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OpenCV for Android

Why another tutorial for OpenCV for Android? I followed a tutorial from the OpenCV official website. It was disappointing. It turned out there are many problems during installation and building examples in my Mac OS X system.

My Android SDK version is 4.2.2 (API 17) with Android Development Tools (ADT) for its IDE. I believe this tutorial works as well with Android 4.3 (API 18) in Mac OS X.

Here is a list of steps to follow to get OpenCV for Android ready for you.

Download OpenCV for Android

  1. Download OpenCV for Android from http://opencv.org/downloads.html. You can find an Android version from the web. As I am writing this, the latest version is 2.4.6.
  2. Unzip the zip file and you will see a folder.
  3. Place the folder into a proper folder. In my case, I created a folder in my Documents and named it as work. And copy the OpenCV folder into the new folder.
  4. This is it for now until we build the libraries and samples.

Download Android NDK

You may find an NDK Plugins item from the menu Help – Install New Software. I tried this. But it shows the following error message.

Cannot complete the request. See the error log for details.
“Android Native Development Tools” will be ignored because it is already installed.

So I went to the Android NDK webpage and found a package. It seems we need to install this manually.

  1. Download a package from http://developer.android.com/tools/sdk/ndk/index.html. You can find two packages for each platform. Just select the first package which is a current and recommended toolchain for the NDK.
  2. Unzip it.
  3. Find a folder named “android-ndk-<version>.”
  4. Place this folder into the “work” folder. See the ‘Download OpenCV for Android’ section for more detail about the “work” folder.

Build OpenCV Library and Samples

Now we are kind of ready to build OpenCV Samples because we have to take a few more steps after importing Android projects from the OpenCV folder to your ADT’s workspace.

There is an NDK item in the Preferences of ADT under the Android section. It looks like we have to put NDK folder into the blank. But this is useless at least for the OpenCV samples. So you may ignore this NDK item in the Preferences.

  1. Select File – Import – Android – Existing Android Code into Workspace.
  2. You will see the ‘Import Project’ dialog.
  3. Choose ‘Root Directory’ by clicking the ‘Browse…’ button. The directory is the top folder of the OpenCV folder that you placed in the section ‘Download OpenCV for Android.’
  4. Now you can see five samples and three tutorials and one library. Select all the projects. If you want to use only one sample or tutorial, please don’t forget to select the project “sdk/java – OpenCV Library.” Then Click the ‘Finish’ button.
  5. If you want to maintain all original samples in the folder, you can check the “Copy projects into workspace” checkbox. This will copy all source code into your workspace.
  6. Some projects will show compile errors. According to OpenCV website tutorials, the errors will be shown only on a non-Windows operating systems. Anyway, I am using a Mac. So I see the errors. The remedy in the web http://docs.opencv.org/doc/tutorials/introduction/android_binary_package/O4A_SDK.html didn’t work for me. Here is what I did.
  7. First of all, NDKROOT is not defined in my system. Add NDKROOT with the value of the actual android-ndk folder that you placed in the section ‘Download Android NDK.’ This should be done all the complaining projects with errors.
    1. Go to Properties (@I) of each project. Note that this is NOT ‘Preferences.’ Select one project and right click. Find the Properties item in the bottom of the context menu.
    2. Find C/C++ Build – Environment.
    3. Add a variable. Name it NDKROOT and put a value with your android-ndk folder.
  8. Then go back the C/C++ Build item in the Properties. You can find ‘Build command:” Its corresponding text input box has either ${NDKROOT}/ndk-build.cmd or “${NDKROOT}/ndk-build.cmd” (Note that the quotation marks!). Remove ‘.cmd’ and the quotation marks if it has. I just want ${NDKROOT}/ndk-build in the text input box.

OpenCV Manager

If your Android phone does not have OpenCV Manager, you should download it from https://play.google.com/store/apps/details?id=org.opencv.engine&hl=en.

That’s it. Enjoy OpenCV for Android!!!

References:

Fundings from National Science Foundation

I am honored to have this great opportunity thanks to many people including my graduate advisor and his team. This would not be possible without full support of our department head and the office of sponsored office at Kettering.

