Introduce PinchHandler

Similar to PinchArea but with improvements:
- Allows rotating and scaling about an arbitrary point rather than the center
- It's possible to require more than 2 fingers.  E.g. maybe you use
  3 fingers to manage a window, 2 fingers to manipulate content inside.
  This could be achieved with two independent PinchHandlers.

Change-Id: Ifd40cfee115d7bc298378b26a58318bea40a8230
Reviewed-by: Jan Arve Sæther <jan-arve.saether@theqtcompany.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickpinchhandler_p.h b/src/quick/handlers/qquickpinchhandler_p.h
new file mode 100644
index 0000000000..0a66d5e02e
--- /dev/null
+++ b/src/quick/handlers/qquickpinchhandler_p.h
@@ -0,0 +1,131 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 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 QQUICKPINCHHANDLER_H
+#define QQUICKPINCHHANDLER_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 "qquickitem.h"
+#include "qevent.h"
+#include "qquickmultipointerhandler_p.h"
+#include <private/qquicktranslate_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class Q_AUTOTEST_EXPORT QQuickPinchHandler : public QQuickMultiPointerHandler
+{
+    Q_OBJECT
+    Q_PROPERTY(qreal minimumScale READ minimumScale WRITE setMinimumScale NOTIFY minimumScaleChanged)
+    Q_PROPERTY(qreal maximumScale READ maximumScale WRITE setMaximumScale NOTIFY maximumScaleChanged)
+    Q_PROPERTY(qreal minimumRotation READ minimumRotation WRITE setMinimumRotation NOTIFY minimumRotationChanged)
+    Q_PROPERTY(qreal maximumRotation READ maximumRotation WRITE setMaximumRotation NOTIFY maximumRotationChanged)
+    Q_PROPERTY(PinchOrigin pinchOrigin READ pinchOrigin WRITE setPinchOrigin NOTIFY pinchOriginChanged)
+    Q_PROPERTY(QPointF center READ center NOTIFY updated)
+    Q_PROPERTY(qreal scale READ scale NOTIFY updated)
+    Q_PROPERTY(qreal rotation READ rotation NOTIFY updated)
+
+public:
+    enum PinchOrigin {
+        FirstPoint, PinchCenter, TargetCenter
+    };
+    Q_ENUM(PinchOrigin)
+
+    QQuickPinchHandler(QObject *parent = 0);
+    ~QQuickPinchHandler();
+
+    qreal minimumScale() const { return m_minimumScale; }
+    void setMinimumScale(qreal minimumScale);
+
+    qreal maximumScale() const { return m_maximumScale; }
+    void setMaximumScale(qreal maximumScale);
+
+    qreal minimumRotation() const { return m_minimumRotation; }
+    void setMinimumRotation(qreal minimumRotation);
+
+    qreal maximumRotation() const { return m_maximumRotation; }
+    void setMaximumRotation(qreal maximumRotation);
+
+    PinchOrigin pinchOrigin() const { return m_pinchOrigin; }
+    void setPinchOrigin(PinchOrigin pinchOrigin);
+
+    QPointF center() const { return m_scaleTransform.origin().toPointF(); }
+    qreal scale() const { return m_scaleTransform.xScale(); }
+    qreal rotation() const { return m_rotationTransform.angle(); }
+
+signals:
+    void requiredPointCountChanged();
+    void minimumScaleChanged();
+    void maximumScaleChanged();
+    void minimumRotationChanged();
+    void maximumRotationChanged();
+    void pinchOriginChanged();
+    void updated();
+
+protected:
+    void onActiveChanged();
+    void onTargetChanged();
+    void handlePointerEventImpl(QQuickPointerEvent *event) override;
+
+private:
+    qreal m_startScale;
+    qreal m_startRotation;
+    qreal m_minimumScale;
+    qreal m_maximumScale;
+    qreal m_minimumRotation;
+    qreal m_maximumRotation;
+    PinchOrigin m_pinchOrigin;
+    QQuickScale m_scaleTransform;
+    QQuickRotation m_rotationTransform;
+};
+
+QT_END_NAMESPACE
+
+QML_DECLARE_TYPE(QQuickPinchHandler)
+
+#endif // QQUICKPINCHHANDLER_H