Thursday, December 30, 2010

Implement takePicture function of Android Camera

In order to implement takePicture function of Android Camera, we have to implement ShutterCallback, PictureCallback for RAW and PictureCallback for JPG. To take picture, simple call camera.takePicture() method passing with the Callbacks.

takePicture

Modify from the last exercise "Add a overlay on Camera Preview SurfaceView". Modify AndroidCamera.java
package com.exercise.AndroidCamera;

import java.io.IOException;

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;
LayoutInflater controlInflater = null;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

getWindow().setFormat(PixelFormat.UNKNOWN);
surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

controlInflater = LayoutInflater.from(getBaseContext());
View viewControl = controlInflater.inflate(R.layout.control, null);
LayoutParams layoutParamsControl
= new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT);
this.addContentView(viewControl, layoutParamsControl);

Button buttonTakePicture = (Button)findViewById(R.id.takepicture);
buttonTakePicture.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
camera.takePicture(myShutterCallback,
myPictureCallback_RAW, myPictureCallback_JPG);
}});
}

ShutterCallback myShutterCallback = new ShutterCallback(){

@Override
public void onShutter() {
// TODO Auto-generated method stub

}};

PictureCallback myPictureCallback_RAW = new PictureCallback(){

@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
// TODO Auto-generated method stub

}};

PictureCallback myPictureCallback_JPG = new PictureCallback(){

@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
// TODO Auto-generated method stub
Bitmap bitmapPicture
= BitmapFactory.decodeByteArray(arg0, 0, arg0.length);
}};

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
if(previewing){
camera.stopPreview();
previewing = false;
}

if (camera != null){
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
previewing = true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}


Download the files.

next:
- Save the camera image using MediaStore



Wednesday, December 29, 2010

Add a overlay on Camera Preview SurfaceView

Modify from last exercise "Camera Preview, version II", a overlay will be add on the Camera Preview SurfaceView. Controls; such as "Take Picture" button is added on the overlay.

Add a overlay on Camera Preview SurfaceView

Keep using the AndroidManifest.xml and main.xml in last exercise "Camera Preview, version II" without change.

Add a layout xml file, control.xml, under /res/layout folder. It define the layout of the control layer.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:gravity="bottom"
 >
<Button
android:id="@+id/takepicture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" * Take Picture "
android:layout_gravity="right"
android:layout_margin="10px"
/>
</LinearLayout>


Modify AndroidCamera.java to inflate a layer using control.xml
package com.exercise.AndroidCamera;

import java.io.IOException;

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;
LayoutInflater controlInflater = null;

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  
     getWindow().setFormat(PixelFormat.UNKNOWN);
     surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
     surfaceHolder = surfaceView.getHolder();
     surfaceHolder.addCallback(this);
     surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
  
     controlInflater = LayoutInflater.from(getBaseContext());
     View viewControl = controlInflater.inflate(R.layout.control, null);
     LayoutParams layoutParamsControl
      = new LayoutParams(LayoutParams.FILL_PARENT,
      LayoutParams.FILL_PARENT);
     this.addContentView(viewControl, layoutParamsControl);
  
 }



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
 int height) {
// TODO Auto-generated method stub
if(previewing){
 camera.stopPreview();
 previewing = false;
}

if (camera != null){
 try {
  camera.setPreviewDisplay(surfaceHolder);
  camera.startPreview();
  previewing = true;
 } catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
}
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}


Download the files.

next:
- Implement takePicture function of Android Camera

Tuesday, December 28, 2010

Pro Android Media: Developing Graphics, Music, Video, and Rich Media Apps for Smartphones and Tablets


Product Description

Mobile devices have evolved to focus on rich media production and consumption. Developers of mobile applications are able to create applications that allow people to play, capture, and share media in a variety of new ways on mobile devices. The popularity of Android has soared in part because the platform offers developers a rich set of capabilities including access to media capturing and playback functions.

Pro Android Media provides concise and clear instruction on how to utilize the media APIs made available through Android to create dynamic apps. It takes you from a simple means to gain access to the camera to complex video capture and sharing examples. It also covers sound, graphics, painting, and more—everything you need to make your app come "alive."

After reading this book, the app you create will showcase the best of multimedia that Android has to offer.

What you’ll learn

  • Develop graphics, music, video and rich media apps for Android smartphones and tablets
  • Build touchscreen input features into Android apps that allow users to draw, paint, and do other creative forms of input.
  • Turn the Android smartphone into a full fledged media player
  • How to integrate and use location based services and media related web service APIs

Who this book is for

This book is aimed primarily at the growing market of Android developers. It is written in such a way that it may be used by those who are familiar with Android, but have no experience developing applications that deal with images, audio, or video.



Camera Preview, version II

In the exercise "Camera Preview on SurfaceView", I show how to using Android's camera preview on a SurfaceView. The preview is set Start/Stop using buttons, it's not a good approach I think. In this exercise, it is re-arranged to handle the preview in SurfaceHolder.Callback methods: surfaceCreated(), surfaceChanged() and surfaceDestroyed().

Android's Camera Preview

Remember to grant permission to access Camera AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exercise.AndroidCamera"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".AndroidCamera"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
<uses-sdk android:minSdkVersion="4" />
<uses-permission android:name="android.permission.CAMERA"></uses-permission>
</manifest>


main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<SurfaceView
android:id="@+id/camerapreview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


AndroidCamera.java
package com.exercise.AndroidCamera;

import java.io.IOException;

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

getWindow().setFormat(PixelFormat.UNKNOWN);
surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
if(previewing){
camera.stopPreview();
previewing = false;
}

if (camera != null){
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
previewing = true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}


Download the files.

next:
- Add a overlay on Camera Preview SurfaceView



Sunday, December 26, 2010

In-correct arrow icon on Spinner with custom ArrayAdapter

Refer to the exercise "Custom ArrayAdapter for Spinner, with different icons"; it implement a Spinner with custom ArrayAdapter, base on Build Target of Android 1.6, and android:minSdkVersion="4".

When it run on AVD of Android 2.1, the drop-down arrow on the right side is in-corret.
Run on AVD of Android 2.1

The same code, when it run on AVD of Android 2.3, the arrow is displayed correctly.
Run on AVD of Android 2.3

Up to this minute, I have no any idea on this problem. Sorry for any inconvenience caused!

Updated@2012-01-13: Please read command by RSZ below.

Saturday, December 25, 2010

Custom ArrayAdapter for Spinner, with different icons

In last exercise "Custom Spinner with icon", a custom spinner have been implemented. But all row have the same icon. In order to display a spinner with difference icons on each row, we can implement our own ArrayAdapter, override getDropDownView() and getView() methods.

Custom ArrayAdapter for Spinner, with different icons

row.xml and main.xml keep no change as in the exercise "Custom Spinner with icon".

AndroidCustomSpinner.java
package com.exercise.AndroidCustomSpinner;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.TextView;

public class AndroidCustomSpinner extends Activity {

String[] DayOfWeek = {"Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday"};

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);

   Spinner mySpinner = (Spinner)findViewById(R.id.spinner);
   mySpinner.setAdapter(new MyCustomAdapter(AndroidCustomSpinner.this, R.layout.row, DayOfWeek));
}

public class MyCustomAdapter extends ArrayAdapter<String>{

public MyCustomAdapter(Context context, int textViewResourceId,
String[] objects) {
super(context, textViewResourceId, objects);
// TODO Auto-generated constructor stub
}

@Override
public View getDropDownView(int position, View convertView,
ViewGroup parent) {
// TODO Auto-generated method stub
return getCustomView(position, convertView, parent);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return getCustomView(position, convertView, parent);
}

public View getCustomView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
//return super.getView(position, convertView, parent);

LayoutInflater inflater=getLayoutInflater();
View row=inflater.inflate(R.layout.row, parent, false);
TextView label=(TextView)row.findViewById(R.id.weekofday);
label.setText(DayOfWeek[position]);

ImageView icon=(ImageView)row.findViewById(R.id.icon);

if (DayOfWeek[position]=="Sunday"){
icon.setImageResource(R.drawable.icon);
}
else{
icon.setImageResource(R.drawable.icongray);
}

return row;
}
}
}
***********
It's a programmatic pitfall here:
in getCustomView(), Condition checking of String ("Sunday") should be checked with:
(DayOfWeek[position].equals("Sunday"))

"==" not always work! refer String Comparison: equals()? ==?
***********



download filesDownload the files.


* Please see the article "In-correct arrow icon on Spinner with custom ArrayAdapter"!

Reposted: Custom ArrayAdapter for Spinner, with custom icons.

Tuesday, December 14, 2010

Custom Spinner with icon

Refer to the exercise "HelloAndroid with Spinner", it's a basic spinner with default format to display simple text in the spinner. Current exercise is modified to have custom display with icon in the spinner, actually it is Spinner version of another exercise "ListView, with icon".

