[autotests] Add a new test case which can verify the rendering of QPainter Scene

Summary:
The idea behind this autotest is inspired by bug 356328 which produced
incorrect rendering results. Also it's inspired by openQA which performs
image reference comparisons.

This test case tries to go further. It creates reference images which
must match the rendering result exactly. So far the test case verifies
the start condition - kwin started and one frame is rendered with default
cursor in the middle of the screen. And it verifies the moving of the
cursor without any windows shown. Whenever the cursor moves a repaint
should be triggered and the old and new area should be properly
repainted.

To support this the test needs some minor changes in KWin:
* Scene provides a frameRendered signal - needed for waiting on frame
* Scene and SceneQPainter are exported
* SceneQPainter provides access to it's Backend, so that we get to the
 backbuffer
* ScriptedEffectLoader is exported for getting a list of all scripted
 effects - (we don't want fade to manipulate the rendering)

Reviewers: #kwin, #plasma_on_wayland

Subscribers: plasma-devel, kwin

Tags: #plasma_on_wayland, #kwin

Differential Revision: https://phabricator.kde.org/D2046

autotests/integration/CMakeLists.txt

@@ -235,3 +235,12 @@ add_executable(testXClipboardSync ${testXClipboardSync_SRCS})
 target_link_libraries( testXClipboardSync kwin Qt5::Test)
 add_test(kwin-testXClipboardSync testXClipboardSync)
 ecm_mark_as_test(testXClipboardSync)
+
+########################################################
+# SceneQPainter Test
+########################################################
+set( testSceneQPainter_SRCS scene_qpainter_test.cpp kwin_wayland_test.cpp )
+add_executable(testSceneQPainter ${testSceneQPainter_SRCS})
+target_link_libraries( testSceneQPainter kwin Qt5::Test)
+add_test(kwin-testSceneQPainter testSceneQPainter)
+ecm_mark_as_test(testSceneQPainter)

