[FEATURE] allow customization of line spacing for legend item labels (#3632)

* [FEATURE] allow customization of line spacing for legend item labels
* add test for legend line spacing and update control images

Author: nirvn

python/core/composer/qgscomposerlegend.sip

@@ -121,6 +121,18 @@ class QgsComposerLegend : QgsComposerItem
     void setStyleMargin( QgsLegendStyle::Style s, double margin );
     void setStyleMargin( QgsLegendStyle::Style s, QgsLegendStyle::Side side, double margin );
 
+    /** Returns the spacing in-between lines in mm
+     * @note added in 3.0
+     * @see setLineSpacing
+     */
+    double lineSpacing() const;
+    /** Sets the spacing in-between multiple lines
+     * @param spacing Double value to use as spacing in between multiple lines
+     * @note added in 3.0
+     * @see lineSpacing
+     */
+    void setLineSpacing( double spacing );
+
     double boxSpace() const;
     void setBoxSpace( double s );
 

src/app/composer/qgscomposerlegendwidget.cpp

@@ -144,6 +144,7 @@ void QgsComposerLegendWidget::setGuiElements()
   mIconLabelSpaceSpinBox->setValue( mLegend->style( QgsLegendStyle::SymbolLabel ).margin( QgsLegendStyle::Left ) );
   mBoxSpaceSpinBox->setValue( mLegend->boxSpace() );
   mColumnSpaceSpinBox->setValue( mLegend->columnSpace() );
+  mLineSpacingSpinBox->setValue( mLegend->lineSpacing() );
 
   mRasterBorderGroupBox->setChecked( mLegend->drawRasterBorder() );
   mRasterBorderWidthSpinBox->setValue( mLegend->rasterBorderWidth() );
@@ -450,6 +451,17 @@ void QgsComposerLegendWidget::on_mColumnSpaceSpinBox_valueChanged( double d )
   }
 }
 
+void QgsComposerLegendWidget::on_mLineSpacingSpinBox_valueChanged( double d )
+{
+  if ( mLegend )
+  {
+    mLegend->beginCommand( tr( "Legend line space" ), QgsComposerMergeCommand::LegendLineSpacing );
+    mLegend->setLineSpacing( d );
+    mLegend->adjustBoxSize();
+    mLegend->update();
+    mLegend->endCommand();
+  }
+}
 
 static void _moveLegendNode( QgsLayerTreeLayer* nodeLayer, int legendNodeIndex, int offset )
 {

src/app/composer/qgscomposerlegendwidget.h

@@ -66,6 +66,7 @@ class QgsComposerLegendWidget: public QgsComposerItemBaseWidget, private Ui::Qgs
     void on_mFontColorButton_colorChanged( const QColor& newFontColor );
     void on_mBoxSpaceSpinBox_valueChanged( double d );
     void on_mColumnSpaceSpinBox_valueChanged( double d );
+    void on_mLineSpacingSpinBox_valueChanged( double d );
     void on_mCheckBoxAutoUpdate_stateChanged( int state );
     void composerMapChanged( QgsComposerItem* item );
     void on_mCheckboxResizeContents_toggled( bool checked );

src/core/composer/qgscomposeritemcommand.h

@@ -111,6 +111,7 @@ class CORE_EXPORT QgsComposerMergeCommand: public QgsComposerItemCommand
       LegendIconSymbolSpace,
       LegendBoxSpace,
       LegendColumnSpace,
+      LegendLineSpacing,
       LegendRasterBorderWidth,
       LegendFontColor,
       LegendRasterBorderColor,

src/core/composer/qgscomposerlegend.cpp

@@ -288,6 +288,9 @@ void QgsComposerLegend::setStyleFont( QgsLegendStyle::Style s, const QFont& f )
 void QgsComposerLegend::setStyleMargin( QgsLegendStyle::Style s, double margin ) { rstyle( s ).setMargin( margin ); }
 void QgsComposerLegend::setStyleMargin( QgsLegendStyle::Style s, QgsLegendStyle::Side side, double margin ) { rstyle( s ).setMargin( side, margin ); }
 
+double QgsComposerLegend::lineSpacing() const { return mSettings.lineSpacing(); }
+void QgsComposerLegend::setLineSpacing( double spacing ) { mSettings.setLineSpacing( spacing ); }
+
 double QgsComposerLegend::boxSpace() const { return mSettings.boxSpace(); }
 void QgsComposerLegend::setBoxSpace( double s ) { mSettings.setBoxSpace( s ); }
 
