Sine Striker
2023-12-27 1571d7b43228a0ed4347f681a16b2b23defccda9
src/widgets/widgetwindowagent_win.cpp
@@ -5,19 +5,47 @@
#include <QtGui/QPainter>
#include <QWKCore/qwindowkit_windows.h>
#include <QWKCore/private/nativeeventfilter_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.
    class WidgetBorderHandler;
    // 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:
        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);
            // Enable dark mode by default, otherwise the frame borders are white
            ctx->setWindowAttribute(QStringLiteral("dark-mode"), true);
            ctx->installNativeEventFilter(this);
            ctx->installSharedEventFilter(this);
@@ -30,17 +58,61 @@
                     (Qt::WindowMinimized | Qt::WindowMaximized | Qt::WindowFullScreen));
        }
        void updateGeometry() {
        inline void updateGeometry() {
            if (isNormalWindow()) {
                widget->setContentsMargins({
                    0,
                    ctx->property("borderThickness").toInt(),
                    0,
                    0,
                });
                widget->setContentsMargins(
                    {0, ctx->windowAttribute(QStringLiteral("border-thickness")).toInt(), 0, 0});
            } else {
                widget->setContentsMargins({});
            }
        }
        inline void resumeWidgetEventAndDraw(QWidget *w, QEvent *event) {
            // Friend class helping to call `event`
            class HackedWidget : public QWidget {
            public:
                friend class QWK::WidgetBorderHandler;
            };
            // Let the widget paint first
            static_cast<HackedWidget *>(w)->event(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) {
            // 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 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("title-bar-rect")).toRect();
            QMargins margins{0, -frame.top(), 0, 0};
            ctx->setWindowAttribute(QStringLiteral("extra-margins"), QVariant::fromValue(margins));
        }
    protected:
@@ -51,34 +123,14 @@
            switch (msg->message) {
                case WM_DPICHANGED: {
                    updateGeometry();
                    updateExtraMargins(widget->isActiveWindow());
                    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();
                    }
                    break;
                }
#  if 0
                case WM_ACTIVATE: {
                    if (LOWORD(msg->wParam) == WA_INACTIVE) {
                        // 窗口失去激活状态
                    } else {
                        // 窗口被激活
                    }
                    updateExtraMargins(LOWORD(msg->wParam) != WA_INACTIVE);
                    break;
                }
#  endif
                default:
                    break;
@@ -90,28 +142,22 @@
            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;
        }
@@ -121,20 +167,7 @@
                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;
                }
@@ -162,8 +195,8 @@
    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