Android文字广告，自定义垂直滚动切换TextView

青旅半醒 2022-12-10 14:34 177阅读 0赞

很多app的首页都会有一个用于显示热点消息的banner，通过垂直切换文本的方式动态展示消息。垂直切换的方式可以有效利用空间显示更多的内容，动态的效果也更能吸引用户的注意力。

![Center][]

实现这个效果，我能想到的方式大概有两种：

1、继承一个LineLayout，在里面添加两个TextView，通过动画实现TextView的移动、显示、隐藏。

2、继承TextView，手动去绘制文字，然后动态的改变文字的绘制，以实现切换的动效。

相比之下，第一种方式要简单一些，而且方法1不只可以添加TextVIew，还可以添加两个ViewGroup，然后构建更加复杂的布局，如添加图片等。为了体现自定义控件的特点，这里使用第二种方式来实现这个功能。具体看下代码的实现：

private static final int DEFAULT_SWITCH_DURATION = 500;
        private static final int DEFAULT_IDLE_DURATION = 2000;
        private Context mContext;
     
        private List<String> lists;//会循环显示的文本内容
        private int contentSize;
        private String outStr;//当前滑出的文本内容
        private String inStr;//当前滑入的文本内容
        private float textBaseY;//文本显示的baseline
        private int currentIndex = 0;//当前显示到第几个文本
     
        private int switchDuaration = DEFAULT_SWITCH_DURATION;//切换时间
        private int idleDuaration = DEFAULT_IDLE_DURATION;//间隔时间
        private int switchOrientation = 0;
     
        private float currentAnimatedValue = 0.0f;
        private ValueAnimator animator;
     
        private int verticalOffset = 0;
        private int mWidth;
        private int mHeight;
        private int paddingLeft = 0;
        private int paddingBottom = 0;
        private int paddingTop = 0;
     
        private Paint mPaint;
     
        //回调接口，用来通知调用者控件当前的状态
        public VerticalSwitchTextViewCbInterface cbInterface;
     
        public VerticalSwitchTextView(Context context) {
            this(context, null);
        }
     
        public VerticalSwitchTextView(Context context, AttributeSet attrs) {
            this(context, attrs, 0);
        }
     
        public VerticalSwitchTextView(Context context, AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
            mContext = context;
            TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.VerticalSwitchTextView);
            try {
                switchDuaration = array.getInt(R.styleable.VerticalSwitchTextView_switchDuaration, DEFAULT_SWITCH_DURATION);
                idleDuaration = array.getInt(R.styleable.VerticalSwitchTextView_idleDuaration, DEFAULT_IDLE_DURATION);
                switchOrientation = array.getInt(R.styleable.VerticalSwitchTextView_switchOrientation, 0);
            } finally {
                array.recycle();
            }
            init();
        }

首先定义一些常量和变量，并实现了三个构造方法。

常量的含义可以直接看代码的标注，构造方法中只有一个参数的方法是在代码里使用new生成View的时候调用的，两个参数的构造方法是在xml中定义View的时候调用，三个参数的构造方法不常用，当有自定义style的时候会用到。构造方法中对自定义属性进行了解析，后面会用到。

上面是自定义属性的内容，分别对应于切换时长、切换间隔和切换方向。

private void init() {
            setOnClickListener(this);
     
            mPaint = getPaint();
            mPaint.setColor(getCurrentTextColor());
     
            animator = ValueAnimator.ofFloat(0f, 1f).setDuration(switchDuaration);
            animator.setStartDelay(idleDuaration);
            animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    currentAnimatedValue = (float) animation.getAnimatedValue();
                    if (currentAnimatedValue < 1.0f) {
                        invalidate();
                    }
                }
            });
            animator.addListener(new Animator.AnimatorListener() {
                @Override
                public void onAnimationStart(Animator animation) {
     
