Android4Pascal

See the page about Android4Pascal, which is the bindings between Pascal programs and the Android Java APIs.

Android API Hello World in Pascal

Here is an example Pascal application written for Android. It shows how to create controls, receive callback events and how to use the timer.

The full directory structure can be download with this svn command:

 svn co https://p-tools.svn.sourceforge.net/svnroot/p-tools/turbochessclock4android turbochessclock4android

Here is the Pascal code from this example:

{

  A simple Chess Clock application

  Author: Felipe Monteiro de Carvalho - 2011

  License: Public Domain

}

program turbochessclock4android;

{$mode objfpc}{$H+}

uses

  Classes, SysUtils, androidpipescomm, androidview, javalang,

  androidapp, androidtimer, androidutil;

type

  TEventHandler = class

  public

    procedure HandleOnTimer(ASender: TObject);

    procedure buttonStartClickCallback(v: TView);

    procedure buttonMoveClickCallback(v: TView);

  end;

var

  layout: TLinearLayout;

  params: TLayoutParams;

  tv, black_label, white_label: TTextView;

  scroller: TScrollView;

  btn_move, btn_start: TButton;

  tp: TTimePicker;

  WhiteTimeCount: Integer = 0;

  BlackTimeCount: Integer = 0;

  MyTimer: TAndroidTimer;

  MyEventHandler: TEventHandler;

  IsWhitePlayerMove: Boolean = True;

procedure TEventHandler.buttonStartClickCallback(v: TView);

begin

  black_label.setVisibility(VISIBLE);

  white_label.setVisibility(VISIBLE);

  btn_move.setVisibility(VISIBLE);

  //

  WhiteTimeCount := tp.getCurrentHour() * 60 * 60 + tp.getCurrentMinute() * 60;

  BlackTimeCount := WhiteTimeCount;

  //

  MyTimer.removeCallbacks();

  MyTimer.postDelayed(100);

end;

procedure TEventHandler.buttonMoveClickCallback(v: TView);

begin

  IsWhitePlayerMove := not IsWhitePlayerMove;

end;

procedure TEventHandler.HandleOnTimer(ASender: TObject);

var

  lSeconds, lMinutes, lHours: Integer;

begin

  if IsWhitePlayerMove then

  begin

    lSeconds := WhiteTimeCount mod 60;

    lMinutes := (WhiteTimeCount mod (60 * 60)) div 60;

    lHours := WhiteTimeCount div (60 * 60);

    white_label.setText(Format('White %d:%d:%d', [lHours, lMinutes, lSeconds]));

    //

    if WhiteTimeCount = 0 then Exit;

    Dec(WhiteTimeCount);

  end

  else

  begin

    lSeconds := BlackTimeCount mod 60;

    lMinutes := (BlackTimeCount mod (60 * 60)) div 60;

    lHours := BlackTimeCount div (60 * 60);

    black_label.setText(Format('Black %d:%d:%d', [lHours, lMinutes, lSeconds]));

    //

    if BlackTimeCount = 0 then Exit;

    Dec(BlackTimeCount);

  end;

  //

  MyTimer.removeCallbacks();

  // Note that this has a low precision, but it enough for this simple app

  // A more precise app would keep another time count instead of just using Dec

  // at each timer call

  MyTimer.postDelayed(1000);

end;

begin

  // Here add any initialization.

  // Any initialization code will be run inside Activity.onCreate,

  // so keep it as short as possible!

  // It should mostly contain GUI initialization

  // User interface

  MyEventHandler := TEventHandler.Create;

  // Prepares the UI of the program

  layout := TLinearLayout.Create;

  params := TLayoutParams.Create(androidview.FILL_PARENT, androidview.FILL_PARENT);

  layout.setLayoutParams(params);

  params.Free;

  layout.setOrientation(androidview.VERTICAL);

  // Game UI

  black_label := TTextView.Create;

  black_label.setText('Black time:');

  black_label.setVisibility(GONE);

  black_label.setTextSize(COMPLEX_UNIT_PX, 40);

  layout.addView(black_label);

  white_label := TTextView.Create;

  white_label.setText('White time:');

  white_label.setVisibility(GONE);

  white_label.setTextSize(COMPLEX_UNIT_PX, 40);

  layout.addView(white_label);

  btn_move := TButton.Create;

  btn_move.setText('Move finished!');

  btn_move.setOnClickListener(@MyEventHandler.buttonMoveClickCallback);

  btn_move.setVisibility(GONE);

  layout.addView(btn_move);

