Android自定义控件——ExpandTextView

Posted 2022-12-08 顾明伟

本文介绍一个这样婶儿的TextView，如图：

点击的时候TextView会伸缩，有种Clip的感觉，原理也很简单，就是把两个TextView重叠起来，一个现实固定的行数的文本，另一个现实全部的文本，初始化的时候，容器的高度等于固定文本的高度，完全展开时的高度等于文本显示全的高度，过程用一个动画控制就可以了。下面贴代码：

ExpandTextView.java

import android.content.Context;
import android.graphics.Color;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.FrameLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;

/**
 * Created by mingwei on 1/20/16.
 */
public class ExpandTextView extends RelativeLayout 

    private TextView mText;

    private TextView mExpandText;

    private int mTextColor = Color.GRAY;

    private int mTextLine = 1;

    private int mStart;

    private int mEnd;

    private boolean isFirst = true;

    private boolean isExpand = false;

    public ExpandTextView(Context context) 
        this(context, null);
    

    public ExpandTextView(Context context, AttributeSet attrs) 
        this(context, attrs, 0);
    

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        final ViewGroup.LayoutParams params = getLayoutParams();
        if (isFirst) 
            isFirst = false;
            mText.post(new Runnable() 
                @Override
                public void run() 
                    mStart = mText.getLineHeight() * mText.getLineCount();
                    params.height = mStart;
                    setLayoutParams(params);
                
            );
            mExpandText.post(new Runnable() 
                @Override
                public void run() 
                    mEnd = mExpandText.getLineHeight() * mExpandText.getLineCount();
                
            );

        

    

    public ExpandTextView(Context context, AttributeSet attrs, int defStyleAttr) 
        super(context, attrs, defStyleAttr);
        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.WRAP_CONTENT);
        mText = new TextView(context, attrs);
        mText.setTextColor(mTextColor);
        mText.setEllipsize(TextUtils.TruncateAt.END);
        mText.setMaxLines(mTextLine);
        addView(mText, params);
        mExpandText = new TextView(context);
        mExpandText.setTextColor(Color.TRANSPARENT);
        addView(mExpandText, params);
    

    public void setText(String text) 
        isFirst = true;
        mText.setText(text);
        mExpandText.setText(text);
        requestLayout();
    

    public void setTextColor(int color) 
        mTextColor = color;
        mText.setTextColor(color);
    

    public void setTextSize(int size) 
        isFirst = true;
        mText.setTextSize(size);
        mExpandText.setTextSize(size);
        requestLayout();
    

    public void setTextMaxLine(int num) 
        mTextLine = num;
        mText.setMaxLines(num);
    

    public void setGravity(int gravity) 
        mText.setGravity(gravity);
        mExpandText.setGravity(gravity);
    

    public void setEllipsize(TextUtils.TruncateAt ell) 
        mText.setEllipsize(ell);
    

    public void setTextLineSpacingExtra(float spac) 
        mText.setLineSpacing(spac, 1.0f);
        mExpandText.setLineSpacing(spac, 1.0f);
    

    public TextView text() 
        return mText;
    

    public TextView expandText() 
        return mExpandText;
    

    public int line() 
        return mTextLine;
    

    public boolean isExpand() 
        return isExpand;
    

    public void expand() 
        if (!isExpand) 
            isExpand = true;
            mText.setTextColor(Color.TRANSPARENT);
            mExpandText.setTextColor(mTextColor);
            Animation animation = new Animation() 
                @Override
                protected void applyTransformation(float interpolatedTime, Transformation t) 
                    ViewGroup.LayoutParams params = ExpandTextView.this.getLayoutParams();
                    params.height = mStart + (int) ((mEnd - mStart) * interpolatedTime);
                    setLayoutParams(params);
                
            ;
            animation.setDuration(500);
            startAnimation(animation);
        

    

    @Override
    public void setLayoutParams(ViewGroup.LayoutParams params) 
        super.setLayoutParams(params);
    

    public void shrink() 
        if (isExpand) 
            isExpand = false;
            Animation animation = new Animation() 
                @Override
                protected void applyTransformation(float interpolatedTime, Transformation t) 
                    ViewGroup.LayoutParams params = ExpandTextView.this.getLayoutParams();
                    params.height = mStart + (int) ((mEnd - mStart) * (1 - interpolatedTime));
                    setLayoutParams(params);
                
            ;
            animation.setAnimationListener(new Animation.AnimationListener() 
                @Override
                public void onAnimationStart(Animation animation) 

                

                @Override
                public void onAnimationEnd(Animation animation) 
                    mText.setTextColor(mTextColor);
                    mExpandText.setTextColor(Color.TRANSPARENT);
                

                @Override
                public void onAnimationRepeat(Animation animation) 

                
            );
            animation.setDuration(500);
            startAnimation(animation);
        
    

    public void switchs() 
        if (isExpand) 
            shrink();
         else 
            expand();
        
    

使用：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.ming.expandtextview.MainActivity">


    <Button
        android:id="@+id/expand"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:text="Expand" />

    <Button
        android:id="@+id/strink"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_toEndOf="@+id/expand"
        android:layout_toRightOf="@+id/expand"
        android:text="Strink" />

    <com.ming.expandtextview.ExpandTextView
        android:id="@+id/expandtextview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/expand">
    </com.ming.expandtextview.ExpandTextView>
</RelativeLayout>

Activity.java

public class MainActivity extends AppCompatActivity 

    private Button mBtnExpand;
    private Button mBtnStrink;
    private ExpandTextView mExpandTextview;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mBtnExpand = (Button) findViewById(R.id.expand);
        mBtnStrink = (Button) findViewById(R.id.strink);
        mExpandTextview = (ExpandTextView) findViewById(R.id.expandtextview);
        mExpandTextview.setTextColor(Color.BLACK);
        mExpandTextview.setTextSize(18);
        mExpandTextview.setTextMaxLine(2);
        mExpandTextview.setText("科技本身蕴含着一种碾压一切的力量，而这种力量会导致我们加速奔向某种设定好的结局。" +
                "这篇文章尝试预测未来最可能的5种结局：黄金时代，虚拟世界，冷平衡，生化人，大寂灭。");
        mBtnExpand.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                mExpandTextview.expand();

                //或者mExpandTextview.switchs();
            
        );
        mBtnStrink.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                mExpandTextview.shrink();
            
        );
    

下载：http://download.csdn.net/detail/u013045971/9416672