                }
     
                @Override
                public void onAnimationEnd(Animator animation) {
                    currentIndex = (++currentIndex) % contentSize;
                    if (cbInterface != null) {
                        cbInterface.showNext(currentIndex);
                    }
                    outStr = lists.get(currentIndex);
                    inStr = lists.get((currentIndex + 1) % contentSize);
     
                    animator.setStartDelay(idleDuaration);
                    animator.start();
                }
     
                @Override
                public void onAnimationCancel(Animator animation) {
     
                }
     
                @Override
                public void onAnimationRepeat(Animator animation) {
     
                }
            });
        }

init()方法中定义了一个属性动画，通过属性值的更新控制绘制的进度，在AnimatorUpdateListener的onAnimationUpdate()方法中，不断调用invalidate()，从而触发View的onDraw()方法回调。在AnimatorListener的onAnimationEnd()方法中，对要显示的内容进行更新，同时延时一定间隔再循环执行动画。

/**
         * 设置循环显示的文本内容
         *
         * @param content 内容list
         */
        public void setTextContent(List<String> content) {
            lists = content;
            if (lists == null || lists.size() == 0) {
                return;
            }
            contentSize = lists.size();
     
            outStr = lists.get(0);
            if (contentSize > 1) {
                inStr = lists.get(1);
            } else {
                inStr = lists.get(0);
            }
     
            if (contentSize > 0) {
                animator.start();
            }
        }

setTextContent()方法用于动态设置切换的文本列表，考虑到大部分应用场景下内容都是动态设置的，这里没有自定义属性提供xml文件的静态设置，如果有需求可以另行优化。

@Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            mWidth = MeasureSpec.getSize(widthMeasureSpec);
     
            Rect bounds = new Rect();
            if (contentSize <= 0) {
                return;
            }
            String text = lists.get(0);
            mPaint.getTextBounds(text, 0, text.length(), bounds);
            int textHeight = bounds.height();
            Log.d("viclee", "onMeasure height is " + mHeight);
     
            paddingLeft = getPaddingLeft();
            paddingBottom = getPaddingBottom();
            paddingTop = getPaddingTop();
            mHeight = textHeight + paddingBottom + paddingTop;
     
            Paint.FontMetrics fontMetrics = mPaint.getFontMetrics();
            //计算文字高度
            float fontHeight = fontMetrics.bottom - fontMetrics.top;
            //计算文字的baseline
            textBaseY = mHeight - (mHeight - fontHeight) / 2 - fontMetrics.bottom;
     
            setMeasuredDimension(mWidth, mHeight);
        }

onMeasure()方法中主要做了两件事：根据文本的高度、padding设置View的高度和确定文本内容绘制的baseline。具体baseline的原理和计算方法请自行google。

@Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            if (contentSize <= 0) {
                return;
            }
     
            //直接使用mHeight控制文本绘制，会因为text的baseline的问题不能居中显示
            verticalOffset = Math.round(2 * textBaseY * (0.5f - currentAnimatedValue));
            Log.d("viclee", "verticalOffset is " + verticalOffset);
            if (switchOrientation == 0) {//向上滚动切换
                if (verticalOffset > 0) {
                    canvas.drawText(outStr, paddingLeft, verticalOffset, mPaint);
                } else {
                    canvas.drawText(inStr, paddingLeft, 2 * textBaseY + verticalOffset, mPaint);
                }
            } else {
                if (verticalOffset > 0) {//向下滚动切换
                    canvas.drawText(outStr, paddingLeft,  2 * textBaseY - verticalOffset, mPaint);
                } else {
                    canvas.drawText(inStr, paddingLeft, -verticalOffset, mPaint);
                }
            }
        }

onDraw()中调用Canvas的drawText()方法绘制文本，根据我们设置的滚动方向的不同，绘制的y坐标的计算方式有所差别，向上滚动时，y值变小，向下滚动时，y值变大。需要注意的是，在调用drawText()的时候，x坐标为设置的左边距paddingLeft，y坐标不是控件的高度mHeight，也不能是字体的高度textHeight，只能是text的baseline，这个大家可以自己验证一下。

