let +/- buttons set the radius to the native map width for each tile zoom level

BUG: 199259

src/lib/MarbleMap.cpp

@@ -354,6 +354,24 @@ void MarbleMap::setRadius( int radius )
 }
 
 
+int MarbleMap::preferredRadiusCeil( int radius )
+{
+    if ( d->m_textureLayer.tileZoomLevel() < 0 )
+        return radius;
+
+    return d->m_textureLayer.preferredRadiusCeil( radius );
+}
+
+
+int MarbleMap::preferredRadiusFloor( int radius )
+{
+    if ( d->m_textureLayer.tileZoomLevel() < 0 )
+        return radius;
+
+    return d->m_textureLayer.preferredRadiusFloor( radius );
+}
+
+
 int MarbleMap::tileZoomLevel() const
 {
     return d->m_textureLayer.tileZoomLevel();

src/lib/MarbleMap.h

@@ -146,6 +146,9 @@ class MARBLE_EXPORT MarbleMap : public QObject
      */
     void setRadius( int radius );
 
+    int preferredRadiusCeil( int radius );
+    int preferredRadiusFloor( int radius );
+
     int tileZoomLevel() const;
 
     /**

src/lib/MarbleWidget.cpp

@@ -548,12 +548,30 @@ void MarbleWidget::zoomViewBy( int zoomStep, FlyToMode mode )
 
 void MarbleWidget::zoomIn( FlyToMode mode )
 {
-    zoomViewBy( d->m_zoomStep, mode );
+    if ( d->m_map->tileZoomLevel() < 0 ) {
+        zoomViewBy( d->m_zoomStep, mode );
+    } else {
+        const int radius = d->m_map->preferredRadiusCeil( d->m_map->radius() + 10 ) + 2;
+
+        GeoDataLookAt target = lookAt();
+        target.setRange( KM2METER * distanceFromRadius( radius ) );
+
+        flyTo( target, mode );
+    }
 }
 
 void MarbleWidget::zoomOut( FlyToMode mode )
 {
-    zoomViewBy( -d->m_zoomStep, mode );
+    if ( d->m_map->tileZoomLevel() < 0 ) {
+        zoomViewBy( -d->m_zoomStep, mode );
+    } else {
+        const int radius = d->m_map->preferredRadiusFloor( d->m_map->radius() - 10 ) + 2;
+
+        GeoDataLookAt target = lookAt();
+        target.setRange( KM2METER * distanceFromRadius( radius ) );
+
+        flyTo( target, mode );
+    }
 }
 
 void MarbleWidget::rotateBy( const Quaternion& incRot )

src/lib/TextureLayer.cpp

@@ -8,11 +8,11 @@
 // Copyright 2006-2007 Torsten Rahn <tackat@kde.org>
 // Copyright 2007      Inge Wallin  <ingwa@kde.org>
 // Copyright 2008, 2009, 2010 Jens-Michael Hoffmann <jmho@c-xx.com>
-// Copyright 2010      Bernhard Beschow  <bbeschow@cs.tu-berlin.de>
-//
+// Copyright 2010,2011 Bernhard Beschow <bbeschow@cs.tu-berlin.de>//
 
 #include "TextureLayer.h"
 
+#include <QtCore/qmath.h>
 #include <QtCore/QCache>
 #include <QtCore/QTimer>
 
@@ -296,6 +296,28 @@ qint64 TextureLayer::volatileCacheLimit() const
     return d->m_tileLoader.volatileCacheLimit();
 }
 
+int TextureLayer::preferredRadiusCeil( int radius ) const
+{
+    const int tileWidth = d->m_tileLoader.tileSize().width();
+    const int levelZeroColumns = d->m_tileLoader.tileColumnCount( 0 );
+    const qreal linearLevel = 4.0 * (qreal)( radius ) / (qreal)( tileWidth * levelZeroColumns );
+    const qreal tileLevelF = log( linearLevel ) / log( 2.0 );
+    const int tileLevel = qCeil( tileLevelF );
+
+    return tileWidth * d->m_tileLoader.tileColumnCount( tileLevel ) / 4;
+}
+
+int TextureLayer::preferredRadiusFloor( int radius ) const
+{
+    const int tileWidth = d->m_tileLoader.tileSize().width();
+    const int levelZeroColumns = d->m_tileLoader.tileColumnCount( 0 );
+    const qreal linearLevel = 4.0 * (qreal)( radius ) / (qreal)( tileWidth * levelZeroColumns );
+    const qreal tileLevelF = log( linearLevel ) / log( 2.0 );
+    const int tileLevel = qFloor( tileLevelF );
+
+    return tileWidth * d->m_tileLoader.tileColumnCount( tileLevel ) / 4;
+}
+
 }
 
 #include "TextureLayer.moc"

src/lib/TextureLayer.h

@@ -5,7 +5,7 @@
 // find a copy of this license in LICENSE.txt in the top directory of
 // the source code.
 //
-// Copyright 2010      Bernhard Beschow  <bbeschow@cs.tu-berlin.de>
+// Copyright 2010,2011 Bernhard Beschow <bbeschow@cs.tu-berlin.de>
 //
 
 #ifndef MARBLE_MARBLETEXTURELAYER_H
@@ -56,6 +56,9 @@ class TextureLayer : public QObject
 
     qint64 volatileCacheLimit() const;
 
+    int preferredRadiusCeil( int radius ) const;
+    int preferredRadiusFloor( int radius ) const;
+
  public Q_SLOTS:
     void paintGlobe( GeoPainter *painter,
                      ViewParams *viewParams,