Custom Spinner with icon

Create a row.xml in /res/layout/. To to setup the layout on each row.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView
android:id="@+id/icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/icon"/>
<TextView
android:id="@+id/weekofday"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>


main.xml layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Spinner
android:id="@+id/spinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


Main Java code, AndroidCustomSpinner.java
package com.exercise.AndroidCustomSpinner;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class AndroidCustomSpinner extends Activity {

String[] DayOfWeek = {"Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday"};

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Spinner mySpinner = (Spinner)findViewById(R.id.spinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
R.layout.row, R.id.weekofday, DayOfWeek);
mySpinner.setAdapter(adapter);
}
}

Download the files.

Related Article:
- Custom ArrayAdapter for Spinner, with different icons

* Please see the article "In-correct arrow icon on Spinner with custom ArrayAdapter"!



Monday, December 13, 2010

Implement a SeekBar to control the volume of Video Player

Modify the former exercise "Play 3gp video file using MediaPlayer" to add a SeekBar to control the volume.



In order to create a volume control using SeekBar, we have to know the maximum volume and current volume. It can be retrieved using the method audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC) and audioManager.getStreamVolume(AudioManager.STREAM_MUSIC). And we can change the volume when SeekBar changed, using the method audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, volume index, flags).

Firstly, modify main.xml to add a SeekBar as Volume Control.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<LinearLayout
android:orientation="horizontal"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
>
<Button
android:id="@+id/playvideoplayer"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="- PLAY Video -"
/>
<Button
android:id="@+id/pausevideoplayer"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="- PAUSE Video -"
/>
</LinearLayout>
<SeekBar
android:id="@+id/volbar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="10px"
/>
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


Modify AndroidVideoPlayer to handle the SeekBar as Volume Control.
package com.exercise.AndroidVideoPlayer;

import java.io.IOException;

import android.app.Activity;
import android.content.Context;
import android.graphics.PixelFormat;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;

public class AndroidVideoPlayer extends Activity implements SurfaceHolder.Callback{

MediaPlayer mediaPlayer;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean pausing = false;

AudioManager audioManager;

String stringPath = "/sdcard/samplevideo.3gp";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);


audioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
int curVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
SeekBar volControl = (SeekBar)findViewById(R.id.volbar);
volControl.setMax(maxVolume);
volControl.setProgress(curVolume);
volControl.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

@Override
public void onStopTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub

}

@Override
public void onStartTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub

}

@Override
public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {
// TODO Auto-generated method stub
audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, arg1, 0);
}
});


Button buttonPlayVideo = (Button)findViewById(R.id.playvideoplayer);
Button buttonPauseVideo = (Button)findViewById(R.id.pausevideoplayer);

getWindow().setFormat(PixelFormat.UNKNOWN);
surfaceView = (SurfaceView)findViewById(R.id.surfaceview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setFixedSize(176, 144);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
mediaPlayer = new MediaPlayer();

buttonPlayVideo.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
pausing = false;

if(mediaPlayer.isPlaying()){
mediaPlayer.reset();
}

mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mediaPlayer.setDisplay(surfaceHolder);

try {
mediaPlayer.setDataSource(stringPath);
mediaPlayer.prepare();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

mediaPlayer.start();


}});

buttonPauseVideo.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(pausing){
pausing = false;
mediaPlayer.start();
}
else{
pausing = true;
mediaPlayer.pause();
}
}});

}



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}
}


Download the files.

Saturday, December 11, 2010

Get supported picture sizes of Android device's camera: getSupportedPictureSizes()

To read the info of supporte picture size of camera, the method getSupportedPictureSizes() can be used. It return a list of supported picture sizes. This method will always return a list with at least one element.

List of Supported Picture Sizes

In order to access Camera, we have to modify AndroidManifest.xml to grant permission of Camera.
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exercise.AndroidCameraPictureSizes"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".AndroidCameraPictureSizes"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
<uses-sdk android:minSdkVersion="7" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
</manifest>


Modify main.xml to have a Spinner to display the list.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Spinner
android:id="@+id/supportedpicturesizes"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


Main Java code
package com.exercise.AndroidCameraPictureSizes;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.hardware.Camera;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class AndroidCameraPictureSizes extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Spinner spinnerSupportedPictureSizes = (Spinner)findViewById(R.id.supportedpicturesizes);

Camera camera = Camera.open();
Camera.Parameters cameraParameters = camera.getParameters();
List<Camera.Size> listSupportedPictureSizes = cameraParameters.getSupportedPictureSizes();

List<String> listStrSupportedPictureSizes = new ArrayList<String>();

for (int i=0; i < listSupportedPictureSizes.size(); i++){

String strSize = String.valueOf(i) + " : "
+ String.valueOf(listSupportedPictureSizes.get(i).height)
+ " x "
+ String.valueOf(listSupportedPictureSizes.get(i).width);
listStrSupportedPictureSizes.add(strSize);
}

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, listStrSupportedPictureSizes);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerSupportedPictureSizes.setAdapter(adapter);

camera.release();
}
}


Download the files.



Tuesday, December 7, 2010

NEWest update of ADT 8.0.1

If you had updated/installed Android SDK for 2.3 with ADT version 8.0.0, It's a new update ADT version 8.0.1 available.

To update ADT, click Help in Eclipse, Check for Updateds, select and install the available updates.

NEWest update of ADT 8.0.1



Monday, December 6, 2010

GALAXY Tab emulator on Android SDK 2.3

GALAXY Tab emulator on Android SDK 2.3
When you install packages in Android SDK and AVD Manager (Eclipse -> Window -> Android SDK and AVD Manager -> Available packages). You can note that there is a new option of Third party Add-ons. It's a GALAXY Tab by Samsung Electronics under it. Click to include it in your installation.

SDK and AVD Manager
A new Virtual device have to be created before it can be used to run your apps.
Eclipse -> Window -> Android SDK and AVD Manager -> Virtual devices, click New button. You can select Target of GALAXY Tab
Create AVD of GALAXY Tab

Once you create new AVD using GALAXY Tab properly, you can create new project with GALAXY Tab as the Build Target.
Create new project with GALAXY Tab as the Build Target

HelloGalaxyTab run on GALAXY Tab Emulator

A problem when update existing Android SDK to 2.3: .../tools/lib/proguard.cfg (No such file or directory)

As stated in Android web site, you can update Android SDK to 2.3 by adding as an SDK component, or install the fresh new SDK starter package.

In my case, I update as an SDK component. I tried to set-up a new project after updated, the error of ".../tools/lib/proguard.cfg (No such file or directory)" reported. proguard.cfg file is automatically generated when you create an Android project(http://developer.android.com/guide/developing/tools/proguard.html).



I compare the content of my existing Android SDK folder after updated, and that of a fresh new downloaded Android SDK, the file /tools/lib/proguard.cfg is missing in my case; may be that's why I can't generate proguard.cfg accordingly. So I re-setup my Eclipse to use the fresh new SDK, the problem have been solved. As it should be, I have to re-setup the Android SDK location and AVD.



Android 2.3 Platform and Updated SDK Tools is here!


Google just announced a new version of the Android platform — Android 2.3 (Gingerbread). It includes many new platform technologies and APIs to help developers create great apps. Some of the highlights include:

Enhancements for game development: To improve overall responsiveness, we’ve added a new concurrent garbage collector and optimized the platform’s overall event handling. We’ve also given developers native access to more parts of the system by exposing a broad set of native APIs. From native code, applications can now access input and sensor events, EGL/OpenGL ES, OpenSL ES, and assets, as well a new framework for managing lifecycle and windows. For precise motion processing, developers can use several new sensor types, including gyroscope.

Rich multimedia: To provide a great multimedia environment for games and other applications, we’ve added support for the new video formats VP8 and WebM, as well as support for AAC and AMR-wideband encoding. The platform also provides new audio effects such as reverb, equalization, headphone virtualization, and bass boost.

New forms of communication: The platform now includes support for front-facing camera, SIP/VOIP, and Near Field Communications (NFC), to let developers include new capabilities in their applications.

For a complete overview of what’s new in the platform, see the Android 2.3 Platform Highlights.

Alongside the new platform, we are releasing updates to the SDK Tools (r8), NDK, and ADT Plugin for Eclipse (8.0.0). New features include:

Simplified debug builds: Developers can easily generate debug packages without having to manually configure the application’s manifest, making workflow more efficient.

Integrated ProGuard support: ProGuard is now packaged with the SDK Tools. Developers can now obfuscate their code as an integrated part of a release build.

HierarchyViewer improvements: The HierarchyViewer tool includes an updated UI and is now accessible directly from the ADT Plugin.

Preview of new UI Builder: An early release of a new visual layout editor lets developers create layouts in ADT by dragging and dropping UI elements from contextual menus. It’s a work in progress and we intend to iterate quickly on it.

To get started developing or testing applications on Android 2.3, visit the Android Developers site for information about theAndroid 2.3 platform, the SDK Tools, the ADT Plugin and the new NDK.



