안드로이드 멀티 터치 줌 기능 구현

안드로이드의 멀티 터치 줌 기능이 필요했다. 

상황은 surfaceview에 카메라를 얹고, 이미지뷰로 그림을 불러와 사용하였다. 

그리고 이미지를 손가락 하나로 이동시키거나, 

손가락 두 개를 이용해 확대/축소 기능도 제공해야 했다. 

다음의 소스를 활용했다. 

xml에서 imageview는 match_parent 속성을 가지고 있어야 한다. 

import android.app.Activity; import android.graphics.Matrix; import android.graphics.PointF; import android.os.Bundle; import android.util.FloatMath; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; public class ZoomInZoomOut extends Activity implements OnTouchListener { private static final String TAG = "Touch"; @SuppressWarnings("unused") private static final float MIN_ZOOM = 1f,MAX_ZOOM = 1f; // These matrices will be used to scale points of the image Matrix matrix = new Matrix(); Matrix savedMatrix = new Matrix(); // The 3 states (events) which the user is trying to perform static final int NONE = 0; static final int DRAG = 1; static final int ZOOM = 2; int mode = NONE; // these PointF objects are used to record the point(s) the user is touching PointF start = new PointF(); PointF mid = new PointF(); float oldDist = 1f; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ImageView view = (ImageView) findViewById(R.id.imageView); view.setOnTouchListener(this); } @Override public boolean onTouch(View v, MotionEvent event) { ImageView view = (ImageView) v; view.setScaleType(ImageView.ScaleType.MATRIX); float scale; dumpEvent(event); // Handle touch events here... switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: // first finger down only savedMatrix.set(matrix); start.set(event.getX(), event.getY()); Log.d(TAG, "mode=DRAG"); // write to LogCat mode = DRAG; break; case MotionEvent.ACTION_UP: // first finger lifted case MotionEvent.ACTION_POINTER_UP: // second finger lifted mode = NONE; Log.d(TAG, "mode=NONE"); break; case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down oldDist = spacing(event); Log.d(TAG, "oldDist=" + oldDist); if (oldDist > 5f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; Log.d(TAG, "mode=ZOOM"); } break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { matrix.set(savedMatrix); matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix of points } else if (mode == ZOOM) { // pinch zooming float newDist = spacing(event); Log.d(TAG, "newDist=" + newDist); if (newDist > 5f) { matrix.set(savedMatrix); scale = newDist / oldDist; // setting the scaling of the // matrix...if scale > 1 means // zoom in...if scale < 1 means // zoom out matrix.postScale(scale, scale, mid.x, mid.y); } } break; } view.setImageMatrix(matrix); // display the transformation on screen return true; // indicate event was handled } /* * -------------------------------------------------------------------------- * Method: spacing Parameters: MotionEvent Returns: float Description: * checks the spacing between the two fingers on touch * ---------------------------------------------------- */ 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); } /* * -------------------------------------------------------------------------- * Method: midPoint Parameters: PointF object, MotionEvent Returns: void * Description: calculates the midpoint between the 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); } /** 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("]"); Log.d("Touch Events ---------", sb.toString()); } }