Drag-and-drop glitches

You or your students may have noticed that drag-and-drop of components on the Viewer screen sometimes doesn't function cleanly: the component being moved is offset from the mouse pointer by a couple of centimetres, and/or the component being moved doesn't "stick" where it is dropped.

• To correct the first problem, it is usually enough to reload the page in the browser, by pressing F5.
• To deal with the second problem, drag the component to its desired position and release it as normal; if it then jumps to the top left, wait a couple of seconds and it should jump back to where it was placed.

Both of these glitches have shown up recently, and hopefully will be addressed in a future update to App Inventor. If you spot any other anomalies, please don't hesitate to get in touch.

Core 1: Coding Update

The Core 1: Coding transcript  has been updated to improve section 2, Code: random movement of mole.

The original version set the X and Y values of the mole's position to a random integer in the range 0 to 300 on a 300x300 pixel canvas. However, since the X and Y values correspond to the top left corner of the sprite, a value above 236 on either axis meant that some or all of the image was not visible. The range for the random integers has therefore been changed to 0 to 236.

A note has also been added to the Corrections section of the Project Brief to call attention to the difference between Video 2 and the updated transcript.

Dolphin Browser

At present, the Silk browser on the Amazon Fire tablet does not reliably open an APK download link passed to it by a QR code reader: it opens a new tab but then closes it immediately without downloading the file. Silk previously worked fine, but an update over the summer has broken it.

For anyone using Amazon Fire tablets who experiences this, Dolphin is an alternative browser that works well. Dolphin is not available in the Amazon App Store; to install it, open the Silk browser and go to http://dolphin.com/download, then click the button marked "Download Dolphin APK for Android". This will download and install the Dolphin mobile browser.

The next time a QR code is scanned, you will be given the option of opening the URL in Dolphin instead of Silk.

Smart Skills Updates 2017-18

Based on teacher and student feedback from last year, a number of changes have been made to the Smart Skills course materials for 2017-18:

New: Student Handbook
Guides students through the course step by step and records their progress
http://unitydcu.ie/ss-shb

New: Video Transcripts
For students who prefer written instructions, and to assist with checking and debugging apps
http://unitydcu.ie/ss-int
http://unitydcu.ie/ss-c1t
http://unitydcu.ie/ss-c2t
http://unitydcu.ie/ss-c3t

Updated: Course Overview for Teachers
More detailed lesson-by-lesson course plan, formal inclusion of third party apps
http://unitydcu.ie/ss-ovr

Updated: Student Resource Centre
Reorganised and consolidated resources for students, referenced by the Student Handbook
http://unitydcu.ie/ss-src

Updated: Hello World App
Separated from Starter Apps document, includes instructions to build and install the app
http://unitydcu.ie/ss-hwa

Updated: Starter Apps
Aligned with updated course content, includes new Hour of Code apps
http://unitydcu.ie/ss-sta

Updated: Project Briefs
Rewritten to include Project Notes and Extra Challenges that were previously in separate documents
http://unitydcu.ie/ss-c1b
http://unitydcu.ie/ss-c2b
http://unitydcu.ie/ss-c3b

MIT App Inventor's New Logo

MIT App Inventor has a fresh new logo, featuring a bee and honeycomb. Read about their rationale and design process in their blog post.

Some changes were made to the Blocks Editor in May of this year, adding features to make it easier to organise and manage code blocks. Read about those changes in this blog post.

Future of ARC Welder

In August 2016, Google announced that they would be "removing support for packaged and hosted apps from Chrome on Windows, Mac, and Linux over the next two years." Although Google have not made a definitive statement either way, it is widely believed that this means that ARC Welder will cease to be a viable solution for running Android apps on Windows machines: it could be removed from the Chrome Web Store in the second half of 2017, meaning no new installations, and stop working entirely from early 2018. The reason for the uncertainty is that while ARC Welder is itself a Chrome Extension, it installs and runs Android apps as Chrome Apps. Whether or not Google will provide an alternative (such as native support for Android apps in the Chrome Browser) is not known at this time.

In the absence of ARC Welder or another solution from Google, alternative methods for testing Android apps are:

• a physical Android device, typically a small tablet such as the Amazon Fire 7
• an Android emulator for Windows such as Nox or BlueStacks
• ARC Welder on a Chrome OS machine, such as a ChromeBook

The preferred and recommended method is to use Android tablets, as this gives students the most engaging experience, allows the use of all sensors and media capabilities, and is typically the most reliable method, requiring only that the tablets have an internet connection. A ratio of one tablet between four students is sufficient: with tablets from €70, a class of 24 students could be facilitated for €420 (the same price as a single iPad).

Android Emulators

Two additional Android emulators, Memu and KO Player, have been evaluated for use with the Smart Skills course. Both install reasonably quickly and run well. Memu doesn't require the user to sign into Google which is an advantage on a shared machine, has a very clean phone-like interface, and is easily flipped between portrait and landscape modes. KO Player is more games oriented, with promoted apps and ads being quite visible.

