From 168b8be9d05c56b12d1dde299ce7d852217322e9 Mon Sep 17 00:00:00 2001
From: Uwe Rathmann <Uwe.Rathmann@tigertal.de>
Date: Tue, 19 Jul 2022 16:50:40 +0200
Subject: [PATCH] flipping QskStackBoxAnimator added

---
 examples/layouts/StackLayoutPage.cpp |  19 ++++-
 src/layouts/QskStackBoxAnimator.cpp  | 121 +++++++++++++++++++++++++++
 src/layouts/QskStackBoxAnimator.h    |  14 ++++
 3 files changed, 153 insertions(+), 1 deletion(-)

diff --git a/examples/layouts/StackLayoutPage.cpp b/examples/layouts/StackLayoutPage.cpp
index 5d31eecf..3f348f39 100644
--- a/examples/layouts/StackLayoutPage.cpp
+++ b/examples/layouts/StackLayoutPage.cpp
@@ -61,6 +61,22 @@ namespace
             Q_EMIT transitionStarted( animator->duration() );
         }
 
+        void incrementFlipping( int offset )
+        {
+            auto animator = dynamic_cast< QskStackBoxAnimator2* >( this->animator() );
+
+            if ( animator == nullptr )
+            {
+                animator = new QskStackBoxAnimator2( this );
+                animator->setDuration( 800 );
+            }
+
+            setAnimator( animator );
+            setCurrentIndex( incrementedIndex( offset ) );
+
+            Q_EMIT transitionStarted( animator->duration() );
+        }
+
         void incrementScrolling( Qt::Orientation orientation, int offset )
         {
             auto animator = dynamic_cast< QskStackBoxAnimator1* >( this->animator() );
@@ -171,7 +187,8 @@ StackLayoutPage::StackLayoutPage( QQuickItem* parent )
     buttonBox->addButton( ">>", [ box ]() { box->incrementScrolling( Qt::Horizontal, -1 ); } );
     buttonBox->addButton( "^", [ box ]() { box->incrementScrolling( Qt::Vertical, -1 ); } );
     buttonBox->addButton( "v", [ box ]() { box->incrementScrolling( Qt::Vertical, +1 ); } );
-    buttonBox->addButton( "Fading", [ box ]() { box->incrementFading( +1 ); } );
+    buttonBox->addButton( "Fade", [ box ]() { box->incrementFading( +1 ); } );
+    buttonBox->addButton( "Flip", [ box ]() { box->incrementFlipping( +1 ); } );
 
     // page indicator
 
diff --git a/src/layouts/QskStackBoxAnimator.cpp b/src/layouts/QskStackBoxAnimator.cpp
index 979b690d..61f4a13c 100644
--- a/src/layouts/QskStackBoxAnimator.cpp
+++ b/src/layouts/QskStackBoxAnimator.cpp
@@ -9,6 +9,10 @@
 #include "QskQuick.h"
 #include "QskFunctions.h"
 
+QSK_QT_PRIVATE_BEGIN
+#include <private/qquickitem_p.h>
+QSK_QT_PRIVATE_END
+
 static Qsk::Direction qskDirection(
     Qt::Orientation orientation, int from, int to, int itemCount )
 {
@@ -56,6 +60,59 @@ static Qsk::Direction qskDirection(
     return direction;
 }
 
