applets: implement dataset modification feature in big number applet

artiq/applets/big_number.py

@@ -1,22 +1,72 @@
 #!/usr/bin/env python3
 
-from PyQt5 import QtWidgets
+from PyQt5 import QtWidgets, QtCore, QtGui
-
 from artiq.applets.simple import SimpleApplet
 
 
-class NumberWidget(QtWidgets.QLCDNumber):
+class QResponsiveLCDNumber(QtWidgets.QLCDNumber):
+    doubleClicked = QtCore.pyqtSignal()
+
+    def mouseDoubleClickEvent(self, event):
+        self.doubleClicked.emit()
+
+
+class QCancellableLineEdit(QtWidgets.QLineEdit):
+    editCancelled = QtCore.pyqtSignal()
+
+    def keyPressEvent(self, event):
+        if event.key() == QtCore.Qt.Key_Escape:
+            self.editCancelled.emit()
+        else:
+            super().keyPressEvent(event)
+
+
+class NumberWidget(QtWidgets.QStackedWidget):
     def __init__(self, args, ctl):
-        QtWidgets.QLCDNumber.__init__(self)
+        QtWidgets.QStackedWidget.__init__(self)
-        self.setDigitCount(args.digit_count)
         self.dataset_name = args.dataset
+        self.ctl = ctl
+
+        self.lcd_widget = QResponsiveLCDNumber()
+        self.lcd_widget.setDigitCount(args.digit_count)
+        self.lcd_widget.doubleClicked.connect(self.start_edit)
+        self.addWidget(self.lcd_widget)
+
+        self.edit_widget = QCancellableLineEdit()
+        self.edit_widget.setValidator(QtGui.QDoubleValidator())
+        self.edit_widget.setAlignment(QtCore.Qt.AlignRight)
+        self.edit_widget.editCancelled.connect(self.cancel_edit)
+        self.edit_widget.returnPressed.connect(self.confirm_edit)
+        self.addWidget(self.edit_widget)
+
+        font = QtGui.QFont()
+        font.setPointSize(60)
+        self.edit_widget.setFont(font)
+
+        self.setCurrentWidget(self.lcd_widget)
+
+    def start_edit(self):
+        # QLCDNumber value property contains the value of zero
+        # if the displayed value is not a number.
+        self.edit_widget.setText(str(self.lcd_widget.value()))
+        self.edit_widget.selectAll()
+        self.edit_widget.setFocus()
+        self.setCurrentWidget(self.edit_widget)
+
+    def confirm_edit(self):
+        value = float(self.edit_widget.text())
+        self.ctl.set_dataset(self.dataset_name, value)
+        self.setCurrentWidget(self.lcd_widget)
+
+    def cancel_edit(self):
+        self.setCurrentWidget(self.lcd_widget)
 
     def data_changed(self, data, mods):
         try:
             n = float(data[self.dataset_name][1])
         except (KeyError, ValueError, TypeError):
             n = "---"
-        self.display(n)
+        self.lcd_widget.display(n)
 
 
 def main():