[FEATURE] Add a color ramp combo to paletted raster renderer

Allows rapid recoloring of palette to match a color ramp

python/core/raster/qgspalettedrasterrenderer.sip

@@ -32,6 +32,8 @@ class QgsPalettedRasterRenderer : QgsRasterRenderer
     void legendSymbologyItems( QList< QPair< QString, QColor > > &symbolItems /Out/ ) const;
 
     QList<int> usesBands() const;
+    void setSourceColorRamp( QgsColorRamp *ramp /Transfer/ );
+    QgsColorRamp *sourceColorRamp() const;
     static QgsPalettedRasterRenderer::ClassData colorTableToClassData( const QList<QgsColorRampShader::ColorRampItem> &table );
 
   private:

src/core/raster/qgspalettedrasterrenderer.cpp

@@ -18,6 +18,7 @@
 #include "qgspalettedrasterrenderer.h"
 #include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
+#include "qgssymbollayerutils.h"
 
 #include <QColor>
 #include <QDomDocument>
@@ -43,6 +44,9 @@ QgsPalettedRasterRenderer::~QgsPalettedRasterRenderer()
 QgsPalettedRasterRenderer *QgsPalettedRasterRenderer::clone() const
 {
   QgsPalettedRasterRenderer *renderer = new QgsPalettedRasterRenderer( nullptr, mBand, mClassData );
+  if ( mSourceColorRamp )
+    renderer->setSourceColorRamp( mSourceColorRamp->clone() );
+
   renderer->copyCommonProperties( this );
   return renderer;
 }
@@ -78,8 +82,17 @@ QgsRasterRenderer *QgsPalettedRasterRenderer::create( const QDomElement &elem, Q
       classData.insert( value, Class( color, label ) );
     }
   }
+
   QgsPalettedRasterRenderer *r = new QgsPalettedRasterRenderer( input, bandNumber, classData );
   r->readXml( elem );
+
+  // try to load color ramp (optional)
+  QDomElement sourceColorRampElem = elem.firstChildElement( QStringLiteral( "colorramp" ) );
+  if ( !sourceColorRampElem.isNull() && sourceColorRampElem.attribute( QStringLiteral( "name" ) ) == QLatin1String( "[source]" ) )
+  {
+    r->setSourceColorRamp( QgsSymbolLayerUtils::loadColorRamp( sourceColorRampElem ) );
+  }
+
   return r;
 }
 
@@ -218,6 +231,13 @@ void QgsPalettedRasterRenderer::writeXml( QDomDocument &doc, QDomElement &parent
   }
   rasterRendererElem.appendChild( colorPaletteElem );
 
+  // save source color ramp
+  if ( mSourceColorRamp )
+  {
+    QDomElement colorRampElem = QgsSymbolLayerUtils::saveColorRamp( QStringLiteral( "[source]" ), mSourceColorRamp.get(), doc );
+    rasterRendererElem.appendChild( colorRampElem );
+  }
+
   parentElem.appendChild( rasterRendererElem );
 }
 
@@ -255,6 +275,16 @@ QList<int> QgsPalettedRasterRenderer::usesBands() const
   return bandList;
 }
 
+void QgsPalettedRasterRenderer::setSourceColorRamp( QgsColorRamp *ramp )
+{
+  mSourceColorRamp.reset( ramp );
+}
+
+QgsColorRamp *QgsPalettedRasterRenderer::sourceColorRamp() const
+{
+  return mSourceColorRamp.get();
+}
+
 QgsPalettedRasterRenderer::ClassData QgsPalettedRasterRenderer::colorTableToClassData( const QList<QgsColorRampShader::ColorRampItem> &table )
 {
   QList<QgsColorRampShader::ColorRampItem>::const_iterator colorIt = table.constBegin();

src/core/raster/qgspalettedrasterrenderer.h

@@ -90,6 +90,19 @@ class CORE_EXPORT QgsPalettedRasterRenderer: public QgsRasterRenderer
 
     QList<int> usesBands() const override;
 
