qgssymbolbutton.cpp

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/***************************************************************************
     qgssymbolbutton.h
     -----------------
    Date                 : July 2017
    Copyright            : (C) 2017 by Nyall Dawson
    Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgssymbolbutton.h"
#include "qgspanelwidget.h"
#include "qgsexpressioncontext.h"
#include "qgsexpressioncontextgenerator.h"
#include "qgsvectorlayer.h"
#include "qgssymbolselectordialog.h"
#include "qgsstyle.h"
#include "qgscolorwidgets.h"
#include "qgscolorschemeregistry.h"
#include "qgscolorswatchgrid.h"
#include "qgssymbollayerutils.h"
#include "qgsapplication.h"
#include "qgsguiutils.h"
#include "qgsexpressioncontextutils.h"
#include "qgsgui.h"
#include "qgscolordialog.h"
#include "qgsfillsymbol.h"
#include "qgslinesymbol.h"
#include "qgsmarkersymbol.h"
 
#include <QMenu>
#include <QClipboard>
#include <QDrag>
#include <QBuffer>
 
QgsSymbolButton::QgsSymbolButton( QWidget *parent, const QString &dialogTitle )
  : QToolButton( parent )
  , mDialogTitle( dialogTitle.isEmpty() ? tr( "Symbol Settings" ) : dialogTitle )
{
  mSymbol.reset( QgsFillSymbol::createSimple( QVariantMap() ) );
 
  setAcceptDrops( true );
  connect( this, &QAbstractButton::clicked, this, &QgsSymbolButton::showSettingsDialog );
 
  //setup dropdown menu
  mMenu = new QMenu( this );
  connect( mMenu, &QMenu::aboutToShow, this, &QgsSymbolButton::prepareMenu );
  setMenu( mMenu );
  setPopupMode( QToolButton::MenuButtonPopup );
 
  //make sure height of button looks good under different platforms
  const QSize size = QToolButton::minimumSizeHint();
  const int fontHeight = static_cast< int >( Qgis::UI_SCALE_FACTOR * fontMetrics().height() * 1.4 );
  mSizeHint = QSize( size.width(), std::max( size.height(), fontHeight ) );
}
 
QgsSymbolButton::~QgsSymbolButton() = default;
 
QSize QgsSymbolButton::minimumSizeHint() const
{
 
  return mSizeHint;
}
 
QSize QgsSymbolButton::sizeHint() const
{
  return mSizeHint;
}
 
void QgsSymbolButton::setSymbolType( Qgis::SymbolType type )
{
  if ( type != mType )
  {
    switch ( type )
    {
      case Qgis::SymbolType::Marker:
        mSymbol.reset( QgsMarkerSymbol::createSimple( QVariantMap() ) );
        break;
 
      case Qgis::SymbolType::Line:
        mSymbol.reset( QgsLineSymbol::createSimple( QVariantMap() ) );
        break;
 
      case Qgis::SymbolType::Fill:
        mSymbol.reset( QgsFillSymbol::createSimple( QVariantMap() ) );
        break;
 
      case Qgis::SymbolType::Hybrid:
        break;
    }
  }
  updatePreview();
  mType = type;
}
 
void QgsSymbolButton::showSettingsDialog()
{
  QgsExpressionContext context;
  if ( mExpressionContextGenerator )
    context  = mExpressionContextGenerator->createExpressionContext();
  else
  {
    context.appendScopes( QgsExpressionContextUtils::globalProjectLayerScopes( mLayer.data() ) );
  }
 
  QgsSymbol *newSymbol = nullptr;
  if ( mSymbol )
  {
    newSymbol = mSymbol->clone();
  }
  else
  {
    switch ( mType )
    {
      case Qgis::SymbolType::Marker:
        newSymbol = QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry );
        break;
      case Qgis::SymbolType::Line:
        newSymbol = QgsSymbol::defaultSymbol( QgsWkbTypes::LineGeometry );
        break;
      case Qgis::SymbolType::Fill:
        newSymbol = QgsSymbol::defaultSymbol( QgsWkbTypes::PolygonGeometry );
        break;
      case Qgis::SymbolType::Hybrid:
        break;
    }
  }
 
  QgsSymbolWidgetContext symbolContext;
  symbolContext.setExpressionContext( &context );
  symbolContext.setMapCanvas( mMapCanvas );
  symbolContext.setMessageBar( mMessageBar );
 
  QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
  if ( panel && panel->dockMode() )
  {
    QgsSymbolSelectorWidget *d = new QgsSymbolSelectorWidget( newSymbol, QgsStyle::defaultStyle(), mLayer, panel );
    d->setPanelTitle( mDialogTitle );
    d->setContext( symbolContext );
    connect( d, &QgsPanelWidget::widgetChanged, this, &QgsSymbolButton::updateSymbolFromWidget );
    connect( d, &QgsPanelWidget::panelAccepted, this, &QgsSymbolButton::cleanUpSymbolSelector );
    panel->openPanel( d );
  }
  else
  {
    QgsSymbolSelectorDialog dialog( newSymbol, QgsStyle::defaultStyle(), mLayer, this );
    dialog.setWindowTitle( mDialogTitle );
    dialog.setContext( symbolContext );
    if ( dialog.exec() )
    {
      setSymbol( newSymbol );
    }
    else
    {
      delete newSymbol;
    }
 
    // reactivate button's window
    activateWindow();
  }
}
 
void QgsSymbolButton::updateSymbolFromWidget()
{
  if ( QgsSymbolSelectorWidget *w = qobject_cast<QgsSymbolSelectorWidget *>( sender() ) )
    setSymbol( w->symbol()->clone() );
}
 
void QgsSymbolButton::cleanUpSymbolSelector( QgsPanelWidget *container )
{
  QgsSymbolSelectorWidget *w = qobject_cast<QgsSymbolSelectorWidget *>( container );
  if ( !w )
    return;
 
  delete w->symbol();
}
 
QgsMapCanvas *QgsSymbolButton::mapCanvas() const
{
  return mMapCanvas;
}
 
void QgsSymbolButton::setMapCanvas( QgsMapCanvas *mapCanvas )
{
  mMapCanvas = mapCanvas;
}
 
void QgsSymbolButton::setMessageBar( QgsMessageBar *bar )
{
  mMessageBar = bar;
}
 
QgsMessageBar *QgsSymbolButton::messageBar() const
{
  return mMessageBar;
}
 
QgsVectorLayer *QgsSymbolButton::layer() const
{
  return mLayer;
}
 
void QgsSymbolButton::setLayer( QgsVectorLayer *layer )
{
  mLayer = layer;
}
 
void QgsSymbolButton::registerExpressionContextGenerator( QgsExpressionContextGenerator *generator )
{
  mExpressionContextGenerator = generator;
}
 
void QgsSymbolButton::setSymbol( QgsSymbol *symbol )
{
  mSymbol.reset( symbol );
  updatePreview();
  emit changed();
}
 
void QgsSymbolButton::setColor( const QColor &color )
{
  if ( !mSymbol )
    return;
 
  QColor opaque = color;
  opaque.setAlphaF( 1.0 );
 
  if ( opaque == mSymbol->color() )
    return;
 
  mSymbol->setColor( opaque );
  updatePreview();
  emit changed();
}
 
void QgsSymbolButton::copySymbol()
{
  QApplication::clipboard()->setMimeData( QgsSymbolLayerUtils::symbolToMimeData( mSymbol.get() ) );
}
 
void QgsSymbolButton::pasteSymbol()
{
  std::unique_ptr< QgsSymbol > symbol( QgsSymbolLayerUtils::symbolFromMimeData( QApplication::clipboard()->mimeData() ) );
  if ( symbol && symbol->type() == mType )
    setSymbol( symbol.release() );
}
 
void QgsSymbolButton::copyColor()
{
  QApplication::clipboard()->setMimeData( QgsSymbolLayerUtils::colorToMimeData( mSymbol->color() ) );
}
 
void QgsSymbolButton::pasteColor()
{
  QColor clipColor;
  bool hasAlpha = false;
  if ( colorFromMimeData( QApplication::clipboard()->mimeData(), clipColor, hasAlpha ) )
  {
    //paste color
    setColor( clipColor );
    QgsRecentColorScheme::addRecentColor( clipColor );
  }
}
 
void QgsSymbolButton::mousePressEvent( QMouseEvent *e )
{
  if ( mPickingColor )
  {
    //don't show dialog if in color picker mode
    e->accept();
    return;
  }
 
  if ( e->button() == Qt::RightButton )
  {
    QToolButton::showMenu();
    return;
  }
  else if ( e->button() == Qt::LeftButton )
  {
    mDragStartPosition = e->pos();
  }
  QToolButton::mousePressEvent( e );
}
 
void QgsSymbolButton::mouseMoveEvent( QMouseEvent *e )
{
  if ( mPickingColor )
  {
    updatePreview( QgsGui::sampleColor( e->globalPos() ) );
    e->accept();
    return;
  }
 
