本文執行個體為大家分享了自定義view實作了類似百度手機助手，首頁評論滾動效果。
看效果：
gif做的不好，其效果就是：幾個viewitem不停的向上滾動，新加入item有個淡入的效果。
說下實作思路：自定義view繼承至LinearLayout，控制item數量及其動畫效果，實作item複用，傳入資料即可，使用友善。
代碼：
public class ViewFlipper extends LinearLayout {
private final int MAX_SHOW_ITEM_SIZE = 5;
private IAdapter mIAdapter;
private int mCount;
//最後一個item動畫
private Animation mLastOneAnimation;
//其它item動畫
private Animation mCommonAnimation;
//資料下标
private int mCurrentIndex;
private static final int DEFAULT_INTERVAL = 2000;
private int mFlipInterval = DEFAULT_INTERVAL;
private boolean mAutoStart = false;
private boolean mRunning = false;
private boolean mStarted = false;
private boolean mVisible = false;
private boolean mUserPresent = true;
public ViewFlipper(Context context) {
super(context);
init(context);
}
public ViewFlipper(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public ViewFlipper(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (Intent.ACTION_SCREEN_OFF.equals(action)) {
mUserPresent = false;
updateRunning();
} else if (Intent.ACTION_USER_PRESENT.equals(action)) {
mUserPresent = true;
updateRunning(false);
}
}
};
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
// Listen for broadcasts related to user-presence
final IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_USER_PRESENT);
// OK, this is gross but needed. This class is supported by the
// remote views machanism and as a part of that the remote views
// can be inflated by a context for another user without the app
// having interact users permission - just for loading resources.
// For exmaple, when adding widgets from a user profile to the
// home screen. Therefore, we register the receiver as the current
// user not the one the context is for.
getContext().registerReceiver(mReceiver, filter);
if (mAutoStart) {
// Automatically start when requested
startFlipping();
}
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
mVisible = false;
getContext().unregisterReceiver(mReceiver);
updateRunning();
}
@Override
protected void onWindowVisibilityChanged(int visibility) {
super.onWindowVisibilityChanged(visibility);
mVisible = visibility == VISIBLE;
updateRunning(mVisible);
// updateRunning(false);
}
private void init(Context context) {
this.setOrientation(LinearLayout.VERTICAL);
}
public void setIAdapter(IAdapter iAdapter) {
this.mIAdapter = iAdapter;
initShowItems();
}
public void startFlipping() {
mStarted = true;
updateRunning();
}
public void stopFlipping() {
mStarted = false;
updateRunning();
}
private void updateRunning() {
updateRunning(true);
}
public boolean isFlipping() {
return mStarted;
}
public void setAutoStart(boolean autoStart) {
mAutoStart = autoStart;
}
public boolean isAutoStart() {
return mAutoStart;
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setClassName(ViewFlipper.class.getName());
}
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setClassName(ViewFlipper.class.getName());
}
private void initShowItems() {
if (mIAdapter != null) {
mCount = mIAdapter.getCount();
for (int i = 0; i < mCount; i++) {
if (i == MAX_SHOW_ITEM_SIZE) {
break;
}
View convertView = getChildAt(i);
View item = mIAdapter.getItemView(convertView, i);
addView(item, i);
}
}
}
private void updateRunning(boolean flipNow) {
boolean running = mVisible && mStarted && mUserPresent;
System.out.println(" updateRunning running:" + running + " mVisible " + mVisible + " userPresent " + mUserPresent);
if (running != mRunning) {
if (running && (mCount > MAX_SHOW_ITEM_SIZE)) {
showItems(mCurrentIndex++, flipNow);
Message msg = mHandler.obtainMessage(FLIP_MSG);
mHandler.sendMessageDelayed(msg, mFlipInterval);
} else {
mHandler.removeMessages(FLIP_MSG);
}
mRunning = running;
}
}
private void showItems(final int position, boolean animate) {
if (animate && (mLastOneAnimation == null || mCommonAnimation == null)) {
mLastOneAnimation = AnimationUtils.loadAnimation(getContext(), R.anim.lastone_anim);
mCommonAnimation = AnimationUtils.loadAnimation(getContext(), R.anim.common_anim);
}
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
child.clearAnimation();
int index = position + i;
child = mIAdapter.getItemView(child, (index >= mIAdapter.getCount()) ? (index - mIAdapter.getCount()) : index);
if (animate) {
if (i == childCount - 1) {
child.setAnimation(mLastOneAnimation);
} else {
child.setAnimation(mCommonAnimation);
}
}
child.setVisibility(View.VISIBLE);
}
if (animate) {
mCommonAnimation.startNow();
mLastOneAnimation.startNow();
}
//保證傳入的position小于getCount
if (mCurrentIndex >= mIAdapter.getCount()) {
mCurrentIndex = 0;
}
}
private final int FLIP_MSG = 1;
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == FLIP_MSG) {
if (mRunning) {
showItems(mCurrentIndex++, true);
msg = obtainMessage(FLIP_MSG);
sendMessageDelayed(msg, mFlipInterval);
}
}
}
};
public interface IAdapter {
public View getItemView(View convertView, int position);
public int getCount();
}
}
再來看看調用部分：
public class MainActivity extends ActionBarActivity implements ViewFlipper.IAdapter {
ViewFlipper viewFlipper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewFlipper = (ViewFlipper) findViewById(R.id.view_flipper);
viewFlipper.setIAdapter(this);
}
@Override
protected void onResume() {
super.onResume();
viewFlipper.startFlipping();
}
@Override
public View getItemView(View convertView, int position) {
View item = null;
TextView textView;
if (convertView == null) {
item = View.inflate(this, R.layout.item, null);
} else {
item = convertView;
}
textView = (TextView) item.findViewById(R.id.textview);
textView.setText("測試資料:" + position);
return item;
}
@Override
public int getCount() {
return 8;
}
}
可以看出，MainActivity實作了ViewFlipper.IAdapter接口，setAdapter後調用startFlipper即可。
這裡布局檔案我就不貼出來了，附上工程源碼，項目裡動畫時間有點長，修改下就ok。
限于水準有限，不足之處難免，望各位不舍指正，與君共勉。
以上就是本文的全部内容，希望對大家的學習有所幫助，也希望大家多多支援腳本之家。