TextView都有跑马灯的效果，如果说让你去监听跑马灯效果的执行，我觉得这个需求有点二了，但是也要实现。
思路：
1.自定义View 继承TextView 这种方法过于麻烦，只是监听一个跑马灯而已。
2.自定义SPan。简单好用，扩展TextView的功能。
关键代码如下：
| @Override | |
| public void draw(Canvas canvas, CharSequence text, int start, int end, | |
| float x, int top, int y, int bottom, Paint paint) { | |
| canvas.save(); | |
| canvas.drawText( text.toString(), x - startX, y, paint); | |
| canvas.restore(); | |
| int measureText = (int) paint.measureText(text, 0, text.length()); | |
| if (valueAnimator == null ) { | |
| initAnimator(measureText - mView.getWidth()); | |
| } | |
| } | |
| private int startX = 0 ; | |
| private final static int DEFULT_DURATION = 2000 ; | |
| private int duration = DEFULT_DURATION ; | |
| @Override | |
| public int getSize(Paint paint, CharSequence text, int start, int end, | |
| FontMetricsInt fm) { | |
| return 40; | |
| } | |
| private void initAnimator(int width ){ | |
| valueAnimator = ValueAnimator.ofInt(0, width , 0 ); | |
| valueAnimator.addUpdateListener(new AnimatorUpdateListener() { | |
| @Override | |
| public void onAnimationUpdate(ValueAnimator animation) { | |
| startX = (Integer) animation.getAnimatedValue() ; | |
| mView.invalidate(); | |
| } | |
| }); | |
| valueAnimator.setInterpolator(new LinearInterpolator()); | |
| valueAnimator.setDuration(duration); | |
| valueAnimator.addListener(new AnimatorListenerAdapter() { | |
| @Override | |
| public void onAnimationRepeat(Animator animation) { | |
| if (mEasySpanListener != null ) { | |
| mEasySpanListener.over(); | |
| } | |
| } | |
| }); | |
| valueAnimator.setRepeatCount(Integer.MAX_VALUE); | |
| valueAnimator.start(); | |
| } |
Span本身就是对TextView的一个功能增强。
使用：
String text = "这个是用来测试的，TextView的跑马灯效果，想要监听他的跑完的事件用的。" ;
SpannableString spannableString = new SpannableString(text);
EasySpan easySpan =new EasySpan(MainActivity.this,test);
easySpan.setDuration(10000);
easySpan.setEasySpanListener(new EasySpanListener() {
@Override
public void over() {
Log.i("Test", "over") ;
}
});
spannableString.setSpan(easySpan, 0, text.length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
test.setText(spannableString);
来源： <https://github.com/flyme2012/EasyListenerSpan/blob/master/src/com/example/easylistenerspan/MainActivity.java>