Android中TextView文本高亮和点击行为的封装方法

 更新时间:2017年03月27日 11:34:54   转载 作者:小松的技术博客  
这篇文章主要介绍了Android中TextView文本高亮和点击行为的封装方法,文中介绍的非常详细,相信对大家具有一定的参考价值,需要的朋友们下面来一起看看吧。

前言

相信大家应该都有所体会,对于一个社交性质的App,业务上少不了给一段文本加上@功能、话题功能,或者是评论上要高亮人名的需求。当然,Android为我们提供了ClickableSpan,用于解决TextView部分内容可点击的问题,但却附加了一堆的坑点:

  1. ClickableSpan 默认没有高亮行为,也不能添加背景颜色;
  2. ClickableSpan 必须配合 MovementMethod 使用
  3. 一旦使用 MovementMethod,TextView 必定消耗事件
  4. 当点击ClickableSpan时,TextView的点击也会随后触发
  5. 当press ClickableSpan 时, TextView的press态也会被触发

这些默认的表现会使得添加 ClickableSpan 后会出现各种不符合预期的问题,因此我们需要对其进行封装。

据个人使用经验,封装后应该能够方便开发实现以下行为:

  1. 让Span支持字体颜色和背景颜色变化,并且有press态行为
  2. Span的click或者press不影响TextView的click和press
  3. 可选择的决定TextView是否应该消耗事件

对于第三点,需要解释下TextView是否消耗事件的影响

用一张图来阐述下我们的目的。我们开发过程中,可能将点击事件加在TextView上,也可能将点击行为添加在TextView的父元素上,例如评论一般是点击整个评论item就可以触发回复。 如果我们把点击事件加在TextView的父元素上,那么我们期待的是点击TextView的绿色区域应该也要响应点击事件,但现实总是残酷的,如果TextView调用了setMovementMethod, 点击绿色区域将不会有任何反应,因为时间被TextView消耗了,并不会传递到TextView的父元素上。

那我们来一步一步看如何实现这几个问题。

首先我们定义一个接口 ITouchableSpan, 用于抽象press和点击:

public interface ITouchableSpan {
 void setPressed(boolean pressed);
 void onClick(View widget);
}

然后建立一个 ClickableSpan的子类 QMUITouchableSpan 来扩充它的表现:

public abstract class QMUITouchableSpan extends ClickableSpan implements ITouchableSpan {
 private boolean mIsPressed;
 @ColorInt private int mNormalBackgroundColor;
 @ColorInt private int mPressedBackgroundColor;
 @ColorInt private int mNormalTextColor;
 @ColorInt private int mPressedTextColor;

 private boolean mIsNeedUnderline = false;

 public abstract void onSpanClick(View widget);

 @Override
 public final void onClick(View widget) {
  if (ViewCompat.isAttachedToWindow(widget)) {
   onSpanClick(widget);
  }
 }


 public QMUITouchableSpan(@ColorInt int normalTextColor,
       @ColorInt int pressedTextColor,
       @ColorInt int normalBackgroundColor,
       @ColorInt int pressedBackgroundColor) {
  mNormalTextColor = normalTextColor;
  mPressedTextColor = pressedTextColor;
  mNormalBackgroundColor = normalBackgroundColor;
  mPressedBackgroundColor = pressedBackgroundColor;
 }

 // .... get/set ...

 public void setPressed(boolean isSelected) {
  mIsPressed = isSelected;
 }

 public boolean isPressed() {
  return mIsPressed;
 }

 @Override
 public void updateDrawState(TextPaint ds) {
  // 通过updateDrawState来更新字体颜色和背景色
  ds.setColor(mIsPressed ? mPressedTextColor : mNormalTextColor);
  ds.bgColor = mIsPressed ? mPressedBackgroundColor
    : mNormalBackgroundColor;
  ds.setUnderlineText(mIsNeedUnderline);
 }
}

