Fix conversion of non rgb gradients to QGradient

qgis · Nov 10, 2021 · b8e4eee · b8e4eee
1 parent 19984d1
commit b8e4eee
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Showing 4 changed files with 96 additions and 7 deletions.
diff --git a/python/core/auto_generated/qgscolorrampimpl.sip.in b/python/core/auto_generated/qgscolorrampimpl.sip.in
@@ -254,7 +254,7 @@ Sets additional info to attach to the gradient ramp (e.g., authorship notes)
 .. seealso:: :py:func:`info`
 %End
 
-    void addStopsToGradient( QGradient *gradient, double opacity = 1 );
+    void addStopsToGradient( QGradient *gradient, double opacity = 1 ) const;
 %Docstring
 Copy color ramp stops to a QGradient
 

diff --git a/src/core/qgscolorrampimpl.cpp b/src/core/qgscolorrampimpl.cpp
@@ -516,7 +516,7 @@ void QgsGradientColorRamp::setStops( const QgsGradientStopsList &stops )
   std::sort( mStops.begin(), mStops.end(), stopLessThan );
 }
 
-void QgsGradientColorRamp::addStopsToGradient( QGradient *gradient, double opacity )
+void QgsGradientColorRamp::addStopsToGradient( QGradient *gradient, double opacity ) const
 {
   //copy color ramp stops to a QGradient
   QColor color1 = mColor1;
@@ -529,15 +529,45 @@ void QgsGradientColorRamp::addStopsToGradient( QGradient *gradient, double opaci
   gradient->setColorAt( 0, color1 );
   gradient->setColorAt( 1, color2 );
 
-  for ( QgsGradientStopsList::const_iterator it = mStops.constBegin();
-        it != mStops.constEnd(); ++it )
+  double lastOffset = 0;
+  for ( const QgsGradientStop &stop : mStops )
   {
-    QColor rampColor = it->color;
+
+    QColor rampColor = stop.color;
     if ( opacity < 1 )
     {
       rampColor.setAlpha( rampColor.alpha() * opacity );
     }
-    gradient->setColorAt( it->offset, rampColor );
+    gradient->setColorAt( stop.offset, rampColor );
+
+    if ( stop.colorSpec() != QColor::Rgb )
+    {
+      // QGradient only supports RGB interpolation. For other color specs we have
+      // to "fake" things by populating the gradient with additional stops
+      for ( double offset = lastOffset + 0.05; offset < stop.offset; offset += 0.05 )
+      {
+        QColor midColor = color( offset );
+        if ( opacity < 1 )
+        {
+          midColor.setAlpha( midColor.alpha() * opacity );
+        }
+        gradient->setColorAt( offset, midColor );
+      }
+    }
+    lastOffset = stop.offset;
+  }
+
+  if ( mColorSpec != QColor::Rgb )
+  {
+    for ( double offset = lastOffset + 0.05; offset < 1; offset += 0.05 )
+    {
+      QColor midColor = color( offset );
+      if ( opacity < 1 )
+      {
+        midColor.setAlpha( midColor.alpha() * opacity );
+      }
+      gradient->setColorAt( offset, midColor );
+    }
   }
 }
 

diff --git a/src/core/qgscolorrampimpl.h b/src/core/qgscolorrampimpl.h
@@ -259,7 +259,7 @@ class CORE_EXPORT QgsGradientColorRamp : public QgsColorRamp
      * by this factor before adding to the gradient.
      * \since QGIS 2.1
      */
-    void addStopsToGradient( QGradient *gradient, double opacity = 1 );
+    void addStopsToGradient( QGradient *gradient, double opacity = 1 ) const;
 
     /**
      * Returns the color specification in which the color component interpolation will occur.

diff --git a/tests/src/python/test_qgscolorramp.py b/tests/src/python/test_qgscolorramp.py
@@ -331,6 +331,65 @@ def testQgsGradientColorRamp(self):
         self.assertEqual(g.stops()[2], (0.9, QColor(40, 60, 100, 127)))
         self.assertEqual(g.stops()[3], (1.0, QColor(0, 200, 0, 127)))
 