Source: Android Developers Blog - Android 2.3 Platform and Updated SDK Tools


Personally, I suggest to install as a fresh new SDK Tools, because there is "A problem when update existing Android SDK to 2.3: .../tools/lib/proguard.cfg (No such file or directory)".

Friday, December 3, 2010

Camera Preview on SurfaceView

With little bit of modification on last exercise "Play 3gp video file using MediaPlayer", it's easy to implement a app to preview Android camera on SurfaceView.

Camera Preview on SurfaceView

Modify AndroidManifest.xml to grant permission to access Camera
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exercise.AndroidCamera"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".AndroidCamera"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
<uses-sdk android:minSdkVersion="4" />

<uses-permission android:name="android.permission.CAMERA"></uses-permission>
</manifest>


Modify main.xml, basically same as the one in the last exercise.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/startcamerapreview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- Start Camera Preview -"
/>
<Button
android:id="@+id/stopcamerapreview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- Stop Camera Preview -"
/>
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


Modify the source code, AndroidCamera.
package com.exercise.AndroidCamera;

import java.io.IOException;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;;

String stringPath = "/sdcard/samplevideo.3gp";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Button buttonStartCameraPreview = (Button)findViewById(R.id.startcamerapreview);
Button buttonStopCameraPreview = (Button)findViewById(R.id.stopcamerapreview);

getWindow().setFormat(PixelFormat.UNKNOWN);
surfaceView = (SurfaceView)findViewById(R.id.surfaceview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

buttonStartCameraPreview.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(!previewing){
camera = Camera.open();
if (camera != null){
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
previewing = true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}});

buttonStopCameraPreview.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(camera != null && previewing){
camera.stopPreview();
camera.release();
camera = null;

previewing = false;
}
}});

}



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}
}


Download the files.

Related Article:
- Camera Preview, version II



Tuesday, November 30, 2010

Play 3gp video file using MediaPlayer

The former exercise show how to "play MIDI audio using MediaPlayer". MediaPlayer can play video file also. This exercise show hoe to play 3gp video file in sdcard using MediaPlayer

(Remark: In my case, the video (and sound) can not be displayed on emulator. But it can work as expected on true phone.)

Play 3gp video file using MediaPlayer

Copy 3gp file to root folder on SD Card.

Modify main.xml to have two buttons and a SurfaceView to show the video.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/playvideoplayer"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PLAY Video -"
/>
<Button
android:id="@+id/pausevideoplayer"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PAUSE Video -"
/>
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


Modify source code, AndroidVideoPlayer.java.
package com.exercise.AndroidVideoPlayer;

import java.io.IOException;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

public class AndroidVideoPlayer extends Activity implements SurfaceHolder.Callback{

MediaPlayer mediaPlayer;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean pausing = false;;

String stringPath = "/sdcard/samplevideo.3gp";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Button buttonPlayVideo = (Button)findViewById(R.id.playvideoplayer);
Button buttonPauseVideo = (Button)findViewById(R.id.pausevideoplayer);

getWindow().setFormat(PixelFormat.UNKNOWN);
surfaceView = (SurfaceView)findViewById(R.id.surfaceview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setFixedSize(176, 144);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
mediaPlayer = new MediaPlayer();

buttonPlayVideo.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
pausing = false;

if(mediaPlayer.isPlaying()){
mediaPlayer.reset();
}

mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mediaPlayer.setDisplay(surfaceHolder);

try {
mediaPlayer.setDataSource(stringPath);
mediaPlayer.prepare();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

mediaPlayer.start();


}});

buttonPauseVideo.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(pausing){
pausing = false;
mediaPlayer.start();
}
else{
pausing = true;
mediaPlayer.pause();
}
}});

}



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}
}


Download the files.

Related Article:
- Implement a SeekBar to control the volume of Video Player



Saturday, November 27, 2010

Play foreground and background music using SoundPool and MediaPlayer

Merge the previous exercises "A simple exercise to play MIDI audio using MediaPlayer" and "Play audio resources using SoundPool", to implement a app to play audio using both MediaPlayer and SoundPool.

Play foreground and background music using SoundPool and MediaPlayer

Copy midi and ogg sound file into res/raw folder.

