双指拖动缩放图片

iv = (ImageView) findViewById(R.id.iv);
iv.setOnTouchListener(new MulitPointTouchListener(iv));
iv.setScaleType(ScaleType.CENTER_INSIDE);

public class MulitPointTouchListener implements OnTouchListener {

    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();

    public ImageView image;
    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;

    public MulitPointTouchListener(ImageView image) {
      super();
      this.image = image;
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
      this.image.setScaleType(ScaleType.MATRIX);

      ImageView view = (ImageView) v;
      // dumpEvent(event);

      switch (event.getAction() & MotionEvent.ACTION_MASK) {

      case MotionEvent.ACTION_DOWN:

        Log.w("FLAG", "ACTION_DOWN");
        matrix.set(view.getImageMatrix());
        savedMatrix.set(matrix);
        start.set(event.getX(), event.getY());
        mode = DRAG;
        break;
      case MotionEvent.ACTION_POINTER_DOWN:
        Log.w("FLAG", "ACTION_POINTER_DOWN");
        oldDist = spacing(event);
        if (oldDist > 10f) {
          savedMatrix.set(matrix);
          midPoint(mid, event);
          mode = ZOOM;
        }
        break;
      case MotionEvent.ACTION_UP:
        Log.w("FLAG", "ACTION_UP");
      case MotionEvent.ACTION_POINTER_UP:
        Log.w("FLAG", "ACTION_POINTER_UP");
        mode = NONE;
        break;
      case MotionEvent.ACTION_MOVE:
        Log.w("FLAG", "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);
    }
  }

实现大图滚动显示

​​http://www.eoeandroid.com/code/2012/0802/2000.html​​

​​Muilti-touch 双指缩放文字​​

import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;

public class ZoomListenter implements OnTouchListener {

  private int mode = 0;
  float oldDist;
  float textSize = 0;

  TextView textView = null;

  @Override
  public boolean onTouch(View v, MotionEvent event) {
    textView = (TextView) v;
    if (textSize == 0) {
      textSize = textView.getTextSize();
    }
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
      mode = 1;
      break;
    case MotionEvent.ACTION_UP:
      mode = 0;
      break;
    case MotionEvent.ACTION_POINTER_UP:
      mode -= 1;
      break;
    case MotionEvent.ACTION_POINTER_DOWN:
      oldDist = spacing(event);
      mode += 1;
      break;

    case MotionEvent.ACTION_MOVE:
      if (mode >= 2) {
        float newDist = spacing(event);
        if (newDist > oldDist + 1) {
          zoom(newDist / oldDist);
          oldDist = newDist;
        }
        if (newDist < oldDist - 1) {
          zoom(newDist / oldDist);
          oldDist = newDist;
        }
      }
      break;
    }
    return true;
  }

  private void zoom(float f) {
    textView.setTextSize(textSize *= f);
  }

  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);
  }

}

使用：

textView = (TextView) findViewById(R.id.textView);     

textView.setOnTouchListener(new ZoomListenter());