autotests/integration/scene_qpainter_test.cpp

@@ -0,0 +1,122 @@
+/********************************************************************
+KWin - the KDE window manager
+This file is part of the KDE project.
+
+Copyright (C) 2016 Martin Gräßlin <mgraesslin@kde.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+#include "kwin_wayland_test.h"
+#include "composite.h"
+#include "effectloader.h"
+#include "cursor.h"
+#include "platform.h"
+#include "scene_qpainter.h"
+#include "wayland_server.h"
+#include "effect_builtins.h"
+
+#include <KConfigGroup>
+
+#include <QPainter>
+
+using namespace KWin;
+static const QString s_socketName = QStringLiteral("wayland_test_kwin_scene_qpainter-0");
+
+class SceneQPainterTest : public QObject
+{
+Q_OBJECT
+private Q_SLOTS:
+    void initTestCase();
+    void testStartFrame();
+    void testCursorMoving();
+};
+
+void SceneQPainterTest::initTestCase()
+{
+    QSignalSpy workspaceCreatedSpy(kwinApp(), &Application::workspaceCreated);
+    QVERIFY(workspaceCreatedSpy.isValid());
+    kwinApp()->platform()->setInitialWindowSize(QSize(1280, 1024));
+    waylandServer()->init(s_socketName.toLocal8Bit());
+
+    // disable all effects - we don't want to have it interact with the rendering
+    auto config = KSharedConfig::openConfig(QString(), KConfig::SimpleConfig);
+    KConfigGroup plugins(config, QStringLiteral("Plugins"));
+    ScriptedEffectLoader loader;
+    const auto builtinNames = BuiltInEffects::availableEffectNames() << loader.listOfKnownEffects();
+    for (QString name : builtinNames) {
+        plugins.writeEntry(name + QStringLiteral("Enabled"), false);
+    }
+
+    config->sync();
+    kwinApp()->setConfig(config);
+
+    qputenv("XCURSOR_THEME", QByteArrayLiteral("DMZ-White"));
+    qputenv("XCURSOR_SIZE", QByteArrayLiteral("24"));
+    qputenv("KWIN_COMPOSE", QByteArrayLiteral("Q"));
+
+    kwinApp()->start();
+    QVERIFY(workspaceCreatedSpy.wait());
+    QVERIFY(Compositor::self());
+}
+
+void SceneQPainterTest::testStartFrame()
+{
+    // this test verifies that the initial rendering is correct
+    Compositor::self()->addRepaintFull();
+    auto scene = qobject_cast<SceneQPainter*>(Compositor::self()->scene());
+    QVERIFY(scene);
+    QSignalSpy frameRenderedSpy(scene, &Scene::frameRendered);
+    QVERIFY(frameRenderedSpy.isValid());
+    QVERIFY(frameRenderedSpy.wait());
+    // now let's render a reference image for comparison
+    QImage referenceImage(QSize(1280, 1024), QImage::Format_RGB32);
+    referenceImage.fill(Qt::black);
+    QPainter p(&referenceImage);
+    const QImage cursorImage = kwinApp()->platform()->softwareCursor();
+    QVERIFY(!cursorImage.isNull());
+    p.drawImage(KWin::Cursor::pos() - kwinApp()->platform()->softwareCursorHotspot(), cursorImage);
+    QCOMPARE(referenceImage, *scene->backend()->buffer());
+}
+
+void SceneQPainterTest::testCursorMoving()
+{
+    // this test verifies that rendering is correct also after moving the cursor a few times
+    auto scene = qobject_cast<SceneQPainter*>(Compositor::self()->scene());
+    QVERIFY(scene);
+    QSignalSpy frameRenderedSpy(scene, &Scene::frameRendered);
+    QVERIFY(frameRenderedSpy.isValid());
+    KWin::Cursor::setPos(0, 0);
+    QVERIFY(frameRenderedSpy.wait());
+    KWin::Cursor::setPos(10, 0);
+    QVERIFY(frameRenderedSpy.wait());
+    KWin::Cursor::setPos(10, 12);
+    QVERIFY(frameRenderedSpy.wait());
+    KWin::Cursor::setPos(12, 14);
+    QVERIFY(frameRenderedSpy.wait());
+    KWin::Cursor::setPos(50, 60);
+    QVERIFY(frameRenderedSpy.wait());
+    KWin::Cursor::setPos(45, 45);
+    QVERIFY(frameRenderedSpy.wait());
+    // now let's render a reference image for comparison
+    QImage referenceImage(QSize(1280, 1024), QImage::Format_RGB32);
+    referenceImage.fill(Qt::black);
+    QPainter p(&referenceImage);
+    const QImage cursorImage = kwinApp()->platform()->softwareCursor();
+    QVERIFY(!cursorImage.isNull());
+    p.drawImage(QPoint(45, 45) - kwinApp()->platform()->softwareCursorHotspot(), cursorImage);
+    QCOMPARE(referenceImage, *scene->backend()->buffer());
+}
+
+WAYLANDTEST_MAIN(SceneQPainterTest)
+#include "scene_qpainter_test.moc"

effectloader.h

@@ -19,6 +19,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #ifndef KWIN_EFFECT_LOADER_H
 #define KWIN_EFFECT_LOADER_H
+#include <kwin_export.h>
 // KDE
 #include <KPluginMetaData>
 #include <KSharedConfig>
@@ -302,7 +303,7 @@ private:
  * @brief Can load scripted Effects
  *
  */
-class ScriptedEffectLoader : public AbstractEffectLoader
+class KWIN_EXPORT ScriptedEffectLoader : public AbstractEffectLoader
 {
     Q_OBJECT
 public:

scene.h

@@ -57,7 +57,7 @@ class Shadow;
 class WindowPixmap;
 
 // The base class for compositing backends.
-class Scene : public QObject
+class KWIN_EXPORT Scene : public QObject
 {
     Q_OBJECT
 public:
@@ -149,6 +149,9 @@ public:
 
     virtual Decoration::Renderer *createDecorationRenderer(Decoration::DecoratedClientImpl *) = 0;
 
+Q_SIGNALS:
+    void frameRendered();
+
 public Q_SLOTS:
     // a window has been destroyed
     void windowDeleted(KWin::Deleted*);

scene_qpainter.cpp

@@ -186,6 +186,8 @@ qint64 SceneQPainter::paint(QRegion damage, ToplevelList toplevels)
     // do cleanup
     clearStackingOrder();
 
+    emit frameRendered();
+
     return renderTimer.nsecsElapsed();
 }
 

scene_qpainter.h

@@ -102,7 +102,7 @@ private:
     bool m_failed;
 };
 
-class SceneQPainter : public Scene
+class KWIN_EXPORT SceneQPainter : public Scene
 {
     Q_OBJECT
 
@@ -121,6 +121,10 @@ public:
 
     QPainter *painter();
 
+    QPainterBackend *backend() const {
+        return m_backend.data();
+    }
+
     static SceneQPainter *createScene(QObject *parent);
 
 protected: