[effects] Fix blur radius not taking dpi into account (fixes #14885)

python/core/auto_generated/effects/qgsblureffect.sip.in

@@ -51,28 +51,96 @@ Constructor for QgsBlurEffect.
     virtual QgsBlurEffect *clone() const /Factory/;
 
 
-    void setBlurLevel( const int level );
+    void setBlurLevel( const double level );
 %Docstring
-Sets blur level (strength)
+Sets blur level (radius)
 
 :param level: blur level. Depending on the current blurMethod(), this parameter
               has different effects
 
 .. seealso:: :py:func:`blurLevel`
 
-.. seealso:: :py:func:`blurMethod`
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. seealso:: :py:func:`setBlurMethod`
 %End
 
-    int blurLevel() const;
+    double blurLevel() const;
 %Docstring
-Returns the blur level (strength)
+Returns the blur level (radius)
 
 :return: blur level. Depending on the current blurMethod(), this parameter
          has different effects
 
 .. seealso:: :py:func:`setBlurLevel`
 
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
 .. seealso:: :py:func:`blurMethod`
+%End
+
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit );
+%Docstring
+Sets the units used for the blur level (radius).
+
+:param unit: units for blur level
+
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    QgsUnitTypes::RenderUnit blurUnit() const;
+%Docstring
+Returns the units used for the blur level (radius).
+
+:return: units for blur level
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale );
+%Docstring
+Sets the map unit scale used for the blur strength (radius).
+
+:param scale: map unit scale for blur strength
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. versionadded:: 3.4.9
+%End
+
+    const QgsMapUnitScale &blurMapUnitScale() const;
+%Docstring
+Returns the map unit scale used for the blur strength (radius).
+
+:return: map unit scale for blur strength
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurUnit`
+
+.. versionadded:: 3.4.9
 %End
 
     void setBlurMethod( const BlurMethod method );

python/core/auto_generated/effects/qgsgloweffect.sip.in

@@ -118,25 +118,91 @@ Returns the map unit scale used for the spread distance.
 .. seealso:: :py:func:`spreadUnit`
 %End
 
-    void setBlurLevel( const int level );
+    void setBlurLevel( const double level );
 %Docstring
-Sets blur level (strength) for the glow. This can be used to smooth the
+Sets blur level (radius) for the glow. This can be used to smooth the
 output from the glow effect.
 
-:param level: blur level. Values between 0 and 16 are valid, with larger
+:param level: blur level.
-              values indicating greater blur strength.
 
 .. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
 %End
 
-    int blurLevel() const;
+    double blurLevel() const;
 %Docstring
-Returns the blur level (strength) for the glow.
+Returns the blur level (radius) for the glow.
 
-:return: blur level. Value will be between 0 and 16, with larger
+:return: blur level.
-         values indicating greater blur strength.
 
 .. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+%End
+
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit );
+%Docstring
+Sets the units used for the glow blur level (radius).
+
+:param unit: units for blur level
+
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    QgsUnitTypes::RenderUnit blurUnit() const;
+%Docstring
+Returns the units used for the glow blur level (radius).
+
+:return: units for blur level
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale );
+%Docstring
+Sets the map unit scale used for the glow blur strength (radius).
+
+:param scale: map unit scale for blur strength
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. versionadded:: 3.4.9
+%End
+
+    const QgsMapUnitScale &blurMapUnitScale() const;
+%Docstring
+Returns the map unit scale used for the glow blur strength (radius).
+
+:return: map unit scale for blur strength
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurUnit`
+
+.. versionadded:: 3.4.9
 %End
 
     void setOpacity( const double opacity );

python/core/auto_generated/effects/qgsshadoweffect.sip.in

@@ -29,24 +29,92 @@ Base class for paint effects which offset, blurred shadows
     virtual void readProperties( const QgsStringMap &props );
 
 
-    void setBlurLevel( const int level );
+    void setBlurLevel( const double level );
 %Docstring
-Sets blur level (strength) for the shadow.
+Sets blur level (radius) for the shadow.
 
-:param level: blur level. Values between 0 and 16 are valid, with larger
+:param level: blur level.
               values indicating greater blur strength.
 
 .. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
 %End
 
-    int blurLevel() const;
+    double blurLevel() const;
 %Docstring
-Returns the blur level (strength) for the shadow.
+Returns the blur level (radius) for the shadow.
 
-:return: blur level. Value will be between 0 and 16, with larger
+:return: blur level.
          values indicating greater blur strength.
 
 .. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+%End
+
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit );
+%Docstring
+Sets the units used for the shadow blur level (radius).
+
+:param unit: units for blur level
+
+.. seealso:: :py:func:`blurUnit`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    QgsUnitTypes::RenderUnit blurUnit() const;
+%Docstring
+Returns the units used for the shadow blur level (radius).
+
+:return: units for blur level
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. versionadded:: 3.4.9
+%End
+
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale );
+%Docstring
+Sets the map unit scale used for the shadow blur strength (radius).
+
+:param scale: map unit scale for blur strength
+
+.. seealso:: :py:func:`blurMapUnitScale`
+
+.. seealso:: :py:func:`setBlurLevel`
+
+.. seealso:: :py:func:`setBlurUnit`
+
+.. versionadded:: 3.4.9
+%End
+
+    const QgsMapUnitScale &blurMapUnitScale() const;
+%Docstring
+Returns the map unit scale used for the shadow blur strength (radius).
+
+:return: map unit scale for blur strength
+
+.. seealso:: :py:func:`setBlurMapUnitScale`
+
+.. seealso:: :py:func:`blurLevel`
+
+.. seealso:: :py:func:`blurUnit`
+
+.. versionadded:: 3.4.9
 %End
 
     void setOffsetAngle( const int angle );

src/core/effects/qgsblureffect.cpp

@@ -18,6 +18,7 @@
 #include "qgsblureffect.h"
 #include "qgsimageoperation.h"
 #include "qgsrendercontext.h"
+#include "qgssymbollayerutils.h"
 
