[FEATURE] Composer map to follow a visibility preset (fixes #13418)

This adds a new option in composer map properties:
"Follow visibility preset" with a combo box to choose the active preset.

This is an alternative to "lock layers" (and "lock layer styles") functionality
which would just copy preset's configuration, while the new option links to preset.

The difference is that when a preset is updated, composer map will automatically
pick the new configuration when following the preset, while there is no update
if "lock layers" (and "lock layer styles") option is used.

python/core/composer/qgscomposermap.sip

@@ -223,6 +223,27 @@ class QgsComposerMap : QgsComposerItem
     /** Stores the current layer styles into style overrides. @note added in 2.8 */
     void storeCurrentLayerStyles();
 
+    /** Whether the map should follow a visibility preset. If true, the layers and layer styles
+     * will be used from given preset name (configured with setFollowVisibilityPresetName() method).
+     * This means when preset's settings are changed, the new settings are automatically
+     * picked up next time when rendering, without having to explicitly update them.
+     * At most one of the flags keepLayerSet() and followVisibilityPreset() should be enabled
+     * at any time since they are alternative approaches - if both are enabled,
+     * following visibility preset has higher priority. If neither is enabled (or if preset name is not set),
+     * map will use the same configuration as the map canvas uses.
+     * @note added in 2.16 */
+    bool followVisibilityPreset() const;
+    /** Sets whether the map should follow a visibility preset. See followVisibilityPreset() for more details.
+     * @note added in 2.16 */
+    void setFollowVisibilityPreset( bool follow );
+    /** Preset name that decides which layers and layer styles are used for map rendering. It is only
+     * used when followVisibilityPreset() returns true.
+     * @note added in 2.16 */
+    QString followVisibilityPresetName() const;
+    /** Sets preset name for map rendering. See followVisibilityPresetName() for more details.
+     * @note added in 2.16 */
+    void setFollowVisibilityPresetName( const QString& name );
+
     // Set cache outdated
     void setCacheUpdated( bool u = false );
 

src/app/composer/qgscomposermapwidget.cpp

@@ -125,12 +125,19 @@ QgsComposerMapWidget::QgsComposerMapWidget( QgsComposerMap* composerMap )
   //set initial state of frame style controls
   toggleFrameControls( false, false, false );
 
-  QMenu* m = new QMenu( this );
-  mLayerListFromPresetButton->setMenu( m );
+  // follow preset combo
+  mFollowVisibilityPresetCombo->setModel( new QStringListModel( mFollowVisibilityPresetCombo ) );
+  connect( mFollowVisibilityPresetCombo, SIGNAL( currentIndexChanged( int ) ), this, SLOT( followVisibilityPresetSelected( int ) ) );
+  connect( QgsProject::instance()->visibilityPresetCollection(), SIGNAL( presetsChanged() ),
+           this, SLOT( onPresetsChanged() ) );
+  onPresetsChanged();
+
+  // keep layers from preset button
+  QMenu* menuKeepLayers = new QMenu( this );
+  mLayerListFromPresetButton->setMenu( menuKeepLayers );
   mLayerListFromPresetButton->setIcon( QgsApplication::getThemeIcon( "/mActionShowAllLayers.png" ) );
   mLayerListFromPresetButton->setToolTip( tr( "Set layer list from a visibility preset" ) );
-
-  connect( m, SIGNAL( aboutToShow() ), this, SLOT( aboutToShowVisibilityPresetsMenu() ) );
+  connect( menuKeepLayers, SIGNAL( aboutToShow() ), this, SLOT( aboutToShowKeepLayersVisibilityPresetsMenu() ) );
 
   if ( composerMap )
   {
@@ -301,28 +308,47 @@ void QgsComposerMapWidget::compositionAtlasToggled( bool atlasEnabled )
   }
 }
 
-void QgsComposerMapWidget::aboutToShowVisibilityPresetsMenu()
+void QgsComposerMapWidget::aboutToShowKeepLayersVisibilityPresetsMenu()
 {
+  // this menu is for the case when setting "keep layers" and "keep layer styles"
+  // and the preset configuration is copied. The preset is not followed further.
+
   QMenu* menu = qobject_cast<QMenu*>( sender() );
   if ( !menu )
     return;
 
   menu->clear();
   Q_FOREACH ( const QString& presetName, QgsProject::instance()->visibilityPresetCollection()->presets() )
   {
-    QAction* a = menu->addAction( presetName, this, SLOT( visibilityPresetSelected() ) );
-    a->setCheckable( true );
-    QStringList layers = QgsVisibilityPresets::instance()->orderedPresetVisibleLayers( presetName );
-    QMap<QString, QString> styles = QgsProject::instance()->visibilityPresetCollection()->presetStyleOverrides( presetName );
-    if ( layers == mComposerMap->layerSet() && styles == mComposerMap->layerStyleOverrides() )
-      a->setChecked( true );
+    menu->addAction( presetName, this, SLOT( keepLayersVisibilityPresetSelected() ) );
   }
 
   if ( menu->actions().isEmpty() )
     menu->addAction( tr( "No presets defined" ) )->setEnabled( false );
 }
 
