Cleanup QgsSvgCache API

- Remove QgsSvgCacheEntry from public API (is an internal detail only)
- Modernize code
- Make protected QgsSvgCache members private, since this class is not
designed to be subclassed

doc/api_break.dox

@@ -319,6 +319,7 @@ should now call QgsCoordinateReferenceSystem::invalidateCache() and QgsCoordinat
 - QgsEditorWidgetConfig was removed. Use QVariantMap instead.
 - QgsScaleExpression. Use QgsProperty with a QgsSizeScalePropertyTransformer instead.
 - QgsSvgAnnotationItem. Use QgsSvgAnnotation instead.
+- QgsSvgCacheEntry. This is an internal class and is no longer exposed to public API.
 - QgsSymbologyV2Conversion was removed. Reading of renderers from pre-1.0 versions is not supported anymore.
 - QgsTextAnnotationItem. Use QgsTextAnnotation instead.
 - QgsTransectSample. This class was unused and unmaintained.
@@ -2289,6 +2290,8 @@ QgsSvgCache        {#qgis_api_break_3_0_QgsSvgCache}
 - containsParamsV2() was removed. Use containsParamsV3() instead.
 - The rasterScaleFactor parameter was removed from all methods
 - svgAsImage(), svgAsPicture(), svgViewboxSize(), svgContent(), insertSvg(), cacheEntry() only accept absolute path to SVG file (relative paths will not be resolved).
+- The protected member insertSvg() was made private. QgsSvgCache is not intended to be subclassed.
+
 
 QgsSvgCacheEntry       {#qgis_api_break_3_0_QgsSvgCacheEntry}
 ----------------

python/core/symbology/qgssvgcache.sip

@@ -11,69 +11,6 @@
 
 
 
-class QgsSvgCacheEntry
-{
-
-%TypeHeaderCode
-#include "qgssvgcache.h"
-%End
-  public:
-
-    QgsSvgCacheEntry();
-
-    QgsSvgCacheEntry( const QString &path, double size, double strokeWidth, double widthScaleFactor, const QColor &fill, const QColor &stroke,
-                      double fixedAspectRatio = 0 ) ;
-%Docstring
- Constructor.
- \param path Absolute path to SVG file (relative paths are not resolved).
- \param size
- \param strokeWidth width of stroke
- \param widthScaleFactor width scale factor
- \param fill color of fill
- \param stroke color of stroke
- \param fixedAspectRatio fixed aspect ratio (optional)
-%End
-    ~QgsSvgCacheEntry();
-
-
-    QString path;
-%Docstring
-Absolute path to SVG file
-%End
-    double size;
-    double strokeWidth;
-    double widthScaleFactor;
-
-    double fixedAspectRatio;
-%Docstring
-Fixed aspect ratio
-%End
-
-    QSizeF viewboxSize;
-%Docstring
- SVG viewbox size.
-.. versionadded:: 2.14
-%End
-
-    QColor fill;
-    QColor stroke;
-    QImage *image;
-    QPicture *picture;
-    QByteArray svgContent;
-
-    QgsSvgCacheEntry *nextEntry;
-    QgsSvgCacheEntry *previousEntry;
-
-    bool operator==( const QgsSvgCacheEntry &other ) const;
-    int dataSize() const;
-%Docstring
-Return memory usage in bytes
- :rtype: int
-%End
-
-  private:
-    QgsSvgCacheEntry( const QgsSvgCacheEntry &rh );
-};
 
 class QgsSvgCache : QObject
 {
@@ -200,39 +137,6 @@ Get SVG content
 Emit a signal to be caught by qgisapp and display a msg on status bar
 %End
 
