多点触控实现图片移动和放大缩小
xml中
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:background="@android:color/black" > <ImageView android:layout_width="match_parent" android:layout_height="match_parent" android:src="@drawable/aefwfaw" android:scaleType="matrix" android:id="@+id/img" /> </LinearLayout>
activity中
package com.bwi.test; import android.os.Bundle; import android.app.Activity; import android.graphics.Matrix; import android.graphics.PointF; import android.util.FloatMath; import android.util.Log; import android.view.Menu; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; public class MainActivity extends Activity implements OnTouchListener { private Matrix matrix = new Matrix(); private Matrix savedMatrix = new Matrix(); private static final int NONE = 0; private static final int DRAG = 1; private static final int ZOOM = 2; private int mode = NONE; // 第一个按下的手指的点 private PointF startPoint = new PointF(); // 两个按下的手指的触摸点的中点 private PointF midPoint = new PointF(); // 初始的两个手指按下的触摸点的距离 private float oriDis = 1f; private ImageView img; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); img = (ImageView) findViewById(R.id.img); img.setOnTouchListener(this); } @Override public boolean onTouch(View v, MotionEvent event) { ImageView view = (ImageView) v; // 进行与操作是为了判断多点触摸 switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: // 第一个手指按下事件 matrix.set(view.getImageMatrix()); savedMatrix.set(matrix); startPoint.set(event.getX(), event.getY()); mode = DRAG; break; case MotionEvent.ACTION_POINTER_DOWN: // 第二个手指按下事件 oriDis = distance(event); if (oriDis > 10f) { savedMatrix.set(matrix); midPoint = middle(event); mode = ZOOM; } break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: // 手指放开事件 mode = NONE; break; case MotionEvent.ACTION_MOVE: // 手指滑动事件 if (mode == DRAG) { // 是一个手指拖动 matrix.set(savedMatrix); matrix.postTranslate(event.getX() - startPoint.x, event.getY() - startPoint.y); } else if (mode == ZOOM) { // 两个手指滑动 float newDist = distance(event); if (newDist > 10f) { matrix.set(savedMatrix); float scale = newDist / oriDis; matrix.postScale(scale, scale, midPoint.x, midPoint.y); } } break; } // 设置ImageView的Matrix view.setImageMatrix(matrix); return true; } private PointF middle(MotionEvent event) { float x = event.getX(0) + event.getX(1); float y = event.getY(0) + event.getY(1); return new PointF(x / 2, y / 2); } private float distance(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); } }