Add support for fine-resolution mouse wheel zooming

m-kuhn · m-kuhn · commit cf5f373f631e · 2016-12-09T10:32:51.000+01:00
Some mouses (notably on mac) have finer resolutions. They send mouse
wheel events in a higher frequency but with smaller angleDelta() values.
So far, zooming with such mouses was leading to unusable fast zoom
actions.
diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
@@ -1449,13 +1449,17 @@ void QgsMapCanvas::wheelEvent( QWheelEvent *e )
   }
 
   double zoomFactor = mWheelZoomFactor;
+
+  // "Normal" mouse have an angle delta of 120, precision mouses provide data faster, in smaller steps
+  zoomFactor = 1.0 + ( zoomFactor - 1.0 ) / 120.0 * qAbs( e->angleDelta().y() );
+
   if ( e->modifiers() & Qt::ControlModifier )
   {
     //holding ctrl while wheel zooming results in a finer zoom
     zoomFactor = 1.0 + ( zoomFactor - 1.0 ) / 20.0;
   }
 
-  double signedWheelFactor = e->delta() > 0 ? 1 / zoomFactor : zoomFactor;
+  double signedWheelFactor = e->angleDelta().y() > 0 ? 1 / zoomFactor : zoomFactor;
 
   // zoom map to mouse cursor by scaling
   QgsPoint oldCenter = center();

Original file line number	Diff line number	Diff line change
`@@ -1449,13 +1449,17 @@ void QgsMapCanvas::wheelEvent( QWheelEvent *e )`
`1449`	`1449`	`}`
`1450`	`1450`
`1451`	`1451`	`double zoomFactor = mWheelZoomFactor;`
	`1452`	`+`
	`1453`	`+ // "Normal" mouse have an angle delta of 120, precision mouses provide data faster, in smaller steps`
	`1454`	`+ zoomFactor = 1.0 + ( zoomFactor - 1.0 ) / 120.0 * qAbs( e->angleDelta().y() );`
	`1455`	`+`
`1452`	`1456`	`if ( e->modifiers() & Qt::ControlModifier )`
`1453`	`1457`	`{`
`1454`	`1458`	`//holding ctrl while wheel zooming results in a finer zoom`
`1455`	`1459`	`zoomFactor = 1.0 + ( zoomFactor - 1.0 ) / 20.0;`
`1456`	`1460`	`}`
`1457`	`1461`
`1458`		`- double signedWheelFactor = e->delta() > 0 ? 1 / zoomFactor : zoomFactor;`
	`1462`	`+ double signedWheelFactor = e->angleDelta().y() > 0 ? 1 / zoomFactor : zoomFactor;`
`1459`	`1463`
`1460`	`1464`	`// zoom map to mouse cursor by scaling`
`1461`	`1465`	`QgsPoint oldCenter = center();`