Designing a Javafx Mobile Application
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Designing a JavaFX Mobile application Fabrizio Giudici Tidalwave s.a.s. 214 AGENDA > Putting JavaFX (Mobile) in context > My case study > Main features of JavaFX (Mobile) > JavaFX Mobile through a few examples > Current status of JavaFX Mobile > Conclusion 2 About the speaker > [email protected] > Senior Architect, Mentor, Technical Writer > Working with Java (all the editions, plus exotic stuff) since 1996 > Working with Java ME since 1999 – First J2ME edition at JavaOne™ (Palm) – Developed a couple of research projects with the University of Genoa – Developed a couple of customer projects with my former company – Consulting for customer projects – Author of mobile FLOSS: windRose and blueBill Mobile > Co-leader of JUG Milano 3 What's wrong with JME > Everything was so good at the old, Palm times – Small devices → no big expectations – One reference platform – One pervasive runtime > With more devices, JME got fragmented – JSR as extension points (e.g. bluetooth, location) – Multiple combinations – Harder and harder to test – windRose pain 4 Hoping in Java FX Mobile > JavaFX announced by Sun Microsystems in 2007 – A specific scripting language + a runtime – Fight the “Ugly Java UI stereotype” – Re-designed UI controls – Integration with graphics designers workflow (e.g. NetBeans + Photoshop) – Profiles for multiple targets (desktop / web, mobile) > JavaFX Mobile profile – Can sit on top of JME (MSA: Mobile Service Architecture, a.k.a. JSR-248) – Maybe no more (or reduced) fragmentation? > Oracle commitment after the Sun buy > A fulfilled promise? – Answers at the end :-) 5 My case study: blueBill Mobile > “The field tool for birdwatchers” – Records geotagged observations – Reference guides with multimedia – Social capabilities (à la Google Friends) > Started in 2009 with JavaFX > Currently the most advanced version is the Android one – JavaFX version being redesigned (more later) > Demo 6 Main features of JavaFX > The languages is both imperative and declarative – Imperative: for normal processing – Declarative: mostly for the UI (no XML, no separate layout descriptor) Binding – Has got closures, mixins > Compiles to the same VM bytecode – Can mix with Java code (e.g. reference a Java library) – On the desktop, can be mixed with Swing (in addition to its own UI widgets) – On the mobile, runs its own UI widgets 7 Some code examples > Example 1: Calling JME code > Example 2: Posting contents (REST) > Example 3: Getting resources (REST) > Example 4: Binding (if time allows) 8 Example: calling JME code > Not much to say: it just works package it.tidalwave.bluebillmfx; import javax.microedition.location.Criteria; import javax.microedition.location.LocationProvider; import javafx.animation.Timeline; import javafx.animation.KeyFrame; import it.tidalwave.geo.mapfx.model.Coordinates; public class PositionTracker { public-read var currentPosition : Coordinates; def criteria = new Criteria(); var locationProvider : LocationProvider; postinit { locationProvider = LocationProvider.getInstance(criteria); pollingTimeline.play(); } 9 Example: calling JME code > Need to copy data in JavaFX classes if you want binding support function getPosition(): Void { def location = locationProvider.getLocation(5); // JME stuff def coordinates = location.getQualifiedCoordinates(); if (coordinates != null ) { def lat = coordinates.getLatitude(); def lon = coordinates.getLongitude(); currentPosition = Coordinates { latitude: lat; longitude: lon }; } } def pollingTimeline = Timeline { repeatCount: Timeline.INDEFINITE keyFrames: KeyFrame { time: 10s; action: periodicTask } }; function periodicTask(): Void { getPosition(); // update the map position, etc... } } 10 Example: posting contents > HttpRequest provides a skeleton public class ObservationRDFUpload extends HttpRequest { public-init var serviceURL = "http://myHost:8084/blueBillGeoService"; override public var method = HttpRequest.POST; public var content : String; override var output on replace { if (output != null) { output.write(content.getBytes()); output.close(); } } override function start(): Void { location = "{serviceURL}/postObservation"; // REST call setHeader("Content-Type", "application/rdf"); super.start(); } } 11 Example: posting contents > HttpRequest provides a skeleton def upload = ObservationRDFUpload { content: // ... assemble the string with the contents }; upload.start(); 12 Example: reading resources > The relevant model class public class Taxon { public-read protected var id : String; public-read var urlsLoaded = false; var urlsLoading = false; var imageURLs : String[]; // [] is a list (“sequence”), not an array var images : DeferredImage[]; public bound function getImage (index : Integer): DeferredImage { def