Update to adv labeling dialog, also addresses #4385

- Fix for resizing of dialog (#4385)
- New label preview pane with custom text entry and background color (preview moved to Label settings tab)
- Fix preview for labels using map units (standardized to 24 pt)
- Preview layout accommodates up 150 pt fonts on larger screens
- Set step increment for buffer to a more reasonable 0.1
- New, fairly complete QFont properties added to GUI (some may not be able to be used until after derived PAL solution)
- Transparency for buffering added to GUI
- New data defined mappings in the GUI to match new layer-level options
- New Show Label and Min/Max Scale mappings added to GUI
- All new options and mappings that are not yet functional are greyed (all greyed with this commit)

src/app/qgslabelinggui.cpp

@@ -42,6 +42,10 @@ QgsLabelingGui::QgsLabelingGui( QgsPalLabeling* lbl, QgsVectorLayer* layer, QgsM
 
   setupUi( this );
 
+  mRefFont = lblFontPreview->font();
+  mPreviewBackgroundBtn->setColor( Qt::white );
+  connect( mPreviewBackgroundBtn, SIGNAL( clicked() ), this, SLOT( changePreviewBackground( ) ) );
+
   connect( btnTextColor, SIGNAL( clicked() ), this, SLOT( changeTextColor() ) );
   connect( btnChangeFont, SIGNAL( clicked() ), this, SLOT( changeTextFont() ) );
   connect( chkBuffer, SIGNAL( toggled( bool ) ), this, SLOT( updatePreview() ) );
@@ -277,7 +281,7 @@ QgsPalLayerSettings QgsLabelingGui::layerSettings()
 
 
   lyr.textColor = btnTextColor->color();
-  lyr.textFont = lblFontPreview->font();
+  lyr.textFont = mRefFont;
   lyr.enabled = chkEnableLabeling->isChecked();
   lyr.priority = sliderPriority->value();
   lyr.obstacle = !chkNoObstacle->isChecked();
@@ -448,6 +452,18 @@ void QgsLabelingGui::populateDataDefinedCombos( QgsPalLayerSettings& s )
   setCurrentComboValue( mRotationComboBox, s, QgsPalLayerSettings::Rotation );
 }
 
+void QgsLabelingGui::changePreviewBackground()
+{
+  QColor color = QColorDialog::getColor( mPreviewBackgroundBtn->color(), this );
+  if ( !color.isValid() )
+    return;
+
+  mPreviewBackgroundBtn->setColor( color );
+  scrollArea_mPreview->widget()->setStyleSheet( QString( "background: rgb(%1, %2, %3);" ).arg( QString::number( color.red() ),
+                                                                                               QString::number( color.green() ),
+                                                                                               QString::number( color.blue() ) ) );
+}
+
 void QgsLabelingGui::changeTextColor()
 {
   QColor color = QColorDialog::getColor( btnTextColor->color(), this );
@@ -463,38 +479,65 @@ void QgsLabelingGui::changeTextFont()
   bool ok;
 #if defined(Q_WS_MAC) && QT_VERSION >= 0x040500 && defined(QT_MAC_USE_COCOA)
   // Native Mac dialog works only for Qt Carbon
-  QFont font = QFontDialog::getFont( &ok, lblFontPreview->font(), 0, QString(), QFontDialog::DontUseNativeDialog );
+  QFont font = QFontDialog::getFont( &ok, mRefFont, 0, QString(), QFontDialog::DontUseNativeDialog );
 #else
-  QFont font = QFontDialog::getFont( &ok, lblFontPreview->font() );
+  QFont font = QFontDialog::getFont( &ok, mRefFont );
 #endif
   if ( ok )
   {
     updateFont( font );
   }
-  mFontSizeSpinBox->setValue( font.pointSizeF() );
+  mFontSizeSpinBox->setValue( mRefFont.pointSizeF() );
 }
 
 void QgsLabelingGui::updateFont( QFont font )
 {
+  // update background reference font
+  if ( font != mRefFont )
+  {
+    mRefFont = font;
+  }
+
   QString fontSizeUnitString = tr( "pt" );
   if ( mFontSizeUnitComboBox->currentIndex() == 1 )
   {
     fontSizeUnitString = tr( "map units" );
   }
-  lblFontName->setText( QString( "%1, %2 %3" ).arg( font.family() ).arg( font.pointSizeF() ).arg( fontSizeUnitString ) );
-  lblFontPreview->setFont( font );
+  lblFontName->setText( QString( "%1, %2 %3" ).arg( font.family() ).arg( mRefFont.pointSizeF() ).arg( fontSizeUnitString ) );
+
   updatePreview();
 }
 
 void QgsLabelingGui::updatePreview()
 {
+  scrollPreview();
+  lblFontPreview->setFont( mRefFont );
+  QFont previewFont = lblFontPreview->font();
+  if ( mFontSizeUnitComboBox->currentIndex() == 1 )
+  {
+    // TODO: maybe match current map zoom level instead?
+    previewFont.setPointSize( 24 );
+    groupBox_mPreview->setTitle( tr( "Sample @ 24 pts (using map units)" ) );
+  }
+  else
+  {
+    previewFont.setPointSize( mFontSizeSpinBox->value() );
+    groupBox_mPreview->setTitle( tr( "Sample" ) );
+  }
+  lblFontPreview->setFont( previewFont );
+
   lblFontPreview->setTextColor( btnTextColor->color() );
   if ( chkBuffer->isChecked() )
     lblFontPreview->setBuffer( spinBufferSize->value(), btnBufferColor->color() );
   else
     lblFontPreview->setBuffer( 0, Qt::white );
 }
 