//回调接口，用来通知调用者控件当前的状态,index表示开始显示哪一个文本内容
        public interface VerticalSwitchTextViewCbInterface {
            void showNext(int index);
            void onItemClick(int index);
        }
     
        public void setCbInterface(VerticalSwitchTextViewCbInterface cb) {
            cbInterface = cb;
        }

最后提供了一个接口，通过回调通知调用者View的状态更新（切换到新的内容或者当前内容被点击等）。如果需要其他功能，可以根据自定义View的原理自行扩展。

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

2016.8.16更新：

增加gravity属性，水平方向的gravity属性可以设置为left、right、center，分别表示文字左对齐、右对齐和居中对齐。

增加ellipsis属性，可以设置为start、end、middle，分别表示当文字长度超出View长度时，在头部、尾部、中间显示省略号。

核心代码分析：

private void generateEllipsisText() {
            if (ellipsisLists != null) {//防止重复计算
                return;
            }
            ellipsisLists = new ArrayList<>();
            if (lists != null && lists.size() != 0) {
                for (String item : lists) {
                    int avail = mWidth - paddingLeft - paddingRight;
                    float remaining = avail - ellipsisLen;
                    if (avail <= 0) {
                        ellipsisLists.add("");
                    } else {
                        float itemWidth = mPaint.measureText(item, 0, item.length());
                        if (itemWidth < avail) {
                            ellipsisLists.add(item);
                        } else if (remaining <= 0) {
                            ellipsisLists.add(ellipsis);
                        } else {
                            int len = item.length();
                            float[] widths = new float[len];
                            mPaint.getTextWidths(item, 0, item.length(), widths);
                            if (mEllipsize == TextUtils.TruncateAt.END) {
                                float blockWidth = 0f;
                                for (int i = 0; i < len; i++) {
                                    blockWidth += widths[i];
                                    if (blockWidth > remaining) {
                                        ellipsisLists.add(item.substring(0, i) + ellipsis);
                                        break;
                                    }
                                }
                            } else if (mEllipsize == TextUtils.TruncateAt.START) {
                                float blockWidth = 0f;
                                for (int i = len - 1; i >= 0; i--) {
                                    blockWidth += widths[i];
                                    if (blockWidth > remaining) {
                                        ellipsisLists.add(ellipsis + item.substring(i, len - 1));
                                        break;
                                    }
                                }
                            } else if (mEllipsize == TextUtils.TruncateAt.MIDDLE) {
                                float blockWidth = 0f;
                                for (int i = 0, j = len - 1; i < j; i++, j--) {
                                    blockWidth += (widths[i] + widths[j]);
                                    if (blockWidth > remaining) {
                                        if (blockWidth - widths[j] < remaining) {
                                            ellipsisLists.add(item.substring(0, i + 1) + ellipsis + item.substring(j, len - 1));
                                        } else {
                                            ellipsisLists.add(item.substring(0, i) + ellipsis + item.substring(j, len - 1));
                                        }
                                        break;
                                    }
                                }
                            }
                        }
                    }
                }
            }
            lists = ellipsisLists;
        }

generateEllipsisText()方法用来对文字内容进行处理，当文字超过View长度时，多余的部分用省略号“...”代替。ellipsisLists就是用来存储处理后的文字的。avail表示可以显示文字的区域宽度，remaining是去除省略号“...”的宽度后，可以显示文字内容的宽度。使用Paint的measureText()方法可以获得字符串的宽度，这个宽度是对应于某一种字体和字号的，字体和字号不同，获得的宽度也就不同。Paint的getTextWidths()方法可以获得一个数组，数组中存储的是每一个字符的宽度。然后根据当前的ellipsize，通过计算字符长度与View宽度的关系，来确定最终要显示的文字内容。