+    /**
+     * Set the source color \a ramp. Ownership is transferred to the renderer.
+     * @note added in QGIS 3.0
+     * @see sourceColorRamp()
+     */
+    void setSourceColorRamp( QgsColorRamp *ramp );
+
+    /** Get the source color ramp
+     * @note added in QGIS 3.0
+     * @see setSourceColorRamp()
+     */
+    QgsColorRamp *sourceColorRamp() const;
+
     /**
      * Converts a raster color \a table to paletted renderer class data.
      * @note added in QGIS 3.0
@@ -102,6 +115,8 @@ class CORE_EXPORT QgsPalettedRasterRenderer: public QgsRasterRenderer
     int mMaxColorIndex = -INT_MAX;
     ClassData mClassData;
 
+    //! Source color ramp
+    std::unique_ptr<QgsColorRamp> mSourceColorRamp;
 
     //! Premultiplied color array
     QRgb *mColors = nullptr;

src/gui/raster/qgspalettedrendererwidget.cpp

@@ -20,6 +20,7 @@
 #include "qgsrasterdataprovider.h"
 #include "qgsrasterlayer.h"
 #include "qgscolordialog.h"
+#include "qgssettings.h"
 
 #include <QColorDialog>
 #include <QInputDialog>
@@ -47,6 +48,11 @@ QgsPalettedRendererWidget::QgsPalettedRendererWidget( QgsRasterLayer *layer, con
   connect( mTreeView, &QTreeView::customContextMenuRequested,  [ = ]( const QPoint & ) { contextMenu->exec( QCursor::pos() ); }
          );
 
+  QgsSettings settings;
+  QString defaultPalette = settings.value( QStringLiteral( "Raster/defaultPalette" ), QString() ).toString();
+  btnColorRamp->setColorRampFromName( defaultPalette );
+  connect( btnColorRamp, &QgsColorRampButton::colorRampChanged, this, &QgsPalettedRendererWidget::applyColorRamp );
+
   if ( mRasterLayer )
   {
     QgsRasterDataProvider *provider = mRasterLayer->dataProvider();
@@ -75,7 +81,13 @@ QgsRasterRenderer *QgsPalettedRendererWidget::renderer()
 {
   QgsPalettedRasterRenderer::ClassData classes = mModel->classData();
   int bandNumber = mBandComboBox->currentData().toInt();
-  return new QgsPalettedRasterRenderer( mRasterLayer->dataProvider(), bandNumber, classes );
+
+  QgsPalettedRasterRenderer *r = new QgsPalettedRasterRenderer( mRasterLayer->dataProvider(), bandNumber, classes );
+  if ( !btnColorRamp->isNull() )
+  {
+    r->setSourceColorRamp( btnColorRamp->colorRamp() );
+  }
+  return r;
 }
 
 void QgsPalettedRendererWidget::setFromRenderer( const QgsRasterRenderer *r )
@@ -85,6 +97,17 @@ void QgsPalettedRendererWidget::setFromRenderer( const QgsRasterRenderer *r )
   {
     //read values and colors and fill into tree widget
     mModel->setClassData( pr->classes() );
+
+    if ( pr->sourceColorRamp() )
+    {
+      whileBlocking( btnColorRamp )->setColorRamp( pr->sourceColorRamp() );
+    }
+    else
+    {
+      QgsSettings settings;
+      QString defaultPalette = settings.value( "/Raster/defaultPalette", "Spectral" ).toString();
+      whileBlocking( btnColorRamp )->setColorRampFromName( defaultPalette );
+    }
   }
   else
   {
@@ -95,6 +118,9 @@ void QgsPalettedRendererWidget::setFromRenderer( const QgsRasterRenderer *r )
       QgsPalettedRasterRenderer::ClassData classes = QgsPalettedRasterRenderer::colorTableToClassData( provider->colorTable( mBandComboBox->currentData().toInt() ) );
       mModel->setClassData( classes );
     }
+    QgsSettings settings;
+    QString defaultPalette = settings.value( "/Raster/defaultPalette", "Spectral" ).toString();
+    whileBlocking( btnColorRamp )->setColorRampFromName( defaultPalette );
   }
 }
 