Modify main.xml to have four buttons to control the playing of the sounds.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/playmediaplayer"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PLAY MediaPlayer -"
/>
<Button
android:id="@+id/pausemediaplayer"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PAUSE MediaPlayer -"
/>
<Button
android:id="@+id/playsoundpool"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PLAY SoundPool -"
/>
<Button
android:id="@+id/pausesoundpool"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PAUSE SoundPool -"
/>
</LinearLayout>


Modify AndroidAudioPlayer.java.
package com.exercise.AndroidAudioPlayer;

import java.util.HashMap;

import android.app.Activity;
import android.content.Context;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.SoundPool;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class AndroidAudioPlayer extends Activity {

MediaPlayer mediaPlayer;
SoundPool soundPool;
HashMap<Integer, Integer> soundPoolMap;
int soundID = 1;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

mediaPlayer = MediaPlayer.create(this, R.raw.midi_sound);
soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 100);
soundPoolMap = new HashMap<Integer, Integer>();
//soundPoolMap.put(soundID, soundPool.load(this, R.raw.midi_sound, 1));
soundPoolMap.put(soundID, soundPool.load(this, R.raw.fallbackring, 1));

Button buttonPlayMediaPlayer = (Button)findViewById(R.id.playmediaplayer);
Button buttonPauseMediaPlayer = (Button)findViewById(R.id.pausemediaplayer);
Button buttonPlaySoundPool = (Button)findViewById(R.id.playsoundpool);
Button buttonPauseSoundPool = (Button)findViewById(R.id.pausesoundpool);
buttonPlayMediaPlayer.setOnClickListener(buttonPlayMediaPlayerOnClickListener);
buttonPauseMediaPlayer.setOnClickListener(buttonPauseMediaPlayerOnClickListener);
buttonPlaySoundPool.setOnClickListener(buttonPlaySoundPoolOnClickListener);
buttonPauseSoundPool.setOnClickListener(buttonPauseSoundPoolOnClickListener);
}

Button.OnClickListener buttonPlayMediaPlayerOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(!mediaPlayer.isPlaying()){
mediaPlayer.start();
Toast.makeText(AndroidAudioPlayer.this,
"soundPool.pause()",
Toast.LENGTH_LONG).show();
}
}
};

Button.OnClickListener buttonPauseMediaPlayerOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(mediaPlayer.isPlaying()){
mediaPlayer.pause();
Toast.makeText(AndroidAudioPlayer.this,
"soundPool.pause()",
Toast.LENGTH_LONG).show();
}
}
};

Button.OnClickListener buttonPlaySoundPoolOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
AudioManager audioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
float curVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
float maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
float leftVolume = curVolume/maxVolume;
float rightVolume = curVolume/maxVolume;
int priority = 1;
int no_loop = 0;
float normal_playback_rate = 1f;
soundPool.play(soundID, leftVolume, rightVolume, priority, no_loop, normal_playback_rate);

Toast.makeText(AndroidAudioPlayer.this,
"soundPool.play()",
Toast.LENGTH_LONG).show();
}
};

Button.OnClickListener buttonPauseSoundPoolOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
soundPool.pause(soundID);
Toast.makeText(AndroidAudioPlayer.this,
"soundPool.pause()",
Toast.LENGTH_LONG).show();
}
};

}


Download the files.

Friday, November 26, 2010

Play audio resources using SoundPool

The SoundPool class manages and plays audio resources for applications.

A SoundPool is a collection of samples that can be loaded into memory from a resource inside the APK or from a file in the file system. The SoundPool library uses the MediaPlayer service to decode the audio into a raw 16-bit PCM mono or stereo stream. This allows applications to ship with compressed streams without having to suffer the CPU load and latency of decompressing during playback.

Play audio resources using SoundPool

Modify the last exercise "play MIDI audio using MediaPlayer" to play a ogg file using SoundPool instead of MediaPlayer.

Copy a ogg sound file into res/raw folder.

Keep using the main.xml file in the last exercise "play MIDI audio using MediaPlayer".

Modify source code, AndroidAudioPlayer.java.
package com.exercise.AndroidAudioPlayer;

import java.util.HashMap;

import android.app.Activity;
import android.content.Context;
import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class AndroidAudioPlayer extends Activity {

SoundPool soundPool;
HashMap<Integer, Integer> soundPoolMap;
int soundID = 1;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 100);
soundPoolMap = new HashMap<Integer, Integer>();
//soundPoolMap.put(soundID, soundPool.load(this, R.raw.midi_sound, 1));
soundPoolMap.put(soundID, soundPool.load(this, R.raw.fallbackring, 1));

Button buttonPlay = (Button)findViewById(R.id.play);
Button buttonPause = (Button)findViewById(R.id.pause);
buttonPlay.setOnClickListener(buttonPlayOnClickListener);
buttonPause.setOnClickListener(buttonPauseOnClickListener);
}

