Android multi-point touch for Image Scaling

 

Package com. Touch;
Import Android. Graphics. matrix;
Import Android. Graphics. pointf;
Import Android. util. floatmath;
Import Android. View. motionevent;
Import Android. View. view;
Import Android. View. View. ontouchlistener;
Import Android. widget. imageview;

Public class mulitpointtouchlistener implements ontouchlistener {
Matrix matrix = new matrix ();
Matrix savedmatrix = new matrix ();

Static final int none = 0;
Static final int drag = 1;
Static final int zoom = 2;
Int mode = none;

Pointf start = new pointf ();
Pointf mid = new pointf ();
Float olddist = 1f;

@ Override
Public Boolean ontouch (view V, motionevent event ){

Imageview view = (imageview) V;

Switch (event. getaction () & motionevent. action_mask ){
Case motionevent. action_down:

Matrix. Set (view. getimagematrix ());
Savedmatrix. Set (matrix );
Start. Set (event. getx (), event. Gety ());
Mode = drag;

Break;
Case motionevent. action_pointer_down:
Olddist = spacing (event );
If (olddist> 10f ){
Savedmatrix. Set (matrix );
Midpoint (MID, event );
Mode = zoom;
}
Break;
Case motionevent. action_up:
Case motionevent. action_pointer_up:
Mode = none;

Break;
Case motionevent. action_move:
If (mode = drag ){
Matrix. Set (savedmatrix );
Matrix. posttranslate (event. getx ()-start. X, event. Gety ()
-Start. y );
} Else if (mode = zoom ){
Float newdist = spacing (event );
If (newdist> 10f ){
Matrix. Set (savedmatrix );
Float scale = newdist/olddist;
Matrix. postscale (scale, scale, mid. X, mid. y );
}
}
Break;
}

View. setimagematrix (matrix );
Return true;
}

Private float spacing (motionevent event ){
Float x = event. getx (0)-event. getx (1 );
Float y = event. Gety (0)-event. Gety (1 );
Return floatmath. SQRT (x * x + y * y );
}

Private void midpoint (pointf point, motionevent event ){
Float x = event. getx (0) + event. getx (1 );
Float y = event. Gety (0) + event. Gety (1 );
Point. Set (X/2, Y/2 );
}
}

Imageview. setontouchlistener (New mulitpointtouchlistener (); in XML, change the image scaling format to matrix.