 QgsPaintEffect *QgsBlurEffect::create( const QgsStringMap &map )
 {
@@ -44,14 +45,16 @@ void QgsBlurEffect::draw( QgsRenderContext &context )
 
 void QgsBlurEffect::drawStackBlur( QgsRenderContext &context )
 {
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
   QImage im = sourceAsImage( context )->copy();
-  QgsImageOperation::stackBlur( im, mBlurLevel );
+  QgsImageOperation::stackBlur( im, blurLevel );
   drawBlurredImage( context, im );
 }
 
 void QgsBlurEffect::drawGaussianBlur( QgsRenderContext &context )
 {
-  QImage *im = QgsImageOperation::gaussianBlur( *sourceAsImage( context ), mBlurLevel );
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
+  QImage *im = QgsImageOperation::gaussianBlur( *sourceAsImage( context ), blurLevel );
   drawBlurredImage( context, *im );
   delete im;
 }
@@ -76,6 +79,8 @@ QgsStringMap QgsBlurEffect::properties() const
   props.insert( QStringLiteral( "blend_mode" ), QString::number( static_cast< int >( mBlendMode ) ) );
   props.insert( QStringLiteral( "opacity" ), QString::number( mOpacity ) );
   props.insert( QStringLiteral( "blur_level" ), QString::number( mBlurLevel ) );
+  props.insert( QStringLiteral( "blur_unit" ), QgsUnitTypes::encodeUnit( mBlurUnit ) );
+  props.insert( QStringLiteral( "blur_unit_scale" ), QgsSymbolLayerUtils::encodeMapUnitScale( mBlurMapUnitScale ) );
   props.insert( QStringLiteral( "blur_method" ), QString::number( static_cast< int >( mBlurMethod ) ) );
   return props;
 }
@@ -107,11 +112,18 @@ void QgsBlurEffect::readProperties( const QgsStringMap &props )
 
   mEnabled = props.value( QStringLiteral( "enabled" ), QStringLiteral( "1" ) ).toInt();
   mDrawMode = static_cast< QgsPaintEffect::DrawMode >( props.value( QStringLiteral( "draw_mode" ), QStringLiteral( "2" ) ).toInt() );
-  int level = props.value( QStringLiteral( "blur_level" ) ).toInt( &ok );
+  double level = props.value( QStringLiteral( "blur_level" ) ).toDouble( &ok );
   if ( ok )
   {
     mBlurLevel = level;
+    if ( !props.contains( QStringLiteral( "blur_unit" ) ) )
+    {
+      // deal with pre blur unit era by assuming 96 dpi and converting pixel values as millimeters
+      mBlurLevel *= 0.2645;
+    }
   }
+  mBlurUnit = QgsUnitTypes::decodeRenderUnit( props.value( QStringLiteral( "blur_unit" ) ) );
+  mBlurMapUnitScale = QgsSymbolLayerUtils::decodeMapUnitScale( props.value( QStringLiteral( "blur_unit_scale" ) ) );
   QgsBlurEffect::BlurMethod method = static_cast< QgsBlurEffect::BlurMethod >( props.value( QStringLiteral( "blur_method" ) ).toInt( &ok ) );
   if ( ok )
   {
@@ -127,9 +139,8 @@ QgsBlurEffect *QgsBlurEffect::clone() const
 
 QRectF QgsBlurEffect::boundingRect( const QRectF &rect, const QgsRenderContext &context ) const
 {
-  Q_UNUSED( context )
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
-
   //plus possible extension due to blur, with a couple of extra pixels thrown in for safety
-  double spread = mBlurLevel * 2.0 + 10;
+  double spread = blurLevel * 2.0 + 10;
   return rect.adjusted( -spread, -spread, spread, spread );
 }

src/core/effects/qgsblureffect.h

@@ -61,22 +61,66 @@ class CORE_EXPORT QgsBlurEffect : public QgsPaintEffect
     QgsBlurEffect *clone() const override SIP_FACTORY;
 
     /**
-     * Sets blur level (strength)
+     * Sets blur level (radius)
      * \param level blur level. Depending on the current blurMethod(), this parameter
      * has different effects
      * \see blurLevel
-     * \see blurMethod
+     * \see setBlurUnit
+     * \see setBlurMapUnitScale
+     * \see setBlurMethod
      */
-    void setBlurLevel( const int level ) { mBlurLevel = level; }
+    void setBlurLevel( const double level ) { mBlurLevel = level; }
 
     /**
-     * Returns the blur level (strength)
+     * Returns the blur level (radius)
      * \returns blur level. Depending on the current blurMethod(), this parameter
      * has different effects
      * \see setBlurLevel
+     * \see blurUnit
+     * \see blurMapUnitScale
      * \see blurMethod
      */
-    int blurLevel() const { return mBlurLevel; }
+    double blurLevel() const { return mBlurLevel; }
+
+    /**
+     * Sets the units used for the blur level (radius).
+     * \param unit units for blur level
+     * \see blurUnit
+     * \see setBlurLevel
+     * \see setBlurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit ) { mBlurUnit = unit; }
+
+    /**
+     * Returns the units used for the blur level (radius).
+     * \returns units for blur level
+     * \see setBlurUnit
+     * \see blurLevel
+     * \see blurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    QgsUnitTypes::RenderUnit blurUnit() const { return mBlurUnit; }
+
+    /**
+     * Sets the map unit scale used for the blur strength (radius).
+     * \param scale map unit scale for blur strength
+     * \see blurMapUnitScale
+     * \see setBlurLevel
+     * \see setBlurUnit
+     * \since QGIS 3.4.9
+     */
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale ) { mBlurMapUnitScale = scale; }
+
+    /**
+     * Returns the map unit scale used for the blur strength (radius).
+     * \returns map unit scale for blur strength
+     * \see setBlurMapUnitScale
+     * \see blurLevel
+     * \see blurUnit
+     * \since QGIS 3.4.9
+     */
+    const QgsMapUnitScale &blurMapUnitScale() const { return mBlurMapUnitScale; }
 
     /**
      * Sets the blur method (algorithm) to use for performing the blur.
@@ -131,7 +175,9 @@ class CORE_EXPORT QgsBlurEffect : public QgsPaintEffect
 
   private:
 