Title:

MRI: Development of High-Throughput ad High-Resolution Three-Dimensional Tissue Scanner with Internet-Connected 3D Virtual Microscope for Large-Scale Automated Histology

  • Investigator: Jaerock Kwon  (Principal Investigator)
  • Start Date: September 1, 2013
  • Expires: August 31, 2016 (Estimated)
  • Awarded amount: $341,563.00

Abstract:

The objective of this program is to develop a high-throughput and high-resolution 3D tissue scanner with an Internet-connected 3D virtual microscope for large-scale automated histology. The instrument will digitize a wide variety of organs and generate 3D data sets. A data processing pipeline will automatically convert the raw data sets into aligned volumetric data sets without human intervention. Therefore immediate access to the large-scale histological data will be possible for a wide variety of research and research training communities.

The intellectual merit is as follows. Large-scale output data of the instrument will be easily acquired and shared through the fast scanner, data processing pipelines, and web-based visualization framework. In the past, investigation of biological organs were limited to either gross system-level studies or highly detailed microscopic analysis of small subsets of the organ. The new tissue scanner will digitally restore tissue structure in 3D with a specialized visualization framework that helps researchers to fully understand function of biological organs.

The broader impacts are three folds: (1) Obtaining digitized high-resolution data for multi-scale investigation of biological organs at a high acquisition rate will open up new areas of research in the community. (2) For education infrastructure, microscopic atlases of whole biological organs can serve as educational materials for students and educators at all levels. (3) For dissemination, the project results will provide research communities with a new 3D tissue scanner with a virtual microscope by which researchers can obtain digitized 3D tissue data in sub-micron level resolution from a tissue sample.

Award URL:

http://www.nsf.gov/awardsearch/showAward?AWD_ID=1337983

iOS Simulator Location Servies Settings

In iOS Simulator, if you choose “Don’t Allow” when you are prompted “Your App” Would Like to Use Your Current Location, there is no obvious way to turn it on back.

Here is a solution.

  1. Start Settings in the simulator.
  2. Select “Reset Location & Privacy” in the General – Reset.
  3.  Select “Reset Warnings” when you are prompted.

That’s all.

Now you will see the selection dialog when you start your app using Core Location.

Problems in updating Android SDK Tools with rev. 22

You may find an error after updating your Android SDK with Rev. 22. When you restart the ADT, you will see this error.

This Android SDK requires Android Developer Toolkit version 22.0.0 or above.
Current version is 21.x.x.
Please update ADT to the latest version.

The problem is you will not be able to update it from the “Check Updates” button. Clicking the button leads you to the “No updates were found” window along with the “Problem Occurred” window. If you ignore the problem, this error prevents us from running any of your existing projects.

This is because of the wrong URL of the Android Developer Tools Update Site. You cannot fix this problem by changing the Install/Update – Available Software Sites – Android Developer Tools Update Site since it adds automatically “content.xml” at the end of the URL.

Here is a list of steps that you need to take.

  1. Help – Install New Software in the ADT menu.
  2. Type https://dl-ssl.google.com/android/eclipse/site.xml in “Work with:” and Enter.
  3. You can see the “Developer Tools” item.
  4. Select it and click Next.
  5. Click Next one more.
  6. Click Finish accepting the terms of the license agreements.
  7. Click OK in the “Security Warning” window.
  8. Let the installer restart ADT after installing the tools.

That’s it.

Posters at the Celebrate Achievement Expo

During Homecoming Weekend, posters from the M:IR lab were presented at the Celebrate Achievement Expo from 9-11 a.m. May 18.

