fix for Qt6

MapView add contrast property
MapView fix plugin

libs/map/mapview.cpp

@@ -81,6 +81,12 @@ void MapView::setZoom(double z) {
 }
 
 
+void MapView::setContrast(double value) {
+	contrast = piClampd(value, 0., 100.);
+	update();
+}
+
+
 QString MapView::cachePath() const {
 	return cache->cacheRoot();
 }
@@ -258,6 +264,11 @@ void MapView::wheelEvent(QWheelEvent * e) {
 void MapView::paintEvent(QPaintEvent *) {
 	QPainter p(this);
 	p.drawPixmap(0, 0, background);
+	if (contrast < 100.) {
+		auto col = palette().color(QPalette::Window);
+		col.setAlphaF(1. - contrast / 100.);
+		p.fillRect(rect(), col);
+	}
 	drawItems(p);
 	updateMouse(mapFromGlobal(QCursor::pos()));
 }