MotinEvent小练习
public class MainActivity extends AppCompatActivity implements View.OnTouchListener {
private ImageView iv_main;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv_main = (ImageView) findViewById(R.id.iv_main);
iv_main.setOnTouchListener(this);
}
private int lastX;
private int lastY;
@Override
public boolean onTouch(View v, MotionEvent event) {
//因为这里是监听,所以移动都都会调用这个方法,也就是移动时,会刷新eventX和eventY
//获得xy轴坐标,相对于屏幕左顶点
int eventX= (int) event.getRawX();
int eventY= (int) event.getRawY();
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
lastX=eventX;
lastY=eventY;
break;
case MotionEvent.ACTION_MOVE:
//获取滑动的距离
int dx=eventX-lastX;
int dy=eventY-lastY;
//根据事件的偏移来移动ImageView
int left=iv_main.getLeft()+dx;
int top=iv_main.getTop()+dy;
int right=iv_main.getRight()+dx;
int bottom=iv_main.getBottom()+dy;
iv_main.layout(left,top,right,bottom);
//移动到某个位置后,标记当前位置
lastX=eventX;
lastY=eventY;
break;
}
return true;
}
}