-void QgsComposerMapWidget::visibilityPresetSelected()
+void QgsComposerMapWidget::followVisibilityPresetSelected( int currentIndex )
+{
+  if ( !mComposerMap )
+    return;
+
+  QString presetName;
+  if ( currentIndex != 0 )
+  {
+    presetName = mFollowVisibilityPresetCombo->currentText();
+  }
+
+  if ( presetName == mComposerMap->followVisibilityPresetName() )
+    return;
+
+  mFollowVisibilityPresetCheckBox->setChecked( true );
+  mComposerMap->setFollowVisibilityPresetName( presetName );
+
+  mComposerMap->cache();
+  mComposerMap->update();
+}
+
+void QgsComposerMapWidget::keepLayersVisibilityPresetSelected()
 {
   QAction* action = qobject_cast<QAction*>( sender() );
   if ( !action )
@@ -344,6 +370,17 @@ void QgsComposerMapWidget::visibilityPresetSelected()
   }
 }
 
+void QgsComposerMapWidget::onPresetsChanged()
+{
+  if ( QStringListModel* model = qobject_cast<QStringListModel*>( mFollowVisibilityPresetCombo->model() ) )
+  {
+    QStringList lst;
+    lst.append( tr( "(none)" ) );
+    lst += QgsProject::instance()->visibilityPresetCollection()->presets();
+    model->setStringList( lst );
+  }
+}
+
 void QgsComposerMapWidget::on_mAtlasCheckBox_toggled( bool checked )
 {
   if ( !mComposerMap )
@@ -668,6 +705,12 @@ void QgsComposerMapWidget::updateGuiElements()
 
   mMapRotationSpinBox->setValue( mComposerMap->mapRotation( QgsComposerObject::OriginalValue ) );
 
+  // follow preset check box
+  mFollowVisibilityPresetCheckBox->setCheckState(
+    mComposerMap->followVisibilityPreset() ? Qt::Checked : Qt::Unchecked );
+  int presetModelIndex = mFollowVisibilityPresetCombo->findText( mComposerMap->followVisibilityPresetName() );
+  mFollowVisibilityPresetCombo->setCurrentIndex( presetModelIndex != -1 ? presetModelIndex : 0 ); // 0 == none
+
   //keep layer list check box
   if ( mComposerMap->keepLayerSet() )
   {
@@ -897,6 +940,30 @@ void QgsComposerMapWidget::on_mUpdatePreviewButton_clicked()
   mUpdatePreviewButton->setEnabled( true );
 }
 
+void QgsComposerMapWidget::on_mFollowVisibilityPresetCheckBox_stateChanged( int state )
+{
+  if ( !mComposerMap )
+  {
+    return;
+  }
+
+  if ( state == Qt::Checked )
+  {
+    mComposerMap->setFollowVisibilityPreset( true );
+
+    // mutually exclusive with keeping custom layer list
+    mKeepLayerListCheckBox->setCheckState( Qt::Unchecked );
+    mKeepLayerStylesCheckBox->setCheckState( Qt::Unchecked );
+
+    mComposerMap->cache();
+    mComposerMap->update();
+  }
+  else
+  {
+    mComposerMap->setFollowVisibilityPreset( false );
+  }
+}
+
 void QgsComposerMapWidget::on_mKeepLayerListCheckBox_stateChanged( int state )
 {
   if ( !mComposerMap )
@@ -908,6 +975,9 @@ void QgsComposerMapWidget::on_mKeepLayerListCheckBox_stateChanged( int state )
   {
     mComposerMap->storeCurrentLayerSet();
     mComposerMap->setKeepLayerSet( true );
+
+    // mutually exclusive with following a preset
+    mFollowVisibilityPresetCheckBox->setCheckState( Qt::Unchecked );
   }
   else
   {