-  protected:
-
-    QgsSvgCacheEntry *insertSvg( const QString &path, double size, const QColor &fill, const QColor &stroke, double strokeWidth,
-                                 double widthScaleFactor, double fixedAspectRatio = 0 );
-%Docstring
- Creates new cache entry and returns pointer to it
- \param path Absolute path to SVG file
- \param size size of cached image
- \param fill color of fill
- \param stroke color of stroke
- \param strokeWidth width of stroke
- \param widthScaleFactor width scale factor
- \param fixedAspectRatio fixed aspect ratio (optional)
- :rtype: QgsSvgCacheEntry
-%End
-
-    void replaceParamsAndCacheSvg( QgsSvgCacheEntry *entry );
-    void cacheImage( QgsSvgCacheEntry *entry );
-    void cachePicture( QgsSvgCacheEntry *entry, bool forceVectorOutput = false );
-    QgsSvgCacheEntry *cacheEntry( const QString &path, double size, const QColor &fill, const QColor &stroke, double strokeWidth,
-                                  double widthScaleFactor, double fixedAspectRatio = 0 );
-%Docstring
-Returns entry from cache or creates a new entry if it does not exist already
- :rtype: QgsSvgCacheEntry
-%End
-
-    void trimToMaximumSize();
-%Docstring
-Removes the least used items until the maximum size is under the limit
-%End
-
-    void takeEntryFromList( QgsSvgCacheEntry *entry );
-
 };
 
 /************************************************************************

src/core/symbology/qgssvgcache.cpp

@@ -36,12 +36,7 @@
 #include <QNetworkReply>
 #include <QNetworkRequest>
 
-QgsSvgCacheEntry::QgsSvgCacheEntry()
-  : path( QString() )
-  , fill( Qt::black )
-  , stroke( Qt::black )
-{
-}
+///@cond PRIVATE
 
 QgsSvgCacheEntry::QgsSvgCacheEntry( const QString &p, double s, double ow, double wsf, const QColor &fi, const QColor &ou, double far )
   : path( p )
@@ -54,13 +49,6 @@ QgsSvgCacheEntry::QgsSvgCacheEntry( const QString &p, double s, double ow, doubl
 {
 }
 
-
-QgsSvgCacheEntry::~QgsSvgCacheEntry()
-{
-  delete image;
-  delete picture;
-}
-
 bool QgsSvgCacheEntry::operator==( const QgsSvgCacheEntry &other ) const
 {
   return other.path == path && qgsDoubleNear( other.size, size ) && qgsDoubleNear( other.strokeWidth, strokeWidth ) && qgsDoubleNear( other.widthScaleFactor, widthScaleFactor )
@@ -80,6 +68,8 @@ int QgsSvgCacheEntry::dataSize() const
   }
   return size;
 }
+///@endcond
+
 
 QgsSvgCache::QgsSvgCache( QObject *parent )
   : QObject( parent )
@@ -127,9 +117,7 @@ QImage QgsSvgCache::svgAsImage( const QString &file, double size, const QColor &
     if ( cachedDataSize > MAXIMUM_SIZE / 2 )
     {
       fitsInCache = false;
-      delete currentEntry->image;
-      currentEntry->image = nullptr;
-      //currentEntry->image = new QImage( 0, 0 );
+      currentEntry->image.reset();
 
       // instead cache picture
       if ( !currentEntry->picture )
@@ -488,18 +476,17 @@ void QgsSvgCache::cacheImage( QgsSvgCacheEntry *entry )
     return;
   }
 
-  delete entry->image;
-  entry->image = nullptr;
+  entry->image.reset();
 
   QSizeF viewBoxSize;
   QSizeF scaledSize;
   QSize imageSize = sizeForImage( *entry, viewBoxSize, scaledSize );
 
   // cast double image sizes to int for QImage
-  QImage *image = new QImage( imageSize, QImage::Format_ARGB32_Premultiplied );
+  std::unique_ptr< QImage > image = qgis::make_unique< QImage >( imageSize, QImage::Format_ARGB32_Premultiplied );
   image->fill( 0 ); // transparent background
 
-  QPainter p( image );
+  QPainter p( image.get() );
   QSvgRenderer r( entry->svgContent );
   if ( qgsDoubleNear( viewBoxSize.width(), viewBoxSize.height() ) )
   {
@@ -513,8 +500,8 @@ void QgsSvgCache::cacheImage( QgsSvgCacheEntry *entry )
     r.render( &p, rect );
   }
 