@@ -137,7 +163,14 @@ void QgsPalettedRendererWidget::deleteEntry()
 void QgsPalettedRendererWidget::addEntry()
 {
   disconnect( mModel, &QgsPalettedRendererModel::classesChanged, this, &QgsPalettedRendererWidget::widgetChanged );
-  mModel->insertRow( mModel->rowCount() );
+
+  QColor color( 150, 150, 150 );
+  std::unique_ptr< QgsColorRamp > ramp( btnColorRamp->colorRamp() );
+  if ( ramp )
+  {
+    color = ramp->color( 1.0 );
+  }
+  mModel->addEntry( color );
   connect( mModel, &QgsPalettedRendererModel::classesChanged, this, &QgsPalettedRendererWidget::widgetChanged );
   emit widgetChanged();
 }
@@ -231,6 +264,39 @@ void QgsPalettedRendererWidget::changeLabel()
   }
 }
 
+void QgsPalettedRendererWidget::applyColorRamp()
+{
+  std::unique_ptr< QgsColorRamp > ramp( btnColorRamp->colorRamp() );
+  if ( !ramp )
+  {
+    return;
+  }
+
+  if ( !btnColorRamp->colorRampName().isEmpty() )
+  {
+    // Remember last used color ramp
+    QgsSettings settings;
+    settings.setValue( QStringLiteral( "Raster/defaultPalette" ), btnColorRamp->colorRampName() );
+  }
+
+  disconnect( mModel, &QgsPalettedRendererModel::classesChanged, this, &QgsPalettedRendererWidget::widgetChanged );
+
+  QgsPalettedRasterRenderer::ClassData data = mModel->classData();
+  QgsPalettedRasterRenderer::ClassData::iterator cIt = data.begin();
+
+  double numberOfEntries = data.count();
+  int i = 0;
+  for ( ; cIt != data.end(); ++cIt )
+  {
+    cIt->color = ramp->color( i / numberOfEntries );
+    i++;
+  }
+  mModel->setClassData( data );
+
+  connect( mModel, &QgsPalettedRendererModel::classesChanged, this, &QgsPalettedRendererWidget::widgetChanged );
+  emit widgetChanged();
+}
+
 //
 // QgsPalettedRendererModel
 //
@@ -465,5 +531,11 @@ bool QgsPalettedRendererModel::insertRows( int row, int count, const QModelIndex
   return true;
 }
 
+void QgsPalettedRendererModel::addEntry( const QColor &color )
+{
+  insertRow( rowCount() );
+  setData( index( mData.count() - 1, 1 ), color );
+}
+
 ///@endcond PRIVATE
 

src/gui/raster/qgspalettedrendererwidget.h

@@ -55,6 +55,8 @@ class QgsPalettedRendererModel : public QAbstractTableModel
     bool removeRows( int row, int count, const QModelIndex &parent = QModelIndex() ) override;
     virtual bool insertRows( int row, int count, const QModelIndex &parent = QModelIndex() ) override;
 
+    void addEntry( const QColor &color );
+
   signals:
 
     void classesChanged();
@@ -98,6 +100,7 @@ class GUI_EXPORT QgsPalettedRendererWidget: public QgsRasterRendererWidget, priv
     void changeColor();
     void changeTransparency();
     void changeLabel();
+    void applyColorRamp();
 };
 