  //handle dragging colors/symbols from button
 
  if ( !( e->buttons() & Qt::LeftButton ) )
  {
    //left button not depressed, so not a drag
    QToolButton::mouseMoveEvent( e );
    return;
  }
 
  if ( ( e->pos() - mDragStartPosition ).manhattanLength() < QApplication::startDragDistance() )
  {
    //mouse not moved, so not a drag
    QToolButton::mouseMoveEvent( e );
    return;
  }
 
  //user is dragging
  QDrag *drag = new QDrag( this );
  drag->setMimeData( QgsSymbolLayerUtils::colorToMimeData( mSymbol->color() ) );
  drag->setPixmap( QgsColorWidget::createDragIcon( mSymbol->color() ) );
  drag->exec( Qt::CopyAction );
  setDown( false );
}
 
void QgsSymbolButton::mouseReleaseEvent( QMouseEvent *e )
{
  if ( mPickingColor )
  {
    //end color picking operation by sampling the color under cursor
    stopPicking( e->globalPos() );
    e->accept();
    return;
  }
 
  QToolButton::mouseReleaseEvent( e );
}
 
void QgsSymbolButton::keyPressEvent( QKeyEvent *e )
{
  if ( !mPickingColor )
  {
    //if not picking a color, use default tool button behavior
    QToolButton::keyPressEvent( e );
    return;
  }
 
  //cancel picking, sampling the color if space was pressed
  stopPicking( QCursor::pos(), e->key() == Qt::Key_Space );
}
 
void QgsSymbolButton::dragEnterEvent( QDragEnterEvent *e )
{
  //is dragged data valid color data?
  QColor mimeColor;
  bool hasAlpha = false;
 
  if ( colorFromMimeData( e->mimeData(), mimeColor, hasAlpha ) )
  {
    //if so, we accept the drag, and temporarily change the button's color
    //to match the dragged color. This gives immediate feedback to the user
    //that colors can be dropped here
    e->acceptProposedAction();
    updatePreview( mimeColor );
  }
}
 
void QgsSymbolButton::dragLeaveEvent( QDragLeaveEvent *e )
{
  Q_UNUSED( e )
  //reset button color
  updatePreview();
}
 
void QgsSymbolButton::dropEvent( QDropEvent *e )
{
  //is dropped data valid format data?
  QColor mimeColor;
  bool hasAlpha = false;
  if ( colorFromMimeData( e->mimeData(), mimeColor, hasAlpha ) )
  {
    //accept drop and set new color
    e->acceptProposedAction();
    mimeColor.setAlphaF( 1.0 );
    mSymbol->setColor( mimeColor );
    QgsRecentColorScheme::addRecentColor( mimeColor );
    updatePreview();
    emit changed();
  }
  updatePreview();
}
 
void QgsSymbolButton::wheelEvent( QWheelEvent *event )
{
  if ( isEnabled() && mSymbol )
  {
    bool symbolChanged = false;
    const double increment = ( ( event->modifiers() & Qt::ControlModifier ) ? 0.1 : 1 ) *
                             ( event->angleDelta().y() > 0 ? 1 : -1 );
    switch ( mSymbol->type() )
    {
      case Qgis::SymbolType::Marker:
      {
        QgsMarkerSymbol *marker = qgis::down_cast<QgsMarkerSymbol *>( mSymbol.get() );
        if ( marker )
        {
          const double size = std::max( 0.0, marker->size() + increment );
          marker->setSize( size );
          symbolChanged = true;
        }
        break;
      }
 
      case Qgis::SymbolType::Line:
      {
        QgsLineSymbol *line = qgis::down_cast<QgsLineSymbol *>( mSymbol.get() );
        if ( line )
        {
          const double width = std::max( 0.0, line->width() + increment );
          line->setWidth( width );
          symbolChanged = true;
        }
        break;
      }
 
      case Qgis::SymbolType::Fill:
      case Qgis::SymbolType::Hybrid:
        break;
    }
 
    if ( symbolChanged )
    {
      updatePreview();
      emit changed();
    }
 
    event->accept();
  }
  else
  {
    QToolButton::wheelEvent( event );
  }
}
 
void QgsSymbolButton::prepareMenu()
{
  //we need to tear down and rebuild this menu every time it is shown. Otherwise the space allocated to any
  //QgsColorSwatchGridAction is not recalculated by Qt and the swatch grid may not be the correct size
  //for the number of colors shown in the grid. Note that we MUST refresh color swatch grids every time this
  //menu is opened, otherwise color schemes like the recent color scheme grid are meaningless
  mMenu->clear();
 
