Add explicit API call for style model icon sizes

Author: nyalldawson

python/core/auto_generated/symbology/qgsstylemodel.sip.in

@@ -63,6 +63,14 @@ The ``style`` object must exist for the lifetime of this model.
     virtual int columnCount( const QModelIndex &parent = QModelIndex() ) const;
 
 
+    void addDesiredIconSize( QSize size );
+%Docstring
+Adds an additional icon ``size`` to generate for Qt.DecorationRole data.
+
+This allows style icons to be generated at an icon size which
+corresponds exactly to the view's icon size in which this model is used.
+%End
+
 };
 
 class QgsStyleProxyModel: QSortFilterProxyModel
@@ -236,6 +244,14 @@ Returns true if the model is showing only favorited entities.
 Sets whether the model should show only favorited entities.
 
 .. seealso:: :py:func:`setFavoritesOnly`
+%End
+
+    void addDesiredIconSize( QSize size );
+%Docstring
+Adds an additional icon ``size`` to generate for Qt.DecorationRole data.
+
+This allows style icons to be generated at an icon size which
+corresponds exactly to the view's icon size in which this model is used.
 %End
 
   public slots:

src/core/symbology/qgsstylemodel.cpp

@@ -71,13 +71,8 @@ QVariant QgsStyleModel::data( const QModelIndex &index, int role ) const
 
     case Qt::DecorationRole:
     {
-      // check the model custom property for icon sizes to generate. This is used
-      // by instances of the model to indicate the required sizes for decorations in all
-      // views connected to the model, and allows the model to have size responsive icons.
-      // By using a QObject property we avoid having public GUI/view related API within
-      // the model, and mostly avoid view related properties contaminating the pure model...
-      const QVariantList iconSizes = property( "icon_sizes" ).toList();
-
+      // Generate icons at all additional sizes specified for the model.
+      // This allows the model to have size responsive icons.
       switch ( index.column() )
       {
         case Name:
@@ -87,7 +82,7 @@ QVariant QgsStyleModel::data( const QModelIndex &index, int role ) const
             QIcon icon;
             icon.addPixmap( QgsSymbolLayerUtils::symbolPreviewPixmap( symbol.get(), QSize( 24, 24 ), 1 ) );
 
-            for ( const QVariant &size : iconSizes )
+            for ( const QVariant &size : mAdditionalSizes )
             {
               QSize s = size.toSize();
               icon.addPixmap( QgsSymbolLayerUtils::symbolPreviewPixmap( symbol.get(), s, static_cast< int >( s.width() * ICON_PADDING_FACTOR ) ) );
@@ -100,7 +95,7 @@ QVariant QgsStyleModel::data( const QModelIndex &index, int role ) const
             std::unique_ptr< QgsColorRamp > ramp( mStyle->colorRamp( name ) );
             QIcon icon;
             icon.addPixmap( QgsSymbolLayerUtils::colorRampPreviewPixmap( ramp.get(), QSize( 24, 24 ), 1 ) );
-            for ( const QVariant &size : iconSizes )
+            for ( const QVariant &size : mAdditionalSizes )
             {
               QSize s = size.toSize();
               icon.addPixmap( QgsSymbolLayerUtils::colorRampPreviewPixmap( ramp.get(), s, static_cast< int >( s.width() * ICON_PADDING_FACTOR ) ) );
@@ -237,6 +232,11 @@ int QgsStyleModel::columnCount( const QModelIndex & ) const
   return 2;
 }
 
+void QgsStyleModel::addDesiredIconSize( QSize size )
+{
+  mAdditionalSizes << size;
+}
+
 void QgsStyleModel::onSymbolAdded( const QString &name, QgsSymbol * )
 {
   const QStringList oldSymbolNames = mSymbolNames;
@@ -466,6 +466,11 @@ void QgsStyleProxyModel::setFavoritesOnly( bool favoritesOnly )
   invalidateFilter();
 }
 
+void QgsStyleProxyModel::addDesiredIconSize( QSize size )
+{
+  mModel->addDesiredIconSize( size );
+}
+
 bool QgsStyleProxyModel::symbolTypeFilterEnabled() const
 {
   return mSymbolTypeFilterEnabled;

src/core/symbology/qgsstylemodel.h

@@ -75,6 +75,14 @@ class CORE_EXPORT QgsStyleModel: public QAbstractItemModel
     int rowCount( const QModelIndex &parent = QModelIndex() ) const override;
     int columnCount( const QModelIndex &parent = QModelIndex() ) const override;
 
