Merge pull request #9286 from signedav/scale_getlegendgraphic_backport-3_6

Backport 3.6 Scaled symbols on GetLegendGraphics

Author: pblottiere

python/core/auto_generated/qgslegendsettings.sip.in

@@ -192,6 +192,24 @@ Sets the legend map ``scale``.
 The ``scale`` value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.
 
 .. seealso:: :py:func:`mapScale`
+%End
+
+    double mapUnitsPerPixel() const;
+%Docstring
+Returns the factor of map units per pixel for symbols with size given in map units calculated by dpi and mmPerMapUnit
+
+.. seealso:: :py:func:`setMapUnitsPerPixel`
+
+.. versionadded:: 3.8
+%End
+
+    void setMapUnitsPerPixel( double mapUnitsPerPixel );
+%Docstring
+Sets the mmPerMapUnit calculated by ``mapUnitsPerPixel`` mostly taken from the map settings.
+
+.. seealso:: :py:func:`mapUnitsPerPixel`
+
+.. versionadded:: 3.8
 %End
 
     int dpi() const;

src/core/qgslegendsettings.cpp

@@ -37,6 +37,16 @@ QgsLegendSettings::QgsLegendSettings()
   rstyle( QgsLegendStyle::SymbolLabel ).rfont().setPointSizeF( 12.0 );
 }
 
+double QgsLegendSettings::mapUnitsPerPixel() const
+{
+  return 1 / ( mMmPerMapUnit * ( mDpi / 25.4 ) );
+}
+
+void QgsLegendSettings::setMapUnitsPerPixel( double mapUnitsPerPixel )
+{
+  mMmPerMapUnit = 1 / mapUnitsPerPixel / ( mDpi / 25.4 );
+}
+
 QStringList QgsLegendSettings::evaluateItemText( const QString &text, const QgsExpressionContext &context ) const
 {
   const QString textToRender = QgsExpression::replaceExpressionText( text, &context );

src/core/qgslegendsettings.h

@@ -178,6 +178,20 @@ class CORE_EXPORT QgsLegendSettings
      */
     void setMapScale( double scale ) { mMapScale = scale; }
 
+    /**
+     * Returns the factor of map units per pixel for symbols with size given in map units calculated by dpi and mmPerMapUnit
+     * \see setMapUnitsPerPixel()
+     * \since QGIS 3.8
+     */
+    double mapUnitsPerPixel() const;
+
+    /**
+     * Sets the mmPerMapUnit calculated by \a mapUnitsPerPixel mostly taken from the map settings.
+     * \see mapUnitsPerPixel()
+     * \since QGIS 3.8
+     */
+    void setMapUnitsPerPixel( double mapUnitsPerPixel );
+
     int dpi() const { return mDpi; }
     void setDpi( int dpi ) { mDpi = dpi; }
 

src/server/services/wms/qgswmsrenderer.cpp

@@ -183,6 +183,16 @@ namespace QgsWms
     std::unique_ptr<QImage> image;
     std::unique_ptr<QPainter> painter;
 
+    // getting scale from bbox
+    if ( !mWmsParameters.bbox().isEmpty() )
+    {
+      QgsMapSettings mapSettings;
+      image.reset( createImage( mWmsParameters.widthAsInt(), mWmsParameters.heightAsInt(), false ) );
+      configureMapSettings( image.get(), mapSettings );
+      legendSettings.setMapScale( mapSettings.scale() );
+      legendSettings.setMapUnitsPerPixel( mapSettings.mapUnitsPerPixel() );
+    }
+
     if ( !mWmsParameters.rule().isEmpty() )
     {
       QString rule = mWmsParameters.rule();

tests/src/python/test_qgsserver_wms_getlegendgraphic.py

@@ -555,6 +555,106 @@ def test_wms_GetLegendGraphic_wmsRootName(self):
         self.assertEqual(-1, h.find(b'Content-Type: text/xml; charset=utf-8'), "Header: %s\nResponse:\n%s" % (h, r))
         self.assertNotEqual(-1, h.find(b'Content-Type: image/png'), "Header: %s\nResponse:\n%s" % (h, r))
 
+    def test_wms_GetLegendGraphic_ScaleSymbol_Min(self):
+        # 1:500000000 min
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "-608.4,-1002.6,698.2,1019.0",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Min", max_size_diff=QSize(1, 1))
+
+        # 1:1000000000 min
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "-1261.7,-2013.5,1351.5,2029.9",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Min", max_size_diff=QSize(15, 15))
+
+    def test_wms_GetLegendGraphic_ScaleSymbol_Scaled_01(self):
+        # 1:10000000 scaled
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "31.8,-12.0,58.0,28.4",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Scaled_01", max_size_diff=QSize(15, 15))
+
+    def test_wms_GetLegendGraphic_ScaleSymbol_Scaled_02(self):
+        # 1:15000000 scaled
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "25.3,-22.1,64.5,38.5",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Scaled_02", max_size_diff=QSize(15, 15))
+
+    def test_wms_GetLegendGraphic_ScaleSymbol_Max(self):
+        # 1:100000 max
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "44.8,8.0,45.0,8.4",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Max", max_size_diff=QSize(15, 15))
+
+        # 1:1000000 max
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": self.testdata_path + 'test_project_scaledsymbols.qgs',
+            "SERVICE": "WMS",
+            "REQUEST": "GetLegendGraphic",
+            "LAYER": "testlayer",
+            "FORMAT": "image/png",
+            "HEIGHT": "550",
+            "WIDTH": "850",
+            "BBOX": "43.6,6.2,46.2,10.2",
+            "CRS": "EPSG:4326"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        self._img_diff_error(r, h, "WMS_GetLegendGraphic_ScaleSymbol_Max", max_size_diff=QSize(15, 15))
+
 
 if __name__ == '__main__':
     unittest.main()