-    int mBlurLevel = 10;
+    double mBlurLevel = 2.645;
+    QgsUnitTypes::RenderUnit mBlurUnit = QgsUnitTypes::RenderMillimeters;
+    QgsMapUnitScale mBlurMapUnitScale;
     BlurMethod mBlurMethod = StackBlur;
     double mOpacity = 1.0;
     QPainter::CompositionMode mBlendMode = QPainter::CompositionMode_SourceOver;

src/core/effects/qgsgloweffect.cpp

@@ -78,9 +78,16 @@ void QgsGlowEffect::draw( QgsRenderContext &context )
   dtProps.ramp = ramp;
   QgsImageOperation::distanceTransform( im, dtProps );
 
-  if ( mBlurLevel > 0 )
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
+  if ( blurLevel <= 16 )
   {
-    QgsImageOperation::stackBlur( im, mBlurLevel );
+    QgsImageOperation::stackBlur( im, blurLevel );
+  }
+  else
+  {
+    QImage *imb = QgsImageOperation::gaussianBlur( im, blurLevel );
+    im = QImage( *imb );
+    delete imb;
   }
 
   QgsImageOperation::multiplyOpacity( im, mOpacity );
@@ -110,6 +117,8 @@ QgsStringMap QgsGlowEffect::properties() const
   props.insert( QStringLiteral( "blend_mode" ), QString::number( int( mBlendMode ) ) );
   props.insert( QStringLiteral( "opacity" ), QString::number( mOpacity ) );
   props.insert( QStringLiteral( "blur_level" ), QString::number( mBlurLevel ) );
+  props.insert( QStringLiteral( "blur_unit" ), QgsUnitTypes::encodeUnit( mBlurUnit ) );
+  props.insert( QStringLiteral( "blur_unit_scale" ), QgsSymbolLayerUtils::encodeMapUnitScale( mBlurMapUnitScale ) );
   props.insert( QStringLiteral( "spread" ), QString::number( mSpread ) );
   props.insert( QStringLiteral( "spread_unit" ), QgsUnitTypes::encodeUnit( mSpreadUnit ) );
   props.insert( QStringLiteral( "spread_unit_scale" ), QgsSymbolLayerUtils::encodeMapUnitScale( mSpreadMapUnitScale ) );
@@ -150,11 +159,18 @@ void QgsGlowEffect::readProperties( const QgsStringMap &props )
   }
   mEnabled = props.value( QStringLiteral( "enabled" ), QStringLiteral( "1" ) ).toInt();
   mDrawMode = static_cast< QgsPaintEffect::DrawMode >( props.value( QStringLiteral( "draw_mode" ), QStringLiteral( "2" ) ).toInt() );
-  int level = props.value( QStringLiteral( "blur_level" ) ).toInt( &ok );
+  double level = props.value( QStringLiteral( "blur_level" ) ).toDouble( &ok );
   if ( ok )
   {
     mBlurLevel = level;
+    if ( !props.contains( QStringLiteral( "blur_unit" ) ) )
+    {
+      // deal with pre blur unit era by assuming 96 dpi and converting pixel values as millimeters
+      mBlurLevel *= 0.2645;
+    }
   }
+  mBlurUnit = QgsUnitTypes::decodeRenderUnit( props.value( QStringLiteral( "blur_unit" ) ) );
+  mBlurMapUnitScale = QgsSymbolLayerUtils::decodeMapUnitScale( props.value( QStringLiteral( "blur_unit_scale" ) ) );
   double spread = props.value( QStringLiteral( "spread" ) ).toDouble( &ok );
   if ( ok )
   {
@@ -210,10 +226,11 @@ QgsGlowEffect &QgsGlowEffect::operator=( const QgsGlowEffect &rhs )
 
 QRectF QgsGlowEffect::boundingRect( const QRectF &rect, const QgsRenderContext &context ) const
 {
-  //spread size
+  //blur radius and spread size
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
   double spread = context.convertToPainterUnits( mSpread, mSpreadUnit, mSpreadMapUnitScale );
   //plus possible extension due to blur, with a couple of extra pixels thrown in for safety
-  spread += mBlurLevel * 2 + 10;
+  spread += blurLevel * 2 + 10;
   return rect.adjusted( -spread, -spread, spread, spread );
 }
 

src/core/effects/qgsgloweffect.h

@@ -109,21 +109,63 @@ class CORE_EXPORT QgsGlowEffect : public QgsPaintEffect
     const QgsMapUnitScale &spreadMapUnitScale() const { return mSpreadMapUnitScale; }
 
     /**
-     * Sets blur level (strength) for the glow. This can be used to smooth the
+     * Sets blur level (radius) for the glow. This can be used to smooth the
      * output from the glow effect.
-     * \param level blur level. Values between 0 and 16 are valid, with larger
+     * \param level blur level.
-     * values indicating greater blur strength.
      * \see blurLevel
+     * \see setBlurUnit
+     * \see setBlurMapUnitScale
      */
-    void setBlurLevel( const int level ) { mBlurLevel = level; }
+    void setBlurLevel( const double level ) { mBlurLevel = level; }
 
     /**
-     * Returns the blur level (strength) for the glow.
+     * Returns the blur level (radius) for the glow.
-     * \returns blur level. Value will be between 0 and 16, with larger
+     * \returns blur level.
-     * values indicating greater blur strength.
      * \see setBlurLevel
+     * \see blurUnit
+     * \see blurMapUnitScale
      */
-    int blurLevel() const { return mBlurLevel; }
+    double blurLevel() const { return mBlurLevel; }
+
+    /**
+     * Sets the units used for the glow blur level (radius).
+     * \param unit units for blur level
+     * \see blurUnit
+     * \see setBlurLevel
+     * \see setBlurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit ) { mBlurUnit = unit; }
+
+    /**
+     * Returns the units used for the glow blur level (radius).
+     * \returns units for blur level
+     * \see setBlurUnit
+     * \see blurLevel
+     * \see blurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    QgsUnitTypes::RenderUnit blurUnit() const { return mBlurUnit; }
+
+    /**
+     * Sets the map unit scale used for the glow blur strength (radius).
+     * \param scale map unit scale for blur strength
+     * \see blurMapUnitScale
+     * \see setBlurLevel
+     * \see setBlurUnit
+     * \since QGIS 3.4.9
+     */
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale ) { mBlurMapUnitScale = scale; }
+
+    /**
+     * Returns the map unit scale used for the glow blur strength (radius).
+     * \returns map unit scale for blur strength
+     * \see setBlurMapUnitScale
+     * \see blurLevel
+     * \see blurUnit
+     * \since QGIS 3.4.9
+     */
+    const QgsMapUnitScale &blurMapUnitScale() const { return mBlurMapUnitScale; }
 
