我正在制作一个阅读应用程序，它具有全屏活动。
当用户选择文本的一部分时，会出现 contextual action bar 并带有复制选项。这是默认行为。但是此操作栏会阻止其下方的文本，因此用户无法选择它。
我尝试从onCreateActionMode 返回false，但是当我这样做时，我也无法选择文本。
我想知道是否有一种标准的方式来实现这一点，因为许多阅读应用程序都使用这种设计。
【问题讨论】：
标签： android textview android-popupwindow android-actionmode
我不知道 Play Books 是如何实现这一点的，但您可以创建一个 PopupWindow 并使用 Layout.getSelectionPath 和一些数学计算基于所选文本的位置。基本上，我们将：
PopupWindow 的边界和初始位置
PopupWindow 偏移到所选文本上方或下方的水平/垂直中心计算选择范围
用高亮表示填充指定的Path 在指定的偏移量之间。这通常是一个矩形或一个 可能不连续的矩形集。如果开始和结束是 同样，返回的路径为空。
因此，在我们的例子中，指定的偏移量将是选择的开始和结束，可以使用Selection.getSelectionStart 和Selection.getSelectionEnd 找到。为方便起见，TextView 给了我们TextView.getSelectionStart、TextView.getSelectionEnd 和TextView.getLayout。
final Path selDest = new Path();
final RectF selBounds = new RectF();
final Rect outBounds = new Rect();
// Calculate the selection start and end offset
final int selStart = yourTextView.getSelectionStart();
final int selEnd = yourTextView.getSelectionEnd();
final int min = Math.max(0, Math.min(selStart, selEnd));
final int max = Math.max(0, Math.max(selStart, selEnd));
// Calculate the selection outBounds
yourTextView.getLayout().getSelectionPath(min, max, selDest);
selDest.computeBounds(selBounds, true /* this param is ignored */);
selBounds.roundOut(outBounds);
现在我们有了选定文本边界的Rect，我们可以选择相对于它放置PopupWindow 的位置。在这种情况下，我们将使其沿所选文本的顶部或底部水平居中，具体取决于显示弹出窗口的空间。
计算初始弹出坐标
接下来我们需要计算弹出内容的边界。为此，我们首先需要调用PopupWindow.showAtLocation，但我们膨胀的View 的边界不会立即可用，所以我建议使用ViewTreeObserver.OnGlobalLayoutListener 来等待它们可用。
popupWindow.showAtLocation(yourTextView, Gravity.TOP, 0, 0)
PopupWindow.showAtLocation 需要：
View 可从中检索有效的 Window token，它只是唯一标识要放置弹出窗口的 Window
Gravity.TOP
由于在布局弹出内容之前我们无法确定 x/y 偏移量，因此我们最初将其放置在默认位置。如果你尝试在你传入的View 布局之前调用PopupWindow.showAtLocation，你会收到一个WindowManager.BadTokenException，所以你可以考虑使用ViewTreeObserver.OnGlobalLayoutListener 来避免这种情况，但它主要出现在你选择文本并旋转您的设备。
final Rect cframe = new Rect();
final int[] cloc = new int[2];
popupContent.getLocationOnScreen(cloc);
popupContent.getLocalVisibleRect(cbounds);
popupContent.getWindowVisibleDisplayFrame(cframe);
final int scrollY = ((View) yourTextView.getParent()).getScrollY();
final int[] tloc = new int[2];
yourTextView.getLocationInWindow(tloc);
final int startX = cloc[0] + cbounds.centerX();
final int startY = cloc[1] + cbounds.centerY() - (tloc[1] - cframe.top) - scrollY;
View.getLocationOnScreen 将返回我们弹出内容的 x/y 坐标。View.getLocalVisibleRect 将返回弹出内容的范围View.getWindowVisibleDisplayFrame 将返回偏移量以适应操作栏（如果存在）View.getScrollY 将为我们的TextView 所在的任何滚动容器返回y 偏移量（在我的情况下为ScrollView）View.getLocationInWindow 将为我们的TextView 返回y 偏移量，以防操作栏将其向下推一点一旦我们获得了我们需要的所有信息，我们就可以计算弹出内容的最终起始 x/y，然后使用它来计算它们与所选文本之间的差异Rect，这样我们就可以@ 987654339@到新位置。
计算偏移弹出坐标
// Calculate the top and bottom offset of the popup relative to the selection bounds
final int popupHeight = cbounds.height();
final int textPadding = yourTextView.getPaddingLeft();
final int topOffset = Math.round(selBounds.top - startY);
final int btmOffset = Math.round(selBounds.bottom - (startY - popupHeight));
// Calculate the x/y coordinates for the popup relative to the selection bounds
final int x = Math.round(selBounds.centerX() + textPadding - startX);
final int y = Math.round(selBounds.top - scrollY < startY ? btmOffset : topOffset);
如果有足够的空间在所选文本上方显示弹出窗口，我们会将其放在那里；否则，我们会将其偏移到所选文本下方。就我而言，我的TextView 周围有16dp 填充，因此也需要考虑到这一点。我们将得到最终的x 和y 位置来抵消PopupWindow。
popupWindow.update(x, y, -1, -1);
-1 这里只是代表我们为PopupWindow 提供的默认宽度/高度，在我们的例子中它将是ViewGroup.LayoutParams.WRAP_CONTENT
监听选择变化
我们希望 PopupWindow 在每次更改所选文本时更新。
侦听选择更改的简单方法是继承TextView 并提供对TextView.onSelectionChanged 的回调。
public class NotifyingSelectionTextView extends AppCompatTextView {
private SelectionChangeListener listener;
public NotifyingSelectionTextView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onSelectionChanged(int selStart, int selEnd) {
