我有一个TextView
,它最初显示长文本的一小部分。
用户可以按下"查看更多"按钮来展开TextView
并查看剩余的文本。
在进行测试时,我可以通过简单地在折叠和展开之间交换TextView.setMaxLines
的值(4和Integer.MAX_VALUE)来实现。
现在,我希望这种行为能够伴随动画效果。我知道在这个问题中,一个解决方案已经几乎完成了,但是我尝试实施它却没有成功。
有人可以帮我吗?
我有一个TextView
,它最初显示长文本的一小部分。
用户可以按下"查看更多"按钮来展开TextView
并查看剩余的文本。
在进行测试时,我可以通过简单地在折叠和展开之间交换TextView.setMaxLines
的值(4和Integer.MAX_VALUE)来实现。
现在,我希望这种行为能够伴随动画效果。我知道在这个问题中,一个解决方案已经几乎完成了,但是我尝试实施它却没有成功。
有人可以帮我吗?
您可以查看我的博客文章关于 ExpandableTexTView:
这个想法是,初始时 TextView 会显示长文本的一小部分,当它被点击时,它会显示剩余的文本。
下面是我解决问题的代码。
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;
}
}
在您的 attr.xml 文件中添加以下行:
<?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main.xml文件中
<?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>
测试你的活动
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);
}
}
ObjectAnimator animation = ObjectAnimator.ofInt(yourTextView, "maxLines", tv.getLineCount());
animation.setDuration(200).start();
这将在200毫秒内完全展开您的TextView。您可以将tv.getLineCount()
替换为您希望折叠回去的文本行数。
----更新----
这里是一些方便的方法,您可以直接使用:
private void expandTextView(TextView tv){
ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", tv.getLineCount());
animation.setDuration(200).start();
}
private void collapseTextView(TextView tv, int numLines){
ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", numLines);
animation.setDuration(200).start();
}
如果你的API版本在16或以上,你可以使用textView.getMaxLines()来轻松确定你的textView是否已经展开。
private void cycleTextViewExpansion(TextView tv){
int collapsedMaxLines = 3;
ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines",
tv.getMaxLines() == collapsedMaxLines? tv.getLineCount() : collapsedMaxLines);
animation.setDuration(200).start();
}
注意:
如果maxLines未设置,或者您已经以像素为单位设置了textView的高度,则可能会出现ArrayIndexOutOfBounds异常。
以上示例无论扩展3行还是400行,始终需要200ms。如果您想要一个一致的扩展速率,可以尝试以下方式:
int duration = (textView.getLineCount() - collapsedMaxLines) * 10;
ellipsize
属性(设为'end'),TextView就无法再被点击并且也无法展开了。 - snark我创建了一个开源库来解决这个问题,因为在网上找到的其他解决方案并没有让我满意。我把这个东西放到了GitHub上,任何人都可以免费使用。
public class ExpandableTextView extends TextView
{
// copy off TextView.LINES
private static final int MAXMODE_LINES = 1;
private OnExpandListener onExpandListener;
private TimeInterpolator expandInterpolator;
private TimeInterpolator collapseInterpolator;
private final int maxLines;
private long animationDuration;
private boolean animating;
private boolean expanded;
private int originalHeight;
public ExpandableTextView(final Context context)
{
this(context, null);
}
public ExpandableTextView(final Context context, final AttributeSet attrs)
{
this(context, attrs, 0);
}
public ExpandableTextView(final Context context, final AttributeSet attrs, final int defStyle)
{
super(context, attrs, defStyle);
// read attributes
final TypedArray attributes = context.obtainStyledAttributes(attrs, R.styleable.ExpandableTextView, defStyle, 0);
this.animationDuration = attributes.getInt(R.styleable.ExpandableTextView_animation_duration, BuildConfig.DEFAULT_ANIMATION_DURATION);
attributes.recycle();
// keep the original value of maxLines
this.maxLines = this.getMaxLines();
// create default interpolators
this.expandInterpolator = new AccelerateDecelerateInterpolator();
this.collapseInterpolator = new AccelerateDecelerateInterpolator();
}
@Override
public int getMaxLines()
{
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
{
return super.getMaxLines();
}
try
{
final Field mMaxMode = TextView.class.getField("mMaxMode");
mMaxMode.setAccessible(true);
final Field mMaximum = TextView.class.getField("mMaximum");
mMaximum.setAccessible(true);
final int mMaxModeValue = (int) mMaxMode.get(this);
final int mMaximumValue = (int) mMaximum.get(this);
return mMaxModeValue == MAXMODE_LINES ? mMaximumValue : -1;
}
catch (final Exception e)
{
return -1;
}
}
/**
* Toggle the expanded state of this {@link ExpandableTextView}.
