Handle XdgShell window geometry in configure request sizes

Summary:
The size passed to an XDG shell configure request should match the
window size of the given window, we don't want to include the size of
any shadows that may be drawn by the client.

Kwin has the same concept of geometry for both window management, input
and rendering.

In order to approach this in a way that does not risk any regressions
with kwin's current structure AbstractClient::geometry remains the
canonical source and we handle the window within that internally within
ShellClient treating the windowGeometry as a set of margins from this.

This is part of a much bigger task (T10867). This patch addresses
windows growing when starting a drag based resize.

BUG: 403376

Test Plan:
Unit test
gtk3-demo

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D20937

autotests/integration/shell_client_test.cpp

@@ -109,6 +109,7 @@ private Q_SLOTS:
     void testXdgInitialState();
     void testXdgInitiallyMaximised();
     void testXdgInitiallyMinimized();
+    void testXdgWindowGeometry();
 };
 
 void TestShellClient::initTestCase()
@@ -1463,6 +1464,41 @@ void TestShellClient::testXdgInitiallyMinimized()
     QVERIFY(c->isMinimized());
 }
 
+void TestShellClient::testXdgWindowGeometry()
+{
+    QScopedPointer<Surface> surface(Test::createSurface());
+    QScopedPointer<XdgShellSurface> shellSurface(Test::createXdgShellStableSurface(surface.data(), nullptr, Test::CreationSetup::CreateOnly));
+    QSignalSpy configureRequestedSpy(shellSurface.data(), &XdgShellSurface::configureRequested);
+    surface->commit(Surface::CommitFlag::None);
+
+    configureRequestedSpy.wait();
+    shellSurface->ackConfigure(configureRequestedSpy.first()[2].toUInt());
+
+    // Create a 160x140 window in with a margin of 10(left), 20(top), 30(right), 40(bottom). Giving a total buffer size 200, 100
+    shellSurface->setWindowGeometry(QRect(10, 20, 160, 40));
+    auto c = Test::renderAndWaitForShown(surface.data(), QSize(200,100), Qt::blue);
+    configureRequestedSpy.wait(); //window activated after being shown
+
+    QSignalSpy geometryChangedSpy(c, &ShellClient::geometryChanged);
+    // resize to 300,200 in kwin terms
+    c->setGeometry(QRect(100, 100, 300, 200));
+    QVERIFY(configureRequestedSpy.wait());
+    // requested geometry should not include the margins we had above
+    const QSize requestedSize = configureRequestedSpy.last()[0].value<QSize>();
+    QCOMPARE(requestedSize, QSize(300, 200) - QSize(10 + 30, 20 + 40));
+    shellSurface->ackConfigure(configureRequestedSpy.last()[2].toUInt());
+    Test::render(surface.data(), requestedSize + QSize(10 + 30, 20 + 40), Qt::blue);
+    geometryChangedSpy.wait();
+
+    // kwin's concept of geometry should remain the same
+    QCOMPARE(c->geometry(), QRect(100, 100, 300, 200));
+
+    c->setFullScreen(true);
+    configureRequestedSpy.wait();
+    // when full screen, the window geometry (i.e without margins) should fill the screen
+    const QSize requestedFullScreenSize = configureRequestedSpy.last()[0].value<QSize>();
+    QCOMPARE(requestedFullScreenSize, QSize(1280, 1024));
+}
 
 WAYLANDTEST_MAIN(TestShellClient)
 #include "shell_client_test.moc"

shell_client.cpp

@@ -372,6 +372,7 @@ void ShellClient::finishInit() {
     SurfaceInterface *s = surface();
     disconnect(s, &SurfaceInterface::committed, this, &ShellClient::finishInit);
 
+    updateWindowMargins();
     if (!isInitialPositionSet()) {
         QRect area = workspace()->clientArea(PlacementArea, Screens::self()->current(), desktop());
         placeIn(area);
@@ -427,6 +428,16 @@ void ShellClient::deleteClient(ShellClient *c)
     delete c;
 }
 