+void QgsLabelingGui::scrollPreview()
+{
+  scrollArea_mPreview->ensureVisible( 0, 0, 0, 0 );
+}
+
 void QgsLabelingGui::showEngineConfigDialog()
 {
   QgsLabelEngineConfigDialog dlg( mLBL, this );
@@ -565,16 +608,26 @@ void QgsLabelingGui::updateOptions()
 
 void QgsLabelingGui::on_mFontSizeSpinBox_valueChanged( double d )
 {
-  QFont font = lblFontPreview->font();
-  font.setPointSizeF( d );
-  lblFontPreview->setFont( font );
-  updateFont( font );
+  mRefFont.setPointSizeF( d );
+  updateFont( mRefFont );
 }
 
 void QgsLabelingGui::on_mFontSizeUnitComboBox_currentIndexChanged( int index )
 {
   Q_UNUSED( index );
-  updateFont( lblFontPreview->font() );
+  updateFont( mRefFont );
+}
+
+void QgsLabelingGui::on_mFontWordSpacingSpinBox_valueChanged( double spacing )
+{
+  mRefFont.setWordSpacing( spacing );
+  updateFont( mRefFont );
+}
+
+void QgsLabelingGui::on_mFontLetterSpacingSpinBox_valueChanged( double spacing )
+{
+  mRefFont.setLetterSpacing( QFont::AbsoluteSpacing, spacing );
+  updateFont( mRefFont );
 }
 
 void QgsLabelingGui::on_mXCoordinateComboBox_currentIndexChanged( const QString & text )
@@ -601,6 +654,18 @@ void QgsLabelingGui::on_mYCoordinateComboBox_currentIndexChanged( const QString
   }
 }
 
+void QgsLabelingGui::on_mPreviewTextEdit_textChanged( const QString & text )
+{
+  lblFontPreview->setText( text );
+  updatePreview();
+}
+
+void QgsLabelingGui::on_mPreviewTextBtn_clicked()
+{
+  mPreviewTextEdit->setText( QString( "Lorem Ipsum" ) );
+  updatePreview();
+}
+
 void QgsLabelingGui::disableDataDefinedAlignment()
 {
   mHorizontalAlignmentComboBox->setCurrentIndex( mHorizontalAlignmentComboBox->findText( "" ) );

src/app/qgslabelinggui.h

@@ -38,6 +38,7 @@ class QgsLabelingGui : public QWidget, private Ui::QgsLabelingGuiBase
 
   public slots:
     void apply();
+    void changePreviewBackground();
     void changeTextColor();
     void changeTextFont();
     void showEngineConfigDialog();
@@ -46,13 +47,19 @@ class QgsLabelingGui : public QWidget, private Ui::QgsLabelingGuiBase
 
     void updateUi();
     void updatePreview();
+    void scrollPreview();
     void updateOptions();
 
     void on_mFontSizeSpinBox_valueChanged( double d );
     void on_mFontSizeUnitComboBox_currentIndexChanged( int index );
+    void on_mFontWordSpacingSpinBox_valueChanged(double spacing );
+    void on_mFontLetterSpacingSpinBox_valueChanged(double spacing );
     void on_mXCoordinateComboBox_currentIndexChanged( const QString & text );
     void on_mYCoordinateComboBox_currentIndexChanged( const QString & text );
 
+    void on_mPreviewTextEdit_textChanged( const QString & text );
+    void on_mPreviewTextBtn_clicked();
+
   protected:
     void populatePlacementMethods();
     void populateFieldNames();
@@ -67,6 +74,9 @@ class QgsLabelingGui : public QWidget, private Ui::QgsLabelingGuiBase
     QgsVectorLayer* mLayer;
     QgsMapCanvas* mMapCanvas;
 
+    // background reference font
+    QFont mRefFont;
+
     void disableDataDefinedAlignment();
     void enableDataDefinedAlignment();
 };

src/app/qgslabelpreview.cpp

@@ -15,6 +15,7 @@
 #include "qgslabelpreview.h"
 
 #include <QPainter>
+#include <QFontMetrics>
 
 #include "qgspallabeling.h"
 
@@ -43,7 +44,10 @@ void QgsLabelPreview::paintEvent( QPaintEvent *e )
 
   p.setRenderHint( QPainter::Antialiasing );
   p.setFont( font() );
-  p.translate( 10, 20 ); // uhm...
+  QFontMetrics fm( font() );
+  p.translate( 0, fm.ascent() + 4 );
+
+//   mBufferColor.setAlpha( 125 );
 
   if ( mBufferSize != 0 )
     QgsPalLabeling::drawLabelBuffer( &p, text(), font(), mBufferSize, mBufferColor );

src/core/qgspallabeling.cpp

@@ -1430,6 +1430,7 @@ void QgsPalLabeling::drawLabelBuffer( QPainter* p, QString text, const QFont& fo
 {
   QPainterPath path;
   path.addText( 0, 0, font, text );
+//   color.setAlpha( 125 );
   QPen pen( color );
   pen.setWidthF( size );
   p->setPen( pen );