gui: green progress marker + background red current-temp line in forecast

Progress line switches from red to green; a new horizontal red line
tracks the live measured temperature, drawn at a lower zorder than the
forecast/progress lines so it never visually covers them.

client/brewpi_gui.py

@@ -118,8 +118,11 @@ class SudForecastPlot(FigureCanvasQTAgg):
 		FigureCanvasQTAgg.__init__(self, figure)
 
 		self.ax = figure.subplots(1, 1)
-		self.line, = self.ax.plot([], [], '-b', linewidth=1.5)
+		self.line, = self.ax.plot([], [], '-b', linewidth=1.5, zorder=2)
-		self.progress_line = self.ax.axvline(0, color='r', linewidth=1.5, visible=False)
+		self.progress_line = self.ax.axvline(0, color='g', linewidth=1.5, visible=False, zorder=2)
+		# Current temperature - drawn behind (lower zorder than) the
+		# forecast/progress lines so it never covers them.
+		self.current_temp_line = self.ax.axhline(0, color='r', linewidth=1.5, visible=False, zorder=1)
 		self.ax.set_xlabel("t [min]")
 		self.ax.set_ylabel("Temp [°C]")
 		_style_axis(self.ax)
@@ -177,6 +180,15 @@ class SudForecastPlot(FigureCanvasQTAgg):
 		self.progress_line.set_visible(False)
 		self.draw_idle()
 
+	def set_current_temp(self, theta):
+		self.current_temp_line.set_ydata([theta, theta])
+		self.current_temp_line.set_visible(True)
+		self.draw_idle()
+
+	def clear_current_temp(self):
+		self.current_temp_line.set_visible(False)
+		self.draw_idle()
+
 
 class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 	# on_sud_changed() runs on the websocket recv thread, but a modal dialog
@@ -335,6 +347,11 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		else:
 			self.forecast_plot.clear_progress()
 
+		if self.plot_temp_ist:
+			self.forecast_plot.set_current_temp(self.plot_temp_ist)
+		else:
+			self.forecast_plot.clear_current_temp()
+
 	def disconnect(self):
 		# ws_client.disconnect() blocks until the websocket's close handshake
 		# completes (or times out, ~10s if the server doesn't ack promptly),