@@ -370,6 +373,7 @@ bool QgsComposerLegend::writeXml( QDomElement& elem, QDomDocument & doc ) const
 
   composerLegendElem.setAttribute( QStringLiteral( "symbolWidth" ), QString::number( mSettings.symbolSize().width() ) );
   composerLegendElem.setAttribute( QStringLiteral( "symbolHeight" ), QString::number( mSettings.symbolSize().height() ) );
+  composerLegendElem.setAttribute( QStringLiteral( "lineSpacing" ), QString::number( mSettings.lineSpacing() ) );
 
   composerLegendElem.setAttribute( QStringLiteral( "rasterBorder" ), mSettings.drawRasterBorder() );
   composerLegendElem.setAttribute( QStringLiteral( "rasterBorderColor" ), QgsSymbolLayerUtils::encodeColor( mSettings.rasterBorderColor() ) );
@@ -501,6 +505,7 @@ bool QgsComposerLegend::readXml( const QDomElement& itemElem, const QDomDocument
 
   mSettings.setSymbolSize( QSizeF( itemElem.attribute( QStringLiteral( "symbolWidth" ), QStringLiteral( "7.0" ) ).toDouble(), itemElem.attribute( QStringLiteral( "symbolHeight" ), QStringLiteral( "14.0" ) ).toDouble() ) );
   mSettings.setWmsLegendSize( QSizeF( itemElem.attribute( QStringLiteral( "wmsLegendWidth" ), QStringLiteral( "50" ) ).toDouble(), itemElem.attribute( QStringLiteral( "wmsLegendHeight" ), QStringLiteral( "25" ) ).toDouble() ) );
+  mSettings.setLineSpacing( itemElem.attribute( QStringLiteral( "lineSpacing" ), "1.0" ).toDouble() );
 
   mSettings.setDrawRasterBorder( itemElem.attribute( QStringLiteral( "rasterBorder" ), QStringLiteral( "1" ) ) != QLatin1String( "0" ) );
   mSettings.setRasterBorderColor( QgsSymbolLayerUtils::decodeColor( itemElem.attribute( QStringLiteral( "rasterBorderColor" ), QStringLiteral( "0,0,0" ) ) ) );

src/core/composer/qgscomposerlegend.h

@@ -149,6 +149,19 @@ class CORE_EXPORT QgsComposerLegend : public QgsComposerItem
     void setStyleMargin( QgsLegendStyle::Style s, double margin );
     void setStyleMargin( QgsLegendStyle::Style s, QgsLegendStyle::Side side, double margin );
 
+    /** Returns the spacing in-between lines in mm
+     * @note added in 3.0
+     * @see setLineSpacing
+     */
+    double lineSpacing() const;
+
+    /** Sets the spacing in-between multiple lines
+     * @param spacing Double value to use as spacing in between multiple lines
+     * @note added in 3.0
+     * @see lineSpacing
+     */
+    void setLineSpacing( double spacing );
+
     double boxSpace() const;
     void setBoxSpace( double s );
 

src/core/layertree/qgslayertreemodellegendnode.cpp

@@ -93,10 +93,11 @@ QSizeF QgsLayerTreeModelLegendNode::drawSymbolText( const QgsLegendSettings& set
 
   QFont symbolLabelFont = settings.style( QgsLegendStyle::SymbolLabel ).font();
   double textHeight = settings.fontHeightCharacterMM( symbolLabelFont, QChar( '0' ) );
+  double textDescent = settings.fontDescentMillimeters( symbolLabelFont );
 
   QStringList lines = settings.splitStringForWrapping( data( Qt::DisplayRole ).toString() );
 
-  labelSize.rheight() = lines.count() * textHeight + ( lines.count() - 1 ) * settings.lineSpacing();
+  labelSize.rheight() = lines.count() * textHeight + ( lines.count() - 1 ) * ( settings.lineSpacing() + textDescent );
 
   double labelX = 0.0, labelY = 0.0;
   if ( ctx )
@@ -120,8 +121,8 @@ QSizeF QgsLayerTreeModelLegendNode::drawSymbolText( const QgsLegendSettings& set
     if ( ctx )
     {
       settings.drawText( ctx->painter, labelX, labelY, *itemPart, symbolLabelFont );
-      if ( itemPart != lines.end() )
-        labelY += settings.lineSpacing() + textHeight;
+      if ( itemPart != ( lines.end() - 1 ) )
+        labelY += textDescent + settings.lineSpacing() + textHeight;
     }
   }
 

src/core/qgslegendrenderer.cpp

@@ -411,7 +411,7 @@ QSizeF QgsLegendRenderer::drawTitle( QPainter* painter, QPointF point, Qt::Align
     size.rwidth() = qMax( width, size.rwidth() );
 