super.onSelectionChanged(selStart, selEnd);
if (listener != null) {
if (hasSelection()) {
listener.onTextSelected();
} else {
listener.onTextUnselected();
}
}
}
public void setSelectionChangeListener(SelectionChangeListener listener) {
this.listener = listener;
}
public interface SelectionChangeListener {
void onTextSelected();
void onTextUnselected();
}
}
监听滚动变化
如果您在ScrollView 之类的滚动容器中有TextView，您可能还想监听滚动变化，以便在滚动时锚定弹出窗口。一个简单的监听方法是继承 ScrollView 并提供一个回调到 View.onScrollChanged
public class NotifyingScrollView extends ScrollView {
private ScrollChangeListener listener;
public NotifyingScrollView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (listener != null) {
listener.onScrollChanged();
}
}
public void setScrollChangeListener(ScrollChangeListener listener) {
this.listener = listener;
}
public interface ScrollChangeListener {
void onScrollChanged();
}
}
创建一个空的ActionMode.Callback
就像您在帖子中提到的那样，我们需要在 ActionMode.Callback.onCreateActionMode 中返回 true，以使我们的文本保持可选状态。但我们还需要在ActionMode.Callback.onPrepareActionMode 中调用Menu.clear，以便删除您在ActionMode 中找到的所有项目。
/** An {@link ActionMode.Callback} used to remove all action items from text selection */
static final class EmptyActionMode extends SimpleActionModeCallback {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
// Return true to ensure the text is still selectable
return true;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
// Remove all action items to provide an actionmode-less selection
menu.clear();
return true;
}
}
现在我们可以使用TextView.setCustomSelectionActionModeCallback 来应用我们的自定义ActionMode。 SimpleActionModeCallback 是一个自定义类，只为ActionMode.Callback 提供存根，有点类似于ViewPager.SimpleOnPageChangeListener
public class SimpleActionModeCallback implements ActionMode.Callback {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
return false;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false;
}
@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
return false;
}
@Override
public void onDestroyActionMode(ActionMode mode) {
}
}
布局
这是我们正在使用的Activity 布局：
<your.package.name.NotifyingScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/notifying_scroll_view"
android:layout_width="match_parent"
android:layout_height="match_parent">
<your.package.name.NotifyingSelectionTextView
android:id="@+id/notifying_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="16dp"
android:textIsSelectable="true"
android:textSize="20sp" />
</your.package.name.NotifyingScrollView>
这是我们的弹出布局：
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/action_mode_popup_bg"
android:orientation="vertical"
tools:ignore="ContentDescription">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageButton
android:id="@+id/view_action_mode_popup_add_note"
style="@style/ActionModePopupButton"
android:src="@drawable/ic_note_add_black_24dp" />
<ImageButton
android:id="@+id/view_action_mode_popup_translate"
style="@style/ActionModePopupButton"
android:src="@drawable/ic_translate_black_24dp" />
<ImageButton
android:id="@+id/view_action_mode_popup_search"
style="@style/ActionModePopupButton"
android:src="@drawable/ic_search_black_24dp" />
</LinearLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_margin="8dp"
android:background="@android:color/darker_gray" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageButton
android:id="@+id/view_action_mode_popup_red"
style="@style/ActionModePopupSwatch"
android:src="@drawable/round_red" />
<ImageButton
android:id="@+id/view_action_mode_popup_yellow"
style="@style/ActionModePopupSwatch"
android:src="@drawable/round_yellow" />
<ImageButton
android:id="@+id/view_action_mode_popup_green"
style="@style/ActionModePopupSwatch"
android:src="@drawable/round_green" />
<ImageButton