Microsoft kinetic sensor for real-time color tracking robot
Matthew Clark, David Feldpausch, and Girma Tewolde, Department of Electrical and Computer Engineering

Low-cost dashboard for an electric scooter
Trifon Tsekov, Girma Tewolde, Jae Kwon and Kevin Bai, Department of Electrical & Computer Engineering

Development of a modular LED display controller

Dan Gudorf and Girma Tewolde, Department of Electrical & Computer Engineering

Kettering University Robotics Team – Intelligent ground vehicle competition
Jorge Horcasitas, Lex Lombardi and Girma Tewolde, Department of Electrical & Computer Engineering

Design and implementation of LED dimming system with intelligent sensor module
Jaerock Kwon, Department of Electrical and Computer Engineering

GoogleMaps Demo

Here is a simple example of Android Maps v2 using MapFragment. We are assuming that the Google Play services SDK is installed. If you don’t have the SDK, please install before this. See details at here.

New Project

  • File > New > Android Application Project
    • Application Name: MapsDemo
    • Package Name: edu.kettering.mapsdemo
    • Minimum Required SDK: API 11: Android 3.0
      • Note: Fragment was introduced in API 11
    • Compile With: Google APIs (Google Inc.) (API 17)
      • If you have not installed Google APIs, Install it using the Android SKD Manager. Google APIs are the superset of Android APIs. This means “Google API level 17” means “Android 4.2.2 (level 17) + Google APIs.”
  • Use default values for all the options.

Adding Library

Add Google Play services library.

  • Project > Properties.
  • Select Android in the left. Find the Library pane. Click “Add…” and select “google-play-services_lib”

Adding MapFragment

  • Open “activity_main.xml” and delete the text view.
  • Drag the “Fragment” in the “Layout” Palette and drop on the main layout.
    • “Choose Fragment Class” will be prompted.
    • Find “MapFragment.”
  • Align the fragment by adjusting the size. The root layout is RelativeLayout. So drag the border lines and drop at the end of the window left, top, right, and bottom.
  • Change the id to “@+id/map”

[code language=”xml”]
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<fragment
android:id="@+id/map"
android:name="com.google.android.gms.maps.MapFragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" />

</RelativeLayout>
[/code]

Using GoogleMap class

We can get a GoogleMap object using FragmentManager. A MapFragment can be acquired from findFragmentById. The map can get from getMap().

[code language=”java”]
package edu.kettering.mapsdemo;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;

public class MainActivity extends Activity {
static final LatLng ketteringLatLng = new LatLng(43.013651,-83.713498);
private GoogleMap map;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

map = ((MapFragment)getFragmentManager().findFragmentById(R.id.map)).getMap();
map.addMarker(new MarkerOptions().position(ketteringLatLng).title("Kettering"));
map.moveCamera(CameraUpdateFactory.newLatLngZoom(ketteringLatLng, 15));
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}
[/code]

Getting an API Key

Get an API Key with the package name, “edu.kettering.mapsdemo” and the SHA-1 fingerprint. See this article for more detail.

Editing AndroidManifest.xml

We need to add permission, uses-permission, use-feature, and meta-data. “edu.kettering.mapsdemo”s in red should be replaced with your app’s package name.

[code language=”java”]
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="edu.kettering.mapsdemo"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="17" />

<!– Start Maps –>
<permission
android:name="edu.kettering.mapsdemo.permission.MAPS_RECEIVE"
android:protectionLevel="signature"/>
<uses-permission android:name="edu.kettering.mapsdemo.permission.MAPS_RECEIVE" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<uses-feature
android:glEsVersion="0x00020000"
android:required="true"/>
<!– End of Maps –>

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >

<!– Start Maps –>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="YOUR_OWN_KEY"/>
<!– End of Maps –>

<activity
android:name="edu.kettering.mapsdemo.MainActivity"
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>

</manifest>
[/code]

Broadcast Receiver Demo

In this demo a broadcast receiver will be implemented to show how to receive a broadcast.

Here is the action list from API 17. You can find the text file inside your ADT directory (/sdk/platforms/android-<version>/data/broadcast_actions.txt).