* @return true if toggled, false otherwise.
*/
public boolean toggle()
{
if (this.expanded)
{
return this.collapse();
}
return this.expand();
}
/**
* Expand this {@link ExpandableTextView}.
* @return true if expanded, false otherwise.
*/
public boolean expand()
{
if (!this.expanded && !this.animating && this.maxLines >= 0)
{
this.animating = true;
// notify listener
if (this.onExpandListener != null)
{
this.onExpandListener.onExpand(this);
}
// get original height
this.measure
(
MeasureSpec.makeMeasureSpec(this.getMeasuredWidth(), MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
);
this.originalHeight = this.getMeasuredHeight();
// set maxLines to MAX Integer
this.setMaxLines(Integer.MAX_VALUE);
// get new height
this.measure
(
MeasureSpec.makeMeasureSpec(this.getMeasuredWidth(), MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
);
final int fullHeight = this.getMeasuredHeight();
final ValueAnimator valueAnimator = ValueAnimator.ofInt(this.originalHeight, fullHeight);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
{
@Override
public void onAnimationUpdate(final ValueAnimator animation)
{
final ViewGroup.LayoutParams layoutParams = ExpandableTextView.this.getLayoutParams();
layoutParams.height = (int) animation.getAnimatedValue();
ExpandableTextView.this.setLayoutParams(layoutParams);
}
});
valueAnimator.addListener(new AnimatorListenerAdapter()
{
@Override
public void onAnimationEnd(final Animator animation)
{
ExpandableTextView.this.expanded = true;
ExpandableTextView.this.animating = false;
}
});
// set interpolator
valueAnimator.setInterpolator(this.expandInterpolator);
// start the animation
valueAnimator
.setDuration(this.animationDuration)
.start();
return true;
}
return false;
}
/**
* Collapse this {@link TextView}.
* @return true if collapsed, false otherwise.
*/
public boolean collapse()
{
if (this.expanded && !this.animating && this.maxLines >= 0)
{
this.animating = true;
// notify listener
if (this.onExpandListener != null)
{
this.onExpandListener.onCollapse(this);
}
// get new height
final int fullHeight = this.getMeasuredHeight();
final ValueAnimator valueAnimator = ValueAnimator.ofInt(fullHeight, this.originalHeight);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
{
@Override
public void onAnimationUpdate(final ValueAnimator animation)
{
final ViewGroup.LayoutParams layoutParams = ExpandableTextView.this.getLayoutParams();
layoutParams.height = (int) animation.getAnimatedValue();
ExpandableTextView.this.setLayoutParams(layoutParams);
}
});
valueAnimator.addListener(new AnimatorListenerAdapter()
{
@Override
public void onAnimationEnd(final Animator animation)
{
// set maxLines to original value
ExpandableTextView.this.setMaxLines(ExpandableTextView.this.maxLines);
ExpandableTextView.this.expanded = false;
ExpandableTextView.this.animating = false;
}
});
// set interpolator
valueAnimator.setInterpolator(this.collapseInterpolator);
// start the animation
valueAnimator
.setDuration(this.animationDuration)
.start();
return true;
}
return false;
}
/**
* Sets the duration of the expand / collapse animation.
* @param animationDuration duration in milliseconds.
*/
public void setAnimationDuration(final long animationDuration)
{
this.animationDuration = animationDuration;
}
/**
* Sets a listener which receives updates about this {@link ExpandableTextView}.
* @param onExpandListener the listener.
*/
public void setOnExpandListener(final OnExpandListener onExpandListener)
{
this.onExpandListener = onExpandListener;
}
/**
* Returns the {@link OnExpandListener}.
* @return the listener.
*/
public OnExpandListener getOnExpandListener()
{
return onExpandListener;
}
/**
* Sets a {@link TimeInterpolator} for expanding and collapsing.
* @param interpolator the interpolator
*/
public void setInterpolator(final TimeInterpolator interpolator)
{
this.expandInterpolator = interpolator;
this.collapseInterpolator = interpolator;
}
/**
* Sets a {@link TimeInterpolator} for expanding.
* @param expandInterpolator the interpolator
*/
public void setExpandInterpolator(final TimeInterpolator expandInterpolator)
{
this.expandInterpolator = expandInterpolator;
}
/**
* Returns the current {@link TimeInterpolator} for expanding.
* @return the current interpolator, null by default.
*/
public TimeInterpolator getExpandInterpolator()
{
return this.expandInterpolator;
}
/**
* Sets a {@link TimeInterpolator} for collpasing.
