From 7bf2c1d73eb952bef8254320691488f081657c51 Mon Sep 17 00:00:00 2001
From: Sebastian Krzyszkowiak <dos@dosowisko.net>
Date: Fri, 22 Feb 2019 18:54:52 +0000
Subject: [PATCH] [wayland] Fix window sizing when restoring a window that was
 initially fullscreen

Summary: When creating a surface and setting it as fullscreen before
attaching its buffer KWin does not know the original dimensions of the
surface and tries to use an invalid value when unsetting the fullscreen
flag. This patch fixes this by sending a configure with the size of 0,0
- which according to xdg-shell spec means that the client is requested
to set its size by itself.

Test Plan:
1. Create a fullscreen Wayland window.
2. Toggle fullscreen off.
3. KWin should send a configure event with size 0,0 instead of 1,1.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: zzag, graesslin, davidedmundson, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D16710
---
 autotests/integration/shell_client_test.cpp | 53 +++++++++++++++++++++
 shell_client.cpp                            |  7 +--
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/autotests/integration/shell_client_test.cpp b/autotests/integration/shell_client_test.cpp
index ada55eb052..f60caeab57 100644
--- a/autotests/integration/shell_client_test.cpp
+++ b/autotests/integration/shell_client_test.cpp
@@ -72,6 +72,8 @@ private Q_SLOTS:
     void testMinimizeActiveWindow();
     void testFullscreen_data();
     void testFullscreen();
+    void testFullscreenRestore_data();
+    void testFullscreenRestore();
     void testUserCanSetFullscreen_data();
     void testUserCanSetFullscreen();
     void testUserSetFullscreenWlShell();
@@ -524,6 +526,57 @@ void TestShellClient::testFullscreen()
     QCOMPARE(c->isDecorated(), decoMode == ServerSideDecoration::Mode::Server);
 }
 
+void TestShellClient::testFullscreenRestore_data()
+{
+    QTest::addColumn<Test::ShellSurfaceType>("type");
+
+    QTest::newRow("xdgShellV5") << Test::ShellSurfaceType::XdgShellV5;
+    QTest::newRow("xdgShellV6") << Test::ShellSurfaceType::XdgShellV6;
+    QTest::newRow("xdgShellWmBase") << Test::ShellSurfaceType::XdgShellStable;
+}
+
+void TestShellClient::testFullscreenRestore()
+{
+    // this test verifies that windows created fullscreen can be later properly restored
+    QScopedPointer<Surface> surface(Test::createSurface());
+    QFETCH(Test::ShellSurfaceType, type);
+    QScopedPointer<QObject> shellSurface(Test::createShellSurface(type, surface.data()));
+
+    XdgShellSurface *xdgShellSurface = nullptr;
+    // fullscreen the window
+    xdgShellSurface = qobject_cast<XdgShellSurface*>(shellSurface.data());
+    xdgShellSurface->setFullscreen(true);
+
+    auto c = Test::renderAndWaitForShown(surface.data(), QSize(screens()->size(0)), Qt::blue);
+    QVERIFY(c);
+    QVERIFY(c->isFullScreen());
+
+    QSignalSpy fullscreenChangedSpy(c, &ShellClient::fullScreenChanged);
+    QVERIFY(fullscreenChangedSpy.isValid());
+    QSignalSpy geometryChangedSpy(c, &ShellClient::geometryChanged);
+    QVERIFY(geometryChangedSpy.isValid());
+    QSignalSpy configureRequestedSpy(shellSurface.data(), SIGNAL(configureRequested(QSize, KWayland::Client::XdgShellSurface::States, quint32)));
+    QVERIFY(configureRequestedSpy.isValid());
+
+    // swap back to normal
+    xdgShellSurface->setFullscreen(false);
+
+    QVERIFY(fullscreenChangedSpy.wait());
+    QVERIFY(configureRequestedSpy.wait());
+    QCOMPARE(configureRequestedSpy.last().first().toSize(), QSize(0, 0));
+    QVERIFY(!c->isFullScreen());
+
+    for (const auto &it: configureRequestedSpy) {
+        xdgShellSurface->ackConfigure(it[2].toInt());
+    }
+
+    Test::render(surface.data(), QSize(100, 50), Qt::red);
+    QVERIFY(geometryChangedSpy.wait());
+    QCOMPARE(geometryChangedSpy.count(), 1);
+    QVERIFY(!c->isFullScreen());
+    QCOMPARE(c->geometry().size(), QSize(100, 50));
+}
+
 void TestShellClient::testUserCanSetFullscreen_data()
 {
     QTest::addColumn<Test::ShellSurfaceType>("type");
diff --git a/shell_client.cpp b/shell_client.cpp
index 892dced092..e156b91a87 100644
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -920,14 +920,15 @@ void ShellClient::setFullScreen(bool set, bool user)
     if (isFullScreen()) {
         setGeometry(workspace()->clientArea(FullScreenArea, this));
     } else {
-        if (!m_geomFsRestore.isNull()) {
+        if (m_geomFsRestore.isValid()) {
             int currentScreen = screen();
             setGeometry(QRect(m_geomFsRestore.topLeft(), adjustedSize(m_geomFsRestore.size())));
             if( currentScreen != screen())
                 workspace()->sendClientToScreen( this, currentScreen );
         } else {
-            // does this ever happen?
-            setGeometry(workspace()->clientArea(MaximizeArea, this));
+            // this can happen when the window was first shown already fullscreen,
+            // so let the client set the size by itself
+            setGeometry(QRect(workspace()->clientArea(PlacementArea, this).topLeft(), QSize(0, 0)));
         }
     }
     updateWindowRules(Rules::Fullscreen|Rules::Position|Rules::Size);