-  entry->image = image;
   mTotalSize += ( image->width() * image->height() * 32 );
+  entry->image = std::move( image );
 }
 
 void QgsSvgCache::cachePicture( QgsSvgCacheEntry *entry, bool forceVectorOutput )
@@ -525,13 +512,12 @@ void QgsSvgCache::cachePicture( QgsSvgCacheEntry *entry, bool forceVectorOutput
     return;
   }
 
-  delete entry->picture;
-  entry->picture = nullptr;
+  entry->picture.reset();
 
   bool isFixedAR = entry->fixedAspectRatio > 0;
 
   //correct QPictures dpi correction
-  QPicture *picture = new QPicture();
+  std::unique_ptr< QPicture > picture = qgis::make_unique< QPicture >();
   QRectF rect;
   QSvgRenderer r( entry->svgContent );
   double hwRatio = 1.0;
@@ -554,9 +540,9 @@ void QgsSvgCache::cachePicture( QgsSvgCacheEntry *entry, bool forceVectorOutput
   s.scale( wSize, hSize, isFixedAR ? Qt::IgnoreAspectRatio : Qt::KeepAspectRatio );
   rect = QRectF( -s.width() / 2.0, -s.height() / 2.0, s.width(), s.height() );
 
-  QPainter p( picture );
+  QPainter p( picture.get() );
   r.render( &p, rect );
-  entry->picture = picture;
+  entry->picture = std::move( picture );
   mTotalSize += entry->picture->size();
 }
 

src/core/symbology/qgssvgcache.h

@@ -34,6 +34,10 @@ class QDomElement;
 class QImage;
 class QPicture;
 
+#ifndef SIP_RUN
+
+///@cond PRIVATE
+
 /**
  * \ingroup core
  * \class QgsSvgCacheEntry
@@ -42,7 +46,7 @@ class CORE_EXPORT QgsSvgCacheEntry
 {
   public:
 
-    QgsSvgCacheEntry();
+    QgsSvgCacheEntry() = default;
 
     /**
      * Constructor.
@@ -56,7 +60,6 @@ class CORE_EXPORT QgsSvgCacheEntry
      */
     QgsSvgCacheEntry( const QString &path, double size, double strokeWidth, double widthScaleFactor, const QColor &fill, const QColor &stroke,
                       double fixedAspectRatio = 0 ) ;
-    ~QgsSvgCacheEntry();
 
     //! QgsSvgCacheEntry cannot be copied.
     QgsSvgCacheEntry( const QgsSvgCacheEntry &rh ) = delete;
@@ -78,10 +81,10 @@ class CORE_EXPORT QgsSvgCacheEntry
      */
     QSizeF viewboxSize;
 
-    QColor fill;
-    QColor stroke;
-    QImage *image = nullptr;
-    QPicture *picture = nullptr;
+    QColor fill = Qt::black;
+    QColor stroke = Qt::black;
+    std::unique_ptr< QImage > image;
+    std::unique_ptr< QPicture > picture;
     //content (with params replaced)
     QByteArray svgContent;
 
@@ -101,6 +104,9 @@ class CORE_EXPORT QgsSvgCacheEntry
 
 };
 
+///@endcond
+#endif
+
 /**
  * \ingroup core
  * A cache for images / pictures derived from svg files. This class supports parameter replacement in svg files
@@ -211,7 +217,10 @@ class CORE_EXPORT QgsSvgCache : public QObject
     //! Emit a signal to be caught by qgisapp and display a msg on status bar
     void statusChanged( const QString  &statusQString );
 
-  protected:
+  private slots:
+    void downloadProgress( qint64, qint64 );
+
+  private:
 
     /**
      * Creates new cache entry and returns pointer to it
@@ -239,10 +248,6 @@ class CORE_EXPORT QgsSvgCache : public QObject
     //Removes entry from the ordered list (but does not delete the entry itself)
     void takeEntryFromList( QgsSvgCacheEntry *entry );
 
-  private slots:
-    void downloadProgress( qint64, qint64 );
-
-  private:
     //! Entry pointers accessible by file name
     QMultiHash< QString, QgsSvgCacheEntry * > mEntryLookup;
     //! Estimated total size of all images, pictures and svgContent