* @param collapseInterpolator the interpolator
*/
public void setCollapseInterpolator(final TimeInterpolator collapseInterpolator)
{
this.collapseInterpolator = collapseInterpolator;
}
/**
* Returns the current {@link TimeInterpolator} for collapsing.
* @return the current interpolator, null by default.
*/
public TimeInterpolator getCollapseInterpolator()
{
return this.collapseInterpolator;
}
/**
* Is this {@link ExpandableTextView} expanded or not?
* @return true if expanded, false if collapsed.
*/
public boolean isExpanded()
{
return this.expanded;
}
public interface OnExpandListener
{
void onExpand(ExpandableTextView view);
void onCollapse(ExpandableTextView view);
}
}
使用ExpandableTextView非常简单,它只是一个带有一些额外功能的TextView。通过定义android:maxLines属性,您可以设置TextView折叠状态下的默认行数。
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<at.blogc.android.views.ExpandableTextView
android:id="@+id/expandableTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/lorem_ipsum"
android:maxLines="5"
android:ellipsize="end"
app:animation_duration="1000"/>
<!-- Optional parameter animation_duration: sets the duration of the expand animation -->
<Button
android:id="@+id/button_toggle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/expand"/>
</LinearLayout>
在您的 Activity 或 Fragment 中:
final ExpandableTextView expandableTextView = (ExpandableTextView) this.findViewById(R.id.expandableTextView);
final Button buttonToggle = (Button) this.findViewById(R.id.button_toggle);
// set animation duration via code, but preferable in your layout files by using the animation_duration attribute
expandableTextView.setAnimationDuration(1000L);
// set interpolators for both expanding and collapsing animations
expandableTextView.setInterpolator(new OvershootInterpolator());
// or set them separately
expandableTextView.setExpandInterpolator(new OvershootInterpolator());
expandableTextView.setCollapseInterpolator(new OvershootInterpolator());
// toggle the ExpandableTextView
buttonToggle.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(final View v)
{
expandableTextView.toggle();
buttonToggle.setText(expandableTextView.isExpanded() ? R.string.collapse : R.string.expand);
}
});
// but, you can also do the checks yourself
buttonToggle.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(final View v)
{
if (expandableTextView.isExpanded())
{
expandableTextView.collapse();
buttonToggle.setText(R.string.expand);
}
else
{
expandableTextView.expand();
buttonToggle.setText(R.string.collapse);
}
}
});
// listen for expand / collapse events
expandableTextView.setOnExpandListener(new ExpandableTextView.OnExpandListener()
{
@Override
public void onExpand(final ExpandableTextView view)
{
Log.d(TAG, "ExpandableTextView expanded");
}
@Override
public void onCollapse(final ExpandableTextView view)
{
Log.d(TAG, "ExpandableTextView collapsed");
}
});
您可以轻松将此库作为Gradle依赖项添加到您的Android项目中。请查看Github上的项目以获取进一步的说明:
expandText.setInterpolator(new OvershootInterpolator()); expandText.setMaxLines(4); expandText.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { if(expandText.isExpanded()){ expandText.collapse(); } else{ expandText.expand(); } } });
- parohy/**
* Ellipsize the text when the lines of text exceeds the value provided by {@link #makeExpandable} methods.
* Appends {@link #MORE} or {@link #LESS} as needed.
* TODO: add animation
* Created by vedant on 3/10/15.
*/
public class ExpandableTextView extends TextView {
private static final String TAG = "ExpandableTextView";
private static final String ELLIPSIZE = "... ";
private static final String MORE = "more";
private static final String LESS = "less";
private String mFullText;
private int mMaxLines;
//...constructors...
