    ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook2, nullptr);
+                    return true;
                 }
 
                 default:
@@ -51,22 +84,22 @@
         }
 
         bool eventFilter(QObject *obj, QEvent *event) override {
+            Q_UNUSED(obj)
             switch (event->type()) {
-                case QEvent::Paint: {
-                    if (widget->windowState() & (Qt::WindowMaximized | Qt::WindowFullScreen))
-                        break;
-
-                    auto paintEvent = static_cast<QPaintEvent *>(event);
-                    auto rect = paintEvent->rect();
-                    auto region = paintEvent->region();
-
-                    QPainter painter(widget);
-                    void *args[] = {
-                        &painter,
-                        &rect,
-                        &region,
+                case QEvent::UpdateRequest: {
+                    // Friend class helping to call `event`
+                    class HackedWidget : public QWidget {
+                    public:
+                        friend class WidgetBorderHandler;
                     };
-                    ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook, args);
+
+                    // Let the widget paint first
+                    static_cast<HackedWidget *>(widget)->event(event);
+
+                    // Due to the timer or user action, Qt will redraw some regions spontaneously,
+                    // even if there is no WM_PAINT message, we must wait for it to finish redrawing
+                    // and then update the upper border area
+                    ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook2, nullptr);
                     return true;
                 }
 
@@ -90,15 +123,16 @@
         QWidget *widget;
         AbstractWindowContext *ctx;
     };
+#endif
 
     void WidgetWindowAgentPrivate::setupWindows10BorderWorkaround() {
+#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDER)
         // Install painting hook
         auto ctx = context.get();
         if (ctx->property("needBorderPainter").toBool()) {
-            std::ignore = new WidgetBorderHandler(hostWidget, ctx, ctx);
+            std::ignore = new WidgetBorderHandler(hostWidget, ctx);
         }
+#endif
     }
 
 }
-
-#include "widgetwindowagent_win.moc"
\ No newline at end of file

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