xdgshellclient: Support set_fullscreen argument

xdgshell allows clients to specify which output should we fill on
set_fullscreen. This change takes this request into consideration
instead of ignoring it.

autotests/integration/xdgshellclient_test.cpp

@@ -9,6 +9,7 @@
 */
 #include "kwin_wayland_test.h"
 #include "abstract_client.h"
+#include "abstract_wayland_output.h"
 #include "cursor.h"
 #include "decorations/decorationbridge.h"
 #include "decorations/settings.h"
@@ -73,6 +74,7 @@ private Q_SLOTS:
 
     void testMaximizedToFullscreen_data();
     void testMaximizedToFullscreen();
+    void testFullscreenMultipleOutputs();
     void testWindowOpensLargerThanScreen();
     void testHidden();
     void testDesktopFileName();
@@ -626,6 +628,59 @@ void TestXdgShellClient::testMaximizedToFullscreen()
     QVERIFY(Test::waitForWindowDestroyed(client));
 }
 
+void TestXdgShellClient::testFullscreenMultipleOutputs()
+{
+    // this test verifies that kwin will place fullscreen windows in the outputs its instructed to
+
+    for (int i = 0; i < screens()->count(); ++i) {
+        XdgShellSurface::States states;
+
+        QSharedPointer<Surface> surface(Test::createSurface());
+        QSharedPointer<XdgShellSurface> shellSurface(Test::createXdgShellStableSurface(surface.data()));
+
+        QVERIFY(surface);
+        QVERIFY(shellSurface);
+
+        auto client = Test::renderAndWaitForShown(surface.data(), QSize(100, 50), Qt::blue);
+        QVERIFY(client);
+        QVERIFY(client->isActive());
+        QVERIFY(!client->isFullScreen());
+        QCOMPARE(client->clientSize(), QSize(100, 50));
+        QVERIFY(!client->isDecorated());
+
+        QSignalSpy fullscreenChangedSpy(client, &AbstractClient::fullScreenChanged);
+        QVERIFY(fullscreenChangedSpy.isValid());
+        QSignalSpy frameGeometryChangedSpy(client, &AbstractClient::frameGeometryChanged);
+        QVERIFY(frameGeometryChangedSpy.isValid());
+        QSignalSpy configureRequestedSpy(shellSurface.data(), &XdgShellSurface::configureRequested);
+        QVERIFY(configureRequestedSpy.isValid());
+
+        // Wait for the compositor to send a configure event with the Activated state.
+        QVERIFY(configureRequestedSpy.wait());
+        QCOMPARE(configureRequestedSpy.count(), 1);
+        states = configureRequestedSpy.last().at(1).value<XdgShellSurface::States>();
+        QVERIFY(states & XdgShellSurface::State::Activated);
+
+        // Ask the compositor to show the window in full screen mode.
+        shellSurface->setFullscreen(true, Test::waylandOutputs()[i]);
+        QVERIFY(configureRequestedSpy.wait());
+        QCOMPARE(configureRequestedSpy.count(), 2);
+        QCOMPARE(configureRequestedSpy.last().at(0).value<QSize>(), screens()->size(i));
+
+        shellSurface->ackConfigure(configureRequestedSpy.last().at(2).value<quint32>());
+        Test::render(surface.data(), configureRequestedSpy.last().at(0).value<QSize>(), Qt::red);
+
+        QVERIFY(!fullscreenChangedSpy.isEmpty() || fullscreenChangedSpy.wait());
+        QCOMPARE(fullscreenChangedSpy.count(), 1);
+
+        QVERIFY(!frameGeometryChangedSpy.isEmpty() || frameGeometryChangedSpy.wait());
+
+        QVERIFY(client->isFullScreen());
+
+        QCOMPARE(client->frameGeometry(), screens()->geometry(i));
+    }
+}
+
 void TestXdgShellClient::testWindowOpensLargerThanScreen()
 {
     // this test creates a window which is as large as the screen, but is decorated

xdgshellclient.cpp

@@ -9,7 +9,9 @@
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 #include "xdgshellclient.h"
+#include "abstract_wayland_output.h"
 #include "deleted.h"
+#include "platform.h"
 #include "screenedge.h"
 #include "screens.h"
 #include "subsurfacemonitor.h"
@@ -1060,7 +1062,8 @@ void XdgToplevelClient::handleUnmaximizeRequested()
 
 void XdgToplevelClient::handleFullscreenRequested(OutputInterface *output)
 {
-    Q_UNUSED(output)
+    m_fullScreenRequestedOutput = waylandServer()->findOutput(output);
+
     if (m_isInitialized) {
         setFullScreen(/* set */ true, /* user */ false);
         scheduleConfigure(ConfigureRequired);
@@ -1071,6 +1074,7 @@ void XdgToplevelClient::handleFullscreenRequested(OutputInterface *output)
 
 void XdgToplevelClient::handleUnfullscreenRequested()
 {
+    m_fullScreenRequestedOutput.clear();
     if (m_isInitialized) {
         setFullScreen(/* set */ false, /* user */ false);
         scheduleConfigure(ConfigureRequired);
@@ -1560,8 +1564,10 @@ void XdgToplevelClient::setFullScreen(bool set, bool user)
     updateDecoration(false, false);
 
     if (set) {
-        setFrameGeometry(workspace()->clientArea(FullScreenArea, this));
+        const int screen = m_fullScreenRequestedOutput ? kwinApp()->platform()->enabledOutputs().indexOf(m_fullScreenRequestedOutput) : screens()->number(frameGeometry().center());
+        setFrameGeometry(workspace()->clientArea(FullScreenArea, screen, desktop()));
     } else {
+        m_fullScreenRequestedOutput.clear();
         if (m_fullScreenGeometryRestore.isValid()) {
             int currentScreen = screen();
             setFrameGeometry(QRect(m_fullScreenGeometryRestore.topLeft(),

xdgshellclient.h

@@ -29,6 +29,7 @@ class XdgToplevelDecorationV1Interface;
 
 namespace KWin
 {
+class AbstractOutput;
 
 class XdgSurfaceConfigure
 {
@@ -216,6 +217,7 @@ private:
     bool m_isInitialized = false;
     bool m_userNoBorder = false;
     bool m_isTransient = false;
+    QPointer<AbstractOutput> m_fullScreenRequestedOutput;
 };
 
 class XdgPopupClient final : public XdgSurfaceClient