Codice per scrolling e zoom di un'immagine.

Ecco il codice che realizza un'immagine scrollabile e zoomabile:

public class MainActivity extends Activity {
 float scale=1f;
 ScaleGestureDetector SGD;
 
 RelativeLayout mainLayout;
 ImageView imageView;
 
 Bitmap bitmap;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  SGD = new ScaleGestureDetector(this, new ScaleListener());
  mainLayout=(RelativeLayout)findViewById(R.id.mainLayout);
  
  bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.angurie2);
  final int larghezza=300;
  final int altezza=300;
  ImageView i=newImage(mainLayout,larghezza, altezza, 10, 10, bitmap, Color.BLACK, ScaleType.MATRIX);
    
  View.OnTouchListener onTouchListener=new View.OnTouchListener() {
   Matrix matrix=new Matrix();
   Matrix inversa=new Matrix();
   float X,Y,currentX, currentY;
   float deltaX, deltaY;
   @Override
   public boolean onTouch(View v, MotionEvent event) {
    switch(event.getAction()){
    case MotionEvent.ACTION_DOWN:
     X=event.getX();
     Y=event.getY();
     
     break;
    case MotionEvent.ACTION_MOVE:
     
     currentX=event.getX();
     currentY=event.getY();
     float[] pts={0,0};
     ((ImageView)v).getImageMatrix().invert(inversa);
     inversa.mapPoints(pts);
     
     
     if(currentX<X){
      if((pts[0]-currentX+X)<(bitmap.getWidth()-larghezza/scale)){
       deltaX=-pts[0]+currentX-X;
      }
      else{
       if((pts[0]-currentX+X)>(bitmap.getWidth()-larghezza/scale))
       deltaX=-(bitmap.getWidth()-larghezza/scale);
       
      }
     }
     if(currentX>X){
      if((pts[0]-currentX+X)>0){
       deltaX=-pts[0]+currentX-X;
      }
      else{
       if((pts[0]-currentX+X)<0) deltaX=0;
      }
     }
     
     if(currentY<Y){
      if((pts[1]-currentY+Y)<(bitmap.getHeight()-altezza/scale)){
       deltaY=-pts[1]+currentY-Y;
      }
      else{
       if((pts[1]-currentY+Y)>(bitmap.getHeight()-altezza/scale))
        deltaY=-(bitmap.getHeight()-altezza/scale);
       
      }
     }
     if(currentY>Y){
      if((pts[1]-currentY+Y)>0){
       deltaY=-pts[1]+currentY-Y;
      }
      else{
       if((pts[1]-currentY+Y)<0) deltaY=0;
      }
     }
     
     
     matrix.setTranslate(deltaX,deltaY);
     matrix.postScale(scale, scale);
     ((ImageView)v).setImageMatrix(matrix);
     X=currentX;
     Y=currentY;
     SGD.onTouchEvent(event);
     break;
    }
    return true;
   }
  };
  i.setOnTouchListener(onTouchListener);
 
  
  
  
 }

 class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener{
  @Override
  public boolean onScale(ScaleGestureDetector SGD){
   scale *= SGD.getScaleFactor();
   return true;
  }
 }
 public ImageView newImage(ViewGroup layout, int larghezza, int altezza, 
   float X, float Y, Bitmap bitmap, int colore, 
   ScaleType scaletype){
  ImageView imageView=new ImageView(this);
  layout.addView(imageView);
  imageView.getLayoutParams().width=larghezza;
  imageView.getLayoutParams().height=altezza;
  imageView.setX(X);
  imageView.setY(Y);

  imageView.setImageBitmap(bitmap);
  imageView.setBackgroundColor(colore);
  imageView.setScaleType(scaletype);
  return imageView;
 }

} 

Ora devo provvedere a metterlo nell'applicazione...
Dopo averla opportunamente SALVATA!!!

Il codice per prendere l'immagine devo andare a ripescarmelo...

Eccolo:

  button.setOnClickListener(new View.OnClickListener() {
   
   @Override
   public void onClick(View v) {
    
    imageView.destroyDrawingCache();
    imageView.buildDrawingCache();
    Bitmap bmp=imageView.getDrawingCache();
    imgControllo.setImageBitmap(bmp);
    
   }
  });