直接上代码，代码很清楚。
import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.graphics.PointF;import android.os.Bundle;import android.util.FloatMath;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.view.ViewGroup.MarginLayoutParams;import android.widget.ImageView;public class MainActivity extends Activity implements OnTouchListener { /** Called when the activity is first created. */ // 放大缩小 Matrix matrix = new Matrix(); Matrix savedMatrix = new Matrix(); PointF start = new PointF(); PointF mid = new PointF(); float oldDist; private ImageView myImageView; // 模式 static final int NONE = 0; static final int DRAG = 1; static final int ZOOM = 2; int mode = NONE; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); myImageView = (ImageView) findViewById(R.id.myImage); myImageView.setOnTouchListener(this); } @Override public boolean onTouch(View v, MotionEvent event) { ImageView myImageView = (ImageView) v; switch (event.getAction() & MotionEvent.ACTION_MASK) { // 设置拖拉模式 case MotionEvent.ACTION_DOWN: matrix.set(myImageView.getImageMatrix()); savedMatrix.set(matrix); start.set(event.getX(), event.getY()); mode = DRAG; break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: mode = NONE; break; // 设置多点触摸模式 case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); if (oldDist > 10f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; } break; // 若为DRAG模式，则点击移动图片 case MotionEvent.ACTION_MOVE: if (mode == DRAG) { matrix.set(savedMatrix); matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); } // 若为ZOOM模式，则点击触摸缩放 else if (mode == ZOOM) { float newDist = spacing(event); if (newDist > 10f) { matrix.set(savedMatrix); float scale = newDist / oldDist; // 设置硕放比例和图片的中点位置 matrix.postScale(scale, scale, mid.x, mid.y); } } break; } myImageView.setImageMatrix(matrix); return true; } // 计算移动距离 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); } // 计算中点位置 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); }}