  QAction *configureAction = new QAction( tr( "Configure Symbol…" ), this );
  mMenu->addAction( configureAction );
  connect( configureAction, &QAction::triggered, this, &QgsSymbolButton::showSettingsDialog );
 
  QAction *copySymbolAction = new QAction( tr( "Copy Symbol" ), this );
  copySymbolAction->setEnabled( !isNull() );
  mMenu->addAction( copySymbolAction );
  connect( copySymbolAction, &QAction::triggered, this, &QgsSymbolButton::copySymbol );
 
  QAction *pasteSymbolAction = new QAction( tr( "Paste Symbol" ), this );
  //enable or disable paste action based on current clipboard contents. We always show the paste
  //action, even if it's disabled, to give hint to the user that pasting symbols is possible
  std::unique_ptr< QgsSymbol > tempSymbol( QgsSymbolLayerUtils::symbolFromMimeData( QApplication::clipboard()->mimeData() ) );
  if ( tempSymbol && tempSymbol->type() == mType )
  {
    const int iconSize = QgsGuiUtils::scaleIconSize( 16 );
    pasteSymbolAction->setIcon( QgsSymbolLayerUtils::symbolPreviewIcon( tempSymbol.get(), QSize( iconSize, iconSize ), 1 ) );
  }
  else
  {
    pasteSymbolAction->setEnabled( false );
  }
  mMenu->addAction( pasteSymbolAction );
  connect( pasteSymbolAction, &QAction::triggered, this, &QgsSymbolButton::pasteSymbol );
 
  if ( mShowNull )
  {
    QAction *nullAction = new QAction( tr( "Clear Current Symbol" ), this );
    nullAction->setEnabled( !isNull() );
    mMenu->addAction( nullAction );
    connect( nullAction, &QAction::triggered, this, &QgsSymbolButton::setToNull );
  }
 
  if ( mSymbol )
  {
    mMenu->addSeparator();
 
    QgsColorWheel *colorWheel = new QgsColorWheel( mMenu );
    colorWheel->setColor( mSymbol->color() );
    QgsColorWidgetAction *colorAction = new QgsColorWidgetAction( colorWheel, mMenu, mMenu );
    colorAction->setDismissOnColorSelection( false );
    connect( colorAction, &QgsColorWidgetAction::colorChanged, this, &QgsSymbolButton::setColor );
    mMenu->addAction( colorAction );
 
    QgsColorRampWidget *alphaRamp = new QgsColorRampWidget( mMenu, QgsColorWidget::Alpha, QgsColorRampWidget::Horizontal );
    QColor alphaColor = mSymbol->color();
    alphaColor.setAlphaF( mSymbol->opacity() );
    alphaRamp->setColor( alphaColor );
    QgsColorWidgetAction *alphaAction = new QgsColorWidgetAction( alphaRamp, mMenu, mMenu );
    alphaAction->setDismissOnColorSelection( false );
    connect( alphaAction, &QgsColorWidgetAction::colorChanged, this, [ = ]( const QColor & color )
    {
      const double opacity = color.alphaF();
      mSymbol->setOpacity( opacity );
      updatePreview();
      emit changed();
    } );
    connect( colorAction, &QgsColorWidgetAction::colorChanged, alphaRamp, [alphaRamp]( const QColor & color ) { alphaRamp->setColor( color, false ); }
           );
    mMenu->addAction( alphaAction );
 
    //get schemes with ShowInColorButtonMenu flag set
    QList< QgsColorScheme * > schemeList = QgsApplication::colorSchemeRegistry()->schemes( QgsColorScheme::ShowInColorButtonMenu );
    QList< QgsColorScheme * >::iterator it = schemeList.begin();
    for ( ; it != schemeList.end(); ++it )
    {
      QgsColorSwatchGridAction *colorAction = new QgsColorSwatchGridAction( *it, mMenu, QStringLiteral( "symbology" ), this );
      colorAction->setBaseColor( mSymbol->color() );
      mMenu->addAction( colorAction );
      connect( colorAction, &QgsColorSwatchGridAction::colorChanged, this, &QgsSymbolButton::setColor );
      connect( colorAction, &QgsColorSwatchGridAction::colorChanged, this, &QgsSymbolButton::addRecentColor );
    }
 
    mMenu->addSeparator();
 
