Use map width instead of diagonal for scale bar calculation based on ellipsoid (because scale is often depending on direction)

mhugent · mhugent · commit 0c1aa34b1d4d · 2012-08-23T12:19:58.000+02:00
diff --git a/src/core/composer/qgscomposerscalebar.cpp b/src/core/composer/qgscomposerscalebar.cpp
@@ -168,12 +168,11 @@ void QgsComposerScaleBar::refreshSegmentMillimeters()
     QRectF composerItemRect = mComposerMap->rect();
 
     //calculate size depending on mNumUnitsPerSegment
-    double itemDiagonal = sqrt( composerItemRect.width() * composerItemRect.width() + composerItemRect.height() * composerItemRect.height() );
-    mSegmentMillimeters = itemDiagonal / mapDiagonal() * mNumUnitsPerSegment;
+    mSegmentMillimeters = composerItemRect.width() / mapWidth() * mNumUnitsPerSegment;
   }
 }
 
-double QgsComposerScaleBar::mapDiagonal() const
+double QgsComposerScaleBar::mapWidth() const
 {
   if ( !mComposerMap )
   {
@@ -183,7 +182,7 @@ double QgsComposerScaleBar::mapDiagonal() const
   QgsRectangle composerMapRect = mComposerMap->extent();
   if ( mUnits == MapUnits )
   {
-    return sqrt( composerMapRect.width() * composerMapRect.width() + composerMapRect.height() * composerMapRect.height() );
+    return composerMapRect.width();
   }
   else
   {
@@ -192,7 +191,7 @@ double QgsComposerScaleBar::mapDiagonal() const
     da.setSourceCrs( mComposerMap->mapRenderer()->destinationCrs().srsid() );
     QSettings s;
     da.setEllipsoid( s.value( "/qgis/measure/ellipsoid", "WGS84" ).toString() );
-    double measure = da.measureLine( QgsPoint( composerMapRect.xMinimum(), composerMapRect.yMaximum() ), QgsPoint( composerMapRect.xMaximum(), composerMapRect.yMinimum() ) );
+    double measure = da.measureLine( QgsPoint( composerMapRect.xMinimum(), composerMapRect.yMinimum() ), QgsPoint( composerMapRect.xMaximum(), composerMapRect.yMinimum() ) );
     if ( mUnits == Feet )
     {
       measure /= 0.3048;
diff --git a/src/core/composer/qgscomposerscalebar.h b/src/core/composer/qgscomposerscalebar.h
@@ -199,7 +199,7 @@ class CORE_EXPORT QgsComposerScaleBar: public QgsComposerItem
     void refreshSegmentMillimeters();
 
     /**Returns diagonal of composer map in selected units (map units / meters / feet)*/
-    double mapDiagonal() const;
+    double mapWidth() const;
 };
 
 #endif //QGSCOMPOSERSCALEBAR_H

Original file line number	Diff line number	Diff line change
`@@ -168,12 +168,11 @@ void QgsComposerScaleBar::refreshSegmentMillimeters()`
`168`	`168`	`QRectF composerItemRect = mComposerMap->rect();`
`169`	`169`
`170`	`170`	`//calculate size depending on mNumUnitsPerSegment`
`171`		`- double itemDiagonal = sqrt( composerItemRect.width() * composerItemRect.width() + composerItemRect.height() * composerItemRect.height() );`
`172`		`- mSegmentMillimeters = itemDiagonal / mapDiagonal() * mNumUnitsPerSegment;`
	`171`	`+ mSegmentMillimeters = composerItemRect.width() / mapWidth() * mNumUnitsPerSegment;`
`173`	`172`	`}`
`174`	`173`	`}`
`175`	`174`
`176`		`-double QgsComposerScaleBar::mapDiagonal() const`
	`175`	`+double QgsComposerScaleBar::mapWidth() const`
`177`	`176`	`{`
`178`	`177`	`if ( !mComposerMap )`
`179`	`178`	`{`
`@@ -183,7 +182,7 @@ double QgsComposerScaleBar::mapDiagonal() const`
`183`	`182`	`QgsRectangle composerMapRect = mComposerMap->extent();`
`184`	`183`	`if ( mUnits == MapUnits )`
`185`	`184`	`{`
`186`		`- return sqrt( composerMapRect.width() * composerMapRect.width() + composerMapRect.height() * composerMapRect.height() );`
	`185`	`+ return composerMapRect.width();`
`187`	`186`	`}`
`188`	`187`	`else`
`189`	`188`	`{`
`@@ -192,7 +191,7 @@ double QgsComposerScaleBar::mapDiagonal() const`
`192`	`191`	`da.setSourceCrs( mComposerMap->mapRenderer()->destinationCrs().srsid() );`
`193`	`192`	`QSettings s;`
`194`	`193`	`da.setEllipsoid( s.value( "/qgis/measure/ellipsoid", "WGS84" ).toString() );`
`195`		`- double measure = da.measureLine( QgsPoint( composerMapRect.xMinimum(), composerMapRect.yMaximum() ), QgsPoint( composerMapRect.xMaximum(), composerMapRect.yMinimum() ) );`
	`194`	`+ double measure = da.measureLine( QgsPoint( composerMapRect.xMinimum(), composerMapRect.yMinimum() ), QgsPoint( composerMapRect.xMaximum(), composerMapRect.yMinimum() ) );`
`196`	`195`	`if ( mUnits == Feet )`
`197`	`196`	`{`
`198`	`197`	`measure /= 0.3048;`