Android - 带有动画的可扩展 TextView [英] Android - Expandable TextView with Animation

问题描述

我有一个 TextView，它首先显示一小部分长文本.

I have a TextView which firstly shows a small portion of a long text.

用户可以按下查看更多"按钮来展开 TextView 并查看该文本的其余部分.

The user can press a "see more" button to expand the TextView and see the rest of that text.

进行测试，我可以通过简单地将 TextView.setMaxLines 的值在 4 用于折叠和 Integer.MAX_VALUE 用于展开来实现.

Making tests, I can reach that by simply interchange the value of TextView.setMaxLines between 4 for collapsing and Integer.MAX_VALUE for expanding.

现在，我希望这种行为伴随着动画.我知道在 this question 中几乎完成了一个解决方案，但我尝试实现它，但我没有成功.

Now, I would like that this behavior would be accompanied by an animation. I know that in this question one solution is almost done, but I tried to implement it and I have no success.

有人可以帮我解决这个问题吗?

Can someone help me with this?

推荐答案

你可以查看我在 ExpandableTexTView 上的博文:

You can check my blog post on ExpandableTexTView:

这个想法是，最初 TextView 将显示一小部分长文本，当单击它时，它将显示其余文本.

The idea is, initially the TextView will show a small portion of a long text and when it is clicked, it will show the rest of the text.

所以这是我如何解决它的代码.

So here is the code that how I solved it.

package com.rokonoid.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.text.SpannableStringBuilder;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;
/**
 * User: Bazlur Rahman Rokon
 * Date: 9/7/13 - 3:33 AM
 */
public class ExpandableTextView extends TextView {
    private static final int DEFAULT_TRIM_LENGTH = 200;
    private static final String ELLIPSIS = ".....";

    private CharSequence originalText;
    private CharSequence trimmedText;
    private BufferType bufferType;
    private boolean trim = true;
    private int trimLength;

    public ExpandableTextView(Context context) {
        this(context, null);
    }

    public ExpandableTextView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ExpandableTextView);
        this.trimLength = typedArray.getInt(R.styleable.ExpandableTextView_trimLength, DEFAULT_TRIM_LENGTH);
        typedArray.recycle();

        setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                trim = !trim;
                setText();
                requestFocusFromTouch();
            }
        });
    }

    private void setText() {
        super.setText(getDisplayableText(), bufferType);
    }

    private CharSequence getDisplayableText() {
        return trim ? trimmedText : originalText;
    }

    @Override
    public void setText(CharSequence text, BufferType type) {
        originalText = text;
        trimmedText = getTrimmedText(text);
        bufferType = type;
        setText();
    }

    private CharSequence getTrimmedText(CharSequence text) {
        if (originalText != null && originalText.length() > trimLength) {
            return new SpannableStringBuilder(originalText, 0, trimLength + 1).append(ELLIPSIS);
        } else {
            return originalText;
        }
    }

    public CharSequence getOriginalText() {
        return originalText;
    }

    public void setTrimLength(int trimLength) {
        this.trimLength = trimLength;
        trimmedText = getTrimmedText(originalText);
        setText();
    }

    public int getTrimLength() {
        return trimLength;
    }
}

并在 attr.xml 中添加以下行

And add the following line in your attr.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="ExpandableTextView">
        <attr name="trimLength" format="integer"/>
    </declare-styleable>
</resources>

将以下内容放入您的 main.xml

Put the following in your main.xml

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">

     <com.rokonoid.widget.ExpandableTextView
         android:id="@+id/lorem_ipsum"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"/>

 </LinearLayout>

并测试您的活动

package com.rokonoid.widget;

import android.app.Activity;
import android.os.Bundle;

public class MyActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        String yourText = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
                "Ut volutpat interdum interdum. Nulla laoreet lacus diam, vitae " +
                "sodales sapien commodo faucibus. Vestibulum et feugiat enim. Donec " +
                "semper mi et euismod tempor. Sed sodales eleifend mi id varius. Nam " +
                "et ornare enim, sit amet gravida sapien. Quisque gravida et enim vel " +
                "volutpat. Vivamus egestas ut felis a blandit. Vivamus fringilla " +
                "dignissim mollis. Maecenas imperdiet interdum hendrerit. Aliquam" +
                " dictum hendrerit ultrices. Ut vitae vestibulum dolor. Donec auctor ante" +
                " eget libero molestie porta. Nam tempor fringilla ultricies. Nam sem " +
                "lectus, feugiat eget ullamcorper vitae, ornare et sem. Fusce dapibus ipsum" +
                " sed laoreet suscipit. ";

        ExpandableTextView expandableTextView = (ExpandableTextView) findViewById(R.id.lorem_ipsum);
        expandableTextView.setText(yourText);
    }
}

参考:Android – 可扩展文本视图

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