dummy = loadImageURLs(); // assignment is a requirement for the bound function return images[index]; } public bound function imageCount(): Integer { return sizeof images; } 13 Example: reading resources > Getting a JSON resource catalog function loadImageURLs(): Boolean { if (not urlsLoading and not urlsLoaded) { urlsLoading = true; def fixedId = clean(id); // get rid of/escape “bad” chars such as :, #, etc... def url = "http://kenai.com/svn/bluebill-mobile~media/catalog/{fixedId}.json"; def request : HttpRequest = HttpRequest { // mere instantiation, not subclassing! location: url; method: HttpRequest.GET; onInput: function (is: InputStream) { // hey, this is not a switch() label! if (request.responseCode != 200) { imageURLs = "media/black_glossy_web20_icon_012.png"; } else { try { def parser = PullParser { documentType: PullParser.JSON; input: is; onEvent: parseEventCallback }; parser.parse(); } catch (e: Exception) { println("Exception {e} while parsing {url}"); } finally { is.close(); 14 } } } Example: reading resources > Getting a JSON resource catalog onException: function (e: Exception) { imageURLs = "media/black_glossy_web20_icon_012.png"; urlsLoaded = true; } onDone: function() { images = for (url in imageURLs) { DeferredImage { url: url }; } imageURLs = null; urlsLoaded = true; } } request.start(); } return urlsLoaded; } def parseEventCallback = function (event: Event): Void { if ((event.type == PullParser.TEXT) and (event.name == "url")) { insert event.text into imageURLs; } 15 } } Example: reading resources > Loading an image > JavaFX Image loads automatically when initialized var imageCounter = 0; public class DeferredImage { public-init var url : String; public-read var progress = bind image.progress; public-read var error = bind image.error; def id = imageCounter++; public-read var image : Image; public function load() { // start loading only when load() is called if (image == null) { image = Image { url: url backgroundLoading: true } } } 16 } Example: binding > Introducing TaxonSearchController – Manages a list of Taxons – Produces a filtered list of Taxons whose names match a substring – Provides a hint for autocompletion Eg. you type “He” That matches only “Heron ***” Hints is “Heron “ 17 Example: binding > Some relevant parts of Taxon public class Taxon { public-read protected var displayName : String; public-read protected var scientificName : String; public-read protected var id : String; override function toString() { return "{displayName} ({scientificName}) ({id})" } } 18 Example: binding > TaxonSearchController (1/3) public class TaxonSearchController { public var taxons: Taxon[]; public var filteredTaxons: Taxon[]; public var selectedTaxonIndex : Integer = -1; // set from the UI public var selectedTaxon = bind if (selectedTaxonIndex < 0) then null else filteredTaxons[selectedTaxonIndex]; // setting this property will trigger filtering public var filter = "" on replace { filteredTaxons = taxons[taxon | matches(taxon, filter)]; updateHint(); } public-read var hint = ""; // the auto-completed hint 19 Example: binding > TaxonSearchController (2/3) protected function matches (taxon : Taxon, string: String) : Boolean { if (string == "") { return true; } if (taxon.displayName.toLowerCase().startsWith(string.toLowerCase())) { return true; // more complex in the real case, as it also deals with scientific name // but not relevant now } return false; } 20 Example: binding > TaxonSearchController (3/3) protected function updateHint(): Void { def hintTry = commonLeadingSubstring(filteredTaxons); // // Sometimes it can't find a better auto-completion than the current filter, // hint = if (hintTry.length() > filter.length()) then hintTry else filter; } } 21 Example: binding > TaxonSearchScreen public class TaxonSearchScreen extends Container // e.g. a UI panel { // warning: there are some simplifications, but the concepts are here public-read def controller = TaxonSearchController { selectedTaxonIndex: bind list.selectedIndex; } def list = ListBox { // the list widget in the UI items: bind controller.filteredTaxons }; def hint = bind controller.hint on replace { if (hint != "") { filter = hint; } } var resetSelectionWhenFilterChanges = bind controller.selectedTaxon on replace { if (controller.selectedTaxon != null) { list.selectedIndex = 0; } } TextBox { // a text input box in the UI text: bind controller.filter with inverse } Text { // a label rendering a text in the UI content: bind "{sizeof controller.filteredTaxons} specie(s)" 22 } JavaFX mobile in 2009 > Development tools available (emulator, etc...) > First capable phones at J1: LG Incite, HTC Touch Diamond > Announced a “JavaFX Mobile player” – Would run JavaFX on MSA (JSR 248) JME phones > Looked very promising – That's why blueBill Mobile started with it 23 Status updates in 2010 >