add PointHandler

Change-Id: Iad9ba3f8121ff22136e85413ec610bc1ee361e37
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

4 files changed, 219 insertions, 0 deletions

diff --git a/src/quick/handlers/handlers.pri b/src/quick/handlers/handlers.pri
index 9e32b9278c..8bd74d95da 100644
--- a/src/quick/handlers/handlers.pri
+++ b/src/quick/handlers/handlers.pri
@@ -5,6 +5,7 @@ HEADERS += \
     $$PWD/qquickpinchhandler_p.h \
     $$PWD/qquickpointerdevicehandler_p.h \
     $$PWD/qquickpointerhandler_p.h \
+    $$PWD/qquickpointhandler_p.h \
     $$PWD/qquicksinglepointhandler_p.h \
     $$PWD/qquicktaphandler_p.h \
 
@@ -15,6 +16,7 @@ SOURCES += \
     $$PWD/qquickpinchhandler.cpp \
     $$PWD/qquickpointerdevicehandler.cpp \
     $$PWD/qquickpointerhandler.cpp \
+    $$PWD/qquickpointhandler.cpp \
     $$PWD/qquicksinglepointhandler.cpp \
     $$PWD/qquicktaphandler.cpp \
 
diff --git a/src/quick/handlers/qquickhandlersmodule.cpp b/src/quick/handlers/qquickhandlersmodule.cpp
index 8472c6a062..c9e08fe4f2 100644
--- a/src/quick/handlers/qquickhandlersmodule.cpp
+++ b/src/quick/handlers/qquickhandlersmodule.cpp
@@ -41,6 +41,7 @@
 #include "qquickpointerhandler_p.h"
 #include "qquickdraghandler_p.h"
 #include "qquickpinchhandler_p.h"
+#include "qquickpointhandler_p.h"
 #include "qquicktaphandler_p.h"
 
 static void initResources()
@@ -82,6 +83,7 @@ static void qt_quickhandlers_defineModule(const char *uri, int major, int minor)
 