//计算绘制的文字中心位置
            switch (alignment) {
                case TEXT_ALIGN_CENTER:
                    inTextCenterX = outTextCenterX = (mWidth - paddingLeft - paddingRight) / 2 + paddingLeft;
                    break;
                case TEXT_ALIGN_LEFT:
                    inTextCenterX = paddingLeft + mPaint.measureText(inStr) / 2;
                    outTextCenterX = paddingLeft + mPaint.measureText(outStr) / 2;
                    break;
                case TEXT_ALIGN_RIGHT:
                    inTextCenterX = mWidth - paddingRight - mPaint.measureText(inStr) / 2;
                    outTextCenterX = mWidth - paddingRight - mPaint.measureText(outStr) / 2;
                    break;
            }

上面的代码根据当前的gravity来计算文字绘制的x轴的中心位置，注意由于每项文字的长度不同，他们x轴的中心位置也不相同。

效果图如下

带有gravity属性和ellipsis属性的效果：

![Center 1][]

普通效果：

![Center 2][]

**实例：**

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
    <resources>
        <declare-styleable name="VerticalSwitchTextView">
            <attr name="switchDuaration" format="integer"/>
            <attr name="idleDuaration" format="integer"/>
            <attr name="switchOrientation">
                <enum name="up"  value="0"/>
                <enum name="down"  value="1"/>
            </attr>
            <attr name="alignment">
                <enum name="center" value="0"/>
                <enum name="left" value="1"/>
                <enum name="right" value="2"/>
            </attr>
        </declare-styleable>
    </resources>

string.xml

<resources>
        <string name="app_name">VerticalSwitchTextView</string>
        <string name="ellipsis">\u2026</string>
    </resources>

VerticalSwitchTextView.java

package com.viclee.verticalswitchtextview;
    
    import android.animation.Animator;
    import android.animation.ValueAnimator;
    import android.content.Context;
    import android.content.res.TypedArray;
    import android.graphics.Canvas;
    import android.graphics.Paint;
    import android.graphics.Rect;
    import android.text.TextUtils;
    import android.util.AttributeSet;
    import android.view.View;
    import android.widget.TextView;
    
    import java.util.ArrayList;
    import java.util.List;
    
    
    public class VerticalSwitchTextView extends TextView implements View.OnClickListener {
        private static final int DEFAULT_SWITCH_DURATION = 500;
        private static final int DEFAULT_IDLE_DURATION = 2000;
        public static final int TEXT_ALIGN_CENTER = 0;
        public static final int TEXT_ALIGN_LEFT = 1;
        public static final int TEXT_ALIGN_RIGHT = 2;
        private Context mContext;
    
        private List<String> lists;//会循环显示的文本内容
        private List<String> ellipsisLists;
        private int contentSize;
        private String outStr;//当前滑出的文本内容
        private String inStr;//当前滑入的文本内容
        private float textBaseY;//文本显示的baseline
        private int currentIndex = 0;//当前显示到第几个文本
        private String ellipsis;
        private float ellipsisLen = 0;
    
        private int switchDuaration = DEFAULT_SWITCH_DURATION;//切换时间
        private int idleDuaration = DEFAULT_IDLE_DURATION;//间隔时间
        private int switchOrientation = 0;
        private int alignment = TEXT_ALIGN_CENTER;
    
        /**
         * 文本中轴线X坐标
         */
        private float inTextCenterX;
        private float outTextCenterX;
        private float currentAnimatedValue = 0.0f;
        private ValueAnimator animator;
    
        private TextUtils.TruncateAt mEllipsize;
    
        private int verticalOffset = 0;
        private int mWidth;
        private int mHeight;
        private int paddingLeft = 0;
        private int paddingBottom = 0;
        private int paddingTop = 0;
        private int paddingRight = 0;
    
        private Paint mPaint;
    