  // Config UI

  tv := TTextView.Create;

  tv.setText('Please select how much to give to the players and press "Start Game":');

  layout.addView(tv);

  tp := TTimePicker.Create;

  tp.setIs24HourView(True);

  tp.setCurrentHour(0);

  tp.setCurrentMinute(30);

  layout.addView(tp);

  btn_start := TButton.Create;

  btn_start.setText('Start game!');

  btn_start.setOnClickListener(@MyEventHandler.buttonStartClickCallback);

  layout.addView(btn_start);

  // And also allow the user to scroll the UI if it is larger then the screen width

  // Scrolling takes place only horizontally

  scroller := TScrollView.Create;

  scroller.addView(layout);

  Activity.setContentView(scroller);

  MyTimer := TAndroidTimer.Create;

  MyTimer.OnTimer := @MyEventHandler.HandleOnTimer;

  // Now tell Java that the initialization has finished

  vAndroidPipesComm.onCreateFinished();

  // Here you can add any other initialization,

  // specially non-GUI code

  // Now we block our execution waiting for callbacks from Java

  vAndroidPipesComm.MessageLoop();

end.

Compiling the example project in Linux

1> Get a working arm-linux cross-compiler which generates ARMv5 eabi with softfloat (as many phones like HTC Wildfire have no FPU)

To do this one can download an unofficial build from here:

http://members.yline.com/~tom_at_work/fpc-2.4.2.UNOFFICIAL.arm-linux.tar . Compiled for ARMv5 eabi with softfloat.

Or build your own. There are instructions here: Setup_Cross_Compile_For_ARM

2> Install the Android SDK. Instructions here:Android_Interface/Using_the_Android_SDK,_Emulator_and_Phones#Using_the_Android_SDK

3> Install ant, for example in Mandriva Linux:

 urpmi ant

4> Open the project turbochessclock/turbochessclock4android.lpi in Lazarus and build it

5> Build the APK file in debug mode

 ant debug

6> Connect your phone and make sure you can connect to it via ADB. More info here:Android_Interface/Using_the_Android_SDK,_Emulator_and_Phones#Recognition_of_devices_under_Linux

7> Install the APK file in your phone via ADB or whatever other method you prefer:

 ../android-sdk-linux_x86/tools/adb install android/bin/TurboChessClock4Android-debug.apk

If the package is already installed you need need to do this instead:

 ../android-sdk-linux_x86/tools/adb uninstall com.pascal.turbochessclock

 ../android-sdk-linux_x86/tools/adb install android/bin/TurboChessClock4Android-debug.apk

Manifest configuration

Control the program restart

By default the program will restart on orientation change, on keyboard change, and in a lot of other cases. This is usually unwanted. To disable program restart o keyboard showing and orientation changed add this to the manifest file:

 <activity

    ...

    android:configChanges="orientation|keyboardHidden"

See also:

·                     http://developer.android.com/guide/topics/manifest/activity-element.html#config

Guidelines for the Icons

Read here: http://developer.android.com/guide/practices/ui_guidelines/icon_design.html

Using the Timer

The Android API bindings include a handy timer control called TAndroidTimer. It works just like a Runnable, and inside it a Handler class is utilized to run the Runnable in the main GUI thread so that event executed in this timer can call Android APIs.

Timer example

program turbochessclock4android;

{$mode objfpc}{$H+}

uses

  Classes, SysUtils, androidpipescomm, androidview, javalang,

  androidapp, androidtimer;//, gles11;

type

  TEventHandler = class

  public

    procedure HandleOnTimer(ASender: TObject);

    procedure buttonClickCallback(v: TView);

  end;

var

  //...

  TimerCount: Integer = 0;

  MyTimer: TAndroidTimer;

  MyEventHandler: TEventHandler;

procedure TEventHandler.buttonClickCallback(v: TView);

begin

  MyTimer.postDelayed(100);

end;

procedure TEventHandler.HandleOnTimer(ASender: TObject);

begin

  Inc(TimerCount);

  tv.setText(Format('Timer event #%d', [TimerCount]));

  MyTimer.postDelayed(1000);

end;

begin

  MyEventHandler := TEventHandler.Create;

  // ...

end.