     y += height;
-    if ( titlePart != lines.end() )
+    if ( titlePart != ( lines.end() - 1 ) )
     {
       y += mSettings.lineSpacing();
     }
@@ -537,7 +537,7 @@ QSizeF QgsLegendRenderer::drawLayerTitle( QgsLayerTreeLayer* nodeLayer, QPainter
     if ( painter ) mSettings.drawText( painter, point.x(), y, *layerItemPart, layerFont );
     qreal width = mSettings.textWidthMillimeters( layerFont, *layerItemPart );
     size.rwidth() = qMax( width, size.width() );
-    if ( layerItemPart != lines.end() )
+    if ( layerItemPart != ( lines.end() - 1 ) )
     {
       y += mSettings.lineSpacing();
     }
@@ -566,7 +566,7 @@ QSizeF QgsLegendRenderer::drawGroupTitle( QgsLayerTreeGroup* nodeGroup, QPainter
     if ( painter ) mSettings.drawText( painter, point.x(), y, *groupPart, groupFont );
     qreal width = mSettings.textWidthMillimeters( groupFont, *groupPart );
     size.rwidth() = qMax( width, size.width() );
-    if ( groupPart != lines.end() )
+    if ( groupPart != ( lines.end() - 1 ) )
     {
       y += mSettings.lineSpacing();
     }

src/core/qgslegendsettings.cpp

@@ -25,7 +25,7 @@ QgsLegendSettings::QgsLegendSettings()
     , mBoxSpace( 2 )
     , mSymbolSize( 7, 4 )
     , mWmsLegendSize( 50, 25 )
-    , mLineSpacing( 1.5 )
+    , mLineSpacing( 1 )
     , mColumnSpace( 2 )
     , mColumnCount( 1 )
     , mSplitLayer( false )
@@ -38,10 +38,10 @@ QgsLegendSettings::QgsLegendSettings()
     , mMapScale( 1 )
     , mDpi( 96 ) // based on QImage's default DPI
 {
-  rstyle( QgsLegendStyle::Title ).setMargin( QgsLegendStyle::Bottom, 2 );
-  rstyle( QgsLegendStyle::Group ).setMargin( QgsLegendStyle::Top, 2 );
-  rstyle( QgsLegendStyle::Subgroup ).setMargin( QgsLegendStyle::Top, 2 );
-  rstyle( QgsLegendStyle::Symbol ).setMargin( QgsLegendStyle::Top, 2 );
+  rstyle( QgsLegendStyle::Title ).setMargin( QgsLegendStyle::Bottom, 3.5 );
+  rstyle( QgsLegendStyle::Group ).setMargin( QgsLegendStyle::Top, 3 );
+  rstyle( QgsLegendStyle::Subgroup ).setMargin( QgsLegendStyle::Top, 3 );
+  rstyle( QgsLegendStyle::Symbol ).setMargin( QgsLegendStyle::Top, 2.5 );
   rstyle( QgsLegendStyle::SymbolLabel ).setMargin( QgsLegendStyle::Top, 2 );
   rstyle( QgsLegendStyle::SymbolLabel ).setMargin( QgsLegendStyle::Left, 2 );
   rstyle( QgsLegendStyle::Title ).rfont().setPointSizeF( 16.0 );

src/ui/composer/qgscomposerlegendwidgetbase.ui

@@ -965,6 +965,23 @@
             </property>
            </widget>
           </item>
+          <item row="7" column="0">
+           <widget class="QLabel" name="label_12">
+            <property name="text">
+             <string>Line space</string>
+            </property>
+           </widget>
+          </item>
+          <item row="7" column="1">
+           <widget class="QgsDoubleSpinBox" name="mLineSpacingSpinBox">
+            <property name="prefix">
+             <string/>
+            </property>
+            <property name="suffix">
+             <string> mm</string>
+            </property>
+           </widget>
+          </item>
           <item row="0" column="0">
            <widget class="QLabel" name="label_10">
             <property name="toolTip">

tests/src/core/testqgslegendrenderer.cpp

@@ -114,6 +114,7 @@ class TestQgsLegendRenderer : public QObject
     void testBigMarker();
     void testMapUnits();
     void testTallSymbol();
+    void testLineSpacing();
     void testLongSymbolText();
     void testThreeColumns();
     void testFilterByMap();
@@ -360,6 +361,28 @@ void TestQgsLegendRenderer::testTallSymbol()
   mVL2->setName( QStringLiteral( "Polygon Layer" ) );
 }
 
+void TestQgsLegendRenderer::testLineSpacing()
+{
+  QString testName = "legend_line_spacing";
+
+  QgsCategorizedSymbolRenderer* catRenderer = dynamic_cast<QgsCategorizedSymbolRenderer*>( mVL3->renderer() );
+  QVERIFY( catRenderer );
+  catRenderer->updateCategoryLabel( 1, "This is\nthree lines\nlong label" );
+
+  mVL2->setName( "This is a two lines\nlong label" );
+
+  QgsLayerTreeModel legendModel( mRoot );
+
+  QgsLegendSettings settings;
+  settings.setWrapChar( "\n" );
+  settings.setLineSpacing( 3 );
+  _setStandardTestFont( settings );
+  _renderLegend( testName, &legendModel, settings );
+  QVERIFY( _verifyImage( testName, mReport ) );
+
+  mVL2->setName( "Polygon Layer" );
+}
+
 void TestQgsLegendRenderer::testLongSymbolText()
 {
   QString testName = QStringLiteral( "legend_long_symbol_text" );