+namespace
+{
+    class Rotation : public QQuickTransform
+    {
+        Q_OBJECT
+
+    public:
+        Rotation( qreal angle, QQuickItem* item )
+            : QQuickTransform( item )
+            , m_angle( angle )
+        {
+            prependToItem( item );
+        }
+
+        void setAngle( qreal angle )
+        {
+            m_angle = angle;
+            update();
+        }
+
+        void applyTo( QMatrix4x4* matrix) const override
+        {
+            if ( const auto item = qobject_cast< QQuickItem* >( parent() ) )
+            {
+                const auto dx = 0.5 * item->width();
+                const auto dy = 0.5 * item->height();
+
+                QTransform transform;
+                transform.translate( dx, dy );
+                transform.rotate( m_angle, Qt::XAxis );
+                transform.translate( -dx, -dy );
+
+                *matrix *= transform;
+            }
+        }
+
+        static Rotation* find( const QQuickItem* item )
+        {
+            const auto& transforms = QQuickItemPrivate::get( item )->transforms;
+            for ( const auto& t : transforms )
+            {
+                if ( auto rotation = qobject_cast< Rotation* >( t ) )
+                    return rotation;
+            }
+
+            return nullptr;
+        }
+
+    private:
+        qreal m_angle = 0.0;
+    };
+}
+
 QskStackBoxAnimator::QskStackBoxAnimator( QskStackBox* parent )
     : QObject( parent )
     , m_startIndex( -1 )
@@ -273,6 +330,69 @@ bool QskStackBoxAnimator1::eventFilter( QObject* object, QEvent* event )
     return QObject::eventFilter( object, event );
 }
 
+QskStackBoxAnimator2::QskStackBoxAnimator2( QskStackBox* parent )
+    : QskStackBoxAnimator( parent )
+{
+}
+
+QskStackBoxAnimator2::~QskStackBoxAnimator2()
+{
+}
+
+void QskStackBoxAnimator2::setup()
+{
+    if ( auto item = itemAt( 0 ) )
+        ( void ) new Rotation( 0.0, item );
+
+    if ( auto item = itemAt( 1 ) )
+        ( void ) new Rotation( 90.0, item );
+}
+
+void QskStackBoxAnimator2::advanceIndex( qreal value )
+{
+    if ( value < 0.5 )
+    {
+        if ( auto item = itemAt( 0 ) )
+        {
+            auto rotation = Rotation::find( item );
+            rotation->setAngle( value * 180.0 );
+            item->setVisible( true );
+        }
+
+        if ( auto item = itemAt( 1 ) )
+        {
+            item->setVisible( false );
+        }
+    }
+    else
+    {
+        if ( auto item = itemAt( 0 ) )
+        {
+            item->setVisible( false );
+        }
+
+        if ( auto item = itemAt( 1 ) )
+        {
+            auto rotation = Rotation::find( item );
+            rotation->setAngle( ( 1.0 - value ) * -180.0 );
+
+            item->setVisible( true );
+        }
+    }
+}
+
+void QskStackBoxAnimator2::done()
+{
+    for ( int i = 0; i < 2; i++ )
+    {
+        if ( auto item = itemAt( i ) )
+        {
+            delete Rotation::find( item );
+            item->setVisible( i == 1 ); // not here !!
+        }
+    }
+}
+
 QskStackBoxAnimator3::QskStackBoxAnimator3( QskStackBox* parent )
     : QskStackBoxAnimator( parent )
 {
@@ -313,3 +433,4 @@ void QskStackBoxAnimator3::done()
 }
 
 #include "moc_QskStackBoxAnimator.cpp"
+#include "QskStackBoxAnimator.moc"
diff --git a/src/layouts/QskStackBoxAnimator.h b/src/layouts/QskStackBoxAnimator.h
index 5538b55b..4e5b7d51 100644
--- a/src/layouts/QskStackBoxAnimator.h
+++ b/src/layouts/QskStackBoxAnimator.h
@@ -71,6 +71,20 @@ class QSK_EXPORT QskStackBoxAnimator1 : public QskStackBoxAnimator
     bool m_hasClip : 1;
 };
 
+class QSK_EXPORT QskStackBoxAnimator2 : public QskStackBoxAnimator
+{
+    Q_OBJECT
+
+  public:
+    QskStackBoxAnimator2( QskStackBox* );
+    ~QskStackBoxAnimator2() override;
+
+  protected:
+    void setup() override;
+    void advanceIndex( qreal value ) override;
+    void done() override;
+};
+
 class QSK_EXPORT QskStackBoxAnimator3 : public QskStackBoxAnimator
 {
     Q_OBJECT