     /**
      * Sets the \a opacity for the effect.
@@ -235,7 +277,9 @@ class CORE_EXPORT QgsGlowEffect : public QgsPaintEffect
     QgsUnitTypes::RenderUnit mSpreadUnit = QgsUnitTypes::RenderMillimeters;
     QgsMapUnitScale mSpreadMapUnitScale;
     QgsColorRamp *mRamp = nullptr;
-    int mBlurLevel = 3;
+    double mBlurLevel = 2.645;
+    QgsUnitTypes::RenderUnit mBlurUnit = QgsUnitTypes::RenderMillimeters;
+    QgsMapUnitScale mBlurMapUnitScale;
     double mOpacity = 0.5;
     QColor mColor;
     QPainter::CompositionMode mBlendMode = QPainter::CompositionMode_SourceOver;

src/core/effects/qgsshadoweffect.cpp

@@ -45,7 +45,18 @@ void QgsShadowEffect::draw( QgsRenderContext &context )
   }
 
   QgsImageOperation::overlayColor( colorisedIm, mColor );
-  QgsImageOperation::stackBlur( colorisedIm, mBlurLevel );
+
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
+  if ( blurLevel <= 16 )
+  {
+    QgsImageOperation::stackBlur( colorisedIm, blurLevel );
+  }
+  else
+  {
+    QImage *imb = QgsImageOperation::gaussianBlur( colorisedIm, blurLevel );
+    colorisedIm = QImage( *imb );
+    delete imb;
+  }
 
   double offsetDist = context.convertToPainterUnits( mOffsetDist, mOffsetUnit, mOffsetMapUnitScale );
 
@@ -88,6 +99,8 @@ QgsStringMap QgsShadowEffect::properties() const
   props.insert( QStringLiteral( "blend_mode" ), QString::number( int( mBlendMode ) ) );
   props.insert( QStringLiteral( "opacity" ), QString::number( mOpacity ) );
   props.insert( QStringLiteral( "blur_level" ), QString::number( mBlurLevel ) );
+  props.insert( QStringLiteral( "blur_unit" ), QgsUnitTypes::encodeUnit( mBlurUnit ) );
+  props.insert( QStringLiteral( "blur_unit_scale" ), QgsSymbolLayerUtils::encodeMapUnitScale( mBlurMapUnitScale ) );
   props.insert( QStringLiteral( "offset_angle" ), QString::number( mOffsetAngle ) );
   props.insert( QStringLiteral( "offset_distance" ), QString::number( mOffsetDist ) );
   props.insert( QStringLiteral( "offset_unit" ), QgsUnitTypes::encodeUnit( mOffsetUnit ) );
@@ -122,11 +135,18 @@ void QgsShadowEffect::readProperties( const QgsStringMap &props )
   }
   mEnabled = props.value( QStringLiteral( "enabled" ), QStringLiteral( "1" ) ).toInt();
   mDrawMode = static_cast< QgsPaintEffect::DrawMode >( props.value( QStringLiteral( "draw_mode" ), QStringLiteral( "2" ) ).toInt() );
-  int level = props.value( QStringLiteral( "blur_level" ) ).toInt( &ok );
+  double level = props.value( QStringLiteral( "blur_level" ) ).toDouble( &ok );
   if ( ok )
   {
     mBlurLevel = level;
+    if ( !props.contains( QStringLiteral( "blur_unit" ) ) )
+    {
+      // deal with pre blur unit era by assuming 96 dpi and converting pixel values as millimeters
+      mBlurLevel *= 0.2645;
+    }
   }
+  mBlurUnit = QgsUnitTypes::decodeRenderUnit( props.value( QStringLiteral( "blur_unit" ) ) );
+  mBlurMapUnitScale = QgsSymbolLayerUtils::decodeMapUnitScale( props.value( QStringLiteral( "blur_unit_scale" ) ) );
   int angle = props.value( QStringLiteral( "offset_angle" ) ).toInt( &ok );
   if ( ok )
   {
@@ -147,10 +167,11 @@ void QgsShadowEffect::readProperties( const QgsStringMap &props )
 
 QRectF QgsShadowEffect::boundingRect( const QRectF &rect, const QgsRenderContext &context ) const
 {
-  //offset distance
+  //blur radius and offset distance
+  int blurLevel = std::round( context.convertToPainterUnits( mBlurLevel, mBlurUnit, mBlurMapUnitScale ) );
   double spread = context.convertToPainterUnits( mOffsetDist, mOffsetUnit, mOffsetMapUnitScale );
   //plus possible extension due to blur, with a couple of extra pixels thrown in for safety
-  spread += mBlurLevel * 2 + 10;
+  spread += blurLevel * 2 + 10;
   return rect.adjusted( -spread, -spread, spread, spread );
 }
 

src/core/effects/qgsshadoweffect.h

@@ -42,20 +42,64 @@ class CORE_EXPORT QgsShadowEffect : public QgsPaintEffect
     void readProperties( const QgsStringMap &props ) override;
 
     /**
-     * Sets blur level (strength) for the shadow.
+     * Sets blur level (radius) for the shadow.
-     * \param level blur level. Values between 0 and 16 are valid, with larger
+     * \param level blur level.
      * values indicating greater blur strength.
      * \see blurLevel
+     * \see setBlurUnit
+     * \see setBlurMapUnitScale
      */
-    void setBlurLevel( const int level ) { mBlurLevel = level; }
+    void setBlurLevel( const double level ) { mBlurLevel = level; }
 
