// Copyright (C) 2023-2024 Stdware Collections (https://www.github.com/stdware)
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// Copyright (C) 2021-2023 wangwenx190 (Yuhang Zhao)
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// SPDX-License-Identifier: Apache-2.0
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#include "widgetwindowagent_p.h"
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#include <QtCore/QDebug>
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#include <QtCore/QDateTime>
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#include <QtGui/QPainter>
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#include <QtCore/private/qcoreapplication_p.h>
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#include <QWKCore/qwindowkit_windows.h>
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#include <QWKCore/private/qwkglobal_p.h>
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#include <QWKCore/private/windows10borderhandler_p.h>
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namespace QWK {
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#if QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDERS)
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// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowsbackingstore.cpp#L42
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// In QtWidgets applications, when repainting happens, QPA at the last calls
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// QWindowsBackingStore::flush() to draw the contents of the buffer to the screen, we need to
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// call GDI drawing the top border after that.
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// After debugging, we know that there are two situations that will lead to repaint.
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//
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// 1. Windows sends a WM_PAINT message, after which Qt immediately generates a QExposeEvent or
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// QResizeEvent and send it to the corresponding QWidgetWindow instance, calling "flush" at the
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// end of its handler.
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//
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// 2. When a timer or user input triggers Qt to repaint spontaneously, the corresponding
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// QWidget receives a QEvent::UpdateRequest event and also calls "flush" at the end of its
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// handler.
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//
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// The above two cases are mutually exclusive, so we just need to intercept the two events
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// separately and draw the border area after the "flush" is called.
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// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowswindow.cpp#L2440
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// Note that we can not draw the border right after WM_PAINT comes or right before the WndProc
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// returns, because Qt calls BeginPaint() and EndPaint() itself. We should make sure that we
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// draw the top border between these two calls, otherwise some display exceptions may arise.
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class WidgetBorderHandler : public QObject, public Windows10BorderHandler {
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public:
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explicit WidgetBorderHandler(QWidget *widget, AbstractWindowContext *ctx,
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QObject *parent = nullptr)
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: QObject(parent), Windows10BorderHandler(ctx), widget(widget) {
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widget->installEventFilter(this);
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// First update
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if (ctx->windowId()) {
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setupNecessaryAttributes();
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}
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WidgetBorderHandler::updateGeometry();
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}
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void updateGeometry() override {
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// The window top border is manually painted by QWK so we want to give
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// some margins to avoid it covering real window contents, however, we
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// found that there are some rounding issues for the thin border and
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// thus this small trick doesn't work very well when the DPR is not
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// integer. So far we haven't found a perfect solution, so just don't
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// set any margins. In theory the window content will only be covered
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// by 1px or so, it should not be a serious issue in the real world.
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//
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// widget->setContentsMargins(isNormalWindow() ? QMargins(0, borderThickness(), 0, 0)
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// : QMargins());
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}
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bool isWindowActive() const override {
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return widget->isActiveWindow();
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}
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inline void forwardEventToWidgetAndDraw(QWidget *w, QEvent *event) {
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// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/widgets/kernel/qapplication.cpp#L3286
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// Deliver the event
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if (!forwardObjectEventFilters(this, w, event)) {
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// Let the widget paint first
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std::ignore = static_cast<QObject *>(w)->event(event);
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QCoreApplicationPrivate::setEventSpontaneous(event, false);
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}
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// Due to the timer or user action, Qt will repaint some regions spontaneously,
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// even if there is no WM_PAINT message, we must wait for it to finish painting
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// and then update the top border area.
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drawBorderNative();
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}
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inline void forwardEventToWindowAndDraw(QWindow *window, QEvent *event) {
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// https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/widgets/kernel/qapplication.cpp#L3286
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// Deliver the event
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if (!forwardObjectEventFilters(ctx, window, event)) {
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// Let Qt paint first
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std::ignore = static_cast<QObject *>(window)->event(event);
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QCoreApplicationPrivate::setEventSpontaneous(event, false);
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}
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// Upon receiving the WM_PAINT message, Qt will repaint the entire view, and we
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// must wait for it to finish painting before drawing this top border area.
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drawBorderNative();
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}
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protected:
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bool sharedEventFilter(QObject *obj, QEvent *event) override {
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Q_UNUSED(obj)
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switch (event->type()) {
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case QEvent::Expose: {
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// Qt will absolutely send a QExposeEvent or QResizeEvent to the QWindow when it
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// receives a WM_PAINT message. When the control flow enters the expose handler,
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// Qt must have already called BeginPaint() and it's the best time for us to
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// draw the top border.
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// Since a QExposeEvent will be sent immediately after the QResizeEvent, we can
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// simply ignore it.
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#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
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struct ExposeEvent : public QExposeEvent {
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inline const QRegion &getRegion() const { return m_region; }
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};
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auto ee = static_cast<ExposeEvent *>(event);
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bool exposeRegionValid = !ee->getRegion().isNull();
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#else
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auto ee = static_cast<QExposeEvent *>(event);
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bool exposeRegionValid = !ee->region().isNull();
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#endif
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auto window = widget->windowHandle();
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if (window->isExposed() && isNormalWindow() && exposeRegionValid) {
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forwardEventToWindowAndDraw(window, event);
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return true;
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}
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break;
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}
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default:
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break;
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}
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return Windows10BorderHandler::sharedEventFilter(obj, event);
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}
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bool eventFilter(QObject *obj, QEvent *event) override {
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Q_UNUSED(obj)
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switch (event->type()) {
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case QEvent::UpdateRequest: {
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if (!isNormalWindow())
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break;
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forwardEventToWidgetAndDraw(widget, event);
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return true;
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}
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case QEvent::WindowStateChange: {
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updateGeometry();
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break;
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}
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case QEvent::WindowActivate:
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case QEvent::WindowDeactivate: {
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widget->update();
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break;
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}
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default:
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break;
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}
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return false;
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}
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QWidget *widget;
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};
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void WidgetWindowAgentPrivate::setupWindows10BorderWorkaround() {
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// Install painting hook
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auto ctx = context.get();
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if (ctx->windowAttribute(QStringLiteral("win10-border-needed")).toBool()) {
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borderHandler = std::make_unique<WidgetBorderHandler>(hostWidget, ctx);
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}
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}
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#endif
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}
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