[FEATURE] Snapping feedback improvements

- tooltips with name of the layer that has been snapped
- different markers for different snap types (cross for vertex, X for intersection, box for edge)
- snapping marker color can be customized in options (default: magenta - as before)
- whether to show tooltips can be customized in options (default: off)

src/app/qgsoptions.cpp

@@ -941,6 +941,9 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl, const QList<QgsOpti
   }
   mSearchRadiusVertexEditComboBox->setCurrentIndex( index );
 
+  mSnappingMarkerColorButton->setColor( mSettings->value( QStringLiteral( "/qgis/digitizing/snap_color" ), QColor( Qt::magenta ) ).value<QColor>() );
+  mSnappingTooltipsCheckbox->setChecked( mSettings->value( QStringLiteral( "/qgis/digitizing/snap_tooltip" ), false ).toBool() );
+
   //vertex marker
   mMarkersOnlyForSelectedCheckBox->setChecked( mSettings->value( QStringLiteral( "/qgis/digitizing/marker_only_for_selected" ), true ).toBool() );
 
@@ -1459,6 +1462,9 @@ void QgsOptions::saveOptions()
   mSettings->setValue( QStringLiteral( "/qgis/digitizing/search_radius_vertex_edit_unit" ),
                        ( mSearchRadiusVertexEditComboBox->currentIndex()  == 0 ? QgsTolerance::ProjectUnits : QgsTolerance::Pixels ) );
 
+  mSettings->setValue( QStringLiteral( "/qgis/digitizing/snap_color" ), mSnappingMarkerColorButton->color() );
+  mSettings->setValue( QStringLiteral( "/qgis/digitizing/snap_tooltip" ), mSnappingTooltipsCheckbox->isChecked() );
+
   mSettings->setValue( QStringLiteral( "/qgis/digitizing/marker_only_for_selected" ), mMarkersOnlyForSelectedCheckBox->isChecked() );
 
   QString markerComboText = mMarkerStyleComboBox->currentText();

src/gui/qgssnapindicator.cpp

@@ -15,8 +15,13 @@
 
 #include "qgssnapindicator.h"
 
+#include "qgsmapcanvas.h"
+#include "qgssettings.h"
+#include "qgsvectorlayer.h"
 #include "qgsvertexmarker.h"
 
+#include <QToolTip>
+
 
 QgsSnapIndicator::QgsSnapIndicator( QgsMapCanvas *canvas )
   : mCanvas( canvas )
@@ -34,17 +39,46 @@ void QgsSnapIndicator::setMatch( const QgsPointLocator::Match &match )
   if ( !mMatch.isValid() )
   {
     mSnappingMarker.reset();
+    QToolTip::hideText();
   }
   else
   {
     if ( !mSnappingMarker )
     {
       mSnappingMarker.reset( new QgsVertexMarker( mCanvas ) );
-      mSnappingMarker->setIconType( QgsVertexMarker::ICON_CROSS );
-      mSnappingMarker->setColor( Qt::magenta );
       mSnappingMarker->setPenWidth( 3 );
     }
+
+    QgsSettings s;
+
+    QColor color = s.value( QStringLiteral( "/qgis/digitizing/snap_color" ), QColor( Qt::magenta ) ).value<QColor>();
+    mSnappingMarker->setColor( color );
+
+    int iconType;
+    if ( match.hasVertex() )
+    {
+      if ( match.layer() )
+        iconType = QgsVertexMarker::ICON_CROSS;  // vertex snap
+      else
+        iconType = QgsVertexMarker::ICON_X;  // intersection snap
+    }
+    else  // must be segment snap
+    {
+      iconType = QgsVertexMarker::ICON_BOX;
+    }
+    mSnappingMarker->setIconType( iconType );
+
     mSnappingMarker->setCenter( match.point() );
+
+    // tooltip
+    if ( s.value( QStringLiteral( "/qgis/digitizing/snap_tooltip" ), false ).toBool() )
+    {
+      QPoint ptCanvas = mSnappingMarker->toCanvasCoordinates( match.point() ).toPoint();
+      QPoint ptGlobal = mCanvas->mapToGlobal( ptCanvas );
+      QRect rect( ptCanvas.x(), ptCanvas.y(), 1, 1 );  // area where is the tooltip valid
+      QString layerName = match.layer() ? match.layer()->name() : QString();
+      QToolTip::showText( ptGlobal, layerName, mCanvas, rect );
+    }
   }
 }
 

