打造一个动态切换文本的TextView
效果图
思路
继承自TextView,在指定时间调用setText()方法切换文本,并且设置进入退出动画
代码解析
代码不多，简洁明了
public class FadingTextView extends TextView {
private Animation fadeInAnimation, fadeOutAnimation;//切换文本动画
private int duration;//切换时间,默认3秒
private final int DEFAULT_DURATION = 3000;
private CharSequence[] textContents;//文本内容
private int textPosition = 0;//当前显示的文本角标
private boolean isShown;//是否可见
public FadingTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
fadeInAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_in);
fadeOutAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_out);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FadingTextView);
duration = a.getInteger(R.styleable.FadingTextView_duration, DEFAULT_DURATION);
textContents = a.getTextArray(R.styleable.FadingTextView_texts);
a.recycle();
}
public FadingTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public FadingTextView(Context context) {
this(context, null);
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
isShown = true;
start();
}
@Override
protected void onDetachedFromWindow() {//涉及动画，需要在detach方法停止不然会造成内存泄漏
super.onDetachedFromWindow();
stop();
}
/**
* 设置文本内容
*
* @param texts
*/
public void setTexts(String... texts) {
if (texts.length < 1) {
throw new IllegalArgumentException("This TextView's contents' length must more than 1");
}
textContents = texts;
}
/**
* 设置文本内容
*
* @param resourceId
*/
public void setTexts(@ArrayRes int resourceId) {
String[] texts = getContext().getResources().getStringArray(resourceId);
if (texts != null) {
if (texts.length < 1) {
throw new IllegalArgumentException("This TextView's contents' length must more than 1");
}
textContents = texts;
}
}
/**
* 设置持续时间
*
* @param duration
*/
public void setDuration(int duration) {
if (duration < 1) {
throw new IllegalArgumentException("duration must more than 1");
}
this.duration = duration;
}
/**
* 获取设置的文本内容
*
* @return
*/
public CharSequence[] getTextContents() {
return textContents;
}
/**
* 开始
*/
private void start() {
setText(textContents[textPosition]);
startAnimation(fadeInAnimation);
postDelayed(animRunnable, duration);
}
/**
* 停止
*/
private void stop() {
if (getAnimation() != null) {
getAnimation().cancel();
}
isShown = false;
removeCallbacks(animRunnable);
}
private final Runnable animRunnable = new Runnable() {
@Override
public void run() {
startAnimation(fadeOutAnimation);
getAnimation().setAnimationListener(new Animation.AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
if (isShown) {
textPosition = (textPosition == (textContents.length - 1)) ? 0 : (textPosition + 1);
start();
}
}
@Override
public void onAnimationRepeat(Animation animation) {
}
});
}
};
}
准备工作：
自定义属性的声明，获取，动画的初始化工作
- 自定义属性声明
<declare-styleable name="FadingTextView">
<attr name="duration" format="integer" />
<attr name="texts" format="reference" />
declare-styleable>- 自定义属性的获取
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FadingTextView);
duration = a.getInteger(R.styleable.FadingTextView_duration, DEFAULT_DURATION);
textContents = a.getTextArray(R.styleable.FadingTextView_texts);
a.recycle();- 动画的声明跟获取
fade_in
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
android:duration="@android:integer/config_longAnimTime"
android:fromAlpha="0.0"
android:toAlpha="1.0"
android:interpolator="@android:anim/linear_interpolator"
/>
set>
fade_out
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
android:duration="@android:integer/config_longAnimTime"
android:fromAlpha="1.0"
android:toAlpha="0.0"
android:interpolator="@android:anim/linear_interpolator"
/>
set>获取动画
fadeInAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_in);
fadeOutAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_out);第一步：
既然是动态切换文本，那需要的text文本肯定是需要多个，不然无法达到切换的目的
/**
* 设置文本内容
*
* @param texts
*/
public void setTexts(String... texts) {
if (texts.length < 1) {
throw new IllegalArgumentException("This TextView's contents' length must more than 1");
}
textContents = texts;
}
/**
* 设置文本内容
*
* @param resourceId
*/
public void setTexts(@ArrayRes int resourceId) {
String[] texts = getContext().getResources().getStringArray(resourceId);
if (texts.length < 1) {
throw new IllegalArgumentException("This TextView's contents' length must more than 1");
}
textContents = texts;
}第二步：
给TextView设置文本、动画，达到渐变效果
/**
* 开始
*/
private void start() {
setText(textContents[textPosition]);
startAnimation(fadeInAnimation);
postDelayed(animRunnable, duration);
}第三步：
定时更新文本内容
private final Runnable animRunnable = new Runnable() {
@Override
public void run() {
startAnimation(fadeOutAnimation);
getAnimation().setAnimationListener(new Animation.AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
if (isShown) {
textPosition = (textPosition == (textContents.length - 1)) ? 0 : (textPosition + 1);
start();
}
}
@Override
public void onAnimationRepeat(Animation animation) {
}
});
}
};第四步：
资源的回收
@Override
protected void onDetachedFromWindow() {//涉及动画，需要在detach方法停止不然会造成内存泄漏
super.onDetachedFromWindow();
stop();
}
/**
* 停止
*/
private void stop() {
if (getAnimation() != null) {
getAnimation().cancel();
}
isShown = false;
removeCallbacks(animRunnable);
}第五步：
使用
<com.qfxl.android.fadingTextView.FadingTextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="@android:color/white"
android:textSize="30sp"
qfxl:duration="2000"
qfxl:texts="@array/arrayTest" />总结
这个是闲暇时间逛github的时候看到的，觉得挺实用简单，就写了一下。
没事多逛逛github，会发现很多惊喜