[code language=”java”]

android.app.action.ACTION_PASSWORD_CHANGED
android.app.action.ACTION_PASSWORD_EXPIRING
android.app.action.ACTION_PASSWORD_FAILED
android.app.action.ACTION_PASSWORD_SUCCEEDED
android.app.action.DEVICE_ADMIN_DISABLED
android.app.action.DEVICE_ADMIN_DISABLE_REQUESTED
android.app.action.DEVICE_ADMIN_ENABLED
android.bluetooth.a2dp.profile.action.CONNECTION_STATE_CHANGED
android.bluetooth.a2dp.profile.action.PLAYING_STATE_CHANGED
android.bluetooth.adapter.action.CONNECTION_STATE_CHANGED
android.bluetooth.adapter.action.DISCOVERY_FINISHED
android.bluetooth.adapter.action.DISCOVERY_STARTED
android.bluetooth.adapter.action.LOCAL_NAME_CHANGED
android.bluetooth.adapter.action.SCAN_MODE_CHANGED
android.bluetooth.adapter.action.STATE_CHANGED
android.bluetooth.device.action.ACL_CONNECTED
android.bluetooth.device.action.ACL_DISCONNECTED
android.bluetooth.device.action.ACL_DISCONNECT_REQUESTED
android.bluetooth.device.action.BOND_STATE_CHANGED
android.bluetooth.device.action.CLASS_CHANGED
android.bluetooth.device.action.FOUND
android.bluetooth.device.action.NAME_CHANGED
android.bluetooth.device.action.UUID
android.bluetooth.devicepicker.action.DEVICE_SELECTED
android.bluetooth.devicepicker.action.LAUNCH
android.bluetooth.headset.action.VENDOR_SPECIFIC_HEADSET_EVENT
android.bluetooth.headset.profile.action.AUDIO_STATE_CHANGED
android.bluetooth.headset.profile.action.CONNECTION_STATE_CHANGED
android.bluetooth.input.profile.action.CONNECTION_STATE_CHANGED
android.bluetooth.pan.profile.action.CONNECTION_STATE_CHANGED
android.hardware.action.NEW_PICTURE
android.hardware.action.NEW_VIDEO
android.hardware.input.action.QUERY_KEYBOARD_LAYOUTS
android.intent.action.ACTION_POWER_CONNECTED
android.intent.action.ACTION_POWER_DISCONNECTED
android.intent.action.ACTION_SHUTDOWN
android.intent.action.AIRPLANE_MODE
android.intent.action.BATTERY_CHANGED
android.intent.action.BATTERY_LOW
android.intent.action.BATTERY_OKAY
android.intent.action.BOOT_COMPLETED
android.intent.action.CAMERA_BUTTON
android.intent.action.CONFIGURATION_CHANGED
android.intent.action.DATE_CHANGED
android.intent.action.DEVICE_STORAGE_LOW
android.intent.action.DEVICE_STORAGE_OK
android.intent.action.DOCK_EVENT
android.intent.action.DREAMING_STARTED
android.intent.action.DREAMING_STOPPED
android.intent.action.EXTERNAL_APPLICATIONS_AVAILABLE
android.intent.action.EXTERNAL_APPLICATIONS_UNAVAILABLE
android.intent.action.FETCH_VOICEMAIL
android.intent.action.GTALK_CONNECTED
android.intent.action.GTALK_DISCONNECTED
android.intent.action.HEADSET_PLUG
android.intent.action.INPUT_METHOD_CHANGED
android.intent.action.LOCALE_CHANGED
android.intent.action.MANAGE_PACKAGE_STORAGE
android.intent.action.MEDIA_BAD_REMOVAL
android.intent.action.MEDIA_BUTTON
android.intent.action.MEDIA_CHECKING
android.intent.action.MEDIA_EJECT
android.intent.action.MEDIA_MOUNTED
android.intent.action.MEDIA_NOFS
android.intent.action.MEDIA_REMOVED
android.intent.action.MEDIA_SCANNER_FINISHED
android.intent.action.MEDIA_SCANNER_SCAN_FILE
android.intent.action.MEDIA_SCANNER_STARTED
android.intent.action.MEDIA_SHARED
android.intent.action.MEDIA_UNMOUNTABLE
android.intent.action.MEDIA_UNMOUNTED
android.intent.action.MY_PACKAGE_REPLACED
android.intent.action.NEW_OUTGOING_CALL
android.intent.action.NEW_VOICEMAIL
android.intent.action.PACKAGE_ADDED
android.intent.action.PACKAGE_CHANGED
android.intent.action.PACKAGE_DATA_CLEARED
android.intent.action.PACKAGE_FIRST_LAUNCH
android.intent.action.PACKAGE_FULLY_REMOVED
android.intent.action.PACKAGE_INSTALL
android.intent.action.PACKAGE_NEEDS_VERIFICATION
android.intent.action.PACKAGE_REMOVED
android.intent.action.PACKAGE_REPLACED
android.intent.action.PACKAGE_RESTARTED
android.intent.action.PACKAGE_VERIFIED
android.intent.action.PHONE_STATE
android.intent.action.PROVIDER_CHANGED
android.intent.action.PROXY_CHANGE
android.intent.action.REBOOT
android.intent.action.SCREEN_OFF
android.intent.action.SCREEN_ON
android.intent.action.TIMEZONE_CHANGED
android.intent.action.TIME_SET
android.intent.action.TIME_TICK
android.intent.action.UID_REMOVED
android.intent.action.USER_PRESENT
android.intent.action.WALLPAPER_CHANGED
android.media.ACTION_SCO_AUDIO_STATE_UPDATED
android.media.AUDIO_BECOMING_NOISY
android.media.RINGER_MODE_CHANGED
android.media.SCO_AUDIO_STATE_CHANGED
android.media.VIBRATE_SETTING_CHANGED
android.media.action.CLOSE_AUDIO_EFFECT_CONTROL_SESSION
android.media.action.OPEN_AUDIO_EFFECT_CONTROL_SESSION
android.net.conn.BACKGROUND_DATA_SETTING_CHANGED
android.net.nsd.STATE_CHANGED
android.net.wifi.NETWORK_IDS_CHANGED
android.net.wifi.RSSI_CHANGED
android.net.wifi.SCAN_RESULTS
android.net.wifi.STATE_CHANGE
android.net.wifi.WIFI_STATE_CHANGED
android.net.wifi.p2p.CONNECTION_STATE_CHANGE
android.net.wifi.p2p.DISCOVERY_STATE_CHANGE
android.net.wifi.p2p.PEERS_CHANGED
android.net.wifi.p2p.STATE_CHANGED
android.net.wifi.p2p.THIS_DEVICE_CHANGED
android.net.wifi.supplicant.CONNECTION_CHANGE
android.net.wifi.supplicant.STATE_CHANGE
android.speech.tts.TTS_QUEUE_PROCESSING_COMPLETED
android.speech.tts.engine.TTS_DATA_INSTALLED

