[layouts] Add option to filter "add layer to legend" dialog to

layers visible within the (linked) map only

Fixes #20186

Author: nyalldawson

python/core/auto_generated/layout/qgslayoutitemmap.sip.in

@@ -470,6 +470,12 @@ will be calculated. This can be expensive to calculate, so if they are not requi
     virtual void finalizeRestoreFromXml();
 
 
+    QList<QgsMapLayer *> layersToRender( const QgsExpressionContext *context = 0 ) const;
+%Docstring
+Returns a list of the layers which will be rendered within this map item, considering
+any locked layers, linked map theme, and data defined settings.
+%End
+
   protected:
 
     virtual void draw( QgsLayoutItemRenderContext &context );

src/app/layout/qgslayoutlegendlayersdialog.cpp

@@ -38,6 +38,7 @@ QgsLayoutLegendLayersDialog::QgsLayoutLegendLayersDialog( QWidget *parent )
   connect( listMapLayers, &QListView::doubleClicked, this, &QgsLayoutLegendLayersDialog::accept );
 
   connect( mFilterLineEdit, &QLineEdit::textChanged, mModel, &QgsMapLayerProxyModel::setFilterString );
+  connect( mCheckBoxVisibleLayers, &QCheckBox::toggled, this, &QgsLayoutLegendLayersDialog::filterVisible );
 }
 
 QgsLayoutLegendLayersDialog::~QgsLayoutLegendLayersDialog()
@@ -46,6 +47,11 @@ QgsLayoutLegendLayersDialog::~QgsLayoutLegendLayersDialog()
   settings.setValue( QStringLiteral( "Windows/LayoutLegendLayers/geometry" ), saveGeometry() );
 }
 
+void QgsLayoutLegendLayersDialog::setVisibleLayers( const QList<QgsMapLayer *> &layers )
+{
+  mVisibleLayers = layers;
+}
+
 QList< QgsMapLayer *> QgsLayoutLegendLayersDialog::selectedLayers() const
 {
   QList< QgsMapLayer * > layers;
@@ -65,3 +71,11 @@ QList< QgsMapLayer *> QgsLayoutLegendLayersDialog::selectedLayers() const
   }
   return layers;
 }
+
+void QgsLayoutLegendLayersDialog::filterVisible( bool enabled )
+{
+  if ( enabled )
+    mModel->setLayerWhitelist( mVisibleLayers );
+  else
+    mModel->setLayerWhitelist( QList< QgsMapLayer * >() );
+}

src/app/layout/qgslayoutlegendlayersdialog.h

@@ -32,12 +32,22 @@ class QgsLayoutLegendLayersDialog: public QDialog, private Ui::QgsLayoutLegendLa
     QgsLayoutLegendLayersDialog( QWidget *parent = nullptr );
     ~QgsLayoutLegendLayersDialog() override;
 
+    /**
+     * Sets a list of visible \a layers, to use for filtering within the dialog.
+     */
+    void setVisibleLayers( const QList<QgsMapLayer *> &layers );
+
     QList< QgsMapLayer * > selectedLayers() const;
 
+  private slots:
+
+    void filterVisible( bool enabled );
+
   private:
     QgsLayoutLegendLayersDialog() = delete;
 
     QgsMapLayerProxyModel *mModel = nullptr;
+    QList< QgsMapLayer * > mVisibleLayers;
 };
 
 #endif //QGSLAYOUTLEGENDLAYERSDIALOG_H

src/app/layout/qgslayoutlegendwidget.cpp

@@ -699,7 +699,19 @@ void QgsLayoutLegendWidget::mAddToolButton_clicked()
     return;
   }
 
+  QList< QgsMapLayer * > visibleLayers;
+  if ( mLegend->linkedMap() )
+  {
+    visibleLayers = mLegend->linkedMap()->layersToRender();
+  }
+  if ( visibleLayers.isEmpty() )
+  {
+    // just use current canvas layers as visible layers
+    visibleLayers = QgisApp::instance()->mapCanvas()->layers();
+  }
+
   QgsLayoutLegendLayersDialog addDialog( this );
+  addDialog.setVisibleLayers( visibleLayers );
   if ( addDialog.exec() == QDialog::Accepted )
   {
     const QList<QgsMapLayer *> layers = addDialog.selectedLayers();

src/core/layout/qgslayoutitemmap.h

@@ -417,6 +417,12 @@ class CORE_EXPORT QgsLayoutItemMap : public QgsLayoutItem
 
     void finalizeRestoreFromXml() override;
 
+    /**
+     * Returns a list of the layers which will be rendered within this map item, considering
+     * any locked layers, linked map theme, and data defined settings.
+     */
+    QList<QgsMapLayer *> layersToRender( const QgsExpressionContext *context = nullptr ) const;
+
   protected:
 
     void draw( QgsLayoutItemRenderContext &context ) override;
@@ -619,9 +625,6 @@ class CORE_EXPORT QgsLayoutItemMap : public QgsLayoutItem
     //! Resets the item tooltip to reflect current map id
     void updateToolTip();
 
-    //! Returns a list of the layers to render for this map item
-    QList<QgsMapLayer *> layersToRender( const QgsExpressionContext *context = nullptr ) const;
-
     //! Returns current layer style overrides for this map item
     QMap<QString, QString> layerStyleOverridesToRender( const QgsExpressionContext &context ) const;
 

src/ui/layout/qgslayoutlegendlayersdialogbase.ui

@@ -17,7 +17,14 @@
    <property name="spacing">
     <number>6</number>
    </property>
-   <item row="2" column="0">
+   <item row="1" column="0">
+    <widget class="QListView" name="listMapLayers">
+     <property name="selectionMode">
+      <enum>QAbstractItemView::ExtendedSelection</enum>
+     </property>
+    </widget>
+   </item>
+   <item row="3" column="0">
     <widget class="QDialogButtonBox" name="buttonBox">
      <property name="orientation">
       <enum>Qt::Horizontal</enum>
@@ -27,20 +34,23 @@
      </property>
     </widget>
    </item>
-   <item row="1" column="0">
-    <widget class="QListView" name="listMapLayers">
-     <property name="selectionMode">
-      <enum>QAbstractItemView::ExtendedSelection</enum>
-     </property>
-    </widget>
-   </item>
    <item row="0" column="0">
     <widget class="QgsFilterLineEdit" name="mFilterLineEdit">
      <property name="placeholderText">
       <string>Search</string>
      </property>
     </widget>
    </item>
+   <item row="2" column="0">
+    <widget class="QCheckBox" name="mCheckBoxVisibleLayers">
+     <property name="toolTip">
+      <string>If checked, only layers visible within the map will be listed</string>
+     </property>
+     <property name="text">
+      <string>Show visible layers only</string>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
  <customwidgets>