Leapster Explorer: Play Your Own Flash Games

This how-to will show you how to load your own flash swf files on to the Leapster Explorer and play them from the standard User Interface. This solution is very very beta, proceed to the Problems section before experimenting with this, it does not work 100% and will require some trial and error to find flash files that work well with the Explorers range of inputs.

Programs Needed

STFP Access

Software Needed

Flash Game (see requirements)

Game Package Template

Requirements

The Flash Lite for the Digital Home, as built for the Leapster Explorer, is a bit hit or miss, when it comes to playing random

• The swf file must be ActionScript2 and compiled for versions no higher than Flash Player 8.
• Flash Lite for the Digital Home does not support all AS2 features. No internet access, etc
• Files built much larger than 320x240, may have issues with displaying, or the exit screen.
• Pick games that have simple inputs. Flash Lite interprets the buttons as these values.

Configure Package and Load It

The easiest way about this, is to download the Template folder. If you have downloaded a game previously, you could make your own. By renaming your file loader.swf and changing a few values as needed in the .json files and meta.inf. The template package includes a loader.swf file, that puts a wrapper around your file, so that you can cleanly exit back to the UI. With out it, you must shut off the device.

The first step is finding a suitable swf file, this can take some trial and error, the Requirements section has some hints about what to look for.

Next rename the file test.swf and copy it into the folder.

Looking through the .json files and meta.inf you can change anything that says OpenDidj. If its a file link, be sure it matches the file you want to link to. Icons are 8 bit png files.

Rename the folder so it does not conflict with any other package you have uploaded.

Using SFTP/SCP/SSH upload your file to the device. /LF/Bulk/ProgramFiles/ is where it needs to be.

Unplug the USB cable and it should bring up the UI with a new menu option, click right arrow if you do not see it.

Then start it like you would any other application. If it fails, it should bring you back to the UI. If not you can test the playability and when you want to exit, hit the home button and confirm.

Problems

Screen goes black, and returns to Explorer UI

• Flash file is newer than ActionScript2.
• Flash file is made for a Flash Player greater Flash 8.
• Flash executed a command that is not available in Flashlite, certain filters, web links, etc.

Controls not responding, or missing

• game or interactive elements not compatible with the limited inputs of the Explorer.

No way to exit Flash

• This is avoidable for the most part, by using the OpenDidj Package Template.
• This is to my knowledge unavoidable with random Flash files, see the Example for how to deal with it on your own files.

Flash runs very slow

• Common problem with games that have a lot of movement or complex physics or any other processor intensive code.

Displays bigger than screen size

• Common problem with flash files whose document stage is bigger than 320x240
• OpenDidj Package Template loader.swf deals with this, but currently it will oversize the exit confirmation screen, forcing you to turn off the device to exit.

Example Flash App

This assumes previous knowledge of Adobe Flash.

Document:

Width: 320

Height: 240

12 Frames Per Second

Publish Settings:

Flash Player 8

ActionScript 2

This sample will print the OS Name, Player version and will capture input codes and print them to the stage which you can use to control the games from LX input. On the stage create two labels and a button. Create three labels text_version, text_keypress and, text_stylus, name the button button_exit.

On the first frame add this for the Actions

 // get version from player
 version = eval("$version");

 // player info vars
 var os_type;  
 var version_array;
 var major_version;
 var major_revision;
 var minor_version;
 var minor_revision;

 // split up version info
 os_array = version.split(' ');
 os_type = os_array[0];
 version_array = os_array[1].split(',');
 
 // populate version vars
 major_version = version_array[0];
 major_revision = version_array[1];
 minor_version = version_array[2];
 minor_revision = version_array[3];

 // populate text_version label
 text_version.text = "Version Info: \n" +
 "OS Version: " + os_type + "\n" +
 "Major Version: " + major_version + "\n" +
 "Major Revision: " + major_revision + "\n" +
 "Minor Version: " + minor_version + "\n" +
 "Minor Revision: " + minor_revision + "\n";

 // populate initial text_keypress label
 text_keypress.text = "Key Press Code:\nKey ASCII Code:";

 // set up key press event listener and function
 var key_listener:Object = new Object();
 key_listener.onKeyDown = function() {
   text_keypress.text = "Key Press Code: " + Key.getCode() + "\n" +
   "Key ASCII Code: " + Key.getAscii();
 };
 Key.addListener(key_listener);

 // capture stylus position
 text_stylus.text = "Stylus: \nX: 0\nY: 0";
 onEnterFrame = function() {
  text_stylus.text = "Stylus: \nX: " + _xmouse + "\n" + 
  "Y: " + _ymouse;
 };

An easy way to make your application exit, is to cause it to crash. Change the label on your button to Exit and make its function do something Flash Lite is not capable of doing, like getURL. This will cause it to fail, and it will go back to the main UI.