+    /**
+     * Adds an additional icon \a size to generate for Qt::DecorationRole data.
+     *
+     * This allows style icons to be generated at an icon size which
+     * corresponds exactly to the view's icon size in which this model is used.
+     */
+    void addDesiredIconSize( QSize size );
+
   private slots:
 
     void onSymbolAdded( const QString &name, QgsSymbol *symbol );
@@ -90,6 +98,7 @@ class CORE_EXPORT QgsStyleModel: public QAbstractItemModel
     QgsStyle *mStyle = nullptr;
     QStringList mSymbolNames;
     QStringList mRampNames;
+    QList< QSize > mAdditionalSizes;
 
 };
 
@@ -252,6 +261,14 @@ class CORE_EXPORT QgsStyleProxyModel: public QSortFilterProxyModel
      */
     void setFavoritesOnly( bool favoritesOnly );
 
+    /**
+     * Adds an additional icon \a size to generate for Qt::DecorationRole data.
+     *
+     * This allows style icons to be generated at an icon size which
+     * corresponds exactly to the view's icon size in which this model is used.
+     */
+    void addDesiredIconSize( QSize size );
+
   public slots:
 
     /**

src/gui/symbology/qgssymbolslistwidget.cpp

@@ -121,7 +121,7 @@ QgsSymbolsListWidget::QgsSymbolsListWidget( QgsSymbol *symbol, QgsStyle *style,
   double iconSize = Qgis::UI_SCALE_FACTOR * fontMetrics().width( 'X' ) * 10;
   viewSymbols->setIconSize( QSize( static_cast< int >( iconSize ), static_cast< int >( iconSize * 0.9 ) ) );  // ~100, 90 on low dpi
 
-  mModel->sourceModel()->setProperty( "icon_sizes", QVariantList() << viewSymbols->iconSize() );
+  mModel->addDesiredIconSize( viewSymbols->iconSize() );
   viewSymbols->setModel( mModel );
 
   connect( viewSymbols->selectionModel(), &QItemSelectionModel::currentChanged, this, &QgsSymbolsListWidget::setSymbolFromStyle );

tests/src/python/test_qgsstylemodel.py

@@ -728,17 +728,18 @@ def testIconSize(self):
         ramp_a = QgsLimitedRandomColorRamp(5)
         self.assertTrue(style.addColorRamp('ramp a', ramp_a, True))
 
-        model = QgsStyleModel(style)
-        self.assertEqual(model.rowCount(), 2)
         for i in range(2):
+            model = QgsStyleModel(style)
+            self.assertEqual(model.rowCount(), 2)
             icon = model.data(model.index(i, 0), Qt.DecorationRole)
             # by default, only 24x24 icon
             self.assertEqual(icon.availableSizes(), [QSize(24, 24)])
             self.assertEqual(icon.actualSize(QSize(10, 10)), QSize(10, 10))
             self.assertEqual(icon.actualSize(QSize(24, 24)), QSize(24, 24))
             self.assertEqual(icon.actualSize(QSize(90, 90)), QSize(24, 24))
 
-            model.setProperty('icon_sizes', [QSize(24, 24), QSize(100, 90)])
+            model.addDesiredIconSize(QSize(24, 24))
+            model.addDesiredIconSize(QSize(100, 90))
             icon = model.data(model.index(i, 0), Qt.DecorationRole)
             self.assertEqual(icon.availableSizes(), [QSize(24, 24), QSize(100, 90)])
             self.assertEqual(icon.actualSize(QSize(10, 10)), QSize(10, 10))
@@ -747,7 +748,9 @@ def testIconSize(self):
             self.assertEqual(icon.actualSize(QSize(90, 90)), QSize(90, 81))
             self.assertEqual(icon.actualSize(QSize(125, 125)), QSize(100, 90))
 
-            model.setProperty('icon_sizes', [QSize(100, 90), QSize(200, 180)])
+            model = QgsStyleModel(style)
+            model.addDesiredIconSize(QSize(100, 90))
+            model.addDesiredIconSize(QSize(200, 180))
             icon = model.data(model.index(i, 0), Qt.DecorationRole)
             self.assertEqual(icon.availableSizes(), [QSize(24, 24), QSize(100, 90), QSize(200, 180)])
             self.assertEqual(icon.actualSize(QSize(10, 10)), QSize(10, 10))
@@ -756,7 +759,6 @@ def testIconSize(self):
             self.assertEqual(icon.actualSize(QSize(90, 90)), QSize(90, 81))
             self.assertEqual(icon.actualSize(QSize(125, 125)), QSize(125, 112))
             self.assertEqual(icon.actualSize(QSize(225, 225)), QSize(200, 180))
-            model.setProperty('icon_sizes', None)
 
     def testSetData(self):
         """