Use exact image coordinates in the desktop crop editor

tools/chatgui/src/avatars/avatarcrop.cpp

@@ -7,6 +7,7 @@
 #include <QLabel>
 #include <QMouseEvent>
 #include <QPainter>
+#include <QPainterPath>
 #include <QPointer>
 #include <QPushButton>
 #include <QRunnable>
@@ -31,7 +32,7 @@ public:
     }
     QRectF selection() const {
         const double s = scale();
-        const QPointF top = rect().center() + offset - QPointF(image.width()*s/2, image.height()*s/2);
+        const QPointF top = QPointF(width()/2.0,height()/2.0) + offset - QPointF(image.width()*s/2, image.height()*s/2);
         const QRectF f = frame();
         return {(f.x()-top.x())/s/image.width(), (f.y()-top.y())/s/image.height(), f.width()/s/image.width(), f.height()/s/image.height()};
     }