 #endif // QGSPALETTEDRENDERERWIDGET_H

src/ui/qgspalettedrendererwidgetbase.ui

@@ -26,7 +26,59 @@
    <property name="bottomMargin">
     <number>3</number>
    </property>
+   <item row="0" column="0">
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <widget class="QLabel" name="mBandLabel">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+       <property name="text">
+        <string>Band</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QComboBox" name="mBandComboBox"/>
+     </item>
+    </layout>
+   </item>
    <item row="2" column="0">
+    <widget class="QTreeView" name="mTreeView">
+     <property name="minimumSize">
+      <size>
+       <width>0</width>
+       <height>280</height>
+      </size>
+     </property>
+    </widget>
+   </item>
+   <item row="1" column="0">
+    <widget class="QgsColorRampButton" name="btnColorRamp">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <property name="minimumSize">
+      <size>
+       <width>120</width>
+       <height>0</height>
+      </size>
+     </property>
+     <property name="maximumSize">
+      <size>
+       <width>16777215</width>
+       <height>16777215</height>
+      </size>
+     </property>
+    </widget>
+   </item>
+   <item row="3" column="0">
     <layout class="QHBoxLayout" name="horizontalLayout_3">
      <item>
       <widget class="QPushButton" name="mAddEntryButton">
@@ -65,38 +117,16 @@
      </item>
     </layout>
    </item>
-   <item row="0" column="0">
-    <layout class="QHBoxLayout" name="horizontalLayout">
-     <item>
-      <widget class="QLabel" name="mBandLabel">
-       <property name="sizePolicy">
-        <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
-         <horstretch>0</horstretch>
-         <verstretch>0</verstretch>
-        </sizepolicy>
-       </property>
-       <property name="text">
-        <string>Band</string>
-       </property>
-      </widget>
-     </item>
-     <item>
-      <widget class="QComboBox" name="mBandComboBox"/>
-     </item>
-    </layout>
-   </item>
-   <item row="1" column="0">
-    <widget class="QTreeView" name="mTreeView">
-     <property name="minimumSize">
-      <size>
-       <width>0</width>
-       <height>280</height>
-      </size>
-     </property>
-    </widget>
-   </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>QgsColorRampButton</class>
+   <extends>QToolButton</extends>
+   <header>qgscolorrampbutton.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
  <tabstops>
   <tabstop>mBandComboBox</tabstop>
   <tabstop>mTreeView</tabstop>

tests/src/python/test_qgsrasterlayer.py

@@ -34,7 +34,8 @@ from qgis.core import (QgsRaster,
                        QgsRenderChecker,
                        QgsPalettedRasterRenderer,
                        QgsSingleBandGrayRenderer,
-                       QgsSingleBandPseudoColorRenderer)
+                       QgsSingleBandPseudoColorRenderer,
+                       QgsLimitedRandomColorRamp)
 from utilities import unitTestDataPath
 from qgis.testing import start_app, unittest
 
@@ -329,6 +330,12 @@ class TestQgsRasterLayer(unittest.TestCase):
         renderer.setLabel(3, 'new class')
         self.assertEqual(renderer.label(3), 'new class')
 
+        # color ramp
+        r = QgsLimitedRandomColorRamp(5)
+        renderer.setSourceColorRamp(r)
+        self.assertEqual(renderer.sourceColorRamp().type(), 'random')
+        self.assertEqual(renderer.sourceColorRamp().count(), 5)
+
         # clone
         new_renderer = renderer.clone()
         classes = new_renderer.classes()
@@ -336,6 +343,8 @@ class TestQgsRasterLayer(unittest.TestCase):
         self.assertEqual(classes[3].label, 'new class')
         self.assertEqual(classes[1].color.name(), '#00ff00')
         self.assertEqual(classes[3].color.name(), '#ff0000')
+        self.assertEqual(new_renderer.sourceColorRamp().type(), 'random')
+        self.assertEqual(new_renderer.sourceColorRamp().count(), 5)
 
         # write to xml and read
         doc = QDomDocument('testdoc')
@@ -350,6 +359,8 @@ class TestQgsRasterLayer(unittest.TestCase):
         self.assertEqual(classes[3].label, 'new class')
         self.assertEqual(classes[1].color.name(), '#00ff00')
         self.assertEqual(classes[3].color.name(), '#ff0000')
+        self.assertEqual(restored.sourceColorRamp().type(), 'random')
+        self.assertEqual(restored.sourceColorRamp().count(), 5)
 
         # render test
         layer.setRenderer(renderer)
@@ -376,5 +387,6 @@ class TestQgsRasterLayer(unittest.TestCase):
         self.assertEqual(classes[3].color.name(), '#00ff00')
         self.assertEqual(classes[6].color.name(), '#0000ff')
 
+
 if __name__ == '__main__':
     unittest.main()