Nanogest Android Java API

Installation in your Android project

Add the com.nanocritical.nanogest Android library to your project

com.nanocritical.nanogest is a Java package and a library for Android.

• Unzip nanogest-VERSION.zip, creating a directory named nanogest-VERSION.
• Reference the library in your project:

  android update project \ --path PATH_TO_YOUR_PROJECT \ --library nanogest-VERSION/android/nanogest

  See the NDK documentation for additional details on referencing an external library in your project.
• Add the appropriate permissions to your AndroidManifest.xml file.

  <uses-permission android:name="android.permission.CAMERA" /> <uses-feature android:name="android.hardware.camera" />

Platform compatibility

Nanogest is compatible with Android 2.3.3+ (API level 10+). Nanogest comes with binaries for all the architectures supported by Android: armeabi, armeabi-v7a, mips, and x86.

Synopsis

import com.nanocritical.nanogest.Nanogest; public class YourActivity extends Activity implements Nanogest.GestureListener { private Nanogest ngest; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ngest = new Nanogest(this, this, null); } @Override public void onResume() { super.onResume(); ngest.start(); } @Override public void onPause() { super.onPause(); ngest.stop(); } @Override public void onGesture(Nanogest.Gesture gesture, double timestamp) { switch (gesture) { case SWIPE_LEFT: onLeft(); break; case SWIPE_RIGHT: onRight(); break; case SWIPE_UP: onUp(); break; case SWIPE_DOWN: onDown(); break; } } }

API

Nanogest.Gesture Enum

The Nanogest.Gesture enum identifies each gesture recognized by Nanogest.

public enum Gesture { NONE(0), SWIPE_LEFT(1), SWIPE_RIGHT(2), SWIPE_UP(3), SWIPE_DOWN(4); }

The gestures are always to be understood with respect to the user. Nanogest takes into account the current orientation of the device automatically.

• SWIPE_LEFT indicates the user performed a swipe gesture to her left.
• SWIPE_RIGHT indicates the user performed a swipe gesture to her right.
• SWIPE_UP indicates the user performed a swipe gesture toward the ceiling.
• SWIPE_DOWN indicates the user performed a swipe gesture toward the floor.

Nanogest.GestureListener Interface

public void onGesture(Gesture gesture, double timestamp);

Notified when the user performs a hand gesture. Called on the main thread.

gesture is the kind of gesture detected. timestamp is the date at which the gesture was detected, in seconds since Epoch (January 1st, 1970, GMT).

Nanogest.ErrorCode Enum

public enum ErrorCode { OK(0), ALLOC(1), INVALID_ARGUMENT(2), OS(3), DISABLED(4), UNKNOWN(5); }

• OK indicates no error.
• ALLOC indicates a memory allocation error.
• OS indicates an error raised by the operating system.
• DISABLED indicates that Nanogest was disabled by a previous unrecoverable error and must be re-initialized.
• UNKNOWN indicates an unknown error (e.g. an unknown and unexpected OS error).

Nanogest.ErrorListener Interface

public void onError(ErrorCode error, String codeName, String message);

Notified when an error occurs in Nanogest. Called on the main thread.

code is the error code. codeName is the string naming the error code (e.g. the string "ALLOC" for the error code Nanogest.ErrorCode.ALLOC). message is a string describing the error.

On error, the Nanogest instance is disabled. When possible, Nanogest.stop() is called. Any further interaction with the disabled Nanogest instance will be ignored.

To recover from an error, a new Nanogest instance should be created and started.

Nanogest Class

public Nanogest(android.content.Context context, GestureListener gestureListener, ErrorListener errorListener);

Create an instance of Nanogest. context must be a valid application context, such as the current Activity. The listeners gestureListener and errorListener may be null, in which case they are ignored.

public void start();

Start gesture recognition. If isRunning() returns true, the call is ignored.

Must be called in your activity's Activity.onResume(), or later. See Android application lifecyle for details.

public void stop();

Stop gesture recognition. If isRunning() returns false, the call is ignored.

Must be called in your activity's Activity.onPause(), or earlier. See Android application lifecyle for details.

Advanced and optional features

public boolean getPreventScreenTimeout(); public void setPreventScreenTimeout(boolean yes);

Whenever a gesture is detected, if set to true, Nanogest will reset the display idle timer. If set to false, gestures detected by Nanogest will not prevent the display from going to sleep. The default value is true.

public boolean isRunning();

Return true if the gesture detection is running. false otherwise.

public void setCustomSurfaceHolder(android.view.SurfaceHolder holder, android.view.View visibleView);

Optional. If used, this method must be called before start. This method can be used to set a user-visible preview for the camera.

visibleView must be a View instance that belongs to the UI hierarchy and is visible whenever Nanogest is in use. This view is used by Nanogest to notify Android that the screen should not sleep when gestures are detected, when getPreventScreenTimeout() is true.

The method setCustomSurfaceHolder() must be called with the pre-conditions of Camera.setPreviewDisplay(SurfaceHolder). Namely, "The SurfaceHolder must already contain a surface when this method is called. If you are using SurfaceView, you will need to register a SurfaceHolder.Callback with addCallback(SurfaceHolder.Callback) and wait for surfaceCreated(SurfaceHolder) before calling setPreviewDisplay() or starting preview."

For instance, to use a SurfaceView as a user-visible preview of the camera:

final SurfaceView cameraPreview = (SurfaceView) findViewById(R.id.cameraPreview); cameraPreview.getHolder().addCallback(new SurfaceHolder.Callback() { public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {} public void surfaceDestroyed(SurfaceHolder holder) {} public void surfaceCreated(SurfaceHolder holder) { ngest.setCustomSurfaceHolder(cameraPreview.getHolder(), cameraPreview); } });

Nanogest calls Camera.setDisplayOrientation() automatically to ensure the correct orientation of the preview.