evdevtouch: Enable touch in multi-screen eglfs environments

Parse the touchDevice property from the KMS/DRM config file. When all
outputs have an explicitly specified index in the virtual desktop, we
can set up a mapping between the device node and the screen index. It
is somewhat fragile (device nodes may change, requires explicit
virtualIndex properties for all outputs, etc.) but better than
nothing.

For example, having the screen on DisplayPort as primary and the
touchscreen on HDMI as the secondary screen breaks by default because
touching the second screen generates touch (and synthesized mouse)
events for the first screen.  Assuming the touchscreen is
/dev/input/event5, the issue can now be fixed by setting
QT_QPA_EGLFS_KMS_CONFIG with a configuration like the following:

  {
    "device": "drm-nvdc",
    "outputs": [
      {
        "name": "HDMI1",
        "touchDevice": "/dev/input/event5",
        "virtualIndex": 1
      },
      {
        "name": "DP1",
        "virtualIndex": 0
      }
    ]
  }

Task-number: QTBUG-54151
Change-Id: If97fa18a65599ccfe64ce408ea43086ec3863682
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

3 files changed, 167 insertions, 0 deletions

diff --git a/src/platformsupport/input/shared/qtouchoutputmapping.cpp b/src/platformsupport/input/shared/qtouchoutputmapping.cpp
new file mode 100644
index 0000000000..55c1dc34f4
--- /dev/null
+++ b/src/platformsupport/input/shared/qtouchoutputmapping.cpp
@@ -0,0 +1,91 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qtouchoutputmapping_p.h"
+#include <QFile>
+#include <QVariantMap>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+
+QT_BEGIN_NAMESPACE
+
+bool QTouchOutputMapping::load()
+{
+    static QByteArray configFile = qgetenv("QT_QPA_EGLFS_KMS_CONFIG");
+    if (configFile.isEmpty())
+        return false;
+
+    QFile file(QString::fromUtf8(configFile));
+    if (!file.open(QFile::ReadOnly)) {
+        qWarning("touch input support: Failed to open %s", configFile.constData());
+        return false;
+    }
+
+    const QJsonDocument doc = QJsonDocument::fromJson(file.readAll());
+    if (!doc.isObject()) {
+        qWarning("touch input support: Failed to parse %s", configFile.constData());
+        return false;
+    }
+
+    // What we are interested is the virtualIndex and touchDevice properties for
+    // each element in the outputs array.
+    const QJsonArray outputs = doc.object().value(QLatin1String("outputs")).toArray();
+    for (int i = 0; i < outputs.size(); ++i) {
+        const QVariantMap output = outputs.at(i).toObject().toVariantMap();
+        if (!output.contains(QStringLiteral("touchDevice")))
+            continue;
+        if (!output.contains(QStringLiteral("virtualIndex"))) {
+            qWarning("evdevtouch: Output %d specifies touchDevice but not virtualIndex, this is wrong", i);
+            continue;
+        }
+        const QString &deviceNode = output.value(QStringLiteral("touchDevice")).toString();
+        const int screenIndex = output.value(QStringLiteral("virtualIndex")).toInt();
+        m_screenIndexTable.insert(deviceNode, screenIndex);
+    }
+
+    return true;
+}
+
+int QTouchOutputMapping::screenIndexForDeviceNode(const QString &deviceNode)
+{
+    return m_screenIndexTable.value(deviceNode, -1);
+}
+
+QT_END_NAMESPACE
diff --git a/src/platformsupport/input/shared/qtouchoutputmapping_p.h b/src/platformsupport/input/shared/qtouchoutputmapping_p.h
new file mode 100644
index 0000000000..74999d93ce
--- /dev/null
+++ b/src/platformsupport/input/shared/qtouchoutputmapping_p.h
@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QTOUCHOUTPUTMAPPING_P_H
+#define QTOUCHOUTPUTMAPPING_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QString>
+#include <QHash>
+
+QT_BEGIN_NAMESPACE
+
+class QTouchOutputMapping
+{
+public:
+    bool load();
+    int screenIndexForDeviceNode(const QString &deviceNode);
+
+private:
+    QHash<QString, int> m_screenIndexTable;
+};
+
+QT_END_NAMESPACE
+
+#endif // QTOUCHOUTPUTMAPPING_P_H
diff --git a/src/platformsupport/input/shared/shared.pri b/src/platformsupport/input/shared/shared.pri
new file mode 100644
index 0000000000..1443235244
--- /dev/null
+++ b/src/platformsupport/input/shared/shared.pri
@@ -0,0 +1,5 @@
+HEADERS += \
+    $$PWD/qtouchoutputmapping_p.h
+
+SOURCES += \
+    $$PWD/qtouchoutputmapping.cpp