        //回调接口，用来通知调用者控件当前的状态
        public VerticalSwitchTextViewCbInterface cbInterface;
    
        public VerticalSwitchTextView(Context context) {
            this(context, null);
        }
    
        public VerticalSwitchTextView(Context context, AttributeSet attrs) {
            this(context, attrs, 0);
        }
    
        public VerticalSwitchTextView(Context context, AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
            mContext = context;
            TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.VerticalSwitchTextView);
            try {
                switchDuaration = array.getInt(R.styleable.VerticalSwitchTextView_switchDuaration, DEFAULT_SWITCH_DURATION);
                idleDuaration = array.getInt(R.styleable.VerticalSwitchTextView_idleDuaration, DEFAULT_IDLE_DURATION);
                switchOrientation = array.getInt(R.styleable.VerticalSwitchTextView_switchOrientation, 0);
                alignment = array.getInt(R.styleable.VerticalSwitchTextView_alignment, TEXT_ALIGN_CENTER);
            } finally {
                array.recycle();
            }
            init();
        }
    
        private void init() {
            setOnClickListener(this);
            mPaint = getPaint();
            mPaint.setTextAlign(Paint.Align.CENTER);
            ellipsis = getContext().getString(R.string.ellipsis);
            ellipsisLen = mPaint.measureText(ellipsis);
            mEllipsize = getEllipsize();
    
            animator = ValueAnimator.ofFloat(0f, 1f).setDuration(switchDuaration);
            animator.setStartDelay(idleDuaration);
            animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    currentAnimatedValue = (float) animation.getAnimatedValue();
                    if (currentAnimatedValue < 1.0f) {
                        invalidate();
                    }
                }
            });
            animator.addListener(new Animator.AnimatorListener() {
                @Override
                public void onAnimationStart(Animator animation) {
    
                }
    
                @Override
                public void onAnimationEnd(Animator animation) {
                    currentIndex = (++currentIndex) % contentSize;
                    if (cbInterface != null) {
                        cbInterface.showNext(currentIndex);
                    }
                    outStr = lists.get(currentIndex);
                    inStr = lists.get((currentIndex + 1) % contentSize);
    
                    animator.setStartDelay(idleDuaration);
                    animator.start();
                }
    
                @Override
                public void onAnimationCancel(Animator animation) {
    
                }
    
                @Override
                public void onAnimationRepeat(Animator animation) {
    
                }
            });
        }
    
        /**
         * 设置循环显示的文本内容
         *
         * @param content 内容list
         */
        public void setTextContent(List<String> content) {
            lists = content;
    //        lists.clear();
    //        lists = new ArrayList<>();
    //        lists.add("1适当放松放松放松点水电费水电费史蒂夫水电费水电费");
    //        lists.add("2适当放松放松放松点水电费水电费史蒂夫水电费水电费");
    //        lists.add("3适当放松放");
    //        lists.add("3适当放松放1111222333");
            if (lists == null || lists.size() == 0) {
                return;
            }
            contentSize = lists.size();
    
            if (contentSize > 0) {
                animator.start();
            }
        }
    
        private void generateEllipsisText() {
            if (ellipsisLists != null) {//防止重复计算
                return;
            }
            ellipsisLists = new ArrayList<>();
            if (lists != null && lists.size() != 0) {
                for (String item : lists) {
                    int avail = mWidth - paddingLeft - paddingRight;
                    float remaining = avail - ellipsisLen;
                    if (avail <= 0) {
                        ellipsisLists.add("");
                    } else {
                        float itemWidth = mPaint.measureText(item, 0, item.length());
                        if (itemWidth < avail) {
                            ellipsisLists.add(item);
                        } else if (remaining <= 0) {
                            ellipsisLists.add(ellipsis);
                        } else {
                            int len = item.length();
                            float[] widths = new float[len];
                            mPaint.getTextWidths(item, 0, item.length(), widths);
                            if (mEllipsize == TextUtils.TruncateAt.END) {
                                float blockWidth = 0f;
                                for (int i = 0; i < len; i++) {
                                    blockWidth += widths[i];
                                    if (blockWidth > remaining) {
                                        ellipsisLists.add(item.substring(0, i) + ellipsis);
                                        break;
                                    }
                                }
                            } else if (mEllipsize == TextUtils.TruncateAt.START) {
                                float blockWidth = 0f;
                                for (int i = len - 1; i >= 0; i--) {
                                    blockWidth += widths[i];
                                    if (blockWidth > remaining) {
                                        ellipsisLists.add(ellipsis + item.substring(i, len - 1));
                                        break;
                                    }
                                }
                            } else if (mEllipsize == TextUtils.TruncateAt.MIDDLE) {
                                float blockWidth = 0f;
                                for (int i = 0, j = len - 1; i < j; i++, j--) {
                                    blockWidth += (widths[i] + widths[j]);
                                    if (blockWidth > remaining) {
                                        if (blockWidth - widths[j] < remaining) {
                                            ellipsisLists.add(item.substring(0, i + 1) + ellipsis + item.substring(j, len - 1));
                                        } else {
                                            ellipsisLists.add(item.substring(0, i) + ellipsis + item.substring(j, len - 1));
                                        }
                                        break;
                                    }
                                }
                            }
                        }
                    }
                }
            }
            lists = ellipsisLists;
        }
    