public void makeExpandable(String fullText, int maxLines) {
mFullText =fullText;
mMaxLines = maxLines;
ViewTreeObserver vto = getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
ViewTreeObserver obs = getViewTreeObserver();
obs.removeOnGlobalLayoutListener(this);
if (getLineCount() <= maxLines) {
setText(mFullText);
} else {
setMovementMethod(LinkMovementMethod.getInstance());
showLess();
}
}
});
}
/**
* truncate text and append a clickable {@link #MORE}
*/
private void showLess() {
int lineEndIndex = getLayout().getLineEnd(mMaxLines - 1);
String newText = mFullText.substring(0, lineEndIndex - (ELLIPSIZE.length() + MORE.length() + 1))
+ ELLIPSIZE + MORE;
SpannableStringBuilder builder = new SpannableStringBuilder(newText);
builder.setSpan(new ClickableSpan() {
@Override
public void onClick(View widget) {
showMore();
}
}, newText.length() - MORE.length(), newText.length(), 0);
setText(builder, BufferType.SPANNABLE);
}
/**
* show full text and append a clickable {@link #LESS}
*/
private void showMore() {
// create a text like subText + ELLIPSIZE + MORE
SpannableStringBuilder builder = new SpannableStringBuilder(mFullText + LESS);
builder.setSpan(new ClickableSpan() {
@Override
public void onClick(View widget) {
showLess();
}
}, builder.length() - LESS.length(), builder.length(), 0);
setText(builder, BufferType.SPANNABLE);
}
}
平滑扩展(使用高度和ObjectAnimator)
FYI:需要API 11
public static void expandCollapsedByMaxLines(@NonNull final TextView text) {
final int height = text.getMeasuredHeight();
text.setHeight(height);
text.setMaxLines(Integer.MAX_VALUE); //expand fully
text.measure(View.MeasureSpec.makeMeasureSpec(text.getMeasuredWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(ViewGroup.LayoutParams.WRAP_CONTENT, View.MeasureSpec.UNSPECIFIED));
final int newHeight = text.getMeasuredHeight();
ObjectAnimator animation = ObjectAnimator.ofInt(text, "height", height, newHeight);
animation.setDuration(250).start();
}
注:我假设TextView被maxLines所限制。
注:感谢Amagi82提供ObjectAnimator示例。
fun toggleReadMoreTextView(linesWhenCollapsed: Float) {
if (viewDataBinding.textView.maxLines != Integer.MAX_VALUE) {
// exapand
viewDataBinding.textView.maxLines = Integer.MAX_VALUE
} else {
// collapse
viewDataBinding.textView.maxLines = linesWhenCollapsed
}
// start animation
TransitionManager.beginDelayedTransition(viewDataBinding.constraintLayout)
}
// initialize integers
int collapsedHeight, expandedHeight;
// get collapsed height after TextView is drawn
textView.post(new Runnable() {
@Override
public void run() {
collapsedHeight = textView.getMeasuredHeight();
}
});
// view that will expand/collapse your TextView
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// number of max lines when collapsed
if (textView.getMaxLines() == 2) {
// expand
textView.setMaxLines(Integer.MAX_VALUE);
textView.measure(View.MeasureSpec.makeMeasureSpec(notifMessage.getMeasuredWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED));
expandedHeight = textView.getMeasuredHeight();
ObjectAnimator animation = ObjectAnimator.ofInt(textView, "height", collapsedHeight, expandedHeight);
animation.setDuration(250).start();
} else {
// collapse
ObjectAnimator animation = ObjectAnimator.ofInt(textView, "height", expandedHeight, collapsedHeight);
animation.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animator) {
}
@Override
public void onAnimationEnd(Animator animator) {
// number of max lines when collapsed
textView.setMaxLines(2);
}
@Override
public void onAnimationCancel(Animator animator) {
}
@Override
public void onAnimationRepeat(Animator animator) {
}
});
animation.setDuration(250).start();
}
}
});
RecyclerView
内展开TextView
,则在滚动期间会展开新的TextView
。要重置TextView
,请在RecyclerView
中使用textView.setLines(2)
。 - CoolMind以下是我使用上述一些答案后的解决方案(此示例中我使用ButterKnife):
private static final MAX_LINE_COUNT = 3;
@Bind(R.id.description)
TextView mDescription;
@Override
protected void onCreate(Bundle savedInstanceState) {
if(!TextUtils.isEmpty(mDescription)) {
mDescription.setText(mItem.description);
mDescription.setMaxLines(MAX_LINE_COUNT);
mDescription.setEllipsize(TextUtils.TruncateAt.END);
} else {
mDescription.setVisibility(View.GONE);
}
}
@OnClick(R.id.description)
void collapseExpandTextView(TextView tv) {
if (tv.getMaxLines() == MAX_LINE_COUNT) {
// collapsed - expand it
tv.setEllipsize(null);
tv.setMaxLines(Integer.MAX_VALUE);
} else {
// expanded - collapse it
tv.setEllipsize(TextUtils.TruncateAt.END);
tv.setMaxLines(MAX_LINE_COUNT);
}
ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", tv.getMaxLines());
animation.setDuration(200).start();
}
// YourCustomeClass.class [your customized class]
// yourTextView [ TextView yourTextView = findViewById(R.id.yourTextView) ];
YourCustomeClass.doResizeTextView(yourTextView, 3, "More", true);
// 3 - No of lines after user wants to expand it.
// "More" : text want to see end of your TextView after shrink
// True : flag for viewMore
dependencies {
implementation 'com.github.arshadbinhamza:ViewMore:1.0.9'
}
// ViewMoreHolder.load(textView_description,text, Typeface of end Text,UnderLine,number_of_lines,click_for_end_text_only);
// ViewMoreHolder.load(tv_description,description, Typeface.DEFAULT,true,3,false);