[/code]

android.intent.action.PHONE_STATE will be used in this demo.

First we need to add READ_PHONE_STATE permission. Open “AndroidManifest.xml” and add the permission.

[code language=”xml”]

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

[/code]

Add a receiver tag with a proper name in the “AndroidManifest.xml” file.

[code language=”xml”]
<receiver android:name="PhoneEventReceiver">
<intent-filter>
<action android:name="android.intent.action.PHONE_STATE">

</action>
</intent-filter>
</receiver>
[/code]

Create a new class named “PhoneEventReceiver” inheriting the “BroadcastReceiver” class.

[code language=”java”]
package edu.kettering.broadcastreceiverdemo;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.util.Log;

public class PhoneEventReceiver extends BroadcastReceiver {
private static final String mDebugTag = "MY_DEBUG" ;
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Bundle extras = intent.getExtras();
if(extras == null)
return;
String state = extras.getString(TelephonyManager.EXTRA_STATE);
Log.d(mDebugTag, state);

if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
String phoneNumber = extras
.getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
Log.d(mDebugTag, phoneNumber);
}
}
}
[/code]

PopupMenu Demo

The PopupMenu is anchored to a View. If a PopupMenu is shown in response to a click event to a button, the Popup will be displayed under the button if there is room.
The PopupMenu needs at least SDK 11. You need to open “AndroidManifest.xml” and change the minimum SDK version (“8”) to “11” since the ADT makes an app template with “8” for the minSdkVersion.

