效果圖
準備知識
merge標籤的使用,可以參考Android 佈局優化之include與merge- ViewAnimator
Android自定義組件
SendCommentButton
新建SendCommentButton繼承自ViewAnimator,而ViewAnimator是繼承自FrameLayout的。
public class SendCommentButton extends ViewAnimator{
//通過代碼new執行該方法
public SendCommentButton(Context context) {
super(context);
init();
}
//通過xml引入會執行該方法
public SendCommentButton(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
}init()方法
private void init() {
LayoutInflater.from(getContext()).inflate(R.layout.view_send_comment_button, this, true);
}把佈局依附到該控件上
R.layout.view_send_comment_button佈局
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<TextView
android:id="@+id/tvSend"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="SEND"
android:textColor="#ffffff"
android:textSize="12sp" />
<TextView
android:id="@+id/tvDone"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="✓"
android:textColor="#ffffff"
android:textSize="12sp" />
</merge>執行init()方法之後會回調ViewAnimator的addView方法，我們來看看ViewAnimator是怎麼處理的
......
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
super.addView(child, index, params);
if (getChildCount() == 1) {
child.setVisibility(View.VISIBLE);
} else {
child.setVisibility(View.GONE);
}
if (index >= 0 && mWhichChild >= index) {
// Added item above current one, increment the index of the displayed child
setDisplayedChild(mWhichChild + 1);
}
}
......從上面可以看到把第一個子View設置爲可見，其他設置GONE，也就是說merge的✓設置爲GONE了。
接下來我們補充SendCommentButton其他邏輯代碼
public class SendCommentButton extends ViewAnimator implements View.OnClickListener {
public static final int STATE_SEND = 0;
public static final int STATE_DONE = 1;
private static final long RESET_STATE_DELAY_MILLIS = 2000;
private int currentState;
private OnSendClickListener onSendClickListener;
//通過代碼new執行該方法
public SendCommentButton(Context context) {
super(context);
init();
}
//通過xml引入會執行該方法
public SendCommentButton(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
LayoutInflater.from(getContext()).inflate(R.layout.view_send_comment_button, this, true);
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
currentState = STATE_SEND;
setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (onSendClickListener != null) {
onSendClickListener.onSendClickListener(this);
}
}
@Override
protected void onDetachedFromWindow() {
removeCallbacks(revertStateRunnable);
super.onDetachedFromWindow();
}
public void setCurrentState(int state) {
if (state == currentState) {
return;
}
currentState = state;
if (state == STATE_DONE) {
setEnabled(false);
postDelayed(revertStateRunnable, RESET_STATE_DELAY_MILLIS);
setInAnimation(getContext(), R.anim.slide_in_done);
setOutAnimation(getContext(), R.anim.slide_out_send);
} else if (state == STATE_SEND) {
setEnabled(true);
setInAnimation(getContext(), R.anim.slide_in_send);
setOutAnimation(getContext(), R.anim.slide_out_done);
}
showNext();
}
private Runnable revertStateRunnable = new Runnable() {
@Override
public void run() {
setCurrentState(STATE_SEND);
}
};
public interface OnSendClickListener {
void onSendClickListener(View v);
}
public void setOnSendClickListener(OnSendClickListener onSendClickListener) {
this.onSendClickListener = onSendClickListener;
}
}上面定義了兩種狀態，暴露了一個接口和設置了進入和進出動畫。這裏解析一下ViewAnimator的showNext()方法，在ViewAnimator的源碼中
......
public void showNext() {
setDisplayedChild(mWhichChild + 1);
}
......showNext會調用setDisplayedChild方法
/**
* Sets which child view will be displayed.
*設置哪個子View將被顯示
* @param whichChild the index of the child view to display 要顯示子view的下標
*/
public void setDisplayedChild(int whichChild) {
mWhichChild = whichChild;
if (whichChild >= getChildCount()) {
mWhichChild = 0;
} else if (whichChild < 0) {
mWhichChild = getChildCount() - 1;
}
boolean hasFocus = getFocusedChild() != null;
// This will clear old focus if we had it
showOnly(mWhichChild);
if (hasFocus) {
// Try to retake focus if we had it
requestFocus(FOCUS_FORWARD);
}
}setDisplayedChild中的主要展示邏輯交給了showOnly方法
/**
* Shows only the specified child. The other displays Views exit the screen,
* optionally with the with the {@link #getOutAnimation() out animation} and
* the specified child enters the screen, optionally with the
* {@link #getInAnimation() in animation}.
*
* @param childIndex The index of the child to be shown.
* @param animate Whether or not to use the in and out animations, defaults
* to true.
*/
void showOnly(int childIndex, boolean animate) {
final int count = getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (i == childIndex) {
if (animate && mInAnimation != null) {
child.startAnimation(mInAnimation);
}
child.setVisibility(View.VISIBLE);
mFirstTime = false;
} else {
if (animate && mOutAnimation != null && child.getVisibility() == View.VISIBLE) {
child.startAnimation(mOutAnimation);
} else if (child.getAnimation() == mInAnimation)
child.clearAnimation();
child.setVisibility(View.GONE);
}
}
}
/**
* Shows only the specified child. The other displays Views exit the screen
* with the {@link #getOutAnimation() out animation} and the specified child
* enters the screen with the {@link #getInAnimation() in animation}.
*正在展示的view退出屏幕，展示指定的view，指定的view以getInAnimation的動畫進入，退出的view以getOutAnimation的動畫退出
* @param childIndex The index of the child to be shown.
*/
void showOnly(int childIndex) {
final boolean animate = (!mFirstTime || mAnimateFirstTime);
showOnly(childIndex, animate);
}重點看下這段代碼
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (i == childIndex) {
if (animate && mInAnimation != null) {
child.startAnimation(mInAnimation);
}
child.setVisibility(View.VISIBLE);
mFirstTime = false;
} else {
if (animate && mOutAnimation != null && child.getVisibility() == View.VISIBLE) {
child.startAnimation(mOutAnimation);
} else if (child.getAnimation() == mInAnimation)
child.clearAnimation();
child.setVisibility(View.GONE);
}
}從上面可以看到ViewAnimator把我們之前設置的setInAnimation(getContext(), R.anim.slide_in_done); 應用到進入和退出
setOutAnimation(getContext(), R.anim.slide_out_send);View上。