Android拖动Button按钮显示效果

package com.oppo.examples; //Download by http://www.codefans.net import android.app.Activity; import android.os.Bundle; import android.util.DisplayMetrics; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.Button; import android.widget.Toast; public class DraftTest extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); DisplayMetrics dm = getResources().getDisplayMetrics(); final int screenWidth = dm.widthPixels; final int screenHeight = dm.heightPixels - 50; final Button b=(Button)findViewById(R.id.btn); b.setOnTouchListener(new OnTouchListener(){ int lastX, lastY; @Override public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub int ea=event.getAction(); Log.i("TAG", "Touch:"+ea); //Toast.makeText(DraftTest.this, "位置："+x+","+y, Toast.LENGTH_SHORT).show(); switch(ea){ case MotionEvent.ACTION_DOWN: lastX = (int) event.getRawX(); lastY = (int) event.getRawY(); break; /** * layout(l,t,r,b) * l Left position, relative to parent t Top position, relative to parent r Right position, relative to parent b Bottom position, relative to parent * */ case MotionEvent.ACTION_MOVE: int dx =(int)event.getRawX() - lastX; int dy =(int)event.getRawY() - lastY; int left = v.getLeft() + dx; int top = v.getTop() + dy; int right = v.getRight() + dx; int bottom = v.getBottom() + dy; if(left < 0){ left = 0; right = left + v.getWidth(); } if(right > screenWidth){ right = screenWidth; left = right - v.getWidth(); } if(top < 0){ top = 0; bottom = top + v.getHeight(); } if(bottom > screenHeight){ bottom = screenHeight; top = bottom - v.getHeight(); } v.layout(left, top, right, bottom); Log.i("", "position：" + left +", " + top + ", " + right + ", " + bottom); lastX = (int) event.getRawX(); lastY = (int) event.getRawY(); break; case MotionEvent.ACTION_UP: break; } return false; }}); } }