sola/qwindowkit.git

			@@ -1,3 +1,7 @@
			// Copyright (C) 2023-2024 Stdware Collections (https://www.github.com/stdware)
			// Copyright (C) 2021-2023 wangwenx190 (Yuhang Zhao)
			// SPDX-License-Identifier: Apache-2.0

			#include "widgetwindowagent_p.h"

			#include <QtCore/QDebug>
			@@ -5,10 +9,33 @@
			#include <QtGui/QPainter>

			#include <QWKCore/qwindowkit_windows.h>
			#include <QWKCore/private/qwkglobal_p.h>

			namespace QWK {

			#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDER)
			#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDERS)
			// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowsbackingstore.cpp#L42
			// In QtWidgets applications, when repainting happens, QPA at the last calls
			// QWindowsBackingStore::flush() to draw the contents of the buffer to the screen, we need to
			// call GDI drawing the top border after that.

			// After debugging, we know that there are two situations that will lead to repaint.
			//
			// 1. Windows sends a WM_PAINT message, after which Qt immediately generates a QExposeEvent or
			// QResizeEvent and send it to the corresponding QWidgetWindow instance, calling "flush" at the
			// end of its handler.
			//
			// 2. When a timer or user input triggers Qt to repaint spontaneously, the corresponding
			// QWidget receives a QEvent::UpdateRequest event and also calls "flush" at the end of its
			// handler.
			//
			// The above two cases are mutually exclusive, so we just need to intercept the two events
			// separately and draw the border area after the "flush" is called.

			// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowswindow.cpp#L2440
			// Note that we can not draw the border right after WM_PAINT comes or right before the WndProc
			// returns, because Qt calls BeginPaint() and EndPaint() itself. We should make sure that we
			// draw the top border between these two calls, otherwise some display exceptions may arise.

			class WidgetBorderHandler : public QObject, public NativeEventFilter, public SharedEventFilter {
			public:
			@@ -21,6 +48,8 @@
			// Must extend top frame to client area
			static QVariant defaultMargins = QVariant::fromValue(QMargins(0, 1, 0, 0));
			ctx->setWindowAttribute(QStringLiteral("extra-margins"), defaultMargins);

			// Enable dark mode by default, otherwise the system borders are white
			ctx->setWindowAttribute(QStringLiteral("dark-mode"), true);

			ctx->installNativeEventFilter(this);
			@@ -43,33 +72,57 @@
			}
			}

			inline void resumeWidgetEventAndDraw(QWidget w, QEvent event) {
			// Let the widget paint first
			Private::ObjectHelper::sendEvent(w, event);

			// Due to the timer or user action, Qt will repaint some regions spontaneously,
			// even if there is no WM_PAINT message, we must wait for it to finish painting
			// and then update the top border area.
			ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook2, nullptr);
			}

			inline void resumeWindowEventAndDraw(QWindow window, QEvent event) {
			// Let Qt paint first
			Private::ObjectHelper::sendEvent(window, event);

			// Upon receiving the WM_PAINT message, Qt will repaint the entire view, and we
			// must wait for it to finish painting before drawing this top border area.
			ctx->virtual_hook(AbstractWindowContext::DrawWindows10BorderHook2, nullptr);
			}

			inline void updateExtraMargins(bool windowActive) {
			if (windowActive) {
			// Restore margins when the window is active
			static QVariant defaultMargins = QVariant::fromValue(QMargins(0, 1, 0, 0));
			ctx->setWindowAttribute(QStringLiteral("extra-margins"), defaultMargins);
			return;
			}

			// 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 need to extend the non-client area to the whole title
			// bar.
			QRect frame = ctx->windowAttribute(QStringLiteral("window-rect")).toRect();
			QMargins margins{0, -frame.top(), 0, 0};
			ctx->setWindowAttribute(QStringLiteral("extra-margins"), QVariant::fromValue(margins));
			}

			protected:
			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();
			updateExtraMargins(widget->isActiveWindow());
			break;
			}

			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);
			}
			updateExtraMargins(LOWORD(msg->wParam) != WA_INACTIVE);
			break;
			}

			@@ -83,51 +136,33 @@
			Q_UNUSED(obj)

			auto window = widget->windowHandle();

			// Qt will absolutely send a QExposeEvent or QResizeEvent 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.

			// Since a QExposeEvent will be sent immediately after the QResizeEvent, we can simply
			// ignore it.
			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);
			if (window->isExposed() && isNormalWindow() && !ee->region().isNull()) {
			resumeWindowEventAndDraw(window, event);
			return true;
			}
			}

			return false;
			}

			bool eventFilter(QObject obj, QEvent event) override {
			Q_UNUSED(obj)

			switch (event->type()) {
			case QEvent::UpdateRequest: {
			if (!isNormalWindow())
			break;

			// Friend class helping to call `event`
			class HackedWidget : public QWidget {
			public:
			friend class QWK::WidgetBorderHandler;
			};

			// 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);
			resumeWidgetEventAndDraw(widget, event);
			return true;
			}