Add API to allow generation of icons for 3d symbols from app

(still not implement -- but a necessary prerequisite to proper icons)

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

@@ -9,6 +9,7 @@
 
 
 
+
 class QgsStyleModel: QAbstractItemModel
 {
 %Docstring
@@ -85,6 +86,7 @@ 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

src/app/3d/qgs3dicongenerator.cpp

@@ -0,0 +1,37 @@
+/***************************************************************************
+    qgs3dicongenerator.cpp
+    ---------------
+    begin                : July 2020
+    copyright            : (C) 2020 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 "qgs3dicongenerator.h"
+#include "qgsapplication.h"
+
+Qgs3DIconGenerator::Qgs3DIconGenerator( QObject *parent )
+  : QgsAbstractStyleEntityIconGenerator( parent )
+{
+
+}
+
+void Qgs3DIconGenerator::generateIcon( QgsStyle *, QgsStyle::StyleEntity type, const QString &name )
+{
+  QIcon icon;
+  const QList< QSize > sizes = iconSizes();
+  if ( sizes.isEmpty() )
+    icon.addFile( QgsApplication::defaultThemePath() + QDir::separator() + QStringLiteral( "3d.svg" ), QSize( 24, 24 ) );
+  for ( const QSize &s : sizes )
+  {
+    icon.addFile( QgsApplication::defaultThemePath() + QDir::separator() + QStringLiteral( "3d.svg" ), s );
+  }
+
+  emit iconGenerated( type, name, icon );
+}

src/app/3d/qgs3dicongenerator.h

@@ -0,0 +1,34 @@
+/***************************************************************************
+    qgs3dicongenerator.h
+    ---------------
+    begin                : July 2020
+    copyright            : (C) 2020 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGS3DICONGENERATOR_H
+#define QGS3DICONGENERATOR_H
+
+#include "qgsstylemodel.h"
+
+class QgsSymbol;
+
+class Qgs3DIconGenerator : public QgsAbstractStyleEntityIconGenerator
+{
+    Q_OBJECT
+
+  public:
+
+    Qgs3DIconGenerator( QObject *parent );
+
+    void generateIcon( QgsStyle *style, QgsStyle::StyleEntity type, const QString &name ) override;
+};
+
+#endif //QGS3DICONGENERATOR_H

src/app/CMakeLists.txt

@@ -262,6 +262,7 @@ IF (WITH_3D)
     3d/qgs3danimationwidget.cpp
     3d/qgs3danimationexportdialog.cpp
     3d/qgs3dapputils.cpp
+    3d/qgs3dicongenerator.cpp
     3d/qgs3dmapcanvas.cpp
     3d/qgs3dmapcanvasdockwidget.cpp
     3d/qgs3dmapconfigwidget.cpp

src/app/qgisapp.cpp

@@ -12657,6 +12657,8 @@ void QgisApp::init3D()
   // initialize 3D registries
   Qgs3D::initialize();
   Qgs3DAppUtils::initialize();
+
+  QgsStyleModel::setIconGenerator( new Qgs3DIconGenerator( QgsApplication::defaultStyleModel() ) );
 #else
   mActionNew3DMapCanvas->setVisible( false );
 #endif

src/core/symbology/qgsstylemodel.cpp

@@ -27,6 +27,33 @@ const double ICON_PADDING_FACTOR = 0.16;
 
 const auto ENTITIES = { QgsStyle::SymbolEntity, QgsStyle::ColorrampEntity, QgsStyle::TextFormatEntity, QgsStyle::LabelSettingsEntity, QgsStyle::LegendPatchShapeEntity, QgsStyle::Symbol3DEntity };
 