然后我们要把press状态和点击行为传递给QMUITouchableSpan,这一层我们可以通过重载 LinkMovementMethod去解决:

public class QMUILinkTouchMovementMethod extends LinkMovementMethod {

 @Override
 public boolean onTouchEvent(TextView widget, Spannable buffer, MotionEvent event) {
  return sHelper.onTouchEvent(widget, buffer, event)
    || Touch.onTouchEvent(widget, buffer, event);
 }

 public static MovementMethod getInstance() {
  if (sInstance == null)
   sInstance = new QMUILinkTouchMovementMethod();

  return sInstance;
 }

 private static QMUILinkTouchMovementMethod sInstance;
 private static QMUILinkTouchDecorHelper sHelper = new QMUILinkTouchDecorHelper();

}

对TextView使用 setMovementMethod 后,TextView的 onTouchEvent 中会调用到 LinkMovementMethod的onTouchEvent,并且会传入Spannable,这是一个去处理Spannable数据的好hook点。 我们抽取一个 QMUILinkTouchDecorHelper 用于处理公共逻辑,因为LinkMovementMethod存在多个行为各异的子类。

public class QMUILinkTouchDecorHelper {
 private ITouchableSpan mPressedSpan;

 public boolean onTouchEvent(TextView textView, Spannable spannable, MotionEvent event) {
  if (event.getAction() == MotionEvent.ACTION_DOWN) {
   mPressedSpan = getPressedSpan(textView, spannable, event);
   if (mPressedSpan != null) {
    mPressedSpan.setPressed(true);
    Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan),
      spannable.getSpanEnd(mPressedSpan));
   }
   if (textView instanceof QMUISpanTouchFixTextView) {
    QMUISpanTouchFixTextView tv = (QMUISpanTouchFixTextView) textView;
    tv.setTouchSpanHint(mPressedSpan != null);
   }
   return mPressedSpan != null;
  } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
   ITouchableSpan touchedSpan = getPressedSpan(textView, spannable, event);
   if (mPressedSpan != null && touchedSpan != mPressedSpan) {
    mPressedSpan.setPressed(false);
    mPressedSpan = null;
    Selection.removeSelection(spannable);
   }
   return mPressedSpan != null;
  } else if (event.getAction() == MotionEvent.ACTION_UP) {
   boolean touchSpanHint = false;
   if (mPressedSpan != null) {
    touchSpanHint = true;
    mPressedSpan.setPressed(false);
    mPressedSpan.onClick(textView);
   }

   mPressedSpan = null;
   Selection.removeSelection(spannable);
   return touchSpanHint;
  } else {
   if (mPressedSpan != null) {
    mPressedSpan.setPressed(false);
   }
   Selection.removeSelection(spannable);
   return false;
  }

 }

 public ITouchableSpan getPressedSpan(TextView textView, Spannable spannable, MotionEvent event) {
  int x = (int) event.getX();
  int y = (int) event.getY();

  x -= textView.getTotalPaddingLeft();
  y -= textView.getTotalPaddingTop();

  x += textView.getScrollX();
  y += textView.getScrollY();

  Layout layout = textView.getLayout();
  int line = layout.getLineForVertical(y);
  int off = layout.getOffsetForHorizontal(line, x);

  ITouchableSpan[] link = spannable.getSpans(off, off, ITouchableSpan.class);
  ITouchableSpan touchedSpan = null;
  if (link.length > 0) {
   touchedSpan = link[0];
  }
  return touchedSpan;
 }
}

上述的很多行为直接取自官方的LinkTouchMovementMethod,然后做了相应的修改。完成这些,我们才仅仅能做到我们想要的第一步而已。

接下来我们看如何处理TextView的click与press与 QMUITouchableSpan 冲突的问题。 这一步我们需要建立一个TextView的子类QMUISpanTouchFixTextView去处理相关细节。

