Android TextView 文本选择答案

【问题标题】：Android TextView text selectionAndroid TextView 文本选择
【发布时间】：2018-11-16 15:22:17
【问题描述】：

是否有 API 可以在 textview 中设置开始和结束选择（索引），以便它可以调用 CustomSelectionActionMode？p>

根据文档，Selection 类有一个 SetSelection 函数，它接受 3 个参数：spannable、start 和 end。但是如何从 TextView 类中检索 Selection 类呢？

【问题讨论】：

【解决方案1】：

这就是答案，

https://stackoverflow.com/a/22833303/1177865

mTextView.setCustomSelectionActionModeCallback(new Callback() {

    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        // Remove the "select all" option
        menu.removeItem(android.R.id.selectAll);
        // Remove the "cut" option
        menu.removeItem(android.R.id.cut);
        // Remove the "copy all" option
        menu.removeItem(android.R.id.copy);
        return true;
    }

    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        // Called when action mode is first created. The menu supplied
        // will be used to generate action buttons for the action mode

        // Here is an example MenuItem
        menu.add(0, DEFINITION, 0, "Definition").setIcon(R.drawable.ic_action_book);
        return true;
    }

    @Override
    public void onDestroyActionMode(ActionMode mode) {
        // Called when an action mode is about to be exited and
        // destroyed
    }

    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        switch (item.getItemId()) {
            case DEFINITION:
                int min = 0;
                int max = mTextView.getText().length();
                if (mTextView.isFocused()) {
                    final int selStart = mTextView.getSelectionStart();
                    final int selEnd = mTextView.getSelectionEnd();

                    min = Math.max(0, Math.min(selStart, selEnd));
                    max = Math.max(0, Math.max(selStart, selEnd));
                }
                // Perform your definition lookup with the selected text
                final CharSequence selectedText = mTextView.getText().subSequence(min, max);
                // Finish and close the ActionMode
                mode.finish();
                return true;
            default:
                break;
        }
        return false;
    }

});

【讨论】：

我已经添加了 setCustomSelectionActionModeCallback。这部分代码最初是有效的，直到我添加了 Touch 监听器。显然，使用触摸侦听器，长按不再选择文本。因此，我的问题是如何手动设置 SelectionStart 和 SelectionEnd 以便触发 CustomSelectionActionModeCallback。
您覆盖了触摸侦听器，并且控件无法像往常一样流动。你可以发布你的 ontouch 听众吗？我认为这个想法是通过使用 return false 继续将控制权传递给父级。 developer.android.com/reference/android/view/…。示例代码stackoverflow.com/questions/11690504/…

【解决方案2】：

bool LongPress()
{
    if (longpressed == 1)
    {
    int x = (int)downX;
    int y = (int)downY;
    x -= textview.PaddingLeft;
    y -= textview.PaddingTop;
    x += textview.ScrollX;
    y += textview.ScrollY;
    Android.Text.Layout layout = textview.Layout;
    int line = layout.GetLineForVertical(y);
    int off = layout.GetOffsetForHorizontal(line, x);
    var clickspans = ss.GetSpans(off, off, Java.Lang.Class.FromType(typeof(ClickableSpan)));
    if (clickspans.Count() > 0)
    {
        ClickableSpan clickspan = (ClickableSpan)clickspans[0];
        startselection = ss.GetSpanStart(clickspan);
        endselection = ss.GetSpanEnd(clickspan);
        /*
        This is where I intend to add Selection.SetSelection(ss, startselection, endselection);
        */
        //textview.StartActionMode(textview.CustomSelectionActionModeCallback, ActionModeType.Floating);
    }
    longpressed = 2;
    }
    return false;
}

private void TouchLabel(object sender, TouchEventArgs e)
{
    MotionEvent motionevt = e.Event;
    if (MotionEvent.ActionToString(motionevt.Action) == "ACTION_DOWN")
    {
    Device.StartTimer(TimeSpan.FromMilliseconds(500), LongPress);
    longpressed = 1;
    }
    else if (MotionEvent.ActionToString(motionevt.Action) == "ACTION_MOVE")
    {
    longpressed = 2;
    }
    else if ((MotionEvent.ActionToString(motionevt.Action) == "ACTION_UP") || (MotionEvent.ActionToString(motionevt.Action) == "ACTION_CANCEL"))
    {
    if (longpressed == 1)
    {
        longpressed = 2;
    }
    longpressed = 0;
    }
}

这是用 C# 为 Xamarin.Android 编写的。我正在使用计时器来检测“LongPress”，并想在 LongPress 函数中设置“选择/突出显示”。

【讨论】：