    QAction *copyColorAction = new QAction( tr( "Copy Color" ), this );
    mMenu->addAction( copyColorAction );
    connect( copyColorAction, &QAction::triggered, this, &QgsSymbolButton::copyColor );
 
    QAction *pasteColorAction = new QAction( tr( "Paste Color" ), this );
    //enable or disable paste action based on current clipboard contents. We always show the paste
    //action, even if it's disabled, to give hint to the user that pasting colors is possible
    QColor clipColor;
    bool hasAlpha = false;
    if ( colorFromMimeData( QApplication::clipboard()->mimeData(), clipColor, hasAlpha ) )
    {
      pasteColorAction->setIcon( createColorIcon( clipColor ) );
    }
    else
    {
      pasteColorAction->setEnabled( false );
    }
    mMenu->addAction( pasteColorAction );
    connect( pasteColorAction, &QAction::triggered, this, &QgsSymbolButton::pasteColor );
 
    QAction *pickColorAction = new QAction( tr( "Pick Color" ), this );
    mMenu->addAction( pickColorAction );
    connect( pickColorAction, &QAction::triggered, this, &QgsSymbolButton::activatePicker );
 
    QAction *chooseColorAction = new QAction( tr( "Choose Color…" ), this );
    mMenu->addAction( chooseColorAction );
    connect( chooseColorAction, &QAction::triggered, this, &QgsSymbolButton::showColorDialog );
  }
}
 
void QgsSymbolButton::addRecentColor( const QColor &color )
{
  QgsRecentColorScheme::addRecentColor( color );
}
 
void QgsSymbolButton::activatePicker()
{
  //activate picker color
  QApplication::setOverrideCursor( QgsApplication::getThemeCursor( QgsApplication::Cursor::Sampler ) );
  grabMouse();
  grabKeyboard();
  mPickingColor = true;
  setMouseTracking( true );
}
 
 
void QgsSymbolButton::changeEvent( QEvent *e )
{
  if ( e->type() == QEvent::EnabledChange )
  {
    updatePreview();
  }
  QToolButton::changeEvent( e );
}
 
void QgsSymbolButton::showEvent( QShowEvent *e )
{
  updatePreview();
  QToolButton::showEvent( e );
}
 
void QgsSymbolButton::resizeEvent( QResizeEvent *event )
{
  QToolButton::resizeEvent( event );
  //recalculate icon size and redraw icon
  mIconSize = QSize();
  updatePreview();
}
 
void QgsSymbolButton::updatePreview( const QColor &color, QgsSymbol *tempSymbol )
{
  QSize currentIconSize;
  //icon size is button size with a small margin
  if ( menu() )
  {
    if ( !mIconSize.isValid() )
    {
      //calculate size of push button part of widget (ie, without the menu dropdown button part)
      QStyleOptionToolButton opt;
      initStyleOption( &opt );
      const QRect buttonSize = QApplication::style()->subControlRect( QStyle::CC_ToolButton, &opt, QStyle::SC_ToolButton,
                               this );
      //make sure height of icon looks good under different platforms
#ifdef Q_OS_WIN
      mIconSize = QSize( buttonSize.width() - 10, height() - 6 );
#else
      mIconSize = QSize( buttonSize.width() - 10, height() - 12 );
#endif
    }
    currentIconSize = mIconSize;
  }
  else
  {
    //no menu
#ifdef Q_OS_WIN
    currentIconSize = QSize( width() - 10, height() - 6 );
#else
    currentIconSize = QSize( width() - 10, height() - 12 );
#endif
  }
 
  if ( !currentIconSize.isValid() || currentIconSize.width() <= 0 || currentIconSize.height() <= 0 )
  {
    return;
  }
 
  std::unique_ptr< QgsSymbol > previewSymbol;
 
  if ( tempSymbol )
  {
    previewSymbol.reset( tempSymbol->clone() );
  }
  else if ( mSymbol )
  {
    previewSymbol.reset( mSymbol->clone() );
  }
  else
  {
    setIconSize( currentIconSize );
    setIcon( QIcon() );
    setToolTip( QString( ) );
    return;
  }
 
  if ( color.isValid() )
    previewSymbol->setColor( color );
 