第一步我们需要判断是否是点击到了QMUITouchableSpan, 这个判断可以放在 QMUILinkTouchDecorHelper#onTouchEvent中完成, 在onTouchEvent中补充以下代码:

public boolean onTouchEvent(TextView textView, Spannable spannable, MotionEvent event) {
 if (event.getAction() == MotionEvent.ACTION_DOWN) {
  // ...
  if (textView instanceof QMUISpanTouchFixTextView) {
   QMUISpanTouchFixTextView tv = (QMUISpanTouchFixTextView) textView;
   tv.setTouchSpanHint(mPressedSpan != null);
  }
  return mPressedSpan != null;
 } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
  // ...
  if (textView instanceof QMUISpanTouchFixTextView) {
   QMUISpanTouchFixTextView tv = (QMUISpanTouchFixTextView) textView;
   tv.setTouchSpanHint(mPressedSpan != null);
  }
  return mPressedSpan != null;
 } else if (event.getAction() == MotionEvent.ACTION_UP) {
  // ...
  Selection.removeSelection(spannable);
  if (textView instanceof QMUISpanTouchFixTextView) {
   QMUISpanTouchFixTextView tv = (QMUISpanTouchFixTextView) textView;
   tv.setTouchSpanHint(touchSpanHint);
  }
  return touchSpanHint;
 } else {
  // ...
  if (textView instanceof QMUISpanTouchFixTextView) {
   QMUISpanTouchFixTextView tv = (QMUISpanTouchFixTextView) textView;
   tv.setTouchSpanHint(false);
  }
  // ...
  return false;
 }
}

这个时候我们在 QMUISpanTouchFixTextView就可以通过是否点击到QMUITouchableSpan来决定不同行为了,对于点击是非常好处理的,代码如下:

@Override
public boolean performClick() {
 if (!mTouchSpanHint) {
  return super.performClick();
 }
 return false;
}

对于press行为,就会有点棘手,因为setPress在 onTouchEvent多次调用,而且在QMUILinkTouchDecorHelper#onTouchEvent前就会被调用到,所以不能简单的用mTouchSpanHint这个变量来管理。来看看我给出的方案:

// 记录每次真正传入的press,每次更改mTouchSpanHint,需要再调用一次setPressed,确保press状态正确
// 第一步: 用一个变量记录setPress传入的值,这个是TextView真正的press值
private boolean mIsPressedRecord = false;

// 第二步,onTouchEvent在调用super前将mTouchSpanHint设为true,这会使得QMUILinkTouchDecorHelper#onTouchEvent的press行为失效,参考第三步
@Override
public boolean onTouchEvent(MotionEvent event) {
 if (!(getText() instanceof Spannable)) {
  return super.onTouchEvent(event);
 }
 mTouchSpanHint = true;
 return super.onTouchEvent(event);
}

// 第三步: final掉setPressed,如果!mTouchSpanHint才调用super.setPressed,开一个onSetPressed给子类覆写
@Override
public final void setPressed(boolean pressed) {
 mIsPressedRecord = pressed;
 if (!mTouchSpanHint) {
  onSetPressed(pressed);
 }
}

protected void onSetPressed(boolean pressed) {
 super.setPressed(pressed);
}

// 第四步: 每次调用setTouchSpanHint是调用一次setPressed,并传入mIsPressedRecord,确保press状态的统一
public void setTouchSpanHint(boolean touchSpanHint) {
 if (mTouchSpanHint != touchSpanHint) {
  mTouchSpanHint = touchSpanHint;
  setPressed(mIsPressedRecord);
 }
}

这几个步骤相互耦合,静下心好好理解下。这样就顺利的解决了第二个问题。那么我们来看看如何消除 MovementMethod造成TextView对事件的消耗行为。

调用 setMovementMethod为何会使得TextView必然消耗事件呢?我们可以看看源码:

public final void setMovementMethod(MovementMethod movement) {
 if (mMovement != movement) {
  mMovement = movement;

  if (movement != null && !(mText instanceof Spannable)) {
   setText(mText);
  }

  fixFocusableAndClickableSettings();

  // SelectionModifierCursorController depends on textCanBeSelected, which depends on
  // mMovement
  if (mEditor != null) mEditor.prepareCursorControllers();
 }
}

private void fixFocusableAndClickableSettings() {
 if (mMovement != null || (mEditor != null && mEditor.mKeyListener != null)) {
  setFocusable(true);
  setClickable(true);
  setLongClickable(true);
 } else {
  setFocusable(false);
  setClickable(false);
  setLongClickable(false);
 }
}