+QgsAbstractStyleEntityIconGenerator *QgsStyleModel::sIconGenerator = nullptr;
+
+//
+// QgsAbstractStyleEntityIconGenerator
+//
+
+QgsAbstractStyleEntityIconGenerator::QgsAbstractStyleEntityIconGenerator( QObject *parent )
+  : QObject( parent )
+{
+
+}
+
+void QgsAbstractStyleEntityIconGenerator::setIconSizes( const QList<QSize> &sizes )
+{
+  mIconSizes = sizes;
+}
+
+QList<QSize> QgsAbstractStyleEntityIconGenerator::iconSizes() const
+{
+  return mIconSizes;
+}
+
+
+//
+// QgsStyleModel
+//
+
 QgsStyleModel::QgsStyleModel( QgsStyle *style, QObject *parent )
   : QAbstractItemModel( parent )
   , mStyle( style )
@@ -55,6 +82,9 @@ QgsStyleModel::QgsStyleModel( QgsStyle *style, QObject *parent )
   // if project color scheme changes, we need to redraw symbols - they may use project colors and accordingly
   // need updating to reflect the new colors
   connect( QgsProject::instance(), &QgsProject::projectColorsChanged, this, &QgsStyleModel::rebuildSymbolIcons );
+
+  if ( sIconGenerator )
+    connect( sIconGenerator, &QgsAbstractStyleEntityIconGenerator::iconGenerated, this, &QgsStyleModel::iconGenerated, Qt::QueuedConnection );
 }
 
 QVariant QgsStyleModel::data( const QModelIndex &index, int role ) const
@@ -326,6 +356,13 @@ QVariant QgsStyleModel::data( const QModelIndex &index, int role ) const
               if ( !icon.isNull() )
                 return icon;
 
+              if ( sIconGenerator && !mPending3dSymbolIcons.contains( name ) )
+              {
+                mPending3dSymbolIcons.insert( name );
+                sIconGenerator->generateIcon( mStyle, QgsStyle::Symbol3DEntity, name );
+              }
+
+              // TODO - use hourglass icon
               if ( mAdditionalSizes.isEmpty() )
                 icon.addFile( QgsApplication::defaultThemePath() + QDir::separator() + QStringLiteral( "3d.svg" ), QSize( 24, 24 ) );
               for ( const QSize &s : mAdditionalSizes )
@@ -553,9 +590,19 @@ void QgsStyleModel::addDesiredIconSize( QSize size )
     return;
 
   mAdditionalSizes << size;
+
+  if ( sIconGenerator )
+    sIconGenerator->setIconSizes( mAdditionalSizes );
+
   mIconCache.clear();
 }
 
+void QgsStyleModel::setIconGenerator( QgsAbstractStyleEntityIconGenerator *generator )
+{
+  sIconGenerator = generator;
+  connect( sIconGenerator, &QgsAbstractStyleEntityIconGenerator::iconGenerated, QgsApplication::defaultStyleModel(), &QgsStyleModel::iconGenerated, Qt::QueuedConnection );
+}
+
 void QgsStyleModel::onEntityAdded( QgsStyle::StyleEntity type, const QString &name )
 {
   mIconCache[ type ].remove( name );
@@ -651,6 +698,29 @@ void QgsStyleModel::rebuildSymbolIcons()
   emit dataChanged( index( 0, 0 ), index( mEntityNames[ QgsStyle::SymbolEntity ].count() - 1, 0 ), QVector<int>() << Qt::DecorationRole );
 }
 
+void QgsStyleModel::iconGenerated( QgsStyle::StyleEntity type, const QString &name, const QIcon &icon )
+{
+  int row = mEntityNames[type].indexOf( name ) + offsetForEntity( type );
+
+  switch ( type )
+  {
+    case QgsStyle::Symbol3DEntity:
+      mPending3dSymbolIcons.remove( name );
+      mIconCache[ QgsStyle::Symbol3DEntity ].insert( name, icon );
+      emit dataChanged( index( row, 0 ), index( row, 0 ) );
+      break;
+
+    case QgsStyle::SymbolEntity:
+    case QgsStyle::TagEntity:
+    case QgsStyle::ColorrampEntity:
+    case QgsStyle::LegendPatchShapeEntity:
+    case QgsStyle::TextFormatEntity:
+    case QgsStyle::SmartgroupEntity:
+    case QgsStyle::LabelSettingsEntity:
+      break;
+  }
+}
+
 QgsStyle::StyleEntity QgsStyleModel::entityTypeFromRow( int row ) const
 {
   int maxRowForEntity = 0;
@@ -946,3 +1016,4 @@ void QgsStyleProxyModel::setEntityFilters( const QList<QgsStyle::StyleEntity> &f
   mEntityFilters = filters;
   invalidateFilter();
 }
+