src/app/composer/qgscomposermapwidget.h

@@ -43,6 +43,7 @@ class QgsComposerMapWidget: public QgsComposerItemBaseWidget, private Ui::QgsCom
     void on_mSetToMapCanvasExtentButton_clicked();
     void on_mViewExtentInCanvasButton_clicked();
     void on_mUpdatePreviewButton_clicked();
+    void on_mFollowVisibilityPresetCheckBox_stateChanged( int state );
     void on_mKeepLayerListCheckBox_stateChanged( int state );
     void on_mKeepLayerStylesCheckBox_stateChanged( int state );
     void on_mDrawCanvasItemsCheckBox_stateChanged( int state );
@@ -168,9 +169,12 @@ class QgsComposerMapWidget: public QgsComposerItemBaseWidget, private Ui::QgsCom
     /** Enables or disables the atlas controls when composer atlas is toggled on/off*/
     void compositionAtlasToggled( bool atlasEnabled );
 
-    void aboutToShowVisibilityPresetsMenu();
+    void aboutToShowKeepLayersVisibilityPresetsMenu();
 
-    void visibilityPresetSelected();
+    void followVisibilityPresetSelected( int currentIndex );
+    void keepLayersVisibilityPresetSelected();
+
+    void onPresetsChanged();
 
   private:
     QgsComposerMap* mComposerMap;

src/core/composer/qgscomposermap.cpp

@@ -53,6 +53,7 @@ QgsComposerMap::QgsComposerMap( QgsComposition *composition, int x, int y, int w
     , mEvaluatedMapRotation( 0 )
     , mKeepLayerSet( false )
     , mKeepLayerStyles( false )
+    , mFollowVisibilityPreset( false )
     , mUpdatesEnabled( true )
     , mMapCanvas( nullptr )
     , mDrawCanvasItems( true )
@@ -98,6 +99,7 @@ QgsComposerMap::QgsComposerMap( QgsComposition *composition )
     , mEvaluatedMapRotation( 0 )
     , mKeepLayerSet( false )
     , mKeepLayerStyles( false )
+    , mFollowVisibilityPreset( false )
     , mUpdatesEnabled( true )
     , mMapCanvas( nullptr )
     , mDrawCanvasItems( true )
@@ -537,28 +539,32 @@ QStringList QgsComposerMap::layersToRender( const QgsExpressionContext* context
 
   QStringList renderLayerSet;
 
-  QVariant exprVal;
-  if ( dataDefinedEvaluate( QgsComposerObject::MapStylePreset, exprVal, *evalContext ) )
+  if ( mFollowVisibilityPreset )
   {
-    QString presetName = exprVal.toString();
+    QString presetName = mFollowVisibilityPresetName;
+
+    // preset name can be overridden by data-defined one
+    QVariant exprVal;
+    if ( dataDefinedEvaluate( QgsComposerObject::MapStylePreset, exprVal, *evalContext ) )
+    {
+      presetName = exprVal.toString();
+    }
 
     if ( QgsProject::instance()->visibilityPresetCollection()->hasPreset( presetName ) )
       renderLayerSet = QgsProject::instance()->visibilityPresetCollection()->presetVisibleLayers( presetName );
+    else  // fallback to using map canvas layers
+      renderLayerSet = mComposition->mapSettings().layers();
   }
-
-  //use stored layer set or read current set from main canvas
-  if ( renderLayerSet.isEmpty() )
+  else if ( mKeepLayerSet )
   {
-    if ( mKeepLayerSet )
-    {
-      renderLayerSet = mLayerSet;
-    }
-    else
-    {
-      renderLayerSet = mComposition->mapSettings().layers();
-    }
+    renderLayerSet = mLayerSet;
+  }
+  else
+  {
+    renderLayerSet = mComposition->mapSettings().layers();
   }
 
+  QVariant exprVal;
   if ( dataDefinedEvaluate( QgsComposerObject::MapLayers, exprVal, *evalContext ) )
   {
     renderLayerSet.clear();
@@ -595,16 +601,29 @@ QStringList QgsComposerMap::layersToRender( const QgsExpressionContext* context
 
