use float precision for screen coordinates

3nids · 3nids · commit 110c8a01f2b8 · 2018-09-29T10:21:57.000-04:00
this should fix rounding error when the map canvas has an odd pixel size
diff --git a/src/quickgui/qgsquickmapsettings.cpp b/src/quickgui/qgsquickmapsettings.cpp
@@ -118,7 +118,10 @@ QPointF QgsQuickMapSettings::coordinateToScreen( const QgsPoint &point ) const
 
 QgsPoint QgsQuickMapSettings::screenToCoordinate( const QPointF &point ) const
 {
-  const QgsPointXY pp = mMapSettings.mapToPixel().toMapCoordinates( point.toPoint() );
+  // use floating point precision with mapToCoordinatesF
+  // this is to avoid rounding errors with an odd screen width or height
+  // and the point being set to the exact center of it
+  const QgsPointXY pp = mMapSettings.mapToPixel().toMapCoordinatesF( point.x(), point.y() );
   return QgsPoint( pp );
 }
 

Original file line number	Diff line number	Diff line change
`@@ -118,7 +118,10 @@ QPointF QgsQuickMapSettings::coordinateToScreen( const QgsPoint &point ) const`
`118`	`118`
`119`	`119`	`QgsPoint QgsQuickMapSettings::screenToCoordinate( const QPointF &point ) const`
`120`	`120`	`{`
`121`		`- const QgsPointXY pp = mMapSettings.mapToPixel().toMapCoordinates( point.toPoint() );`
	`121`	`+ // use floating point precision with mapToCoordinatesF`
	`122`	`+ // this is to avoid rounding errors with an odd screen width or height`
	`123`	`+ // and the point being set to the exact center of it`
	`124`	`+ const QgsPointXY pp = mMapSettings.mapToPixel().toMapCoordinatesF( point.x(), point.y() );`
`122`	`125`	`return QgsPoint( pp );`
`123`	`126`	`}`
`124`	`127`