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Android中TextView文本高亮和点击行为的封装方法

程序员文章站 2023-11-23 10:39:52
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clic...

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

Android中TextView文本高亮和点击行为的封装方法

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,谢谢大家对的支持。