  //create an icon pixmap
  const QIcon icon = QgsSymbolLayerUtils::symbolPreviewIcon( previewSymbol.get(), currentIconSize );
  setIconSize( currentIconSize );
  setIcon( icon );
 
  // set tooltip
  // create very large preview image
  const int width = static_cast< int >( Qgis::UI_SCALE_FACTOR * fontMetrics().horizontalAdvance( 'X' ) * 23 );
  const int height = static_cast< int >( width / 1.61803398875 ); // golden ratio
 
  const QPixmap pm = QgsSymbolLayerUtils::symbolPreviewPixmap( previewSymbol.get(), QSize( width, height ), height / 20 );
  QByteArray data;
  QBuffer buffer( &data );
  pm.save( &buffer, "PNG", 100 );
  setToolTip( QStringLiteral( "<img src='data:image/png;base64, %3'>" ).arg( QString( data.toBase64() ) ) );
}
 
bool QgsSymbolButton::colorFromMimeData( const QMimeData *mimeData, QColor &resultColor, bool &hasAlpha )
{
  hasAlpha = false;
  const QColor mimeColor = QgsSymbolLayerUtils::colorFromMimeData( mimeData, hasAlpha );
 
  if ( mimeColor.isValid() )
  {
    resultColor = mimeColor;
    return true;
  }
 
  //could not get color from mime data
  return false;
}
 
QPixmap QgsSymbolButton::createColorIcon( const QColor &color ) const
{
  //create an icon pixmap
  const int iconSize = QgsGuiUtils::scaleIconSize( 16 );
  QPixmap pixmap( iconSize, iconSize );
  pixmap.fill( Qt::transparent );
 
  QPainter p;
  p.begin( &pixmap );
 
  //draw color over pattern
  p.setBrush( QBrush( color ) );
 
  //draw border
  p.setPen( QColor( 197, 197, 197 ) );
  p.drawRect( 0, 0, iconSize - 1, iconSize - 1 );
  p.end();
  return pixmap;
}
 
void QgsSymbolButton::stopPicking( QPoint eventPos, bool samplingColor )
{
  //release mouse and keyboard, and reset cursor
  releaseMouse();
  releaseKeyboard();
  QgsApplication::restoreOverrideCursor();
  setMouseTracking( false );
  mPickingColor = false;
 
  if ( !samplingColor )
  {
    //not sampling color, restore old icon
    updatePreview();
    return;
  }
 
  const QColor newColor = QgsGui::sampleColor( eventPos );
  setColor( newColor );
  addRecentColor( newColor );
}
 
void QgsSymbolButton::showColorDialog()
{
  if ( !mSymbol )
    return;
 
  QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
  if ( panel && panel->dockMode() )
  {
    const QColor currentColor = mSymbol->color();
    QgsCompoundColorWidget *colorWidget = new QgsCompoundColorWidget( panel, currentColor, QgsCompoundColorWidget::LayoutVertical );
    colorWidget->setPanelTitle( tr( "Symbol Color" ) );
    colorWidget->setAllowOpacity( true );
 
    if ( currentColor.isValid() )
    {
      colorWidget->setPreviousColor( currentColor );
    }
 
    connect( colorWidget, &QgsCompoundColorWidget::currentColorChanged, this, [ = ]( const QColor & newColor )
    {
      if ( newColor.isValid() )
      {
        setColor( newColor );
      }
    } );
    panel->openPanel( colorWidget );
    return;
  }
 
  QgsColorDialog dialog( this, Qt::WindowFlags(), mSymbol->color() );
  dialog.setTitle( tr( "Symbol Color" ) );
  dialog.setAllowOpacity( true );
 
  if ( dialog.exec() && dialog.color().isValid() )
  {
    setColor( dialog.color() );
  }
 
  // reactivate button's window
  activateWindow();
}
 
void QgsSymbolButton::setDialogTitle( const QString &title )
{
  mDialogTitle = title;
}
 
QString QgsSymbolButton::dialogTitle() const
{
  return mDialogTitle;
}
 
QgsSymbol *QgsSymbolButton::symbol()
{
  return mSymbol.get();
}
 
void QgsSymbolButton::setShowNull( bool showNull )
{
  mShowNull = showNull;
}
 
bool QgsSymbolButton::showNull() const
{
  return mShowNull;
}
 
bool QgsSymbolButton::isNull() const
{
  return !mSymbol;
}
 
void QgsSymbolButton::setToNull()
{
  setSymbol( nullptr );
}