Add opacity parameter to image cache

qgis · Dec 5, 2018 · ad4b876 · nyalldawson · Dec 5, 2018 · ad4b876
1 parent ce5636a
commit ad4b876
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Showing 5 changed files with 50 additions and 23 deletions.
diff --git a/python/core/auto_generated/qgsimagecache.sip.in b/python/core/auto_generated/qgsimagecache.sip.in
@@ -35,7 +35,7 @@ QgsImageCache is not usually directly created, but rather accessed through
 Constructor for QgsImageCache, with the specified ``parent`` object.
 %End
 
-    QImage pathAsImage( const QString &path, QSize size, bool keepAspectRatio, bool &fitsInCache /Out/ );
+    QImage pathAsImage( const QString &path, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache /Out/ );
 %Docstring
 Returns the specified ``path`` rendered as an image. If possible, a pre-existing cached
 version of the image will be used. If not, the image is fetched and resampled to the desired
@@ -49,6 +49,8 @@ original raster image size (with no resampling).
 If ``keepAspectRatio`` is true, then the original raster aspect ratio will be maintained during
 any resampling operations.
 
+An ``opacity`` parameter dictates the opacity of the image.
+
 If the resultant raster was of a sufficiently small size to store in the cache, then ``fitsInCache``
 will be set to true.
 %End

diff --git a/src/core/qgsimagecache.cpp b/src/core/qgsimagecache.cpp
@@ -41,18 +41,19 @@
 
 ///@cond PRIVATE
 
-QgsImageCacheEntry::QgsImageCacheEntry( const QString &path, QSize size, const bool keepAspectRatio )
+QgsImageCacheEntry::QgsImageCacheEntry( const QString &path, QSize size, const bool keepAspectRatio, const double opacity )
   : QgsAbstractContentCacheEntry( path )
   , size( size )
   , keepAspectRatio( keepAspectRatio )
+  , opacity( opacity )
 {
 }
 
 bool QgsImageCacheEntry::isEqual( const QgsAbstractContentCacheEntry *other ) const
 {
   const QgsImageCacheEntry *otherImage = dynamic_cast< const QgsImageCacheEntry * >( other );
   // cheapest checks first!
-  if ( !otherImage || otherImage->keepAspectRatio != keepAspectRatio || otherImage->size != size || otherImage->path != path )
+  if ( !otherImage || otherImage->keepAspectRatio != keepAspectRatio || otherImage->size != size || otherImage->path != path || otherImage->opacity != opacity )
     return false;
 
   return true;
@@ -99,13 +100,13 @@ QgsImageCache::QgsImageCache( QObject *parent )
   connect( this, &QgsAbstractContentCacheBase::remoteContentFetched, this, &QgsImageCache::remoteImageFetched );
 }
 
-QImage QgsImageCache::pathAsImage( const QString &file, const QSize size, const bool keepAspectRatio, bool &fitsInCache )
+QImage QgsImageCache::pathAsImage( const QString &file, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache )
 {
   QMutexLocker locker( &mMutex );
 
   fitsInCache = true;
 
-  QgsImageCacheEntry *currentEntry = findExistingEntry( new QgsImageCacheEntry( file, size, keepAspectRatio ) );
+  QgsImageCacheEntry *currentEntry = findExistingEntry( new QgsImageCacheEntry( file, size, keepAspectRatio, opacity ) );
 
   QImage result;
 
@@ -115,7 +116,7 @@ QImage QgsImageCache::pathAsImage( const QString &file, const QSize size, const
   if ( currentEntry->image.isNull() )
   {
     long cachedDataSize = 0;
-    result = renderImage( file, size, keepAspectRatio );
+    result = renderImage( file, size, keepAspectRatio, opacity );
     cachedDataSize += result.width() * result.height() * 32;
     if ( cachedDataSize > mMaxCacheSize / 2 )
     {
@@ -161,7 +162,7 @@ QSize QgsImageCache::originalSize( const QString &path ) const
   return QSize();
 }
 
-QImage QgsImageCache::renderImage( const QString &path, QSize size, const bool keepAspectRatio ) const
+QImage QgsImageCache::renderImage( const QString &path, QSize size, const bool keepAspectRatio, const double opacity ) const
 {
   QImage im;
   // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
@@ -211,6 +212,12 @@ QImage QgsImageCache::renderImage( const QString &path, QSize size, const bool k
     }
   }
 
+  if ( !im.hasAlphaChannel() )
+    im = im.convertToFormat( QImage::Format_ARGB32 );
+
+  if ( opacity < 1.0 )
+    QgsSymbolLayerUtils::multiplyImageOpacity( &im, opacity );
+
   // render image at desired size -- null size means original size
   if ( !size.isValid() || size.isNull() || im.size() == size )
     return im;

diff --git a/src/core/qgsimagecache.h b/src/core/qgsimagecache.h
@@ -41,19 +41,22 @@ class CORE_EXPORT QgsImageCacheEntry : public QgsAbstractContentCacheEntry
   public:
 
     /**
-     * Constructor for QgsImageCacheEntry, corresponding to the specified image \a path and \a size.
+     * Constructor for QgsImageCacheEntry, corresponding to the specified image \a path , \a size and \a opacity.
      *
      * If \a keepAspectRatio is true then the original raster aspect ratio will always be preserved
      * when resizing.
      */
-    QgsImageCacheEntry( const QString &path, QSize size, bool keepAspectRatio ) ;
+    QgsImageCacheEntry( const QString &path, QSize size, bool keepAspectRatio, double opacity ) ;
 
     //! Rendered image size
     QSize size;
 
     //! True if original raster aspect ratio was kept during resizing
     bool keepAspectRatio = true;
 
+    //! Rendered image opacity
+    double opacity = 1.0;
+
     //! Rendered, resampled image.
     QImage image;
 
@@ -108,10 +111,12 @@ class CORE_EXPORT QgsImageCache : public QgsAbstractContentCache< QgsImageCacheE
      * If \a keepAspectRatio is true, then the original raster aspect ratio will be maintained during
      * any resampling operations.
      *
+     * An \a opacity parameter dictates the opacity of the image.
+     *
      * If the resultant raster was of a sufficiently small size to store in the cache, then \a fitsInCache
      * will be set to true.
      */
-    QImage pathAsImage( const QString &path, QSize size, bool keepAspectRatio, bool &fitsInCache SIP_OUT );
+    QImage pathAsImage( const QString &path, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache SIP_OUT );
 
     /**
      * Returns the original size (in pixels) of the image at the specified \a path.
@@ -134,7 +139,7 @@ class CORE_EXPORT QgsImageCache : public QgsAbstractContentCache< QgsImageCacheE
 
   private:
 
-    QImage renderImage( const QString &path, QSize size, const bool keepAspectRatio ) const;
+    QImage renderImage( const QString &path, QSize size, const bool keepAspectRatio, const double opacity ) const;
 
     //! SVG content to be rendered if SVG file was not found.
     QByteArray mMissingSvg;