UpMarqueeTextView一个简单的向上滚动的相似跑马灯效果，项目中用到的时候是接受到推送过来的消息向上滚动一次。没有做动态的gif效果，所以都是一些纯文字的简单记录。
UpMarqueeTextView通过实现TextView使用Animator动画来实现，所以须要满足3.0以下的版本号须要使用nineold-androids来实现效果。事实上原理什么非常easy看看代码就能了解。
public class UpMarqueeTextView extends TextView implements Animator.AnimatorListener {
private static final String TAG = "UpMarqueeTextView";
private static final int ANIMATION_DURATION = 200;
private float height;
private AnimatorSet mAnimatorStartSet;
private AnimatorSet mAnimatorEndSet;
private String mText;
public UpMarqueeTextView(Context context) {
super(context);
}
public UpMarqueeTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Log.w(TAG, "--- onDraw ---");
height = getHeight();// 确保view的高度
}
/**--- 初始化向上脱离屏幕的动画效果 ---*/
private void initStartAnimation() {
ObjectAnimator translate = ObjectAnimator.ofFloat(this, "translationY", 0, -height);
ObjectAnimator alpha = ObjectAnimator.ofFloat(this, "alpha", 1f, 0f);
mAnimatorStartSet = new AnimatorSet();
mAnimatorStartSet.play(translate).with(alpha);
mAnimatorStartSet.setDuration(ANIMATION_DURATION);
mAnimatorStartSet.addListener(this);
}
/**--- 初始化从屏幕以下向上的动画效果 ---*/
private void initEndAnimation() {
ObjectAnimator translate = ObjectAnimator.ofFloat(this, "translationY", height, 0);
ObjectAnimator alpha = ObjectAnimator.ofFloat(this, "alpha", 0f, 1f);
mAnimatorEndSet = new AnimatorSet();
mAnimatorEndSet.play(translate).with(alpha);
mAnimatorEndSet.setDuration(ANIMATION_DURATION);
}
/**--- 设置内容 ---**/
public void setText(String text) {
if (TextUtils.isEmpty(text)) {
Log.e(TAG, "--- 请确保text不为空 ---");
return;
}
mText = text;
if (null == mAnimatorStartSet) {
initStartAnimation();
}
mAnimatorStartSet.start();
}
@Override
public void onAnimationStart(Animator animator) {
}
@Override
public void onAnimationEnd(Animator animator) {
super.setText(mText);
if (null == mAnimatorEndSet) {
initEndAnimation();
}
mAnimatorEndSet.start();
}
@Override
public void onAnimationCancel(Animator animator) {
}
@Override
public void onAnimationRepeat(Animator animator) {
}
}功能确实非常easy，设置下动画代码就可以实现了。苍蝇虽小也是肉。项目体验下载地址：
https://github.com/Neacy/UpMarqueerTextView/tree/master