     qmlRegisterUncreatableType<QQuickPointerHandler>(uri,major,minor,"PointerHandler",
         QQuickPointerHandler::tr("PointerHandler is an abstract base class"));
+    qmlRegisterType<QQuickPointHandler>(uri,major,minor,"PointHandler");
     qmlRegisterType<QQuickDragHandler>(uri,major,minor,"DragHandler");
     qmlRegisterUncreatableType<QQuickDragAxis>(uri, major, minor, "DragAxis",
         QQuickDragHandler::tr("DragAxis is only available as a grouped property of DragHandler"));
diff --git a/src/quick/handlers/qquickpointhandler.cpp b/src/quick/handlers/qquickpointhandler.cpp
new file mode 100644
index 0000000000..d40837c43e
--- /dev/null
+++ b/src/quick/handlers/qquickpointhandler.cpp
@@ -0,0 +1,134 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick 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 "qquickpointhandler_p.h"
+#include <private/qquickwindow_p.h>
+#include <QDebug>
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \qmltype PointHandler
+    \instantiates QQuickPointHandler
+    \inqmlmodule QtQuick
+    \ingroup qtquick-handlers
+    \brief Handler for reacting to a single touchpoint
+
+    PointHandler can be used to show feedback about a touchpoint or the mouse
+    position, or to otherwise react to pointer events. By being only a passive
+    grabber, it has the ability to keep oversight of all movements, and its
+    grab cannot be stolen even when other gestures are detected and exclusive
+    grabs occur.
+
+    If your goal is orthogonal surveillance of eventpoints, an older
+    alternative was QObject::installEventFilter(), but that has never been a
+    built-in QtQuick feature: it requires a custom C++ QQuickItem subclass.
+    PointHandler is more efficient than that, because only pointer events will
+    be delivered to it, during the course of normal event delivery in
+    QQuickWindow, whereas an event filter needs to filter all events of all
+    types, and thus sets itself up as a potential event delivery bottleneck.
+
+    One possible use case is to add this handler to a transparent Item which is
+    on top of the rest of the scene, so that when a point is freshly pressed,
+    it will be delivered to that Item and its handlers first, providing the
+    opportunity to take the passive grab as early as possible. Then such an
+    item (like a pane of glass over the whole UI) also becomes a good parent
+    for other Items which visualize the kind of reactive feedback which must
+    always be on top; and likewise it can be the parent for popups, popovers,
+    dialogs and so on. For example, a declared Window can have an Item with a
+    high Z value so that it stays on top. It can also be helpful for your
+    main.cpp to use QQmlContext::setContextProperty() to make the "glass pane"
+    accessible by ID to the entire UI, so that other Items and PointHandlers
+    can be reparented to it.
+
+    Inside a PointHandler you can declare a \l target Item, but PointHandler
+    will not automatically manipulate it in any way. The target Item can bind to
+    properties of the PointHandler. In this way it can follow a point's movements.
+
+    \sa MultiPointTouchArea
+*/
+
+QQuickPointHandler::QQuickPointHandler(QObject *parent)
+    : QQuickSinglePointHandler(parent)
+{
+    setIgnoreAdditionalPoints();
+}
+
+QQuickPointHandler::~QQuickPointHandler()
+{
+}
+
+bool QQuickPointHandler::wantsEventPoint(QQuickEventPoint *pt)
+{
+    // On press, we want it unless a sibling of the same type also does.
+    if (pt->state() == QQuickEventPoint::Pressed && QQuickSinglePointHandler::wantsEventPoint(pt)) {
+        for (const QQuickPointerHandler *grabber : pt->passiveGrabbers()) {
+            if (grabber && grabber->parent() == parent() &&
+                    grabber->metaObject()->className() == metaObject()->className())
+                return false;
+        }
+        return true;
+    }
+    // If we've already been interested in a point, stay interested, even if it has strayed outside bounds.
+    return (pt->state() != QQuickEventPoint::Pressed && point().id() == pt->pointId());
+}
+
+void QQuickPointHandler::handleEventPoint(QQuickEventPoint *point)
+{
+    switch (point->state()) {
+    case QQuickEventPoint::Pressed:
+        setPassiveGrab(point);
+        setActive(true);
+        break;
+    case QQuickEventPoint::Released:
+        setActive(false);
+        break;
+    default:
+        break;
+    }
+    point->setAccepted(false); // Just lurking... don't interfere with propagation
+    emit translationChanged();
+}
+
+QVector2D QQuickPointHandler::translation() const
+{
+    return QVector2D(point().position() - point().pressPosition());
+}
+
+QT_END_NAMESPACE
diff --git a/src/quick/handlers/qquickpointhandler_p.h b/src/quick/handlers/qquickpointhandler_p.h
new file mode 100644
index 0000000000..5babab0c4d
--- /dev/null
+++ b/src/quick/handlers/qquickpointhandler_p.h
@@ -0,0 +1,81 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick 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 QQUICKPONTHANDLER_H
+#define QQUICKPONTHANDLER_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 "qquicksinglepointhandler_p.h"
+
+QT_BEGIN_NAMESPACE
+
+class Q_AUTOTEST_EXPORT QQuickPointHandler : public QQuickSinglePointHandler
+{
+    Q_OBJECT
+    Q_PROPERTY(QVector2D translation READ translation NOTIFY translationChanged)
+
+public:
+    explicit QQuickPointHandler(QObject *parent = 0);
+    ~QQuickPointHandler();
+
+    QVector2D translation() const;
+
+Q_SIGNALS:
+    void translationChanged();
+
+protected:
+    bool wantsEventPoint(QQuickEventPoint *pt) override;
+    void handleEventPoint(QQuickEventPoint *point) override;
+};
+
+QT_END_NAMESPACE
+
+QML_DECLARE_TYPE(QQuickPointHandler)
+
+#endif // QQUICKPONTHANDLER_H