原来设置MovementMethod后会把clickable,longClickable和focusable都设置为true,这样必然TextView会消耗事件了。因此我们想到的解决方案就是:如果我们想不让TextView消耗事件,那么我们就在 setMovementMethod之后再改一次clickable,longClickable和focusable。

public void setShouldConsumeEvent(boolean shouldConsumeEvent) {
 mShouldConsumeEvent = shouldConsumeEvent;
 setFocusable(shouldConsumeEvent);
 setClickable(shouldConsumeEvent);
 setLongClickable(shouldConsumeEvent);
}

public void setMovementMethodCompat(MovementMethod movement){
 setMovementMethod(movement);
 if(!mShouldConsumeEvent){
  setShouldConsumeEvent(false);
 }
}

仅仅这样还不够,我们还必须在 onTouchEvent里面返回false:

@Override
public boolean onTouchEvent(MotionEvent event) {
 if (!(getText() instanceof Spannable)) {
  return super.onTouchEvent(event);
 }
 mTouchSpanHint = true;
 // 调用super.onTouchEvent,会走到QMUILinkTouchMovementMethod
 // 会走到QMUILinkTouchMovementMethod#onTouchEvent会修改mTouchSpanHint
 boolean ret = super.onTouchEvent(event);
 if(!mShouldConsumeEvent){
  return mTouchSpanHint;
 }
 return ret;
}

经过层层fix,我们终于可以给出一份不错的封装代码提供给业务方使用了:

public class QMUISpanTouchFixTextView extends TextView {
 private boolean mTouchSpanHint;

 // 记录每次真正传入的press,每次更改mTouchSpanHint,需要再调用一次setPressed,确保press状态正确
 private boolean mIsPressedRecord = false;
 private boolean mShouldConsumeEvent = true; // TextView是否应该消耗事件

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

 public QMUISpanTouchFixTextView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public QMUISpanTouchFixTextView(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  setHighlightColor(Color.TRANSPARENT);
  setMovementMethod(QMUILinkTouchMovementMethod.getInstance());
 }

 public void setShouldConsumeEvent(boolean shouldConsumeEvent) {
  mShouldConsumeEvent = shouldConsumeEvent;
  setFocusable(shouldConsumeEvent);
  setClickable(shouldConsumeEvent);
  setLongClickable(shouldConsumeEvent);
 }

 public void setMovementMethodCompat(MovementMethod movement){
  setMovementMethod(movement);
  if(!mShouldConsumeEvent){
   setShouldConsumeEvent(false);
  }
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  if (!(getText() instanceof Spannable)) {
   return super.onTouchEvent(event);
  }
  mTouchSpanHint = true;
  // 调用super.onTouchEvent,会走到QMUILinkTouchMovementMethod
  // 会走到QMUILinkTouchMovementMethod#onTouchEvent会修改mTouchSpanHint
  boolean ret = super.onTouchEvent(event);
  if(!mShouldConsumeEvent){
   return mTouchSpanHint;
  }
  return ret;
 }

 public void setTouchSpanHint(boolean touchSpanHint) {
  if (mTouchSpanHint != touchSpanHint) {
   mTouchSpanHint = touchSpanHint;
   setPressed(mIsPressedRecord);
  }
 }

 @Override
 public boolean performClick() {
  if (!mTouchSpanHint && mShouldConsumeEvent) {
   return super.performClick();
  }
  return false;
 }

 @Override
 public boolean performLongClick() {
  if (!mTouchSpanHint && mShouldConsumeEvent) {
   return super.performLongClick();
  }
  return false;
 }

 @Override
 public final void setPressed(boolean pressed) {
  mIsPressedRecord = pressed;
  if (!mTouchSpanHint) {
   onSetPressed(pressed);
  }
 }

 protected void onSetPressed(boolean pressed) {
  super.setPressed(pressed);
 }
}

总结

以上就是这篇文章的全部内容了,希望本文的内容对给位Android开发者们能带来一定的帮助,如果有疑问大家可以留言交流,谢谢大家对脚本之家的支持。

相关文章

最新评论