触摸事件

<ImageView

    android:id="@+id/image"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:scaleType="matrix"

    android:src="@drawable/image" />

public class MainActivity extends Activity {

   private ImageView imageView;

   @Override

   protected void onCreate(Bundle savedInstanceState) {

      super.onCreate(savedInstanceState);

      setContentView(R.layout.activity_main);

      imageView = (ImageView) findViewById(R.id.image);

      imageView.setOnTouchListener(new MyOnTouchListener());

   }

   private class MyOnTouchListener implements OnTouchListener {

      private floatx;

      private floaty;

      private Matrix currentMatrix = new Matrix(); // 用来操作图片的矩阵

      private Matrix oldMatrix = new Matrix();

      public boolean onTouch(View v, MotionEvent event) {

          switch (event.getAction()) {

             case MotionEvent.ACTION_DOWN:         // 按下时

                x = event.getX();               // 获取x轴坐标

                y = event.getY();                  // 获取y轴坐标

                oldMatrix.set(imageView.getImageMatrix());      // 记住位置

                break;

             case MotionEvent.ACTION_MOVE:         // 移动时

                currentMatrix.set(oldMatrix);      // 设置成按下时记住的位置

                currentMatrix.postTranslate(event.getX() - x, event.getY() - y); // 改变位置

                break;

          }

          imageView.setImageMatrix(currentMatrix); // 移动图片

          return true;

      }

   }

}

public class MainActivity extends Activity {

   private ImageView imageView;

   @Override

   protected void onCreate(Bundle savedInstanceState) {

      super.onCreate(savedInstanceState);

      setContentView(R.layout.activity_main);

      imageView = (ImageView) findViewById(R.id.image);

      imageView.setOnTouchListener(new MyOnTouchListener());

   }

   private class MyOnTouchListener implements OnTouchListener {

      private floatx;      // 图片移动前的x轴坐标

      private floaty;      // 图片移动前的y轴坐标

      private Matrix currentMatrix = new Matrix();    // 用来移动图片的矩阵

      private Matrix oldMatrix = new Matrix();     // 图片移动前的矩阵

      private inttype;     // 操作类型, 一根手指触摸还是两根手指触摸

      private floatstart;  // 第二根手指按下时的距离

      private floatend;    // 两根手指移动后的距离

      private PointF point; // 放大时的中心点

      public boolean onTouch(View v, MotionEvent event) {

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

             case MotionEvent.ACTION_DOWN:

                type = 1;

                x = event.getX();

                y = event.getY();

                oldMatrix.set(imageView.getImageMatrix());

                break;

             case MotionEvent.ACTION_MOVE:

                currentMatrix.set(oldMatrix);

                if (type == 1) {   // 1根手指触摸

                   currentMatrix.postTranslate(event.getX() - x, event.getY() - y);

                } else {        // 2跟手指触摸

                   end = countDistance(event); // 计算结束时距离

                   float scale = end / start;      // 计算缩放比例

                   currentMatrix.postScale(scale, scale, point.x, point.y); // 设置缩放

                }

                break;

             case MotionEvent.ACTION_POINTER_DOWN:

                type = 2;

                start = countDistance(event);      // 计算开始时距离

                point = countPoint(event);         // 计算中心点

                oldMatrix.set(imageView.getImageMatrix());

                break;

          }

         imageView.setImageMatrix(currentMatrix); // 改变图片

          return true;

      }

   }

   public float countDistance(MotionEvent event) {

      float a = event.getX(1) - event.getX(0); // x轴距离

      float b = event.getY(1) - event.getY(0); // y轴距离

      return (float) Math.sqrt(a * a + b * b); // 勾股定理

   }

   public PointF countPoint(MotionEvent event) {

      float x = (event.getX(0) + event.getX(1)) / 2;

// x轴中间点

      float y = (event.getY(0) + event.getY(1)) / 2;

// y轴中间点

      return new PointF(x, y);

   }

}