+QSize ShellClient::toWindowGeometry(const QSize &size) const
+{
+    QSize adjustedSize = size - QSize(borderLeft() + borderRight(), borderTop() + borderBottom());
+    // a client going fullscreen should have the window the contents size of the screen
+    if (!isFullScreen() && requestedMaximizeMode() != MaximizeFull) {
+        adjustedSize -= QSize(m_windowMargins.left() + m_windowMargins.right(), m_windowMargins.top() + m_windowMargins.bottom());
+    }
+    return adjustedSize;
+}
+
 QStringList ShellClient::activities() const
 {
     // TODO: implement
@@ -519,6 +530,7 @@ void ShellClient::addDamage(const QRegion &damage)
     auto s = surface();
     if (s->size().isValid()) {
         m_clientSize = s->size();
+        updateWindowMargins();
         updatePendingGeometry();
     }
     markAsMapped();
@@ -617,11 +629,11 @@ void ShellClient::setGeometry(int x, int y, int w, int h, ForceGeometry_t force)
         // reset geometry to the one before blocking, so that we can compare properly
         geom = geometryBeforeUpdateBlocking();
     }
-    // TODO: better merge with Client's implementation
     const QSize requestedClientSize = QSize(w, h) - QSize(borderLeft() + borderRight(), borderTop() + borderBottom());
+    const QSize requestedWindowGeometrySize = toWindowGeometry(QSize(w, h));
 
     if (requestedClientSize == m_clientSize && !isWaitingForMoveResizeSync() &&
-        (m_requestedClientSize.isEmpty() || requestedClientSize == m_requestedClientSize)) {
+        (m_requestedClientSize.isEmpty() || requestedWindowGeometrySize == m_requestedClientSize)) {
         // size didn't change, and we don't need to explicitly request a new size
         doSetGeometry(QRect(x, y, w, h));
         updateMaximizeMode(m_requestedMaximizeMode);
@@ -1107,7 +1119,7 @@ bool ShellClient::requestGeometry(const QRect &rect)
 
     QSize size;
     if (rect.isValid()) {
-        size = rect.size() - QSize(borderLeft() + borderRight(), borderTop() + borderBottom());
+        size = toWindowGeometry(rect.size());
     } else {
         size = QSize(0, 0);
     }
@@ -1126,7 +1138,7 @@ bool ShellClient::requestGeometry(const QRect &rect)
         if (parent) {
             const QPoint globalClientContentPos = parent->geometry().topLeft() + parent->clientPos();
             const QPoint relativeOffset = rect.topLeft() - globalClientContentPos;
-            serialId = m_xdgShellPopup->configure(QRect(relativeOffset, rect.size()));
+            serialId = m_xdgShellPopup->configure(QRect(relativeOffset, size));
         }
     }
 
@@ -1867,6 +1879,34 @@ void ShellClient::updateClientOutputs()
     surface()->setOutputs(clientOutputs);
 }
 
+void ShellClient::updateWindowMargins()
+{
+    QRect windowGeometry;
+    QSize clientSize = m_clientSize;
+
+    if (m_xdgShellSurface) {
+        windowGeometry = m_xdgShellSurface->windowGeometry();
+    } else if (m_xdgShellPopup) {
+        windowGeometry = m_xdgShellPopup->windowGeometry();
+        if (!clientSize.isValid()) {
+            clientSize = m_xdgShellPopup->initialSize();
+        }
+    } else {
+        return;
+    }
+
+    if (windowGeometry.isEmpty() ||
+        windowGeometry.width() > clientSize.width() ||
+        windowGeometry.height() > clientSize.height()) {
+        m_windowMargins = QMargins();
+    } else {
+        m_windowMargins = QMargins(windowGeometry.left(),
+                                    windowGeometry.top(),
+                                    clientSize.width() - (windowGeometry.right() + 1),
+                                    clientSize.height() - (windowGeometry.bottom() + 1));
+    }
+}
+
 bool ShellClient::isPopupWindow() const
 {
     if (Toplevel::isPopupWindow()) {

shell_client.h

@@ -214,6 +214,7 @@ private:
     void setTransient();
     bool shouldExposeToWindowManagement();
     void updateClientOutputs();
+    void updateWindowMargins();
     KWayland::Server::XdgShellSurfaceInterface::States xdgSurfaceStates() const;
     void updateShowOnScreenEdge();
     void updateMaximizeMode(MaximizeMode maximizeMode);
@@ -222,6 +223,8 @@ private:
     QPoint popupOffset(const QRect &anchorRect, const Qt::Edges anchorEdge, const Qt::Edges gravity, const QSize popupSize) const;
     static void deleteClient(ShellClient *c);
 
+    QSize toWindowGeometry(const QSize &geometry) const;
+
     KWayland::Server::ShellSurfaceInterface *m_shellSurface;
     KWayland::Server::XdgShellSurfaceInterface *m_xdgShellSurface;
     KWayland::Server::XdgShellPopupInterface *m_xdgShellPopup;
@@ -291,6 +294,8 @@ private:
     QString m_captionSuffix;
     QHash<qint32, PingReason> m_pingSerials;
 
+    QMargins m_windowMargins;
+
     bool m_compositingSetup = false;
 };