        /**
         * 主要用来调整TextView的高度
         *
         * @param widthMeasureSpec
         * @param heightMeasureSpec
         */
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            mWidth = MeasureSpec.getSize(widthMeasureSpec);
    
            Rect bounds = new Rect();
            if (contentSize <= 0) {
                return;
            }
            String text = lists.get(0);
            mPaint.getTextBounds(text, 0, text.length(), bounds);
            int textHeight = bounds.height();
    
            paddingLeft = getPaddingLeft();
            paddingRight = getPaddingRight();
            paddingBottom = getPaddingBottom();
            paddingTop = getPaddingTop();
    
            if (mEllipsize != null) {
                generateEllipsisText();
            }
    
            outStr = lists.get(0);
            if (contentSize > 1) {
                inStr = lists.get(1);
            } else {
                inStr = lists.get(0);
            }
    
            mHeight = textHeight + paddingBottom + paddingTop;
    
            Paint.FontMetrics fontMetrics = mPaint.getFontMetrics();
            //计算文字高度
            float fontHeight = fontMetrics.bottom - fontMetrics.top;
            //计算文字的baseline
            textBaseY = mHeight - (mHeight - fontHeight) / 2 - fontMetrics.bottom;
    
            setMeasuredDimension(mWidth, mHeight);
        }
    
        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            if (contentSize <= 0) {
                return;
            }
            //计算绘制的文字中心位置
            switch (alignment) {
                case TEXT_ALIGN_CENTER:
                    inTextCenterX = outTextCenterX = (mWidth - paddingLeft - paddingRight) / 2 + paddingLeft;
                    break;
                case TEXT_ALIGN_LEFT:
                    inTextCenterX = paddingLeft + mPaint.measureText(inStr) / 2;
                    outTextCenterX = paddingLeft + mPaint.measureText(outStr) / 2;
                    break;
                case TEXT_ALIGN_RIGHT:
                    inTextCenterX = mWidth - paddingRight - mPaint.measureText(inStr) / 2;
                    outTextCenterX = mWidth - paddingRight - mPaint.measureText(outStr) / 2;
                    break;
            }
    
            //直接使用mHeight控制文本绘制，会因为text的baseline的问题不能居中显示
            verticalOffset = Math.round(2 * textBaseY * (0.5f - currentAnimatedValue));
    //        L.d("verticalOffset is " + verticalOffset);
            if (switchOrientation == 0) {//向上滚动切换
                if (verticalOffset > 0) {
                    canvas.drawText(outStr, outTextCenterX, verticalOffset, mPaint);
                } else {
                    canvas.drawText(inStr, inTextCenterX, 2 * textBaseY + verticalOffset, mPaint);
                }
            } else {
                if (verticalOffset > 0) {//向下滚动切换
                    canvas.drawText(outStr, outTextCenterX, 2 * textBaseY - verticalOffset, mPaint);
                } else {
                    canvas.drawText(inStr, inTextCenterX, -verticalOffset, mPaint);
                }
            }
        }
    
