current conditions ready for data

server/scripts/modules/currentweatherscroll.js

@@ -0,0 +1,96 @@
+'use strict';
+
+/* globals draw, navigation */
+
+// eslint-disable-next-line no-unused-vars
+const currentWeatherScroll = (() => {
+	// local variables
+	let context;	// currently active context
+	let blankDrawArea;	// original state of context
+	let station;
+	let interval;
+	let screenIndex = 0;
+
+	// start drawing conditions
+	// reset starts from the first item in the text scroll list
+	const start = (_context) => {
+		// see if there is a context available
+		if (!_context) return;
+		// store see if the context is new
+		if (_context !== context) {
+			// clean the outgoing context
+			cleanLastContext();
+			// store the new blank context
+			blankDrawArea = _context.getImageData(0, 405, 640, 75);
+		}
+		// store the context locally
+		context = _context;
+
+		// set up the interval if needed
+		if (!interval) {
+			interval = setInterval(incrementInterval, 700);
+		}
+
+		// draw the data
+		drawScreen();
+
+	};
+
+	const stop = (reset) => {
+		cleanLastContext();
+		if (interval) interval = clearInterval(interval);
+		if (reset) screenIndex = 0;
+	};
+
+	const cleanLastContext = () => {
+		if (blankDrawArea) context.putImageData(blankDrawArea, 0, 405);
+		blankDrawArea = undefined;
+		context = undefined;
+	};
+
+	// increment interval, roll over
+	const incrementInterval = () => {
+		screenIndex = (screenIndex+1)%2;
+		// draw new text
+		drawScreen();
+	};
+
+	const drawScreen = () => {
+		// get the conditions
+		const data = navigation.getCurrentWeather();
+
+		// nothing to do if there's no data yet
+		if (!data) return;
+		if (!station) return;
+
+		// clean up any old text
+		context.putImageData(blankDrawArea, 0, 405);
+
+		switch (screenIndex) {
+		case 0:
+		default:
+			drawCondition(`Conditions at ${station.name.substr(0,20)}`);
+			break;
+		case 1:
+			drawCondition(`Page 2`);
+			break;
+		}
+	};
+
+	// internal draw function with preset parameters
+	const drawCondition = (text) => {
+		draw.text(context, 'Star4000', '24pt', '#ffffff', 70, 430, text, 2);
+	};
+
+	// store the latest station data
+	const setStation = (weatherParameters) => {
+		station = weatherParameters.stations[0].properties;
+	};
+
+	// return the api
+	return {
+		start,
+		stop,
+		setStation,
+	};
+})();