Gestures detection and canvas scale, translate and rotate.

In this article we are going to implement GestureOverlayView to detect gestures input, and apply scale, translate and rotate on canvas accordingly. (May be I build the Gestures too simple, the detection is not accurate. You are advised to create your own.) -

 Modify main.xml to add android.gesture.GestureOverlayView.

- Modify MyGameActivity.java to handle Gesture.

package com.MyGame;
 
import java.util.ArrayList;
 
import android.app.Activity;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.gesture.GestureOverlayView.OnGesturePerformedListener;
import android.gesture.Prediction;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.SurfaceView;
import android.widget.Toast;
 
public class MyGameActivity extends Activity {
  
 MyGameSurfaceView myGameSurfaceView1;
 MyForeground myForeground;
  
 //MyAccelerometer myAccelerometer;
  
 GestureLibrary gestureLibrary = null;
 GestureOverlayView gestureOverlayView;
  
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  myGameSurfaceView1 = (MyGameSurfaceView)findViewById(R.id.myview1);
  myForeground = (MyForeground)findViewById(R.id.myforeground);
 
  //Set myForeground using transparent background
  myForeground.setZOrderOnTop(true);
  myForeground.getHolder().setFormat(PixelFormat.TRANSPARENT);
 
  //myAccelerometer = new MyAccelerometer(this);
 
  gestureOverlayView = (GestureOverlayView)findViewById(R.id.gestures);
  gestureLibrary = GestureLibraries.fromRawResource(this, R.raw.gestures);
  gestureLibrary.load();
  gestureOverlayView.addOnGesturePerformedListener(gesturePerformedListener);
 
}
 
OnGesturePerformedListener gesturePerformedListener
= new OnGesturePerformedListener(){
 
  @Override
  public void onGesturePerformed(GestureOverlayView view, Gesture gesture) {
   ArrayList prediction = gestureLibrary.recognize(gesture);
    
     if(prediction.size() > 0){
      String gesturePerformed = prediction.get(0).name;
      if(gesturePerformed.equals("up")){
       myForeground.canvasUp();
       Toast.makeText(MyGameActivity.this,
         "up", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("down")){
       myForeground.canvasDown();
       Toast.makeText(MyGameActivity.this,
         "down", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("left")){
       myForeground.canvasLeft();
       Toast.makeText(MyGameActivity.this,
         "left", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("right")){
       myForeground.canvasRight();
       Toast.makeText(MyGameActivity.this,
         "right", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("clockwise")){
       myForeground.canvasClockwise();
       Toast.makeText(MyGameActivity.this,
         "clockwise", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("anti-clockwise")){
       myForeground.canvasAntiClockwise();
       Toast.makeText(MyGameActivity.this,
         "anti-clockwise", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("enlarge")){
       myForeground.canvasEnlarge();
       Toast.makeText(MyGameActivity.this,
         "enlarge", Toast.LENGTH_LONG).show();
      }else if(gesturePerformed.equals("reduce")){
       myForeground.canvasReduce();
       Toast.makeText(MyGameActivity.this,
         "reduce", Toast.LENGTH_LONG).show();
      }
     }
    
  }
  
};
 
 @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();
  myGameSurfaceView1.MyGameSurfaceView_OnResume();
  myForeground.MyGameSurfaceView_OnResume();
   
  //myAccelerometer.registerListener();
 
 }
 
 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  super.onPause();
  myGameSurfaceView1.MyGameSurfaceView_OnPause();
  myForeground.MyGameSurfaceView_OnPause();
   
  //myAccelerometer.unregisterListener();
 }
  
 void updateAccelerometer(float tx, float ty){
  int w = myForeground.getWidth();
  int h = myForeground.getHeight();
   
  float x = ((w/2) * tx) + (w/2);
  float y = ((h/2) * ty) + (h/2);
  myForeground.updateAccelerometer(x, y);
 }
 
}

Modify MyForeground.java to handle canvas scale, translate and rotate.

package com.MyGame;
 
import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;
 
public class MyForeground extends MyGameSurfaceView {
  
 Sprite mySprite;
  
 float canvasScaleX = 1.0f;
 float canvasScaleY = 1.0f;
 float canvasTranslateX = 0.0f;
 float canvasTranslateY = 0.0f;
 float canvasRotate = 0.0f;
 
 public MyForeground(Context context) {
  super(context);
  init();
 }
 
 public MyForeground(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }
 
 public MyForeground(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
  
 private void init(){
  mySprite = new Sprite(
    BitmapFactory.decodeResource(getResources(), R.drawable.icon_me),
    100, 100);
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
  //Clear Canvas with transparent background
  canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
   
  canvas.scale(canvasScaleX, canvasScaleY);
  canvas.translate(canvasTranslateX, canvasTranslateY);
  canvas.rotate(canvasRotate, mySprite.getX(), mySprite.getY());
  mySprite.draw(canvas);
   
 }
 
 @Override
 public void updateStates() {
  // TODO Auto-generated method stub
  mySprite.update();
 }
  
 void updateAccelerometer(float tx, float ty){
  mySprite.setX((int)tx);
  mySprite.setY((int)ty);
 }
  
 public void canvasUp(){
  canvasTranslateY -= 10.0f;
 }
  
 public void canvasDown(){
  canvasTranslateY += 10.0f;
 }
  
 public void canvasLeft(){
  canvasTranslateX -= 10.0f;
 }
  
 public void canvasRight(){
  canvasTranslateX += 10.0f;
 }
  
 public void canvasClockwise(){
  canvasRotate += 10.0f;
 }
  
 public void canvasAntiClockwise(){
  canvasRotate -= 10.0f;
 }
  
 public void canvasEnlarge(){
  canvasScaleX *= 2.0f;
  canvasScaleY *= 2.0f;
 }
  
 public void canvasReduce(){
  canvasScaleX /= 2.0f;
  canvasScaleY /= 2.0f;
 }
 
}

Cheers Guys!!!!!!!!