        @Override
        public void onClick(View v) {
            if (contentSize > currentIndex) {
                if (cbInterface != null) {
                    cbInterface.onItemClick(currentIndex);
                }
            }
        }
    
        @Override
        protected void onDetachedFromWindow() {
            super.onDetachedFromWindow();
            mContext = null;
            if (animator != null) {
                animator.cancel();
            }
        }
    
        //回调接口，用来通知调用者控件当前的状态,index表示开始显示哪一个文本内容
        public interface VerticalSwitchTextViewCbInterface {
            void showNext(int index);
    
            void onItemClick(int index);
        }
    
        public void setCbInterface(VerticalSwitchTextViewCbInterface cb) {
            cbInterface = cb;
        }
    }

activity\_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:vswitch="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity">
        <com.viclee.verticalswitchtextview.VerticalSwitchTextView
            android:id="@+id/vertical_switch_textview1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:textColor="#aa0090"
            android:textSize="30sp"
            android:padding="8dp"
            android:background="#999999"
            android:ellipsize="end"
            vswitch:alignment="left"
            vswitch:switchDuaration = "500"
            vswitch:idleDuaration = "1500"
            vswitch:switchOrientation="up"/>
        <com.viclee.verticalswitchtextview.VerticalSwitchTextView
            android:id="@+id/vertical_switch_textview2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_centerInParent="true"
            android:textColor="#aa0090"
            android:textSize="30sp"
            android:padding="8dp"
            android:background="#999999"
            android:ellipsize="start"
            vswitch:alignment="center"
            vswitch:switchDuaration = "800"
            vswitch:idleDuaration = "1000"
            vswitch:switchOrientation="down"/>
    </LinearLayout>

MainActivity.java

package com.viclee.verticalswitchtextview;
    
    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;
    import android.util.Log;
    import android.view.WindowManager;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    
    public class MainActivity extends AppCompatActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
            setContentView(R.layout.activity_main);
    
            ArrayList<String> list = new ArrayList<String>(Arrays.asList("能够适应多行长文本的Android TextView的例子", "理解的也很简单，我只是列出这个库里面我用到的一些方法",
                    "适当放松放", "破解密钥", "实现了两种方式来检测Android app前后台切换的状态", "科比"));
            VerticalSwitchTextView verticalSwitchTextView1 = (VerticalSwitchTextView) findViewById(R.id.vertical_switch_textview1);
            VerticalSwitchTextView verticalSwitchTextView2 = (VerticalSwitchTextView) findViewById(R.id.vertical_switch_textview2);
            verticalSwitchTextView1.setCbInterface(new VerticalSwitchTextView.VerticalSwitchTextViewCbInterface() {
                @Override
                public void showNext(int index) {
    
                }
    
                @Override
                public void onItemClick(int index) {
                    Log.e("aaaaaaaaa", "点击了" + index);
                }
            });
            verticalSwitchTextView2.setCbInterface(new VerticalSwitchTextView.VerticalSwitchTextViewCbInterface() {
                @Override
                public void showNext(int index) {
    
                }
    
                @Override
                public void onItemClick(int index) {
                    Log.e("aaaaaaaaa", "点击了" + index);
                }
            });
            verticalSwitchTextView1.setTextContent(list);
            verticalSwitchTextView2.setTextContent(list);
        }
    }

完！！！

**注：此方法会频繁更新绘制，容易造成页面卡顿！！！**

**可以考虑使用TextSwitcher控件，参考下一篇**

[Center]: /images/20221123/1f71e9837ffd48869ed05ef133c41236.png
[Center 1]: /images/20221123/2cf27cfb09d84cc0b346e5329c9ff3d7.png
[Center 2]: /images/20221123/0fa72a27c8dd499491ff91f789e80454.png