GUI: add MIN_DTZ to panel and set minimum dtz in scan settings panel to 108

gui/src/aaregui/panels/scan_settings_panel.py

@@ -11,6 +11,7 @@ logger = setup_logger("aareGUI")
 class ScanSettingsPanel(QWidget):
     dtz_updated = Signal(float)
     dtz_move = Signal(float)
+    MIN_DTZ = 108.0
     transmission_updated = Signal(float)
 
     def __init__(self, diffraction: DiffractionGeometry,
@@ -45,7 +46,7 @@ class ScanSettingsPanel(QWidget):
         self.high_res_enter.newValue.connect(self.set_high_res)
 
         self._layout.addWidget(QLabel("Detector distance", parent=self), 1, 0)
-        self.dtz_enter = NumberLineEdit(108, 1000, decimals=2, default=self._dtz, parent=self)
+        self.dtz_enter = NumberLineEdit(self.MIN_DTZ, 1000, decimals=2, default=self._dtz, parent=self)
         self._layout.addWidget(self.dtz_enter, 1, 1, 1, 3)
         self._layout.addWidget(QLabel("mm", parent=self), 1, 4)
 
@@ -141,6 +142,8 @@ class ScanSettingsPanel(QWidget):
     def set_high_res(self, v: float):
         self._high_res = v
         self._dtz = self.__diffraction.calc_dtz_mm(v)
+        if self._dtz < self.MIN_DTZ:
+            self._dtz = self.MIN_DTZ
         self.dtz_enter.update_value(self._dtz)
         self.dtz_updated.emit(self._dtz)