AI2 Inventor Forum News: 06/11/17

2017년 6월 11일 일요일

FAQ for Arduino and Bluetooth

⦁ Delimiter usage for receiving one message per ReadText
⦁ Sending Slider Data to Arduino - Neil Kenyon
⦁ Reconnecting BlueTooth across screens
⦁ How to send CR - Christophe L
⦁ ⦁ ESP8266 Controlled with Android App (MIT App Inventor) - Randomnerdtutorials.com
⦁ ⦁ Martyn Currey:
⦁ ⦁ ⦁ Turning a LED on and off with an Arduino, a HC-06 and Android
⦁ ⦁ ⦁ Turning a LED on and off with an Arduino, Bluetooth and Android. Part II: 2 way control
⦁ ⦁ ⦁ Turning a LED on and off with an Arduino, Bluetooth and Android. Part III 3 LEDs and 3 Switches
⦁ ⦁ ⦁ http://www.martyncurrey.com/android-mit-app-inventor-auto-connect-to-bluetooth/
⦁ ⦁ ⦁ Instructables YouTube course on Arduino/AI2 - Magesh Jayakumar
⦁ ⦁ ⦁ http://mitappsinventor.blogspot.com/ Magesh Jayakumar
⦁ ⦁ ⦁ Arduino via USB
⦁ ⦁ ⦁ Arduino USB - Pavitra and Thunkable
⦁ ⦁ ⦁ Martyn Arduino Bluetooth sketch
⦁ ⦁ ⦁ How to enable Bluetooth
⦁ ⦁ ⦁ Arduino HC-06 tutorials
⦁ ⦁ ⦁ Which Bluetooth protocols are supported? (discussion)

Send a picture and ESC sequences to a bluetooth printer

I want to print on a bluetooth termal printer a little logo with BluetoothClient object.

Is it possible? How can I do it? With which method?

Then, How can I send ESC sequences to set printer as I need?

I have the necessary sequences, but I don't know how to send them to the printer.

For example: the hex sequence 1B 21 20

I have tried with SendText method using "\x1B\x21\x20" in the text, but nothing.

Look in the Gallery for application CRLF.

It has a hexify() procedure that uses a trick of the Web component to create single byte text

blocks from hex. JOIN them together and sent them as text.

Sending a picture is harder.

You need access to the coding technique used by your printer.

See the BlueTooth section of my FAQ at the beginning of this board for sample apps.

FAQ for Arduino and Bluetooth
FAQ for Bluetooth/BLE

excuse me but in Blocks section I don't find the procedure "Web.HtmlDecodeText" with parameter "for component".

Between the blocks available for Web component, I see only the block with "htmlText" parameter (see below)

I'm looking for this:

Where I have to search for it? Do I need any upgrade?

It's in the Any Component section of the Blocks Editor.

Invalid JWT

I put a quotify method like it says on the Frequently Made Errors with Fusiontables and how to fix them, but it still gives me an Invalid JWT signature. Can you please tell me what I did wrong?

do the Pizza Party tutorial to learn how to work with fusiontables and how to setup the service account method

How does the new property Webviewer.WebViewString work?

in the new release there was introduced the new property Webviewer.WebViewString

how can this be used?

sorry, the documentation does not help me very much ...

from the release notes:

WebViewer: You can now communicate with the Javascript environment in the WebViewer by providing a string it can read

from the documentation

WebViewString

Gets the WebView's String, which is viewable through Javascript in the WebView as the window.AppInventor object

I'm also interested in knowing a bit better how this new feature works,

maybe it will be easy to pass values via javascript and web pages with web component, but how?

an example is really appreciated! thanks!

You can use WebViewString to communicate values back and forth between your App, and the WebViewer.

In your App, you get and set the WebViewer.WebViewString properties.

In you webviewer, you open to a page that has Javascript that references the window.AppInventor object, using its getWebViewString() and setWebViewString(text) methods.

For example, if the WebView opens to a page that contains the Javascript

<script>
document.write("The value from the app is<br />" + window.AppInventor.getWebViewString());
</script>

and if you set the WebView.WebVewString property to "hello from my app", then the web page will show

The value from the app is
hello from my app.

Also, if the web page contains javascript the executes the command

windowAppInventor.setWebViewString("hello from Javascript")

then the value of the Webviewer.WebViewString property will be the text "hello from Javascript"

Taifun has done a lot of tricks that use the Web page title as a communication channel. This is essentially the same thing, but
without needing to use the title.

We'll update the documentation to be more clear.

Does this explanation help?

How about some blocks Hal? Thanks.

Great update.

.--

Does this explanation help?

thank you Hal, this should help me to prepare an example soon

a basic example how to use this can now be found here http://puravidaapps.com/snippets.php#2webviewstring
webviewstring.aia

Thank you Hal! This offers some possibilities!

Jeff deserves the credit, not me -- I just reported what he did.

Thanks for writing this up!!

By the way, then I create those Javascript pages, i use android file transfer to put them in a directory like /Temp/stuff.html
Then from the app, I use the URL file:///sdcard/Temp/stuff.html

That works both in developer mode and production mode, although it does leave junk in the file system that has to be deleted lateer

Good example Taifun.

The example sets a global true/false variable development but instead refers
to a hardwired true in the Screen1.Initialize URL choice step.

The if/then/else should query development.

--

thank you ABG, now fixed

a probably more useful example is now available here

App Inventor and Dynamic Table Layout now using the new WebViewString property

Say I wanted to send 2 paragraphs from a textbox in my app to an html page with the necessary Javascript, what is the limit of characters I can send without error?

JavaScript to pass information from HTML to WebViewString

I'm managing a list of proverbs in the WebView component as follow;

document.write(window.AppInventor.getWebViewString()); as the JavaScript to receive the HTML content or <body>.

The WebViewString is set to:

<ul>

<li>Maisha mazuri</li>

<li>tenda wema nenda zako</li>

</ul>

Now I wanted to extract the <li>( innerHTML) with an onclick event and share it using the SHARING component.

I tried this <li onclick="javascript:window.AppInventor.setWebViewString(this.innerHTML);">
but failed to get the text via window.AppInventor.setWebViewString() as shown in this tutorial.
webviewstring.aia

Please, I need your Help!

Three things to try:

Check that "this.InnerHTML" actually contains what you want back?

Remove the word javascript:

onclick="window.AppInventor.setWebViewString(this.innerHTML);"

Might it need to be in a "link" ?

<a href="javascript:;">onclick="window.AppInventor.setWebViewString(this.InnerHTML)"></a>

<a href="javascript:;">onclick="window.AppInventor.setWebViewString('this.InnerHTML')"></a>

Also , just an observation (based upon what you have disclosed):

If you are seeking to collect the same information as you are feeding the html, why not setWebViewString as an index number, collect that, and use the index to call up the data from a list?

Unless I have missed something?

Thanks a lot Tim.

I tried these methods on Samsung Galaxy Note 2(android 4.1.2), it worked very well.

But failed on other devices (android 4.4.1 and higher)...

--
refer to: How does the new property Webviewer.WebViewString work?