src/ui/qgsoptionsbase.ui

@@ -4112,6 +4112,9 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                   <string>Snapping</string>
                  </property>
                  <layout class="QGridLayout" name="_10">
+                  <item row="6" column="5">
+                   <widget class="QgsColorButton" name="mSnappingMarkerColorButton"/>
+                  </item>
                   <item row="1" column="1" colspan="6">
                    <widget class="QCheckBox" name="mSnappingEnabledDefault">
                     <property name="text">
@@ -4126,6 +4129,13 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                     </property>
                    </widget>
                   </item>
+                  <item row="6" column="1">
+                   <widget class="QLabel" name="label_2">
+                    <property name="text">
+                     <string>Snapping marker color</string>
+                    </property>
+                   </widget>
+                  </item>
                   <item row="2" column="1">
                    <widget class="QLabel" name="mDefaultSnapModeLabel">
                     <property name="text">
@@ -4189,6 +4199,20 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                     </property>
                    </widget>
                   </item>
+                  <item row="4" column="6">
+                   <widget class="QComboBox" name="mSearchRadiusVertexEditComboBox">
+                    <item>
+                     <property name="text">
+                      <string>map units</string>
+                     </property>
+                    </item>
+                    <item>
+                     <property name="text">
+                      <string>pixels</string>
+                     </property>
+                    </item>
+                   </widget>
+                  </item>
                   <item row="4" column="5">
                    <widget class="QDoubleSpinBox" name="mSearchRadiusVertexEditSpinBox">
                     <property name="decimals">
@@ -4222,19 +4246,8 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                     </property>
                    </spacer>
                   </item>
-                  <item row="4" column="6">
-                   <widget class="QComboBox" name="mSearchRadiusVertexEditComboBox">
-                    <item>
-                     <property name="text">
-                      <string>map units</string>
-                     </property>
-                    </item>
-                    <item>
-                     <property name="text">
-                      <string>pixels</string>
-                     </property>
-                    </item>
-                   </widget>
+                  <item row="5" column="5" colspan="2">
+                   <widget class="QComboBox" name="mSnappingMainDialogComboBox"/>
                   </item>
                   <item row="4" column="1" colspan="3">
                    <widget class="QLabel" name="mVertexSearchRadiusVertexEditLabel">
@@ -4243,16 +4256,20 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                     </property>
                    </widget>
                   </item>
-                  <item row="5" column="5" colspan="2">
-                   <widget class="QComboBox" name="mSnappingMainDialogComboBox"/>
-                  </item>
                   <item row="3" column="1" colspan="2">
                    <widget class="QLabel" name="mDefaultSnappingToleranceTextLabel">
                     <property name="text">
                      <string>Default snapping tolerance</string>
                     </property>
                    </widget>
                   </item>
+                  <item row="7" column="1" colspan="6">
+                   <widget class="QCheckBox" name="mSnappingTooltipsCheckbox">
+                    <property name="text">
+                     <string>Show snapping tooltips</string>
+                    </property>
+                   </widget>
+                  </item>
                  </layout>
                 </widget>
                </item>
@@ -4829,7 +4846,7 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                 <x>0</x>
                 <y>0</y>
                 <width>866</width>
-                <height>822</height>
+                <height>930</height>
                </rect>
               </property>
               <layout class="QVBoxLayout" name="verticalLayout_33">