     /**
-     * Returns the blur level (strength) for the shadow.
+     * Returns the blur level (radius) for the shadow.
-     * \returns blur level. Value will be between 0 and 16, with larger
+     * \returns blur level.
      * values indicating greater blur strength.
      * \see setBlurLevel
+     * \see blurUnit
+     * \see blurMapUnitScale
      */
-    int blurLevel() const { return mBlurLevel; }
+    double blurLevel() const { return mBlurLevel; }
+
+    /**
+     * Sets the units used for the shadow blur level (radius).
+     * \param unit units for blur level
+     * \see blurUnit
+     * \see setBlurLevel
+     * \see setBlurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    void setBlurUnit( const QgsUnitTypes::RenderUnit unit ) { mBlurUnit = unit; }
+
+    /**
+     * Returns the units used for the shadow blur level (radius).
+     * \returns units for blur level
+     * \see setBlurUnit
+     * \see blurLevel
+     * \see blurMapUnitScale
+     * \since QGIS 3.4.9
+     */
+    QgsUnitTypes::RenderUnit blurUnit() const { return mBlurUnit; }
+
+    /**
+     * Sets the map unit scale used for the shadow blur strength (radius).
+     * \param scale map unit scale for blur strength
+     * \see blurMapUnitScale
+     * \see setBlurLevel
+     * \see setBlurUnit
+     * \since QGIS 3.4.9
+     */
+    void setBlurMapUnitScale( const QgsMapUnitScale &scale ) { mBlurMapUnitScale = scale; }
+
+    /**
+     * Returns the map unit scale used for the shadow blur strength (radius).
+     * \returns map unit scale for blur strength
+     * \see setBlurMapUnitScale
+     * \see blurLevel
+     * \see blurUnit
+     * \since QGIS 3.4.9
+     */
+    const QgsMapUnitScale &blurMapUnitScale() const { return mBlurMapUnitScale; }
 
     /**
      * Sets the angle for offsetting the shadow.
@@ -186,7 +230,9 @@ class CORE_EXPORT QgsShadowEffect : public QgsPaintEffect
      */
     virtual bool exteriorShadow() const = 0;
 
-    int mBlurLevel = 10;
+    double mBlurLevel = 2.645;
+    QgsUnitTypes::RenderUnit mBlurUnit = QgsUnitTypes::RenderMillimeters;
+    QgsMapUnitScale mBlurMapUnitScale;
     int mOffsetAngle = 135;
     double mOffsetDist = 2.0;
     QgsUnitTypes::RenderUnit mOffsetUnit = QgsUnitTypes::RenderMillimeters;

src/gui/effects/qgspainteffectwidget.cpp

@@ -117,12 +117,16 @@ QgsBlurWidget::QgsBlurWidget( QWidget *parent )
 {
   setupUi( this );
   connect( mBlurTypeCombo, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsBlurWidget::mBlurTypeCombo_currentIndexChanged );
-  connect( mBlurStrengthSpnBx, static_cast< void ( QSpinBox::* )( int ) >( &QSpinBox::valueChanged ), this, &QgsBlurWidget::mBlurStrengthSpnBx_valueChanged );
+  connect( mBlurStrengthSpnBx, static_cast< void ( QDoubleSpinBox::* )( double ) >( &QDoubleSpinBox::valueChanged ), this, &QgsBlurWidget::mBlurStrengthSpnBx_valueChanged );
+  connect( mBlurUnitWidget, &QgsUnitSelectionWidget::changed, this, &QgsBlurWidget::mBlurUnitWidget_changed );
   connect( mDrawModeComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsBlurWidget::mDrawModeComboBox_currentIndexChanged );
   connect( mBlendCmbBx, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsBlurWidget::mBlendCmbBx_currentIndexChanged );
 
-  mBlurTypeCombo->addItem( tr( "Stack blur (fast)" ), QgsBlurEffect::StackBlur );
+  mBlurTypeCombo->addItem( tr( "Stack blur (fast, doesn't support high dpi)" ), QgsBlurEffect::StackBlur );
-  mBlurTypeCombo->addItem( tr( "Gaussian blur (quality)" ), QgsBlurEffect::GaussianBlur );
+  mBlurTypeCombo->addItem( tr( "Gaussian blur (quality, supports high dpi)" ), QgsBlurEffect::GaussianBlur );
+
+  mBlurUnitWidget->setUnits( QgsUnitTypes::RenderUnitList() << QgsUnitTypes::RenderMillimeters << QgsUnitTypes::RenderPixels << QgsUnitTypes::RenderMapUnits
+                             << QgsUnitTypes::RenderPoints << QgsUnitTypes::RenderInches );
 
   initGui();
   connect( mOpacityWidget, &QgsOpacityWidget::opacityChanged, this, &QgsBlurWidget::opacityChanged );
@@ -187,7 +191,7 @@ void QgsBlurWidget::mBlurTypeCombo_currentIndexChanged( int index )
   emit changed();
 }
 
-void QgsBlurWidget::mBlurStrengthSpnBx_valueChanged( int value )
+void QgsBlurWidget::mBlurStrengthSpnBx_valueChanged( double value )
 {
   if ( !mEffect )
     return;
@@ -196,6 +200,18 @@ void QgsBlurWidget::mBlurStrengthSpnBx_valueChanged( int value )
   emit changed();
 }
 
+void QgsBlurWidget::mBlurUnitWidget_changed()
+{
+  if ( !mEffect )
+  {
+    return;
+  }
+
+  mEffect->setBlurUnit( mBlurUnitWidget->unit() );
+  mEffect->setBlurMapUnitScale( mBlurUnitWidget->getMapUnitScale() );
+  emit changed();
+}
+
 void QgsBlurWidget::opacityChanged( double value )
 {
   if ( !mEffect )
@@ -244,7 +260,8 @@ QgsShadowEffectWidget::QgsShadowEffectWidget( QWidget *parent )
   connect( mShadowColorBtn, &QgsColorButton::colorChanged, this, &QgsShadowEffectWidget::mShadowColorBtn_colorChanged );
   connect( mDrawModeComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsShadowEffectWidget::mDrawModeComboBox_currentIndexChanged );
   connect( mShadowBlendCmbBx, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsShadowEffectWidget::mShadowBlendCmbBx_currentIndexChanged );
-  connect( mShadowRadiuSpnBx, static_cast< void ( QSpinBox::* )( int ) >( &QSpinBox::valueChanged ), this, &QgsShadowEffectWidget::mShadowRadiuSpnBx_valueChanged );
+  connect( mShadowRadiuSpnBx, static_cast< void ( QDoubleSpinBox::* )( double ) >( &QDoubleSpinBox::valueChanged ), this, &QgsShadowEffectWidget::mShadowRadiuSpnBx_valueChanged );
+  connect( mBlurUnitWidget, &QgsUnitSelectionWidget::changed, this, &QgsShadowEffectWidget::mBlurUnitWidget_changed );
 
   mShadowColorBtn->setAllowOpacity( false );
   mShadowColorBtn->setColorDialogTitle( tr( "Select Shadow Color" ) );
@@ -253,6 +270,8 @@ QgsShadowEffectWidget::QgsShadowEffectWidget( QWidget *parent )
 
   mOffsetUnitWidget->setUnits( QgsUnitTypes::RenderUnitList() << QgsUnitTypes::RenderMillimeters << QgsUnitTypes::RenderPixels << QgsUnitTypes::RenderMapUnits
                                << QgsUnitTypes::RenderPoints << QgsUnitTypes::RenderInches );
+  mBlurUnitWidget->setUnits( QgsUnitTypes::RenderUnitList() << QgsUnitTypes::RenderMillimeters << QgsUnitTypes::RenderPixels << QgsUnitTypes::RenderMapUnits
+                             << QgsUnitTypes::RenderPoints << QgsUnitTypes::RenderInches );
 
   initGui();
 