Button.OnClickListener buttonPlayOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
AudioManager audioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
float curVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
float maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
float leftVolume = curVolume/maxVolume;
float rightVolume = curVolume/maxVolume;
int priority = 1;
int no_loop = 0;
float normal_playback_rate = 1f;
soundPool.play(soundID, leftVolume, rightVolume, priority, no_loop, normal_playback_rate);

Toast.makeText(AndroidAudioPlayer.this,
"soundPool.play()",
Toast.LENGTH_LONG).show();
}
};

Button.OnClickListener buttonPauseOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
soundPool.pause(soundID);
Toast.makeText(AndroidAudioPlayer.this,
"soundPool.pause()",
Toast.LENGTH_LONG).show();
}
};

}


Download the files.

Related article:
- Play foreground and background music using SoundPool and MediaPlayer



Thursday, November 25, 2010

A simple exercise to play MIDI audio using MediaPlayer

MediaPlayer class can be used to control playback of audio/video files and streams.

A simple exercise to play MIDI audio using MediaPlayer

Put a MIDI file into the res/raw folder of your project, where the Eclipse plugin (or aapt) will find it and make it into a resource that can be referenced from your R class. "midi_sound.mid" in my exercise.

Modify main.xml to have two buttons to play and pause.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/play"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PLAY -"
/>
<Button
android:id="@+id/pause"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="- PAUSE -"
/>
</LinearLayout>


Modify source code, AndroidAudioPlayer.java.
package com.exercise.AndroidAudioPlayer;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class AndroidAudioPlayer extends Activity {

MediaPlayer mediaPlayer;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

mediaPlayer = MediaPlayer.create(this, R.raw.midi_sound);

Button buttonPlay = (Button)findViewById(R.id.play);
Button buttonPause = (Button)findViewById(R.id.pause);
buttonPlay.setOnClickListener(buttonPlayOnClickListener);
buttonPause.setOnClickListener(buttonPauseOnClickListener);
}

Button.OnClickListener buttonPlayOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(!mediaPlayer.isPlaying()){
mediaPlayer.start();
Toast.makeText(AndroidAudioPlayer.this,
"mediaPlayer.start()",
Toast.LENGTH_LONG).show();
}
}
};

Button.OnClickListener buttonPauseOnClickListener
= new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(mediaPlayer.isPlaying()){
mediaPlayer.pause();
Toast.makeText(AndroidAudioPlayer.this,
"mediaPlayer.pause()",
Toast.LENGTH_LONG).show();
}
}
};

}


Download the files.

Related articles:
- Play audio resources using SoundPool
- Play foreground and background music using SoundPool and MediaPlayer
- Play 3gp video file using MediaPlayer

Wednesday, November 24, 2010

Android Market introduce Content Rating

Starting in a few weeks, Android Market will be showing content ratings for all applications. This new capability will provide users with additional information to help them select the best applications for them.

Applications will be rated according to four content rating levels: All, Pre-teen, Teen, & Mature.

To prepare for this launch, starting next week, developers submitting new or updated applications will be required to include a rating for all applications and games uploaded onto Android Market. In addition, developers will have the next several weeks to add a rating to their existing applications and games. Once content rating is visible to users, any applications or games that do not include a rating will be treated as “Mature”.

Source: Android Developers Blog: Content Rating for Android Market

Tuesday, November 23, 2010

ProgressBar running in AsyncTask

It's a exercise of a Horizontal ProgressBar which running in a background AsyncTask.

ProgressBar running in AsyncTask

Modify main.xml to have a button to start the progress, and the ProgressBar.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/startprogress"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Start"
/>
<ProgressBar
android:layout_width="fill_parent"
android:layout_height="wrap_content"
style="?android:attr/progressBarStyleHorizontal"
android:id="@+id/progressbar_Horizontal"
android:max="100"
/>
</LinearLayout>


Modify the java code.
package com.exercise.AndroidAsyncTaskProgressBar;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.Toast;

public class AndroidAsyncTaskProgressBar extends Activity {

ProgressBar progressBar;
Button buttonStartProgress;

public class BackgroundAsyncTask extends
AsyncTask<Void, Integer, Void> {

int myProgress;

@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
Toast.makeText(AndroidAsyncTaskProgressBar.this,
"onPostExecute", Toast.LENGTH_LONG).show();
buttonStartProgress.setClickable(true);
}

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
Toast.makeText(AndroidAsyncTaskProgressBar.this,
"onPreExecute", Toast.LENGTH_LONG).show();
myProgress = 0;
}

@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
while(myProgress<100){
myProgress++;
publishProgress(myProgress);
SystemClock.sleep(100);
}
return null;
}

@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
progressBar.setProgress(values[0]);
}

}


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

buttonStartProgress = (Button)findViewById(R.id.startprogress);
progressBar = (ProgressBar)findViewById(R.id.progressbar_Horizontal);
progressBar.setProgress(0);

buttonStartProgress.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
new BackgroundAsyncTask().execute();
buttonStartProgress.setClickable(false);
}});
}
}


Download the files.

