TextView文本高亮与点击行为完美封装
gdedk242
8年前
<p>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：</p> <ol> <li>ClickableSpan 默认没有高亮行为，也不能添加背景颜色；</li> <li>ClickableSpan 必须配合 MovementMethod 使用</li> <li>一旦使用 MovementMethod ， TextView 必定消耗事件</li> <li>当点击 ClickableSpan 时，TextView的点击也会随后触发</li> <li>当press ClickableSpan 时， TextView的press态也会被触发</li> </ol> <p>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：</p> <ol> <li>让Span支持字体颜色和背景颜色变化，并且有press态行为</li> <li>Span的click或者press不影响TextView的click和press</li> <li>可选择的决定TextView是否应该消耗事件</li> </ol> <p>对于第三点，需要解释下TextView是否消耗事件的影响</p> <p><img src="https://simg.open-open.com/show/f9161c693d0bbe2102a42b65c3d9b252.png"></p> <p>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。</p> <p>那我们来一步一步看如何实现这几个问题。</p> <p>首先我们定义一个接口 ITouchableSpan , 用于抽象press和点击:</p> <pre> <code class="language-java">public interface ITouchableSpan { void setPressed(boolean pressed); void onClick(View widget); }</code></pre> <p>然后建立一个 ClickableSpan 的子类 QMUITouchableSpan 来扩充它的表现：</p> <pre> <code class="language-java">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); } }</code></pre> <p>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：</p> <pre> <code class="language-java">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(); }</code></pre> <p>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。</p> <pre> <code class="language-java">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; } }</code></pre> <p>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。</p> <p>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。</p> <p>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：</p> <pre> <code class="language-java">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; } }</code></pre> <p>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：</p> <pre> <code class="language-java">@Override public boolean performClick() { if (!mTouchSpanHint) { return super.performClick(); } return false; }</code></pre> <p>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：</p> <pre> <code class="language-java">// 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); } }</code></pre> <p>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。</p> <p>调用 setMovementMethod 为何会使得TextView必然消耗事件呢？我们可以看看源码：</p> <pre> <code class="language-java">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); } }</code></pre> <p>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 。</p> <pre> <code class="language-java">public void setShouldConsumeEvent(boolean shouldConsumeEvent) { mShouldConsumeEvent = shouldConsumeEvent; setFocusable(shouldConsumeEvent); setClickable(shouldConsumeEvent); setLongClickable(shouldConsumeEvent); } public void setMovementMethodCompat(MovementMethod movement){ setMovementMethod(movement); if(!mShouldConsumeEvent){ setShouldConsumeEvent(false); } }</code></pre> <p>仅仅这样还不够，我们还必须在 onTouchEvent 里面返回false:</p> <pre> <code class="language-java">@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; }</code></pre> <p>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：</p> <pre> <code class="language-java">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); } }</code></pre> <p>参考链接：</p> <p><a href="/misc/goto?guid=4959742861089200542" rel="nofollow,noindex">TextView ClickableSpan 事件分发的两个坑</a></p> <p> </p> <p>来自：http://blog.cgsdream.org/2017/03/22/textview-highlight-clickablespan/</p> <p> </p>