Unfortunately, both require administrator privileges to run each time they are launched (rather than just at installation), which rules them out for school use. Nox and BlueStacks therefore remain the emulators of choice.

BlueStacks Update

The latest version of BlueStacks (2.7.320) has a more conventional tablet-like appearance than previous versions, and starts up in landscape mode with the ability to switch to portrait mode once an app is running. The promotion of game downloads is somewhat less intrusive than it previously was, though still present on the main screen. A major improvement for our purposes is that BlueStacks TV video streaming is no longer launched automatically.

As before, BlueStacks requires the user to log in to Google during the initial setup. This account is not logged out when BlueStacks is closed, so the best approach in the school environment is to create a dedicated Google account for use with BlueStacks, and leave that account logged into all instances of BlueStacks. Students would still use their individual Google accounts with App Inventor when building their apps.

WhoIsQuiz Sample Apps

A new version of the WhoIsQuiz app has been added to the Downloads page for Core 2: Brainstorming http://unitydcu.ie/ss-c2d

WhoIsQuiz_example_1.aia shows how the app would appear at the end of video 5 (users type in answers), while WhoIsQuiz_example_2.aia shows how the app would appear at the end of video 8 (welcome screen, users select answers from a list). To load either of these into App Inventor, download and save the .aia file, then use Projects -> Import project (.aia) from my computer to upload it.

Both versions include the correction to the end-of-game logic described in the Project Notes document http://unitydcu.ie/ss-c2n. If this logic correction is not applied, the app as built in the videos crashes when the last question is answered. It may be a useful exercise to have students try to debug and correct the app themselves; the ability to do so demonstrates the transition from following the instructions in the video to understanding the logic and flow of the code.

App Inventor Update

An update to MIT App Inventor was pushed out on 27 January, and users will see a pop-up screen alerting them to this on their first sign-in after that date. None of the updates described in the release notes should have an impact on existing Smart Skills apps.

If you have installed the AI2 Companion App on an Android device in order to use the WiFi or USB 'live debug' methods, it will need to be updated to use the new features in this App Inventor release. If you installed the Companion App from the Google Play store, it will update automatically; if you installed it directly to your device, you will need to manually update to version 2.40 at appinv.us/companion.

Cloud Storage: TinyWebDB

MIT App Inventor includes a TinyDB component which allows a simple database to be created on the Android device; this could be used to store a local high score in a game, for example. TinyDB is also useful for passing data between screens in a multi-screen app, as normally it's only possible to pass one value between screens.

There's also a cloud-based equivalent, TinyWebDB, which allows data to be stored online: it can therefore be shared between different apps and different devices. This could be used to store a global high score, shared with all players of a game, and updated if they beat it. It could also be used to build a rudimentary message storage and retrieval system, allowing messages to be sent from one client device to another via a central server: the basis of email or messaging.

The default cloud-based database is a shared resource, and data written to it will be overwritten at some point, depending on how many other App Inventor apps are using it.

We have therefore created a new TinyWebDB service specifically for UniTY teachers and students: it is still shared of course, but only among participating schools. Data should therefore be persistent provided (a) unique keys are used to prevent accidentally deleting or modifying someone else's data, and (b) nobody deliberately deletes or modifies data other than their own. Be warned that data stored in the database is not private!

The UniTY database can be selected by setting the ServiceURL to http://unity-dcu-tinywebdb.appspot.com/

A demo app using TinyDB and TinyWebDB has been added to the UniTY section of the app library.

Resizing images for the Brainstormer Quiz app

For those students who want to use their own images in the Who-Is-Quiz app built as part of the Core 2: Brainstormer project, it's best to resize the images before uploading them to App Inventor. Most image processing programs offer the ability to resize or scale an image: one such program is Autodesk Pixlr, which can either be downloaded and installed as a desktop app, or used online as a web app called Pixlr Express - the latter is useful if students do not have install rights on their PCs. For the quiz, a maximum image dimension (height or width) of 240 pixels should work well for most images.

Also, a reminder that the Project Notes for Core 2: Brainstormer (http://unitydcu.ie/ss-c2n) include important information about fixing a crash in the version of the app described in the videos.

Near Field Communications (NFC) Demo

App Inventor supports very basic Near Field Communications (NFC) capability, allowing the reading and writing of text tags. NFC is the short range communications protocol that underlies contactless payments ('tap to pay') capabilities on credit and debit cards, as well as services like Samsung Pay that allow a phone to be used for payments. It's also used in Leap Cards, office access badges, and hotel room keycards.

An app to read and wite NFC tags has been added to the UniTY section of the App Library. Some things to consider before trying out the app:

1. NFC is not supported on Amazon Fire tablets, but is supported on many Android phones.
2. NFC tags must already be configured as Text Tags to work with this app; this can be done with an app such as NFC Tools, as most NFC tags are blank when purchased.
3. NFC tags can be purchased directly from companies such as ZipNFC or through their eBay store for under 50c each, plus postage.

App Orientation (BlueStacks)

The BlueStacks emulator opens in landscape mode every time, and can only be switched to portrait after an app is running. The sample Smart Skills apps provided at the Download link for each project have therefore been updated to set the Screen1 property ScreenOrientation to Portrait. This automatically switches BlueStacks to portrait mode when the app is launched.