@@ -283,6 +302,8 @@ void QgsShadowEffectWidget::initGui()
   mOffsetUnitWidget->setUnit( mEffect->offsetUnit() );
   mOffsetUnitWidget->setMapUnitScale( mEffect->offsetMapUnitScale() );
   mShadowRadiuSpnBx->setValue( mEffect->blurLevel() );
+  mBlurUnitWidget->setUnit( mEffect->blurUnit() );
+  mBlurUnitWidget->setMapUnitScale( mEffect->blurMapUnitScale() );
   mOpacityWidget->setOpacity( mEffect->opacity() );
   mShadowColorBtn->setColor( mEffect->color() );
   mShadowBlendCmbBx->setBlendMode( mEffect->blendMode() );
@@ -298,6 +319,7 @@ void QgsShadowEffectWidget::blockSignals( const bool block )
   mShadowOffsetSpnBx->blockSignals( block );
   mOffsetUnitWidget->blockSignals( block );
   mShadowRadiuSpnBx->blockSignals( block );
+  mBlurUnitWidget->blockSignals( block );
   mOpacityWidget->blockSignals( block );
   mShadowColorBtn->blockSignals( block );
   mShadowBlendCmbBx->blockSignals( block );
@@ -361,7 +383,7 @@ void QgsShadowEffectWidget::mShadowColorBtn_colorChanged( const QColor &color )
   emit changed();
 }
 
-void QgsShadowEffectWidget::mShadowRadiuSpnBx_valueChanged( int value )
+void QgsShadowEffectWidget::mShadowRadiuSpnBx_valueChanged( double value )
 {
   if ( !mEffect )
     return;
@@ -370,6 +392,18 @@ void QgsShadowEffectWidget::mShadowRadiuSpnBx_valueChanged( int value )
   emit changed();
 }
 
+void QgsShadowEffectWidget::mBlurUnitWidget_changed()
+{
+  if ( !mEffect )
+  {
+    return;
+  }
+
+  mEffect->setBlurUnit( mBlurUnitWidget->unit() );
+  mEffect->setBlurMapUnitScale( mBlurUnitWidget->getMapUnitScale() );
+  emit changed();
+}
+
 void QgsShadowEffectWidget::mDrawModeComboBox_currentIndexChanged( int index )
 {
   Q_UNUSED( index )
@@ -408,7 +442,8 @@ QgsGlowWidget::QgsGlowWidget( QWidget *parent )
   connect( mColorBtn, &QgsColorButton::colorChanged, this, &QgsGlowWidget::mColorBtn_colorChanged );
   connect( mBlendCmbBx, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsGlowWidget::mBlendCmbBx_currentIndexChanged );
   connect( mDrawModeComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsGlowWidget::mDrawModeComboBox_currentIndexChanged );
-  connect( mBlurRadiusSpnBx, static_cast< void ( QSpinBox::* )( int ) >( &QSpinBox::valueChanged ), this, &QgsGlowWidget::mBlurRadiusSpnBx_valueChanged );
+  connect( mBlurRadiusSpnBx, static_cast< void ( QDoubleSpinBox::* )( double ) >( &QDoubleSpinBox::valueChanged ), this, &QgsGlowWidget::mBlurRadiusSpnBx_valueChanged );
+  connect( mBlurUnitWidget, &QgsUnitSelectionWidget::changed, this, &QgsGlowWidget::mBlurUnitWidget_changed );
 
   mColorBtn->setAllowOpacity( false );
   mColorBtn->setColorDialogTitle( tr( "Select Glow Color" ) );
@@ -416,6 +451,8 @@ QgsGlowWidget::QgsGlowWidget( QWidget *parent )
 
   mSpreadUnitWidget->setUnits( QgsUnitTypes::RenderUnitList() << QgsUnitTypes::RenderMillimeters << QgsUnitTypes::RenderPixels << QgsUnitTypes::RenderMapUnits
                                << QgsUnitTypes::RenderPoints << QgsUnitTypes::RenderInches );
+  mBlurUnitWidget->setUnits( QgsUnitTypes::RenderUnitList() << QgsUnitTypes::RenderMillimeters << QgsUnitTypes::RenderPixels << QgsUnitTypes::RenderMapUnits
+                             << QgsUnitTypes::RenderPoints << QgsUnitTypes::RenderInches );
 
   btnColorRamp->setShowGradientOnly( true );
 
@@ -538,7 +575,7 @@ void QgsGlowWidget::mColorBtn_colorChanged( const QColor &color )
   emit changed();
 }
 
-void QgsGlowWidget::mBlurRadiusSpnBx_valueChanged( int value )
+void QgsGlowWidget::mBlurRadiusSpnBx_valueChanged( double value )
 {
   if ( !mEffect )
     return;
@@ -547,6 +584,18 @@ void QgsGlowWidget::mBlurRadiusSpnBx_valueChanged( int value )
   emit changed();
 }
 