[code language=”xml”]
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="17" />
[/code]

Just like any other Android API Guides, the section of the PopupMenu (http://developer.android.com/guide/topics/ui/menus.html#PopupMenu) is good for just lying-down-readers for fun but not good enough for someones who really need to use it.

Here I would like to provide a complete tutorial. But notice that this is not something that you can copy and paste it to build. You have to understand what you are doing.

First let us add a button to show a Popup menu. Please notice that the android:onClick attribute has the “showPopup” method name.

[code language=”xml”]
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".PopupMenuDemoActivity" >

<Button
android:id="@+id/buttonShowMePopup"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:onClick="showPopup"
android:text="Show Me Popup" />

</RelativeLayout>
[/code]

It is always good idea to use resources to maintain strings.

[code language=”xml”]
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">PopupMenuDemo</string>
<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="archive">Archive</string>
<string name="delete">Delete</string>
<string name="popup_menu_archive_selected">Archive is selected.</string>
<string name="popup_menu_delete_selected">Delete is selected.</string>
</resources>
[/code]

A new menu XML file must be added. Add a new Android XML with “Menu” Resource Type. Use “actions.xml” as its name. Please insert two items for this demo.

[code language=”xml”]
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item android:id="@+id/archive" android:title="@string/archive"></item>
<item android:id="@+id/delete" android:title="@string/delete"></item>
</menu>
[/code]

Then we are pretty much ready to write code. For the sake of simplicity I decided to use the main activity (named PopupMenuDemoActivity) as a target of the “PopupMenu.OnMenuItemClickListener” interface. This means the activity should implement the interface. When the user selects an item, Android system will call the onMenuItemClick() callback.

[code language=”java”]
package edu.kettering.popupmenudemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.PopupMenu;
import android.widget.Toast;

public class PopupMenuDemoActivity extends Activity 
implements PopupMenu.OnMenuItemClickListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_popup_menu_demo);
}

public void showPopup(View v)
{
PopupMenu popupMenu = new PopupMenu(this, v);
popupMenu.getMenuInflater().inflate(R.menu.actions, popupMenu.getMenu());
popupMenu.setOnMenuItemClickListener(this);
popupMenu.show();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.popup_menu_demo, menu);
return true;
}

@Override
public boolean onMenuItemClick(MenuItem item) {
String msg;
switch(item.getItemId()) {
case R.id.archive:
msg = getResources().getString(R.string.popup_menu_archive_selected);
Toast.makeText(getApplicationContext(), 
                   msg, Toast.LENGTH_LONG).show(); 
return true;
case R.id.delete:
msg = getResources().getString(R.string.popup_menu_delete_selected);
Toast.makeText(getApplicationContext(), 
                    msg, Toast.LENGTH_LONG).show(); 
return true;
}
return false;
}

}
[/code]

 

ProgressBar Demo

According to Android API Guides, we should avoid ProgressDialog. Instead, using ProgressBar in the layout is recommended.

Her is my layout xml. You may use other than RelativeLayout if you do not like it.

[code language=”xml”]
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".ProgressBarDemo2Activity" >

<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" />
</RelativeLayout>
[/code]

After putting a ProgressBar into my layout, I create a Runnable object and a Thread. Call the thread with the runnable object that has my own overridden run() method.

[code language=”java”]
package edu.kettering.progressbardemo2;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.ProgressBar;

public class ProgressBarDemo2Activity extends Activity {
private ProgressBar mProgressBar;
private int mProgress = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_progress_bar_demo2);

mProgressBar = (ProgressBar)findViewById(R.id.progressBar);

Runnable runWork = new Runnable() {
@Override
public void run() {
while(mProgress < 100) {
mProgress = doWork();
mProgressBar.setProgress(mProgress);
}
}
};
Thread thread = new Thread(runWork);
thread.start();
}

private int doWork() {
// sleep 50 millisecond
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mProgress++;

return mProgress;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.progress_bar_demo2, menu);
return true;
}
}
[/code]