constrain legend rect to be fully inside viewbox; simplest solution to fix #113

src/gui_qt/lib/pg_objects.py

@@ -5,7 +5,7 @@ from pyqtgraph import (
     LinearRegionItem, mkBrush,
     mkColor, mkPen,
     PlotDataItem,
-    LegendItem,
+    LegendItem, ViewBox,
 )
 
 from nmreval.lib.colors import BaseColor, Colors
@@ -472,11 +472,18 @@ class LegendItemBlock(LegendItem):
     def mouseDragEvent(self, ev):
         if ev.button() == QtCore.Qt.LeftButton:
             ev.accept()
+
             dpos = ev.pos() - ev.lastPos()
+
+            upper_left = self.pos()
+            lower_right = self.pos()
+            lower_right.setX(lower_right.x() + self.width())
+            lower_right.setY(lower_right.y() + self.height())
+
             vb_rect = self.parentItem().rect()
-            pos = self.pos()
-            # upper left corner and a point a little more to the bottom right must be inside
-            if vb_rect.contains(pos+dpos) and vb_rect.contains(pos+dpos+QtCore.QPointF(20., 20.)):
-                self.autoAnchor(pos + dpos)
+
+            # upper left and lower right corner must be inside viewbox
+            if vb_rect.contains(upper_left + dpos) and vb_rect.contains(lower_right + dpos):
+                self.autoAnchor(upper_left + dpos)
             else:
-                self.autoAnchor(pos)
+                self.autoAnchor(upper_left)