 // on key press make Flash error
 on(release){
   getURL("error_out");
 }

Make sure your settings are to Flash Player 8 and ActionScript 2 and publish your file. Save it as test.swf if you're using the OpenDidj Template. Load the files as configured above to your device and if all went well, you should see the Flash Player version and OS type once you run the application. Now press the stylus on the screen and move it around, you will its X and Y coordinates at the bottom.

Developing

The Explorer uses Flash Lite 3.1 For The Digital Home, which is a version meant for System On a Chip hardware. Unlike the Mobile version which is for mobile phones and those such devices. With Digital Home, the hardware vendor uses their own sources, in conjunction with Actionscript Extensions. The Extensions are to provide the Flash Lite player with specific access to items on the hardware. If this was a media set top box, then it could be used to give Flash Lite access to a volume circuit or the ability to change channels. Essentially an AS file is created, that is similar to a C++ header file, which is imported into the Flash app during development. The hardware vendor also creates a corresponding C++ file with the actual working code in it, which is compiled along with the Flash Lite player from the Adobe provided source code. Which unless you're a company with a good pitch, you probably won't be getting any time soon. Thus leaving you needing to reverse engineer the added functionality of the hardware you are trying to develop Flash for. If it is the Explorer you would surely want to be able to exit your Flash app with out having to shut down your device. There may very well also be some other features you would like to incorporate, if you planned on creating your own User Interface, or application that needs lower level hardware access. I will explain the process to incorporating any functions you may find, that you would like access to in your Flash app.

The functions are listed in plain text in the Plugin binaries, on your LX look in /LF/Base/Flash/plugins, you will find AppManagerPlugin.so CYOPlugin.so etc. I used Notepad++ to open these, its a text editor, and while you will see a bunch of garbage, if you scroll down thru the file, you will see some plain text, of what look like some function names. AppManagerPlugin.so happened to have the exit function in it, popApp. It will take some figuring out, popApp sounds like taking an element out of an array, there was also pushApp. You may also want to check the log file found in /LF/Base/FR/ as I did a search for popApp after it didn't work I found a reference to a kPopApp, after some fiddling with the name it turned out to be PopApp() a capital P instead of lower case. Also in the binary you should find the plain text LF.AppManager, this turns out to be the name of what you will import into Flash.

So now that we have our information, lets build the file needed by Flash to use the LF exit function, instead of that nasty crash back to the UI way. Create a folder in your project directory named LF/ inside that file create a file named AppManager.as then open it with your favorite text editor and put in

 intrinsic dynamic class LF.AppManager
 {
     public static function PopApp():Void;
 }

Intrinsic tells it that this file just basically has the prototypes of the functions, dynamic allows the objects to be changed, and won't do strict type checks. AS Extensions for Flash Lite Digital Home This file will explain it much better. I went with Dynamic simply because this is going to take some trial and error. Looking at your binary in a text editor, should give you some clues as to what sort of data is expected or is sent. Look for things like function_arg(%s) or function_return() %s. Its a bit cryptic but with some practice, you should be able to decipher some of it. Create an entry for each function you would like access to, and put this in the Actions/Actionscript file of your Flash project.

 import LF.AppManager;

Which will make the function PopApp() available in your application, and allow the swf to compile with out complaint. Things I noted while trying this out, the compiler complained the function wasn't static, you may want to play around with it. Though it was noted in the linked document, private is not appropriate, as all of that will be taken care of in the C++ files themselves.

This is a rather generic explanation of the process, and should be applicable to all SoC's that use Flash Lite in a standalone fashion for their UI or other features. And of course, check with the manufacturer on the legality of what you are attempting or more importantly, how you are doing it, so think before you leap, least you want some trouble. Some good resources I found linked to on the internet, explaining Adobe Flashlite for Digital Home.

Getting Started with Flashlite Digital Home

Developing Apps for Flashlite Digital Home

AS Extenions for Flashlite Digital Home

Optimizing Flashlite Digital Home