android:id="@+id/view_action_mode_popup_blue"
style="@style/ActionModePopupSwatch"
android:src="@drawable/round_blue" />
<ImageButton
android:id="@+id/view_action_mode_popup_clear_format"
style="@style/ActionModePopupSwatch"
android:src="@drawable/ic_format_clear_black_24dp"
android:visibility="gone" />
</LinearLayout>
</LinearLayout>
这些是我们的弹出按钮样式：
<style name="ActionModePopupButton">
<item name="android:layout_width">48dp</item>
<item name="android:layout_height">48dp</item>
<item name="android:layout_weight">1</item>
<item name="android:background">?selectableItemBackground</item>
</style>
<style name="ActionModePopupSwatch" parent="ActionModePopupButton">
<item name="android:padding">12dp</item>
</style>
实用程序
您将看到的ViewUtils.onGlobalLayout 只是处理一些ViewTreeObserver.OnGlobalLayoutListener 样板的实用方法。
public static void onGlobalLayout(final View view, final Runnable runnable) {
final OnGlobalLayoutListener listener = new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
runnable.run();
}
};
view.getViewTreeObserver().addOnGlobalLayoutListener(listener);
}
完全实现
所以，现在我们已经：
Activity 和弹出布局把所有东西放在一起可能看起来像：
public class ActionModePopupActivity extends AppCompatActivity
implements ScrollChangeListener, SelectionChangeListener {
private static final int DEFAULT_WIDTH = -1;
private static final int DEFAULT_HEIGHT = -1;
private final Point currLoc = new Point();
private final Point startLoc = new Point();
private final Rect cbounds = new Rect();
private final PopupWindow popupWindow = new PopupWindow();
private final ActionMode.Callback emptyActionMode = new EmptyActionMode();
private NotifyingSelectionTextView yourTextView;
@SuppressLint("InflateParams")
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_action_mode_popup);
// Initialize the popup content, only add it to the Window once we've selected text
final LayoutInflater inflater = LayoutInflater.from(this);
popupWindow.setContentView(inflater.inflate(R.layout.view_action_mode_popup, null));
popupWindow.setWidth(WRAP_CONTENT);
popupWindow.setHeight(WRAP_CONTENT);
// Initialize to the NotifyingScrollView to observe scroll changes
final NotifyingScrollView scroll
= (NotifyingScrollView) findViewById(R.id.notifying_scroll_view);
scroll.setScrollChangeListener(this);
// Initialize the TextView to observe selection changes and provide an empty ActionMode
yourTextView = (NotifyingSelectionTextView) findViewById(R.id.notifying_text_view);
yourTextView.setText(IPSUM);
yourTextView.setSelectionChangeListener(this);
yourTextView.setCustomSelectionActionModeCallback(emptyActionMode);
}
@Override
public void onScrollChanged() {
// Anchor the popup while the user scrolls
if (popupWindow.isShowing()) {
final Point ploc = calculatePopupLocation();
popupWindow.update(ploc.x, ploc.y, DEFAULT_WIDTH, DEFAULT_HEIGHT);
}
}
@Override
public void onTextSelected() {
final View popupContent = popupWindow.getContentView();
if (popupWindow.isShowing()) {
// Calculate the updated x/y pop coordinates
final Point ploc = calculatePopupLocation();
popupWindow.update(ploc.x, ploc.y, DEFAULT_WIDTH, DEFAULT_HEIGHT);
} else {
// Add the popup to the Window and position it relative to the selected text bounds
ViewUtils.onGlobalLayout(yourTextView, () -> {
popupWindow.showAtLocation(yourTextView, TOP, 0, 0);
// Wait for the popup content to be laid out
ViewUtils.onGlobalLayout(popupContent, () -> {
final Rect cframe = new Rect();
final int[] cloc = new int[2];
popupContent.getLocationOnScreen(cloc);
popupContent.getLocalVisibleRect(cbounds);
popupContent.getWindowVisibleDisplayFrame(cframe);
final int scrollY = ((View) yourTextView.getParent()).getScrollY();
final int[] tloc = new int[2];
yourTextView.getLocationInWindow(tloc);
final int startX = cloc[0] + cbounds.centerX();
