Fix sampling ring positioning for picker tool

In the QGraphicsView renderer. It didn't properly map the position to
scene coordinates before, now it does.

src/desktop/scene/canvasview.cpp

@@ -2076,12 +2076,17 @@ void CanvasView::moveDrag(const QPoint &point)
 	m_dragLastPoint = point;
 }
 
+bool CanvasView::setSceneColorPick(
+	int source, const QPointF &posf, const QColor &color)
+{
+	return m_scene->setColorPick(source, mapToScene(posf.toPoint()), color);
+}
+
 void CanvasView::pickColor(
 	int source, const QPointF &point, const QPointF &posf)
 {
 	QColor color = m_scene->model()->pickColor(point.x(), point.y(), 0, 0);
-	m_pickingColor =
-		m_scene->setColorPick(source, mapToScene(posf.toPoint()), color);
+	m_pickingColor = setSceneColorPick(source, posf, color);
 }
 
 void CanvasView::touchColorPick(const QPointF &posf)

src/desktop/scene/canvasview.h

@@ -188,6 +188,9 @@ public slots:
 	void setViewFlip(bool flip);
 	void setViewMirror(bool mirror);
 
+	bool
+	setSceneColorPick(int source, const QPointF &posf, const QColor &color);
+
 	void setLockReasons(QFlags<view::Lock::Reason> reasons);
 	void setLockDescription(const QString &lockDescription);
 	void setToolState(int toolState);

src/desktop/scene/scenewrapper.cpp

@@ -312,8 +312,8 @@ void SceneWrapper::connectDocument(Document *doc)
 		toolCtrl, &tools::ToolController::colorUsed, m_scene,
 		&CanvasScene::setComparisonColor);
 	connect(
-		toolCtrl, &tools::ToolController::colorPickRequested, m_scene,
-		&CanvasScene::setColorPick);
+		toolCtrl, &tools::ToolController::colorPickRequested, m_view,
+		&CanvasView::setSceneColorPick);
 	connect(
 		toolCtrl, &tools::ToolController::maskPreviewRequested, m_scene,
 		&CanvasScene::setMaskPreview);