package com.example.drag04;


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 Touch implements OnTouchListener {

 // These matrices will be used to move and zoom image
 Matrix matrix = new Matrix();
 Matrix savedMatrix = new Matrix();

 // We can be in one of these 3 states
 static final int NONE = 0;
 static final int DRAG = 1;
 static final int ZOOM = 2;
 int mode = NONE;

 // Remember some things for zooming
 PointF start = new PointF();
 PointF mid = new PointF();
 float oldDist = 1f;

 
 @Override
 public boolean onTouch(View v, MotionEvent event) {
  ImageView view = (ImageView) v;
  // Dump touch event to log
  dumpEvent(event);

  // Handle touch events here...
  switch (event.getAction() & MotionEvent.ACTION_MASK) {
  case MotionEvent.ACTION_DOWN:
   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; // indicate event was handled
 }

 /** Show an event in the LogCat view, for debugging */
 private void dumpEvent(MotionEvent event) {
  String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
    "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
  StringBuilder sb = new StringBuilder();
  int action = event.getAction();
  int actionCode = action & MotionEvent.ACTION_MASK;
  sb.append("event ACTION_").append(names[actionCode]);
  if (actionCode == MotionEvent.ACTION_POINTER_DOWN
    || actionCode == MotionEvent.ACTION_POINTER_UP) {
   sb.append("(pid ").append(
     action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
   sb.append(")");
  }
  sb.append("[");
  for (int i = 0; i < event.getPointerCount(); i++) {
   sb.append("#").append(i);
   sb.append("(pid ").append(event.getPointerId(i));
   sb.append(")=").append((int) event.getX(i));
   sb.append(",").append((int) event.getY(i));
   if (i + 1 < event.getPointerCount())
    sb.append(";");
  }
  sb.append("]");
 }

 /** Determine the space between the first two fingers */
 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);
 }

 /** Calculate the mid point of the first two fingers */
 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);
 }
}