• TextView实现打印机效果 ,字符串逐字显示


    https://github.com/lygttpod/AndroidCustomView/blob/master/app/src/main/java/com/allen/androidcustomview/widget/FadeInTextView.java

    上述是自定义好的Textview,可以直接使用,具体如何实现,我们一起学习一下

      1 public class FadeInTextView extends TextView {
      2 
      3 
      4     private Rect textRect = new Rect();
      5 
      6     private StringBuffer stringBuffer = new StringBuffer();
      7 
      8     private String[] arr;
      9 
     10     private int textCount;
     11 
     12     private int currentIndex = -1;
     13 
     14     /**
     15      * 每个字出现的时间
     16      */
     17     private int duration = 300;
     18     private ValueAnimator textAnimation;
     19 
     20     private TextAnimationListener textAnimationListener;
     21 
     22 
     23     public FadeInTextView setTextAnimationListener(TextAnimationListener textAnimationListener) {
     24         this.textAnimationListener = textAnimationListener;
     25         return this;
     26     }
     27 
     28     public FadeInTextView(Context context) {
     29         this(context, null);
     30     }
     31 
     32     public FadeInTextView(Context context, @Nullable AttributeSet attrs) {
     33         super(context, attrs);
     34 
     35     }
     36 
     37     @Override
     38     protected void onDraw(final Canvas canvas) {
     39         super.onDraw(canvas);
     40         if (stringBuffer != null) {
     41             drawText(canvas, stringBuffer.toString());
     42         }
     43     }
     44 
     45     /**
     46      * 绘制文字
     47      *
     48      * @param canvas 画布
     49      */
     50     private void drawText(Canvas canvas, String textString) {
     51         textRect.left = getPaddingLeft();
     52         textRect.top = getPaddingTop();
     53         textRect.right = getWidth() - getPaddingRight();
     54         textRect.bottom = getHeight() - getPaddingBottom();
     55         Paint.FontMetricsInt fontMetrics = getPaint().getFontMetricsInt();
     56         int baseline = (textRect.bottom + textRect.top - fontMetrics.bottom - fontMetrics.top) / 2;
     57         //文字绘制到整个布局的中心位置
     58         canvas.drawText(textString, getPaddingLeft(), baseline, getPaint());
     59     }
     60 
     61     /**
     62      * 文字逐个显示动画  通过插值的方式改变数据源
     63      */
     64     private void initAnimation() {
     65 
     66         //从0到textCount - 1  是设置从第一个字到最后一个字的变化因子
     67         textAnimation = ValueAnimator.ofInt(0, textCount - 1);
     68         //执行总时间就是每个字的时间乘以字数
     69         textAnimation.setDuration(textCount * duration);
     70         //匀速显示文字
     71         textAnimation.setInterpolator(new LinearInterpolator());
     72         textAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
     73             @Override
     74             public void onAnimationUpdate(ValueAnimator valueAnimator) {
     75                 int index = (int) valueAnimator.getAnimatedValue();
     76                 //过滤去重,保证每个字只重绘一次
     77                 if (currentIndex != index) {
     78                     stringBuffer.append(arr[index]);
     79                     currentIndex = index;
     80                     //所有文字都显示完成之后进度回调结束动画
     81                     if (currentIndex == (textCount - 1)) {
     82                         if (textAnimationListener != null) {
     83                             textAnimationListener.animationFinish();
     84                         }
     85                     }
     86 
     87                     invalidate();
     88                 }
     89             }
     90         });
     91     }
     92 
     93     /**
     94      * 设置逐渐显示的字符串
     95      *
     96      * @param textString
     97      * @return
     98      */
     99     public FadeInTextView setTextString(String textString) {
    100         if (textString != null) {
    101             //总字数
    102             textCount = textString.length();
    103             //存放单个字的数组
    104             arr = new String[textCount];
    105             for (int i = 0; i < textCount; i++) {
    106                 arr[i] = textString.substring(i, i + 1);
    107             }
    108             initAnimation();
    109         }
    110 
    111         return this;
    112     }
    113 
    114     /**
    115      * 开启动画
    116      *
    117      * @return
    118      */
    119     public FadeInTextView startFadeInAnimation() {
    120         if (textAnimation != null) {
    121             stringBuffer.setLength(0);
    122             currentIndex = -1;
    123             textAnimation.start();
    124         }
    125         return this;
    126     }
    127 
    128     /**
    129      * 停止动画
    130      *
    131      * @return
    132      */
    133     public FadeInTextView stopFadeInAnimation() {
    134         if (textAnimation != null) {
    135             textAnimation.end();
    136         }
    137         return this;
    138     }
    139 
    140     /**
    141      * 回调接口
    142      */
    143     public interface TextAnimationListener {
    144         void animationFinish();
    145     }
    146 }
    147 
    148     Contact GitHub API Training Shop Blog About 
    149 
    150     © 2017 GitHub, Inc. Terms Privacy Security Status Help 

    在此说明,俺们也是看大神写的代码学习学习,并非自己写的,在此是供大家学习!

  • 相关阅读:
    英语阅读重点单词总结
    Redis 应用
    Python 列表[::-1]翻转
    golang数据类型
    golang变量
    k8s 容器控制台日志收集
    css显示模式
    css选择器
    css样式引入
    GIL锁
  • 原文地址:https://www.cnblogs.com/wangying222/p/7007334.html
Copyright © 2020-2023  润新知