安卓控件TextSwitcher的使用（实现Textview的上下滚动）

经常可以在app上面看到许多的上下滚动textview，是可以直接使用TextSwitcher直接实现的。

开始还写了个自定义view来实现，然后发现官方原来有(:з」∠)。

控件还有ImageSwitcher和ViewSwitcher。TextSwitcher和ImageSwitcher都是继承于ViewSwitcher的，所以使用方法都一样只不过对象不一样罢了。

效果

只是稍微截取了gif

使用

布局

<TextSwitcher
android:id="@+id/textSwitcher"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</TextSwitcher>

直接放置一个TextSwitcher即可

activity中调用

TextSwitcher textSwitcher = (TextSwitcher) findViewById(R.id.textSwitcher);
textSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
@Override
public View makeView() {
return new TextView(context);
}
});
List<String> texts = new ArrayList<>();
for (int i = 0; i < 10; i++) {
texts.add("循环....."+i);
}
textSwitcher.setText(texts.get(0));

最简单的设置属性，其中只要实现ViewFactory的重写即可，其他的ImageSwitcher和ViewSwitcher都是一样的，只不过设置的view不同！

当需要循环的时候只需要设置一个Handler来每次改变textSwitcher的setText中的值。

比如

private Handler handler = new Handler();
private Runnable task = new Runnable() {
@Override
public void run() {
marker = ++marker % texts.size();
textSwitcher.setText(texts.get(marker));
handler.postDelayed(task, 4000);
}
};

在然后是通过调用

textSwitcher.setInAnimation();
textSwitcher.setOutAnimation();

方法来控制textSwitcher的进出动画

实现动画切换并且自动循环

创建一个类来统一管理textSwitcher的动画和循环

import android.os.Handler;
import android.util.Log;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationSet;
import android.view.animation.TranslateAnimation;
import android.widget.TextSwitcher;

import java.util.List;

/**
* TextSwitcherAnimation
* Author: gjn.
* Time: 2018/2/22.
*/

public class TextSwitcherAnimation {
private static final int DURATION = 1000;

private TextSwitcher textSwitcher;
private List<String> texts;
private int marker;
private AnimationSet InAnimationSet;
private AnimationSet OutAnimationSet;

private int delayTime = 2000;
private Handler handler = new Handler();
private Runnable task = new Runnable() {
@Override
public void run() {
nextView();
handler.postDelayed(task, delayTime * 2);
}
};

public TextSwitcherAnimation(TextSwitcher textSwitcher, List<String> texts) {
this.textSwitcher = textSwitcher;
this.texts = texts;
}

public void start() {
stop();
handler.postDelayed(task, delayTime);
}

public void stop(){
handler.removeCallbacks(task);
}

public int getMarker() {
return marker;
}

public TextSwitcherAnimation setTexts(List<String> texts) {
this.texts = texts;
return this;
}

public void setDelayTime(int delayTime) {
this.delayTime = delayTime;
}

public void create() {
marker = 0;
if (texts == null){
Log.w("TextSwitcherAnimation", "texts is null");
return;
}
if (textSwitcher == null) {
Log.w("TextSwitcherAnimation", "textSwitcher is null");
return;
}
textSwitcher.setText(texts.get(0));
createAnimation();
textSwitcher.setInAnimation(InAnimationSet);
textSwitcher.setOutAnimation(OutAnimationSet);
start();
}

private void createAnimation() {
AlphaAnimation alphaAnimation;
TranslateAnimation translateAnimation;

int h = textSwitcher.getHeight();
if (h <= 0) {
textSwitcher.measure(0,0);
h = textSwitcher.getMeasuredHeight();
}

InAnimationSet = new AnimationSet(true);
OutAnimationSet = new AnimationSet(true);

alphaAnimation = new AlphaAnimation(0,1);
translateAnimation = new TranslateAnimation(Animation.ABSOLUTE, 0, Animation.ABSOLUTE, 0,
Animation.ABSOLUTE, h, Animation.ABSOLUTE, 0);
InAnimationSet.addAnimation(alphaAnimation);
InAnimationSet.addAnimation(translateAnimation);
InAnimationSet.setDuration(DURATION);

alphaAnimation = new AlphaAnimation(1,0);
translateAnimation = new TranslateAnimation(Animation.ABSOLUTE, 0, Animation.ABSOLUTE, 0,
Animation.ABSOLUTE, 0, Animation.ABSOLUTE, -h);
OutAnimationSet.addAnimation(alphaAnimation);
OutAnimationSet.addAnimation(translateAnimation);
OutAnimationSet.setDuration(DURATION);
}

private void nextView() {
marker = ++marker % texts.size();
textSwitcher.setText(texts.get(marker));
}
}

实现很简单，就是做了一个进出动画和Handler来控制循环。这边就不复述了。

使用如下

List<String> texts = new ArrayList<>();
for (int i = 0; i < 10; i++) {
texts.add("循环....."+i);
}
textSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
@Override
public View makeView() {
TextView t = new TextView(mContext);
return t;
}
});
new TextSwitcherAnimation(textSwitcher,texts).create();