android 控件放大缩小效果实现

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">像android tv中很多应用一样，焦点在控件上的时候，控件放大，失去焦点时，控件还原。</span>

小小的实现一个简单的demo。

public class ScaleRunnable implements Runnable {private static int ZOOM_ANIMATION_DURATION = 200;private final View mView;private float mStartScale;private float mTargetScale;private long mStartTime;private int scaleAnimTime;private Boolean mIsRun = false;//Boolean是包装类型，boolean是基本类型private Boolean mStop;private Boolean mZoomIn;private float mVelocity;private onScaleEndListen monScaleEndListen;ScaleRunnable(View view){this(view, ZOOM_ANIMATION_DURATION);//构造函数不能直接调用}public ScaleRunnable(View view, int Animtime) {// TODO Auto-generated constructor stubmView = view;scaleAnimTime = Animtime;}public void setOnScaleEndListen(onScaleEndListen l){monScaleEndListen = l;}public void start(float startScale, float targetScale){if(mIsRun){return;}mStartScale = startScale;mTargetScale = targetScale;mVelocity = (mTargetScale - mStartScale)/scaleAnimTime;mZoomIn = (mTargetScale > mStartScale) ? true:false;mStartTime = System.currentTimeMillis();mStop = false;mIsRun = true;mView.post(this);//在ui线程中运行,会调用run()函数}public void stop(){mStop = true;mIsRun = false;mView.buildDrawingCache();}@Overridepublic void run() {// TODO Auto-generated method stubsif(mStop){return;}long time = System.currentTimeMillis();long elapsed = time - mStartTime;float newScale = mStartScale + elapsed * mVelocity;if(newScale == mTargetScale || (mZoomIn == (newScale > mTargetScale))){mView.setScaleX(mTargetScale);mView.setScaleY(mTargetScale);if(null != monScaleEndListen){monScaleEndListen.onScaleEnd();}stop();}else{mView.setScaleX(newScale);mView.setScaleY(newScale);}if (!mStop) {mView.post(this);//在放大没完成时，继续放大}}public static interface onScaleEndListen{public void onScaleEnd();}}

ScaleRunnable继承自Runnable，在run()中缩放view

在MainActivity中，

public class MainActivity extends Activity implements OnClickListener{private Button mBtnA;private Button mBtnB;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mBtnA = (Button)findViewById(R.id.btn_a);mBtnA.setOnClickListener(this);mBtnA.setOnFocusChangeListener(new OnFocusChangeListener() {@Overridepublic void onFocusChange(View arg0, boolean arg1) {// TODO Auto-generated method stubScaleRunnable scale = new ScaleRunnable(mBtnA);scale.setOnScaleEndListen(new onScaleEndListen(){@Overridepublic void onScaleEnd() {// TODO Auto-generated method stubLog.i("TAG", "ScaleSucceed A");}});if(arg1){Log.i("TAG", "mBtnA focus");scale.start(1.0f, 1.5f);}else{Log.i("TAG", "mBtnA lost focus");scale.start(1.5f, 1.0f);}}});mBtnB = (Button)findViewById(R.id.btn_b);mBtnB.setOnFocusChangeListener(new OnFocusChangeListener() {@Overridepublic void onFocusChange(View arg0, boolean arg1) {// TODO Auto-generated method stubScaleRunnable scale = new ScaleRunnable(mBtnB);scale.setOnScaleEndListen(new onScaleEndListen(){@Overridepublic void onScaleEnd() {// TODO Auto-generated method stubLog.i("TAG", "ScaleSucceed B");}});if(arg1){Log.i("TAG", "mBtnB focus");scale.start(1.0f, 1.5f);}else{Log.i("TAG", "mBtnB lost focus");scale.start(1.5f, 1.0f);}}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// TODO Auto-generated method stubreturn super.onOptionsItemSelected(item);}}

就可实现放大缩小的效果。