 QMap<QString, QString> QgsComposerMap::layerStyleOverridesToRender( const QgsExpressionContext& context ) const
 {
-  QVariant exprVal;
-  if ( dataDefinedEvaluate( QgsComposerObject::MapStylePreset, exprVal, context ) )
+  if ( mFollowVisibilityPreset )
   {
-    QString presetName = exprVal.toString();
+    QString presetName = mFollowVisibilityPresetName;
+
+    QVariant exprVal;
+    if ( dataDefinedEvaluate( QgsComposerObject::MapStylePreset, exprVal, context ) )
+    {
+      presetName = exprVal.toString();
+    }
 
     if ( QgsProject::instance()->visibilityPresetCollection()->hasPreset( presetName ) )
       return QgsProject::instance()->visibilityPresetCollection()->presetStyleOverrides( presetName );
-
+    else
+      return QMap<QString, QString>();
+  }
+  else if ( mKeepLayerStyles )
+  {
+    return mLayerStyleOverrides;
+  }
+  else
+  {
+    return QMap<QString, QString>();
   }
-  return mLayerStyleOverrides;
 }
 
 double QgsComposerMap::scale() const
@@ -1294,6 +1313,10 @@ bool QgsComposerMap::writeXML( QDomElement& elem, QDomDocument & doc ) const
   extentElem.setAttribute( "ymax", qgsDoubleToString( mExtent.yMaximum() ) );
   composerMapElem.appendChild( extentElem );
 
+  // follow visibility preset
+  composerMapElem.setAttribute( "followPreset", mFollowVisibilityPreset ? "true" : "false" );
+  composerMapElem.setAttribute( "followPresetName", mFollowVisibilityPresetName );
+
   //map rotation
   composerMapElem.setAttribute( "mapRotation", QString::number( mMapRotation ) );
 
@@ -1395,6 +1418,10 @@ bool QgsComposerMap::readXML( const QDomElement& itemElem, const QDomDocument& d
     mMapRotation = itemElem.attribute( "mapRotation", "0" ).toDouble();
   }
 
+  // follow visibility preset
+  mFollowVisibilityPreset = itemElem.attribute( "followPreset" ).compare( "true" ) == 0;
+  mFollowVisibilityPresetName = itemElem.attribute( "followPresetName" );
+
   //mKeepLayerSet flag
   QString keepLayerSetFlag = itemElem.attribute( "keepLayerSet" );
   if ( keepLayerSetFlag.compare( "true", Qt::CaseInsensitive ) == 0 )

src/core/composer/qgscomposermap.h

@@ -262,6 +262,27 @@ class CORE_EXPORT QgsComposerMap : public QgsComposerItem
     /** Stores the current layer styles into style overrides. @note added in 2.8 */
     void storeCurrentLayerStyles();
 
+    /** Whether the map should follow a visibility preset. If true, the layers and layer styles
+     * will be used from given preset name (configured with setFollowVisibilityPresetName() method).
+     * This means when preset's settings are changed, the new settings are automatically
+     * picked up next time when rendering, without having to explicitly update them.
+     * At most one of the flags keepLayerSet() and followVisibilityPreset() should be enabled
+     * at any time since they are alternative approaches - if both are enabled,
+     * following visibility preset has higher priority. If neither is enabled (or if preset name is not set),
+     * map will use the same configuration as the map canvas uses.
+     * @note added in 2.16 */
+    bool followVisibilityPreset() const { return mFollowVisibilityPreset; }
+    /** Sets whether the map should follow a visibility preset. See followVisibilityPreset() for more details.
+     * @note added in 2.16 */
+    void setFollowVisibilityPreset( bool follow ) { mFollowVisibilityPreset = follow; }
+    /** Preset name that decides which layers and layer styles are used for map rendering. It is only
+     * used when followVisibilityPreset() returns true.
+     * @note added in 2.16 */
+    QString followVisibilityPresetName() const { return mFollowVisibilityPresetName; }
+    /** Sets preset name for map rendering. See followVisibilityPresetName() for more details.
+     * @note added in 2.16 */
+    void setFollowVisibilityPresetName( const QString& name ) { mFollowVisibilityPresetName = name; }
+
     // Set cache outdated
     void setCacheUpdated( bool u = false );
 
@@ -888,6 +909,14 @@ class CORE_EXPORT QgsComposerMap : public QgsComposerItem
     /** Stored style names (value) to be used with particular layer IDs (key) instead of default style */
     QMap<QString, QString> mLayerStyleOverrides;
 
+    /** Whether layers and styles should be used from a preset (preset name is stored
+     * in mVisibilityPresetName and may be overridden by data-defined expression).
+     * This flag has higher priority than mKeepLayerSet. */
+    bool mFollowVisibilityPreset;
+    /** Visibility preset name to be used for map's layers and styles in case mFollowVisibilityPreset
+     *  is true. May be overridden by data-defined expression. */
+    QString mFollowVisibilityPresetName;
+
     /** Whether updates to the map are enabled */
     bool mUpdatesEnabled;