This change also forces the Nox emulator to switch to portrait mode when the app is launched, however with Nox it is possible to configure the initial screen size and orientation in the Advanced Settings, which should be set to Phone and 480x800 for optimum compatibility with the apps.

This change has no effect on ARC Welder orientation, which must be set when an app is first loaded in each session, as described in the previous post.

ARC Welder: Invisible Dropdowns

Those of you using ARC Welder to test apps may have noticed a problem with "invisible dropdowns" when trying to set the recommended Orientation (Portrait) and Form Factor (Phone) on first use. As shown below, the triangle points upward when the selector is clicked, but the dropdown is not visible.

This appears to be intermittent and is a recent problem, possibly introduced with the current version of ARC Welder in early August. The dropdowns are in fact still active, but are invisible: it is therefore still possible to select the desired Orientation and Form Factor by clicking once to open the dropdown (triangle points upwards), and then clicking where the desired option should appear, by reference to the images below. Typically the desired settings are Portrait for Orientation, and Phone for Form Factor.

 

While not ideal, and potentially difficult to have students do successfully, this at least allows the orientation and form factor of ARC Welder to be set to match the apps created by App Inventor. On the positive side, it only needs to be done once per session, provided ARC Welder is not closed.

The images with the dropdowns visible as expected were taken from the version of Chrome Portable and ARC Welder provided on a USB during the Smart Skills Training sessions. This may be a viable alternative, at the cost of needing to manually copy Chrome Portable onto every student PC, and ensuring that students open Chrome Portable and not the normal Chrome installation when using App Inventor and ARC Welder.

BlueStacks Update

The latest version of BlueStacks (2.4.44) requires the user to log in to Google during the initial setup. This was previously optional, with a One Time Setup screen being displayed from time to time: this screen is now gone, as is the Welcome screen, with the result that the new setup procedure is more predictable and the overall user experience is cleaner. Performance and stability have also been improved steadily over the last few months.

Note: The Google account is not logged out when BlueStacks is closed, so users should consider manually disconnecting their Google account when using BlueStacks on a shared machine: go to Settings - Accounts - Google and select Remove account from the dropdown menu in the top right. Alternatively, a school may choose to create a dedicated Google account for use with BlueStacks, and leave that account logged into all instances of BlueStacks. Students would still use their individual Google accounts with App Inventor.

For more information about Bluestacks, refer to this earlier post.

Raspberry Pi and App Inventor

We have uploaded a selection of apps and accompanying Python files to the App Library which demonstrate how App Inventor can be used to build apps that interface to a Raspberry Pi. Examples include controlling LEDs, reading sensors, driving a robot, and viewing webcam images. There's also a multifunction app that combines all of these and adds speech synthesis for full remote control of a Raspberry Pi robot.

Coding: Next Steps

For teachers or students interested in growing their software development skills beyond the contents of the Smart Skills course, there are any number of paths to follow. This document lists some popular sources of further training, but is by no means exhaustive.

Chrome Portable and ARC Welder

Some schools may not be able to install ARC Welder from the Chrome Web Store as described in the instructional videos because of computer or network security restrictions. While we will assist schools to investigate and attempt to resolve these issues, we are also making an alternative installation method available.

This involves copying a version of Chrome Portable with ARC Welder already installed and configured onto each student PC. Since this only requires copying files onto the PC, it can be done without administrator rights. 

1. Download the zipped archive here, and extract the contents. It may be convenient to copy the unzipped folder to a USB drive in order to install it on multiple PCs.
2. Copy the entire folder called 'GoogleChromePortable' to the root of the C: drive on the target PC. It is important not to rename the folder or copy it to any other location, as the configuration of ARC Welder depends on this location.
3. Create a shortcut on the desktop to this copy of Chrome Portable: in the C:\GoogleChromePortable folder, right-click on the shortcut 'Chrome for Smart Skills' and choose 'Send to Desktop (create shortcut)', or drag it to the desktop.
4. On the desktop, double-click the newly created shortcut to open Chrome Portable. Click on the Apps bookmark to find ARC Welder. For convenience, the bookmarks bar also contains links to App Inventor and the Smart Skills Student Resource Centre.

Note that this installation of Chrome Portable can co-exist with a normal installation of Google Chrome, so it is important to distinguish between the two when students are opening a browser to begin a lesson.

MIT App Inventor Update

An update to MIT App Inventor was pushed out on 16 June, and users will see a pop-up screen alerting them to this on their first sign-in after that date. None of the updates described in the release notes should have an impact on existing Smart Skills apps. The new Pedometer component may be of interest for the development of exercise and fitness apps.

If you have installed the AI2 Companion App on an Android device in order to use the WiFi or USB 'live debug' methods, it will need to be updated to use the new features in this App Inventor release. If you installed the Companion App from the Google Play store, it will update automatically; if you installed it directly to your device, you will need to manually update to version 2.37 at appinv.us/companion.