Related articles:
- ProgressBar running in Runnable()
- AsyncTask: perform background operations and publish results on the UI thread
- onPostExecute() of AsyncTask

Thursday, November 18, 2010

Recent changes to Android Market that require developers' attention

First, Google have added support for a recent changes feature, which allows developers to add notes about changes specific to the newest version of application. Developers are able to submit these from the Developer Console, similar to descriptions. In the Market app, these notes will appear under the app description as "Recent changes."

Second, there is now a ‘draft upload’ capability for application updates. This feature enables developers to edit app listing and upload a new version without affecting the version live in Market. The app listing edits will not change the live listing until developer select “Publish.”

Finally, Google are adding support for larger promotional graphics to showcase application. In addition to the currently required app screenshot, developers will be required to upload one “feature” graphic. Supported promotional assets will now include:
- A “feature” graphic, landscape aspect ratio, 1024 x 500 (required).
- A high-res icon, 512 x 512 (required).. The Android icon design guidelines located at http://developer.android.com/guide/practices/ui_guidelines/icon_design.html apply.
- 2 screen shots, 320w x 480h, 480w x 854h, or 480w x 800h, increasing to 8 screen shots in the future (1 required).
- A link for a promotional video hosted on YouTube (optional).

~ from a Mail from Google



Wednesday, November 17, 2010

onPostExecute() of AsyncTask

In my old exercise "AsyncTask: perform background operations and publish results on the UI thread", doInBackground() is a infinite loop without return, such that the onPostExecute() method will not be called.

In order to make onPostExecute() taking effect, a button to stop the background task is implemented. When user click on the button, the onPostExecute() will end with and return, and onPostExecute() will be called.



Modify main.xml to add a Stop button.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button
android:id="@+id/stop"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Stop"
/>
<TextView
android:id="@+id/mytext"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="This Text will be Turn ON/OFF triggered by AsyncTask."
/>

</LinearLayout>


Modify AndroidBackgroundAsyncTask.java
package com.exercise.AndroidBackgroundAsyncTask;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidBackgroundAsyncTask extends Activity {

TextView myText;
boolean stopRun = false;

public class BackgroundAsyncTask extends
AsyncTask<Void, Boolean, Void> {

boolean myTextOn;

@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub

while(!stopRun)
{
myTextOn = !myTextOn;
publishProgress(myTextOn);
SystemClock.sleep(1000);
}
return null;
}

@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
Toast.makeText(AndroidBackgroundAsyncTask.this,
"onPostExecute", Toast.LENGTH_LONG).show();
}

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
myTextOn = true;
Toast.makeText(AndroidBackgroundAsyncTask.this,
"onPreExecute", Toast.LENGTH_LONG).show();
}

@Override
protected void onProgressUpdate(Boolean... values) {
// TODO Auto-generated method stub

if (values[0]){
myText.setVisibility(View.GONE);
}
else{
myText.setVisibility(View.VISIBLE);
}
}


}

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myText = (TextView)findViewById(R.id.mytext);

Button buttonStop = (Button)findViewById(R.id.stop);
buttonStop.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
stopRun = true;
}});

new BackgroundAsyncTask().execute();
}
}


Download the files.

Related article:
- ProgressBar running in AsyncTask



Tuesday, November 16, 2010

Example of using Color Resource

Color XML resource that carries a color value (a hexadecimal color).

The value always begins with a pound (#) character and then followed by the Alpha-Red-Green-Blue information in one of the following formats:

  • #RGB
  • #ARGB
  • #RRGGBB
  • #AARRGGBB




create /res/values/colors.xml to add our Color Resources in XML
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="background_color">#f0f0f0</color>
<color name="text_color_red">#ff0000</color>
</resources>


Modify main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@color/background_color"
>
<TextView
android:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
</LinearLayout>


Java Code
package com.exercise.AndroidColorResources;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidColorResources extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

TextView Text = (TextView)findViewById(R.id.text);
Text.setTextColor(getResources().getColor(R.color.text_color_red));
}
}


Download the files.