Android自定义View--使用ViewAnimator实现一个提交按钮

效果图

准备知识

• merge标签的使用,可以参考Android 布局优化之include与merge
• ViewAnimator
• Android自定义组件

SendCommentButton

新建SendCommentButton继承自ViewAnimator,而ViewAnimator是继承自FrameLayout的。

public class SendCommentButton extends ViewAnimator{        //通过代码new执行该方法    public SendCommentButton(Context context) {        super(context);        init();    }    //通过xml引入会执行该方法    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);    }

把布局依附到该控件上
R.layout.view_send_comment_button布局

<?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>

执行init()方法之后会回调ViewAnimator的addView方法，我们来看看ViewAnimator是怎么处理的

    ......    @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);        }    }    ......

从上面可以看到把第一个子View设置为可见，其他设置GONE，也就是说merge的✓设置为GONE了。
接下来我们补充SendCommentButton其他逻辑代码

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;    //通过代码new执行该方法    public SendCommentButton(Context context) {        super(context);        init();    }    //通过xml引入会执行该方法    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;    }}

上面定义了两种状态，暴露了一个接口和设置了进入和进出动画。这里解析一下ViewAnimator的showNext()方法，在ViewAnimator的源码中

    ...... public void showNext() {        setDisplayedChild(mWhichChild + 1);    }    ......

showNext会调用setDisplayedChild方法

 /**     * Sets which child view will be displayed.     *设置哪个子View将被显示     * @param whichChild the index of the child view to display 要显示子view的下标     */ 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中的主要展示逻辑交给了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的动画进入，退出的view以getOutAnimation的动画退出     * @param childIndex The index of the child to be shown.     */    void showOnly(int childIndex) {        final boolean animate = (!mFirstTime || mAnimateFirstTime);        showOnly(childIndex, animate);    }

重点看下这段代码

  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);            }        }

从上面可以看到ViewAnimator把我们之前设置的setInAnimation(getContext(), R.anim.slide_in_done);
setOutAnimation(getContext(), R.anim.slide_out_send);应用到进入和退出View上。

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参考