动画 -- 按钮 --- 从无到有（中心）

 1 // sa = new ScaleAnimation(0, 1, 0, 1,100,50);  2 // sa = new ScaleAnimation(0, 1, 0, 1, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f)  3 // sa.setDuration(1000);

 4         

 5         findViewById(R.id.btnScaleMe).setOnClickListener(new View.OnClickListener() {  6  @Override  7             public void onClick(View arg0) {  8                 arg0.startAnimation(AnimationUtils.loadAnimation(MainActivity.this, R.anim.sa));  9  } 10         });

 1 <?xml version="1.0" encoding="utf-8"?>  2 <scale xmlns:android="http://schemas.android.com/apk/res/android"  3  android:fromXScale="0"  4  android:toXScale="1"  5  android:fromYScale="0"  6  android:toYScale="1"  7  android:duration="1000"  8  android:pivotX="50%"  9  android:pivotY="50%" > 10 11 </scale>