怎么在Android在实现一个文字上下滚动效果
这篇文章给大家介绍怎么在Android在实现一个文字上下滚动效果,内容非常详细,感兴趣的小伙伴们可以参考借鉴,希望对大家能有所帮助。
首先介绍第一种方法:
实现思路:自定义TextView,在TextView中加上从下到上滚动的动画效果,然后设置循环播放;
创建一个AutoTextVieW使之继承TextView,然后在onDraw方法中调用getHeight()方法获取textview当前的高度。
在接下来的动画翻转效果中,根据这个高度设置TextView上下滚动的距离。下面是动画实现的方法:
/** * 向上脱离屏幕的动画效果 */ private void animationStart() { ObjectAnimator translate = ObjectAnimator.ofFloat(this, "translationY", 0, -height); ObjectAnimator alpha = ObjectAnimator.ofFloat(this, "alpha", 1f, 0f); mAnimStart = new AnimatorSet(); mAnimStart.play(translate).with(alpha); mAnimStart.setDuration(DURATION); mAnimStart.addListener(this); } /** * 从屏幕下面向上的动画效果 */ public void animationOver() { ObjectAnimator translate = ObjectAnimator.ofFloat(this, "translationY", height, 0); ObjectAnimator alpha = ObjectAnimator.ofFloat(this, "alpha", 0f, 1f); mAnimOver = new AnimatorSet(); mAnimOver.play(translate).with(alpha); mAnimOver.setDuration(DURATION); }
接下来实现ObjectAnimator的监听事件,在onAnimationEnd 调用setText方法,在动画没结束一次更新文字,并且继续执行动画效果
@Override public void onAnimationEnd(Animator animator) { super.setText(mText); if (mAnimOver == null) { animationOver(); } mAnimOver.start(); }
然后调用一个可以设置循环滚动的类,这里可以使用ScheduledExecutorService,也可以使用 Timer几设置计时滚动,在更新UI的时候,调用Handler方法更新;
因为采用Timer执行定时任务时只创建一个线程,所以这里建议采用ScheduledExecutorService;
/** * 获取数据并设置滚动播放 * @param textView * @param list * @param autoPlayTime */ public void getTextData(final IdeaAutoTextview textView, List<String> list, int autoPlayTime) { this.textView = textView; this.textList = list; if (autoPlayTime != 0) { scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(); scheduledExecutorService.scheduleWithFixedDelay(new WeakTimerTask(this), autoPlayTime, autoPlayTime, TimeUnit.SECONDS); } } private TimeTaskHandler mHandler = new TimeTaskHandler(this); private static class WeakTimerTask extends TimerTask { private WeakReference<IdeaAutoTextview> autoTextReference; public WeakTimerTask(IdeaAutoTextview mautoText) { this.autoTextReference = new WeakReference<>(mautoText); } @Override public void run() { IdeaAutoTextview autoText = autoTextReference.get(); if (autoText != null) { if (autoText.isShown()) { autoText.mHandler.sendEmptyMessage(0); } } else { cancel(); } } }
定时刷新频率较高,容易产生内存泄漏,这里采用弱引用避免这个情况发生
private final class TimeTaskHandler extends Handler { private WeakReference<IdeaAutoTextview> autoTextReference; public TimeTaskHandler(IdeaAutoTextview autoText) { this.autoTextReference = new WeakReference<>(autoText); } @Override public void handleMessage(Message msg) { IdeaAutoTextview autoText = autoTextReference.get(); if (autoText!=null) { /** * 设置当前文字 */ String text = textList.get(index); index++; if (index > textList.size() - 1) { index = 0; } textView.setAutoText(text); } } }
到此第一种方法介绍完毕。
第二种方法实现的原理和轮播图的原理类似,轮播图一般是左右横向滚动,这里需要把ViewPager改成上下滑动,关于上下滑动的viewpager,可以在给github上找到;
其次轮播图中播放的是图片,把图片换成文字即可;
然后同样调用Timer或者ScheduledExecutorService使ViewPager自行滚动;
以下是代码:
package com.idea.idea.viewutils; import android.content.Context; import android.os.Handler; import android.os.Message; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.widget.RelativeLayout; import java.lang.ref.WeakReference; import java.util.TimerTask; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; /** * todo:修改ViewPager方法实现文字滚动 * * @author: Create by qjj * @email: gxuqjj@163.com */ public class AutoViewpager extends RelativeLayout{ private VerticalViewPager mVerticalViewPager; private PagerAdapter mAdapter; private int autoPlayTime; private ScheduledExecutorService scheduledExecutorService; public AutoViewpager(Context context){ this(context,null); } public AutoViewpager(Context context, AttributeSet attrs) { this(context, attrs, 0); } public AutoViewpager(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initView(); } /** * 初始化view */ private void initView(){ if(mVerticalViewPager!=null){ removeView(mVerticalViewPager); } mVerticalViewPager = new VerticalViewPager(getContext()); mVerticalViewPager.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); addView(mVerticalViewPager); } private final static class TimeTaskHandler extends Handler { private WeakReference<AutoViewpager> mRollPagerViewWeakReference; public TimeTaskHandler(AutoViewpager autoViewpager) { this.mRollPagerViewWeakReference = new WeakReference<>(autoViewpager); } @Override public void handleMessage(Message msg) { AutoViewpager autoViewpager = mRollPagerViewWeakReference.get(); int cur = autoViewpager.getViewPager().getCurrentItem()+1; if(cur>= autoViewpager.mAdapter.getCount()){ cur=0; } autoViewpager.getViewPager().setCurrentItem(cur); } } private TimeTaskHandler mHandler = new TimeTaskHandler(this); private static class WeakTimerTask extends TimerTask { private WeakReference<AutoViewpager> mRollPagerViewWeakReference; public WeakTimerTask(AutoViewpager mAutoViewpager) { this.mRollPagerViewWeakReference = new WeakReference<>(mAutoViewpager); } @Override public void run() { AutoViewpager autoViewpager = mRollPagerViewWeakReference.get(); if (autoViewpager !=null){ if(autoViewpager.isShown()){ autoViewpager.mHandler.sendEmptyMessage(0); } }else{ cancel(); } } } /** * 开始滚动 */ private void autoPlay(){ if(autoPlayTime<=0||mAdapter == null||mAdapter.getCount()<=1){ return; } scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(); scheduledExecutorService.scheduleWithFixedDelay(new WeakTimerTask(this), autoPlayTime, autoPlayTime, TimeUnit.SECONDS); } public void setAutoTime(int autoPlayTime){ this.autoPlayTime = autoPlayTime; autoPlay(); } /** * viewpager * @return */ public ViewPager getViewPager() { return mVerticalViewPager; } /** * 设置Adapter * @param adapter */ public void setAdapter(PagerAdapter adapter){ mVerticalViewPager.setAdapter(adapter); mAdapter = adapter; dataChanged(); } private void dataChanged(){ autoPlay(); } }
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