+void QgsGlowWidget::mBlurUnitWidget_changed()
+{
+  if ( !mEffect )
+  {
+    return;
+  }
+
+  mEffect->setBlurUnit( mBlurUnitWidget->unit() );
+  mEffect->setBlurMapUnitScale( mBlurUnitWidget->getMapUnitScale() );
+  emit changed();
+}
+
 void QgsGlowWidget::mBlendCmbBx_currentIndexChanged( int index )
 {
   Q_UNUSED( index )

src/gui/effects/qgspainteffectwidget.h

@@ -120,7 +120,8 @@ class GUI_EXPORT QgsBlurWidget : public QgsPaintEffectWidget, private Ui::Widget
   private slots:
 
     void mBlurTypeCombo_currentIndexChanged( int index );
-    void mBlurStrengthSpnBx_valueChanged( int value );
+    void mBlurStrengthSpnBx_valueChanged( double value );
+    void mBlurUnitWidget_changed();
     void opacityChanged( double value );
     void mDrawModeComboBox_currentIndexChanged( int index );
     void mBlendCmbBx_currentIndexChanged( int index );
@@ -161,7 +162,8 @@ class GUI_EXPORT QgsShadowEffectWidget : public QgsPaintEffectWidget, private Ui
     void mShadowColorBtn_colorChanged( const QColor &color );
     void mDrawModeComboBox_currentIndexChanged( int index );
     void mShadowBlendCmbBx_currentIndexChanged( int index );
-    void mShadowRadiuSpnBx_valueChanged( int value );
+    void mShadowRadiuSpnBx_valueChanged( double value );
+    void mBlurUnitWidget_changed();
 };
 
 
@@ -196,7 +198,8 @@ class GUI_EXPORT QgsGlowWidget : public QgsPaintEffectWidget, private Ui::Widget
     void mColorBtn_colorChanged( const QColor &color );
     void mBlendCmbBx_currentIndexChanged( int index );
     void mDrawModeComboBox_currentIndexChanged( int index );
-    void mBlurRadiusSpnBx_valueChanged( int value );
+    void mBlurRadiusSpnBx_valueChanged( double value );
+    void mBlurUnitWidget_changed();
     void applyColorRamp();
 
 };

src/ui/effects/widget_blur.ui

@@ -31,7 +31,7 @@
         <property name="bottomMargin">
          <number>0</number>
         </property>
-        <item row="0" column="1">
+        <item row="0" column="1" colspan="2">
          <widget class="QComboBox" name="mBlurTypeCombo"/>
         </item>
         <item row="2" column="0">
@@ -48,19 +48,41 @@
           </property>
          </widget>
         </item>
-        <item row="3" column="1">
+        <item row="3" column="1" colspan="2">
          <widget class="QgsBlendModeComboBox" name="mBlendCmbBx"/>
         </item>
         <item row="1" column="1">
-         <widget class="QgsSpinBox" name="mBlurStrengthSpnBx">
+         <widget class="QgsDoubleSpinBox" name="mBlurStrengthSpnBx">
+          <property name="decimals">
+           <number>4</number>
+          </property>
+          <property name="minimum">
+           <double>0.000000000000000</double>
+          </property>
           <property name="maximum">
-           <number>16</number>
+           <double>9999999.000000000000000</double>
+          </property>
+          <property name="singleStep">
+           <double>0.200000000000000</double>
           </property>
           <property name="showClearButton" stdset="0">
            <bool>false</bool>
           </property>
          </widget>
         </item>
+        <item row="1" column="2">
+         <widget class="QgsUnitSelectionWidget" name="mBlurUnitWidget" native="true">
+          <property name="minimumSize">
+           <size>
+            <width>0</width>
+            <height>0</height>
+           </size>
+          </property>
+          <property name="focusPolicy">
+           <enum>Qt::StrongFocus</enum>
+          </property>
+         </widget>
+        </item>
         <item row="0" column="0">
          <widget class="QLabel" name="label">
           <property name="text">
@@ -75,7 +97,7 @@
           </property>
          </widget>
         </item>
-        <item row="4" column="1">
+        <item row="4" column="1" colspan="2">
          <widget class="QgsEffectDrawModeComboBox" name="mDrawModeComboBox"/>
         </item>
         <item row="4" column="0">
@@ -85,7 +107,7 @@
           </property>
          </widget>
         </item>
-        <item row="2" column="1">
+        <item row="2" column="1" colspan="2">
          <widget class="QgsOpacityWidget" name="mOpacityWidget" native="true">
           <property name="focusPolicy">
            <enum>Qt::StrongFocus</enum>
@@ -114,9 +136,9 @@
  </widget>
  <customwidgets>
   <customwidget>
-   <class>QgsSpinBox</class>
+   <class>QgsDoubleSpinBox</class>
-   <extends>QSpinBox</extends>
+   <extends>QDoubleSpinBox</extends>
-   <header>qgsspinbox.h</header>
+   <header>qgsdoublespinbox.h</header>
   </customwidget>
   <customwidget>
    <class>QgsBlendModeComboBox</class>

src/ui/effects/widget_glow.ui

@@ -84,6 +84,9 @@
           <property name="maximum">
            <double>9999999.000000000000000</double>
           </property>
+          <property name="singleStep">
+           <double>0.200000000000000</double>
+          </property>
           <property name="showClearButton" stdset="0">
            <bool>false</bool>
           </property>
@@ -102,16 +105,38 @@
           </property>
          </widget>
         </item>
-        <item row="1" column="1" colspan="2">
+        <item row="1" column="1">
-         <widget class="QgsSpinBox" name="mBlurRadiusSpnBx">
+         <widget class="QgsDoubleSpinBox" name="mBlurRadiusSpnBx">
+          <property name="decimals">
+           <number>4</number>
+          </property>
+          <property name="minimum">
+           <double>0.000000000000000</double>
+          </property>
           <property name="maximum">
-           <number>16</number>
+           <double>9999999.000000000000000</double>
+          </property>
+          <property name="singleStep">
+           <double>0.200000000000000</double>
           </property>
           <property name="showClearButton" stdset="0">
            <bool>false</bool>
           </property>
          </widget>
         </item>
+        <item row="1" column="2">
+         <widget class="QgsUnitSelectionWidget" name="mBlurUnitWidget" native="true">
+          <property name="minimumSize">
+           <size>
+            <width>0</width>
+            <height>0</height>
+           </size>
+          </property>
+          <property name="focusPolicy">
+           <enum>Qt::StrongFocus</enum>
+          </property>
+         </widget>
+        </item>
         <item row="4" column="1" colspan="2">
          <widget class="QgsColorRampButton" name="btnColorRamp">
           <property name="sizePolicy">