src/core/symbology/qgsstylemodel.h

@@ -27,6 +27,68 @@
 
 class QgsSymbol;
 
+#ifndef SIP_RUN
+
+/**
+ * \ingroup core
+ * \class QgsAbstractStyleEntityIconGenerator
+ *
+ * An abstract base class for icon generators for a QgsStyleModel.
+ *
+ * This base class allows for creation of specialised icon generators for
+ * entities in a style database, and allows for deferred icon generation.
+ *
+ * \note Not available in Python bindings
+ * \since QGIS 3.16
+ */
+class CORE_EXPORT QgsAbstractStyleEntityIconGenerator : public QObject
+{
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Constructor for QgsAbstractStyleEntityIconGenerator, with the specified \a parent
+     * object.
+     */
+    QgsAbstractStyleEntityIconGenerator( QObject *parent );
+
+    /**
+     * Triggers generation of an icon for an entity from the specified \a style database,
+     * with matching entity \a type and \a name.
+     */
+    virtual void generateIcon( QgsStyle *style, QgsStyle::StyleEntity type, const QString &name ) = 0;
+
+    /**
+     * Sets the list of icon \a sizes to generate.
+     *
+     * \see iconSizes()
+     */
+    void setIconSizes( const QList< QSize > &sizes );
+
+    /**
+     * Returns the list of icon \a sizes to generate.
+     *
+     * \see setIconSizes()
+     */
+    QList< QSize > iconSizes() const;
+
+  signals:
+
+    /**
+     * Emitted when the \a icon for the style entity with matching \a type and \a name
+     * has been generated.
+     */
+    void iconGenerated( QgsStyle::StyleEntity type, const QString &name, const QIcon &icon );
+
+  private:
+
+    QList< QSize > mIconSizes;
+
+};
+
+#endif
+
 /**
  * \ingroup core
  * \class QgsStyleModel
@@ -99,6 +161,16 @@ class CORE_EXPORT QgsStyleModel: public QAbstractItemModel
      */
     void addDesiredIconSize( QSize size );
 
+    /**
+     * Sets the icon \a generator to use for deferred style entity icon generation.
+     *
+     * Currently this is used for 3D symbol icons only.
+     *
+     * \note Not available in Python bindings
+     * \since QGIS 3.16
+     */
+    static void setIconGenerator( QgsAbstractStyleEntityIconGenerator *generator ) SIP_SKIP;
+
   private slots:
 
     void onEntityAdded( QgsStyle::StyleEntity type, const QString &name );
@@ -107,6 +179,7 @@ class CORE_EXPORT QgsStyleModel: public QAbstractItemModel
     void onEntityRename( QgsStyle::StyleEntity type, const QString &oldName, const QString &newName );
     void onTagsChanged( int entity, const QString &name, const QStringList &tags );
     void rebuildSymbolIcons();
+    void iconGenerated( QgsStyle::StyleEntity type, const QString &name, const QIcon &icon );
 
   private:
 
@@ -119,6 +192,9 @@ class CORE_EXPORT QgsStyleModel: public QAbstractItemModel
 
     mutable QHash< QgsStyle::StyleEntity, QHash< QString, QIcon > > mIconCache;
 
+    static QgsAbstractStyleEntityIconGenerator *sIconGenerator;
+    mutable QSet< QString > mPending3dSymbolIcons;
+
     QgsStyle::StyleEntity entityTypeFromRow( int row ) const;
 
     int offsetForEntity( QgsStyle::StyleEntity entity ) const;