final int startY = cloc[1] + cbounds.centerY() - (tloc[1] - cframe.top) - scrollY;
startLoc.set(startX, startY);
final Point ploc = calculatePopupLocation();
popupWindow.update(ploc.x, ploc.y, DEFAULT_WIDTH, DEFAULT_HEIGHT);
});
});
}
}
@Override
public void onTextUnselected() {
popupWindow.dismiss();
}
/** Used to calculate where we should position the {@link PopupWindow} */
private Point calculatePopupLocation() {
final ScrollView parent = (ScrollView) yourTextView.getParent();
// Calculate the selection start and end offset
final int selStart = yourTextView.getSelectionStart();
final int selEnd = yourTextView.getSelectionEnd();
final int min = Math.max(0, Math.min(selStart, selEnd));
final int max = Math.max(0, Math.max(selStart, selEnd));
// Calculate the selection bounds
final RectF selBounds = new RectF();
final Path selection = new Path();
yourTextView.getLayout().getSelectionPath(min, max, selection);
selection.computeBounds(selBounds, true /* this param is ignored */);
// Retrieve the center x/y of the popup content
final int cx = startLoc.x;
final int cy = startLoc.y;
// Calculate the top and bottom offset of the popup relative to the selection bounds
final int popupHeight = cbounds.height();
final int textPadding = yourTextView.getPaddingLeft();
final int topOffset = Math.round(selBounds.top - cy);
final int btmOffset = Math.round(selBounds.bottom - (cy - popupHeight));
// Calculate the x/y coordinates for the popup relative to the selection bounds
final int scrollY = parent.getScrollY();
final int x = Math.round(selBounds.centerX() + textPadding - cx);
final int y = Math.round(selBounds.top - scrollY < cy ? btmOffset : topOffset);
currLoc.set(x, y - scrollY);
return currLoc;
}
/** An {@link ActionMode.Callback} used to remove all action items from text selection */
static final class EmptyActionMode extends SimpleActionModeCallback {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
// Return true to ensure the yourTextView is still selectable
return true;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
// Remove all action items to provide an actionmode-less selection
menu.clear();
return true;
}
}
}
结果
With the action bar (link to video):
Without the action bar (link to video):
奖金 - 动画
因为我们知道PopupWindow 的起始位置和选择更改时的偏移位置，所以我们可以轻松地在两个值之间执行线性插值，以在我们移动物体时创建漂亮的动画。
public static float lerp(float a, float b, float v) {
return a + (b - a) * v;
}
private static final int DEFAULT_ANIM_DUR = 350;
private static final int DEFAULT_ANIM_DELAY = 500;
@Override
public void onTextSelected() {
final View popupContent = popupWindow.getContentView();
if (popupWindow.isShowing()) {
// Calculate the updated x/y pop coordinates
popupContent.getHandler().removeCallbacksAndMessages(null);
popupContent.postDelayed(() -> {
// The current x/y location of the popup
final int currx = currLoc.x;
final int curry = currLoc.y;
// Calculate the updated x/y pop coordinates
final Point ploc = calculatePopupLocation();
currLoc.set(ploc.x, ploc.y);
// Linear interpolate between the current and updated popup coordinates
final ValueAnimator anim = ValueAnimator.ofFloat(0f, 1f);
anim.addUpdateListener(animation -> {
final float v = (float) animation.getAnimatedValue();
final int x = Math.round(AnimUtils.lerp(currx, ploc.x, v));
final int y = Math.round(AnimUtils.lerp(curry, ploc.y, v));
popupWindow.update(x, y, DEFAULT_WIDTH, DEFAULT_HEIGHT);
});
anim.setDuration(DEFAULT_ANIM_DUR);
anim.start();
}, DEFAULT_ANIM_DELAY);
} else {
...
}
}
结果
With the action bar - animation (link to video)
额外
我不讨论如何将点击侦听器附加到弹出操作，并且可能有几种方法可以通过不同的计算和实现来实现相同的效果。但我会提到，如果您想检索选定的文本然后对其进行处理，you'd just need to CharSequence.subSequence the min and max from the selected text。
无论如何，我希望这对您有所帮助！如果您有任何问题，请告诉我。
【讨论】：