From 6b2d31247dc2c2804e571b31a71c8a423c1db9d4 Mon Sep 17 00:00:00 2001
From: Sine Striker <trueful@163.com>
Date: 周二, 26 12月 2023 01:44:03 +0800
Subject: [PATCH] Totally fix top border issue on Win10 for QtWidgets

---
 src/widgets/widgetwindowagent_win.cpp |  134 ++++++++++++++++++++++++++++++--------------
 1 files changed, 90 insertions(+), 44 deletions(-)

diff --git a/src/widgets/widgetwindowagent_win.cpp b/src/widgets/widgetwindowagent_win.cpp
index ccac368..3eb6beb 100644
--- a/src/widgets/widgetwindowagent_win.cpp
+++ b/src/widgets/widgetwindowagent_win.cpp
@@ -1,33 +1,45 @@
 #include "widgetwindowagent_p.h"
 
+#include <QtCore/QDebug>
+#include <QtCore/QDateTime>
 #include <QtGui/QPainter>
 
 #include <QWKCore/qwindowkit_windows.h>
-#include <QWKCore/private/nativeeventfilter_p.h>
 
 namespace QWK {
 
-    class WidgetBorderHandler : public QObject, public NativeEventFilter {
-        Q_OBJECT
+#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDER)
+
+    class WidgetBorderHandler : public QObject, public NativeEventFilter, public SharedEventFilter {
     public:
-        explicit WidgetBorderHandler(QWidget *widget, AbstractWindowContext *ctx)
-            : QObject(ctx), widget(widget), ctx(ctx) {
+        explicit WidgetBorderHandler(QWidget *widget, AbstractWindowContext *ctx,
+                                     QObject *parent = nullptr)
+            : QObject(parent), widget(widget), ctx(ctx) {
             widget->installEventFilter(this);
 
+            // https://github.com/microsoft/terminal/blob/71a6f26e6ece656084e87de1a528c4a8072eeabd/src/cascadia/WindowsTerminal/NonClientIslandWindow.cpp#L940
+            // Must extend top frame to client area
+            static QVariant defaultMargins = QVariant::fromValue(QMargins(0, 1, 0, 0));
+            ctx->setWindowAttribute(QStringLiteral("extra-margins"), defaultMargins);
+            ctx->setWindowAttribute(QStringLiteral("dark-mode"), true);
+
             ctx->installNativeEventFilter(this);
+            ctx->installSharedEventFilter(this);
+
             updateGeometry();
         }
 
-        void updateGeometry() {
-            if (widget->windowState() & (Qt::WindowMaximized | Qt::WindowFullScreen)) {
-                widget->setContentsMargins({});
+        inline bool isNormalWindow() const {
+            return !(widget->windowState() &
+                     (Qt::WindowMinimized | Qt::WindowMaximized | Qt::WindowFullScreen));
+        }
+
+        inline void updateGeometry() {
+            if (isNormalWindow()) {
+                widget->setContentsMargins(
+                    {0, ctx->windowAttribute(QStringLiteral("border-thickness")).toInt(), 0, 0});
             } else {
-                widget->setContentsMargins({
-                    0,
-                    ctx->property("borderThickness").toInt(),
-                    0,
-                    0,
-                });
+                widget->setContentsMargins({});
             }
         }
 
@@ -35,25 +47,28 @@
         bool nativeEventFilter(const QByteArray &eventType, void *message,
                                QT_NATIVE_EVENT_RESULT_TYPE *result) override {
             Q_UNUSED(eventType)
-            auto msg = reinterpret_cast<const MSG *>(message);
+            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 WM_SETTINGCHANGE: {
-                    if (!msg->wParam && msg->lParam &&
-                        std::wcscmp(reinterpret_cast<LPCWSTR>(msg->lParam), L"ImmersiveColorSet") ==
-                            0) {
-                        widget->update();
+                case WM_ACTIVATE: {
+                    if (LOWORD(msg->wParam) == WA_INACTIVE) {
+                        // https://github.com/microsoft/terminal/blob/71a6f26e6ece656084e87de1a528c4a8072eeabd/src/cascadia/WindowsTerminal/NonClientIslandWindow.cpp#L904
+                        // When the window is inactive, there is a transparency bug in the top
+                        // border and we needs to extend the non-client area to the whole title
+                        // bar.
+                        QRect frame =
+                            ctx->windowAttribute(QStringLiteral("title-bar-rect")).toRect();
+                        QMargins margins{0, -frame.top(), 0, 0};
+                        ctx->setWindowAttribute(QStringLiteral("extra-margins"),
+                                                QVariant::fromValue(margins));
+                    } else {
+                        // Restore margins when the window is active
+                        static QVariant defaultMargins = QVariant::fromValue(QMargins(0, 1, 0, 0));
+                        ctx->setWindowAttribute(QStringLiteral("extra-margins"), defaultMargins);
                     }
                     break;
                 }
@@ -64,24 +79,56 @@
             return false;
         }
 
+        bool sharedEventFilter(QObject *obj, QEvent *event) override {
+            Q_UNUSED(obj)
+
+            auto window = widget->windowHandle();
+            if (event->type() == QEvent::Expose) {
+                // Qt will absolutely send a QExposeEvent to the QWindow when it receives a
+                // WM_PAINT message. When the control flow enters the expose handler, Qt must
+                // have already called BeginPaint() and it's the best time for us to draw the
+                // top border.
+                auto ee = static_cast<QExposeEvent *>(event);
+                if (isNormalWindow() && window->isExposed() && !ee->region().isNull()) {
+                    // Friend class helping to call `event`
+                    class HackedWindow : public QWindow {
+                    public:
+                        friend class QWK::WidgetBorderHandler;
+                    };
+
+                    // Let Qt paint first
+                    static_cast<HackedWindow *>(window)->event(event);
+
+                    // 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;
+                }
+            }
+            return false;
+        }
+
         bool eventFilter(QObject *obj, QEvent *event) override {
+            Q_UNUSED(obj)
             switch (event->type()) {
-                case QEvent::Paint: {
-                    if (widget->windowState() & (Qt::WindowMaximized | Qt::WindowFullScreen))
+                case QEvent::UpdateRequest: {
+                    if (!isNormalWindow())
                         break;
 
-                    auto paintEvent = static_cast<QPaintEvent *>(event);
-                    auto rect = paintEvent->rect();
-                    auto region = paintEvent->region();
-
-                    QPainter painter(widget);
-                    void *args[] = {
-                        &painter,
-                        &rect,
-                        &region,
+                    // Friend class helping to call `event`
+                    class HackedWidget : public QWidget {
+                    public:
+                        friend class QWK::WidgetBorderHandler;
                     };
-                    ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook, args);
-                    break;
+
+                    // 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;
                 }
 
                 case QEvent::WindowStateChange: {
@@ -108,11 +155,10 @@
     void WidgetWindowAgentPrivate::setupWindows10BorderWorkaround() {
         // Install painting hook
         auto ctx = context.get();
-        if (ctx->property("needBorderPainter").toBool()) {
-            std::ignore = new WidgetBorderHandler(hostWidget, ctx);
+        if (ctx->windowAttribute(QStringLiteral("win10-border-needed")).toBool()) {
+            borderHandler = std::make_unique<WidgetBorderHandler>(hostWidget, ctx);
         }
     }
+#endif
 
 }
-
-#include "widgetwindowagent_win.moc"
\ No newline at end of file

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