Android 打印机一样显示TextView

矫情吗；* 2022-06-14 10:37 258阅读 0赞

![这里写图片描述][SouthEast]

package com.example.ylwang.myapplication;
    
    import android.animation.ValueAnimator;
    import android.content.Context;
    import android.support.annotation.Nullable;
    import android.util.AttributeSet;
    import android.view.animation.LinearInterpolator;
    import android.widget.TextView;
    
    /** * Created by ylWang on 2017/6/17. * <p> * AppendTextView appendTextView = (AppendTextView) findViewById(R.id.tv_fade); * appendTextView * .setTextString("可以像打印机一样动态显示的TextView...") * .startFadeInAnimation() * .setTextAnimationListener(new AppendTextView.TextAnimationListener() { * * @Override public void animationFinish() { * //TODO:打印完成之后的逻辑 * } * }); */
    
    public class AppendTextView extends TextView { 
    
        private StringBuffer stringBuffer = new StringBuffer();
        private String[] arr;
        private int textCount;
        private int currentIndex = -1;
        //每个字出现的时间
        private static final int DURATION = 300;
        private ValueAnimator textAnimation;
        //自定义接口用于监听动画完成
        private TextAnimationListener textAnimationListener;
    
    
        public AppendTextView setTextAnimationListener(TextAnimationListener textAnimationListener) {
            this.textAnimationListener = textAnimationListener;
            return this;
        }
    
        public AppendTextView(Context context) {
            this(context, null);
        }
    
        public AppendTextView(Context context, @Nullable AttributeSet attrs) {
            super(context, attrs);
        }
    
        /** * 文字逐个显示动画 通过插值的方式改变数据源 */
        private void initAnimation() {
            //从0到textCount - 1 是设置从第一个字到最后一个字的变化因子
            textAnimation = ValueAnimator.ofInt(0, textCount - 1);
            //执行总时间就是每个字的时间乘以字数
            textAnimation.setDuration(textCount * DURATION);
            //匀速显示文字
            textAnimation.setInterpolator(new LinearInterpolator());
            textAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator valueAnimator) {
                    int index = (int) valueAnimator.getAnimatedValue();
                    //过滤去重，保证每个字只重绘一次
                    if (currentIndex != index) {
                        stringBuffer.append(arr[index]);
                        currentIndex = index;
                        //所有文字都显示完成之后进度回调结束动画
                        if (currentIndex == (textCount - 1)) {
                            if (textAnimationListener != null) {
                                textAnimationListener.animationFinish();
                            }
                        }
                        setText(stringBuffer.toString());
                    }
                }
            });
        }
    
        /** * 设置逐渐显示的字符串 * * @param textString * @return */
        public AppendTextView setTextString(String textString) {
            if (textString != null) {
                //总字数
                textCount = textString.length();
                //存放单个字的数组
                arr = new String[textCount];
                for (int i = 0; i < textCount; i++) {
                    arr[i] = textString.substring(i, i + 1);
                }
                initAnimation();
            }
            return this;
        }
    
        /** * 开启动画 * * @return */
        public AppendTextView startFadeInAnimation() {
            if (textAnimation != null) {
                stringBuffer.setLength(0);
                currentIndex = -1;
                textAnimation.start();
            }
            return this;
        }
    
        /** * 停止动画 * * @return */
        public AppendTextView stopFadeInAnimation() {
            if (textAnimation != null) {
                textAnimation.end();
            }
            return this;
        }
    
        /** * 回调接口 */
        public interface TextAnimationListener { 
            void animationFinish();
        }
    }

[SouthEast]: /images/20220614/64370316d61c4ff5831622210a766aba.png