src/ui/effects/widget_shadoweffect.ui

@@ -42,6 +42,9 @@
           <property name="maximum">
            <double>9999999.000000000000000</double>
           </property>
+          <property name="singleStep">
+           <double>0.200000000000000</double>
+          </property>
           <property name="showClearButton" stdset="0">
            <bool>false</bool>
           </property>
@@ -107,16 +110,38 @@
         <item row="5" column="1" colspan="2">
          <widget class="QgsBlendModeComboBox" name="mShadowBlendCmbBx"/>
         </item>
-        <item row="2" column="1" colspan="2">
+        <item row="2" column="1">
-         <widget class="QgsSpinBox" name="mShadowRadiuSpnBx">
+         <widget class="QgsDoubleSpinBox" name="mShadowRadiuSpnBx">
+          <property name="decimals">
+           <number>4</number>
+          </property>
+          <property name="minimum">
+           <double>0.000000000000000</double>
+          </property>
           <property name="maximum">
-           <number>16</number>
+           <double>9999999.000000000000000</double>
+          </property>
+          <property name="singleStep">
+           <double>0.200000000000000</double>
           </property>
           <property name="showClearButton" stdset="0">
            <bool>false</bool>
           </property>
          </widget>
         </item>
+        <item row="2" column="2">
+         <widget class="QgsUnitSelectionWidget" name="mBlurUnitWidget" native="true">
+          <property name="minimumSize">
+           <size>
+            <width>0</width>
+            <height>0</height>
+           </size>
+          </property>
+          <property name="focusPolicy">
+           <enum>Qt::StrongFocus</enum>
+          </property>
+         </widget>
+        </item>
         <item row="0" column="1" colspan="2">
          <layout class="QHBoxLayout" name="horizontalLayout_24">
           <item>

tests/src/core/testqgspainteffect.cpp

@@ -360,8 +360,8 @@ void TestQgsPaintEffect::blur()
   QCOMPARE( effect->opacity(), 0.5 );
   effect->setEnabled( false );
   QCOMPARE( effect->enabled(), false );
-  effect->setBlurLevel( 6 );
+  effect->setBlurLevel( 6.0 );
-  QCOMPARE( effect->blurLevel(), 6 );
+  QCOMPARE( effect->blurLevel(), 6.0 );
   effect->setBlurMethod( QgsBlurEffect::GaussianBlur );
   QCOMPARE( effect->blurMethod(), QgsBlurEffect::GaussianBlur );
   effect->setDrawMode( QgsPaintEffect::Modifier );
@@ -434,8 +434,8 @@ void TestQgsPaintEffect::dropShadow()
   QCOMPARE( effect->opacity(), 0.5 );
   effect->setEnabled( false );
   QCOMPARE( effect->enabled(), false );
-  effect->setBlurLevel( 6 );
+  effect->setBlurLevel( 6.0 );
-  QCOMPARE( effect->blurLevel(), 6 );
+  QCOMPARE( effect->blurLevel(), 6.0 );
   effect->setOffsetAngle( 77 );
   QCOMPARE( effect->offsetAngle(), 77 );
   effect->setOffsetDistance( 9.7 );
@@ -531,8 +531,8 @@ void TestQgsPaintEffect::glow()
   QCOMPARE( effect->opacity(), 0.5 );
   effect->setEnabled( false );
   QCOMPARE( effect->enabled(), false );
-  effect->setBlurLevel( 6 );
+  effect->setBlurLevel( 6.0 );
-  QCOMPARE( effect->blurLevel(), 6 );
+  QCOMPARE( effect->blurLevel(), 6.0 );
   effect->setSpread( 7.8 );
   QCOMPARE( effect->spread(), 7.8 );
   effect->setSpreadUnit( QgsUnitTypes::RenderMapUnits );

tests/src/python/test_qgstextformatwidget.py

@@ -41,7 +41,7 @@ class PyQgsTextFormatWidget(unittest.TestCase):
         s.setOpacity(0.5)
         s.setJoinStyle(Qt.RoundJoin)
         s.setBlendMode(QPainter.CompositionMode_Difference)
-        s.setPaintEffect(QgsBlurEffect.create({'blur_level': '10', 'enabled': '1'}))
+        s.setPaintEffect(QgsBlurEffect.create({'blur_level': '2.0', 'blur_unit': QgsUnitTypes.encodeUnit(QgsUnitTypes.RenderMillimeters), 'enabled': '1'}))
         return s
 
     def checkBufferSettings(self, s):
@@ -56,7 +56,7 @@ class PyQgsTextFormatWidget(unittest.TestCase):
         self.assertEqual(s.joinStyle(), Qt.RoundJoin)
         self.assertEqual(s.blendMode(), QPainter.CompositionMode_Difference)
         self.assertTrue(s.paintEffect())
-        self.assertEqual(s.paintEffect().blurLevel(), 10)
+        self.assertEqual(s.paintEffect().blurLevel(), 2.0)
 
     def createBackgroundSettings(self):
         s = QgsTextBackgroundSettings()
@@ -83,7 +83,7 @@ class PyQgsTextFormatWidget(unittest.TestCase):
         s.setStrokeWidth(7)
         s.setStrokeWidthUnit(QgsUnitTypes.RenderMapUnits)
         s.setStrokeWidthMapUnitScale(QgsMapUnitScale(QgsMapUnitScale(25, 26)))
-        s.setPaintEffect(QgsBlurEffect.create({'blur_level': '6', 'enabled': '1'}))
+        s.setPaintEffect(QgsBlurEffect.create({'blur_level': '6.0', 'blur_unit': QgsUnitTypes.encodeUnit(QgsUnitTypes.RenderMillimeters), 'enabled': '1'}))
         return s
 
     def checkBackgroundSettings(self, s):
@@ -112,7 +112,7 @@ class PyQgsTextFormatWidget(unittest.TestCase):
         self.assertEqual(s.strokeWidthUnit(), QgsUnitTypes.RenderMapUnits)
         self.assertEqual(s.strokeWidthMapUnitScale(), QgsMapUnitScale(25, 26))
         self.assertTrue(s.paintEffect())
-        self.assertEqual(s.paintEffect().blurLevel(), 6)
+        self.assertEqual(s.paintEffect().blurLevel(), 6.0)
 
     def createShadowSettings(self):
         s = QgsTextShadowSettings()