+        # add to gradient, non-RGB color model
+        g = QGradient()
+        rr = QgsGradientColorRamp(QColor.fromHsvF(0.2, 0.3, 0.4), QColor.fromHsvF(0.8, 1.0, 0.6))
+        rr.setColorSpec(QColor.Hsv)
+        rr.addStopsToGradient(g, 0.5)
+        res = [(round(stop[0], 2), round(stop[1].hsvHueF(), 2), round(stop[1].hsvSaturationF(), 2),
+                round(stop[1].valueF(), 2), round(stop[1].alphaF(), 2)) for stop in g.stops()]
+        self.assertEqual(res, [(0.0, 0.2, 0.3, 0.4, 0.5),
+                               (0.05, 0.23, 0.34, 0.41, 0.5),
+                               (0.1, 0.26, 0.37, 0.42, 0.5),
+                               (0.15, 0.29, 0.41, 0.43, 0.5),
+                               (0.2, 0.32, 0.44, 0.44, 0.5),
+                               (0.25, 0.35, 0.48, 0.45, 0.5),
+                               (0.3, 0.38, 0.51, 0.46, 0.5),
+                               (0.35, 0.41, 0.55, 0.47, 0.5),
+                               (0.4, 0.44, 0.58, 0.48, 0.5),
+                               (0.45, 0.47, 0.61, 0.49, 0.5),
+                               (0.5, 0.5, 0.65, 0.5, 0.5),
+                               (0.55, 0.53, 0.69, 0.51, 0.5),
+                               (0.6, 0.56, 0.72, 0.52, 0.5),
+                               (0.65, 0.59, 0.76, 0.53, 0.5),
+                               (0.7, 0.62, 0.79, 0.54, 0.5),
+                               (0.75, 0.65, 0.83, 0.55, 0.5),
+                               (0.8, 0.68, 0.86, 0.56, 0.5),
+                               (0.85, 0.71, 0.9, 0.57, 0.5),
+                               (0.9, 0.74, 0.93, 0.58, 0.5),
+                               (0.95, 0.77, 0.96, 0.59, 0.5),
+                               (1.0, 0.8, 1.0, 0.6, 0.5)])
+        # with stops
+        stop = QgsGradientStop(0.6, QColor.fromHsvF(0.1, 0.7, 0.3, 0.4))
+        stop.setColorSpec(QColor.Hsl)
+        stop.setDirection(Qgis.AngularDirection.Clockwise)
+        rr.setStops([stop])
+        g = QGradient()
+        rr.addStopsToGradient(g, 0.5)
+        res = [(round(stop[0], 2), round(stop[1].hsvHueF(), 2), round(stop[1].hsvSaturationF(), 2),
+                round(stop[1].valueF(), 2), round(stop[1].alphaF(), 2)) for stop in g.stops()]
+        self.assertEqual(res, [(0.0, 0.2, 0.3, 0.4, 0.5),
+                               (0.05, 0.19, 0.34, 0.4, 0.47),
+                               (0.1, 0.18, 0.38, 0.39, 0.45),
+                               (0.15, 0.17, 0.42, 0.38, 0.42),
+                               (0.2, 0.17, 0.46, 0.38, 0.4),
+                               (0.25, 0.16, 0.49, 0.37, 0.37),
+                               (0.3, 0.15, 0.53, 0.36, 0.35),
+                               (0.35, 0.14, 0.56, 0.35, 0.33),
+                               (0.4, 0.13, 0.59, 0.35, 0.3),
+                               (0.45, 0.12, 0.62, 0.33, 0.27),
+                               (0.5, 0.12, 0.65, 0.32, 0.25),
+                               (0.55, 0.11, 0.67, 0.31, 0.22),
+                               (0.6, 0.1, 0.7, 0.3, 0.2),
+                               (0.65, 0.19, 0.74, 0.34, 0.24),
+                               (0.7, 0.28, 0.78, 0.38, 0.27),
+                               (0.75, 0.36, 0.81, 0.41, 0.31),
+                               (0.8, 0.45, 0.85, 0.45, 0.35),
+                               (0.85, 0.54, 0.89, 0.49, 0.39),
+                               (0.9, 0.62, 0.93, 0.53, 0.42),
+                               (0.95, 0.71, 0.96, 0.56, 0.46),
+                               (1.0, 0.8, 1.0, 0.6, 0.5)])
+
         # test that stops are ordered when setting them
         # first add some out-of-order stops
         r.setStops([QgsGradientStop(0.4, QColor(100, 100, 40)),