android - 如何在android中创建像键盘键这样的按钮？

Question

这个问题看起来微不足道。我想为我的应用程序创建一个类似键盘键的按钮。当我单击它时，该按钮上方会出现一个弹出窗口，显示按下的字母。到目前为止，一切都很好，除了一件事。当我将 onFocusChangedListener 添加到按钮时，没有任何反应。我需要让我的按钮充当键盘键，但我不知道该怎么做。

正如您在此处看到的，当按钮获得焦点时，会出现一个弹出窗口。我想这样做，但是 onFocusChangeListener 不起作用。我知道我可以使用 KeyboardView 来实现这一点，但我不想使用它，因为有一些其他问题，例如居中按钮和使用 layout_weight 设置键的高度。所以我需要用普通按钮来制作它。

我尝试了什么:

我的第一次尝试:

button.setOnFocusChangeListener(new View.OnFocusChangeListener() {
    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if (hasFocus) {
            popupWindow.showAtLocation(keyboardPopup, Gravity.NO_GRAVITY, location.left - 10, location.top - button.getHeight());
        } else {
            popupWindow.dismiss();
        }
    }
});

结果: 什么都没发生。弹出窗口根本没有出现。

编辑: 在我按照 Ashley 的建议添加了 button.setFocusableInTouchMode(true); 之后，onFocusChanged 现在被调用了，但它起作用了太奇怪了。弹出窗口有时显示，但在显示的同时，它永远不会消失...

我的第二次尝试:

button.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                popupWindow.showAtLocation(keyboardPopup, Gravity.NO_GRAVITY, location.left - 10, location.top - button.getHeight());
                break;
            case MotionEvent.ACTION_UP:
                popupWindow.dismiss();
                break;
        }
        return true;
    }
});

结果: 这只怪怪的。弹出窗口有时会显示，有时不会，但是当它显示时，按钮也不会改变其状态。它应该已经聚焦，但按钮没有任何变化，它就像处于正常状态一样(按钮的背景不会随着我的可绘制 xml 中声明的 state_focused 而改变)。 onTouchListener 似乎覆盖了按钮的功能。

这是我的布局的一部分:

<LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="3">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="Q"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="W"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="E"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="R"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="T"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="Y"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="U"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="I"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="O"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="P"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <View
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="0.5" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="A"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="S"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="D"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="F"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="G"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="H"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="J"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="K"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="L"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <View
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="0.5" />

    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <View
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1.5" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="Z"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="X"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="C"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="V"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="B"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="N"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <Button
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="M"
            android:background="@drawable/keyboard_button"
            android:textColor="#FFFFFF"
            android:onClick="onKeyboardClick" />

        <View
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1.5" />

    </LinearLayout>

</LinearLayout>

在代码中:

public void onKeyboardClick(View view) {
    //The view pressed is a button.
    final Button button = (Button) view;

    //Create a PopupWindow.
    LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
    final View keyboardPopup = inflater.inflate(R.layout.keyboard_popup, null);
    final PopupWindow popupWindow = new PopupWindow(keyboardPopup, view.getWidth() + 20, view.getHeight());
    TextView keyboardKey = (TextView) keyboardPopup.findViewById(R.id.keyboard_key);
    keyboardKey.setText(button.getText().toString());

    //Get button location to show the popup above it.
    int[] keyLocation = new int[2];
    button.getLocationOnScreen(keyLocation);
    final Rect location = new Rect();
    location.left = keyLocation[0];
    location.top = keyLocation[1];
    location.right = location.left + button.getWidth();
    location.bottom = location.top + button.getHeight();

    //This is a temporary solution. I don't want to use that.
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //Show popup.
            popupWindow.showAtLocation(keyboardPopup, Gravity.NO_GRAVITY, location.left - 10, location.top - button.getHeight());
            Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    //Dismiss popup.
                    popupWindow.dismiss();
                }
            }, 200);
        }
    });
}

任何帮助将不胜感激。谢谢。

Answer 1

我建议你用第二次试试onTouchListener ! 你有 2 个问题:

<强>1。按钮不改变状态

确实，当您覆盖 onTouchListener你必须自己模拟状态。请看一下这个 SO 线程，了解它是如何完成的: "Press and hold" button on Android needs to change states (custom XML selector) using onTouchListener

<强>2。有时显示有时不显示

这不应该发生，特别是如果您正确处理所有相关的触摸事件情况。您需要在用户按下按钮时显示弹出窗口，并在用户移出按钮(通过向外滑动或将手指离开屏幕)时隐藏弹出窗口。

请尝试以下代码示例:

button.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                v.setPressed(true);
                showPopupWindow(...);
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_OUTSIDE:
            case MotionEvent.ACTION_CANCEL:
                v.setPressed(false);
                hidePopupWindow(...);
                break;
        }
        return true;
    }
});

• 注意 getActionMasked 的使用而不是 getAction更好地处理多点触控。
• 注意 v.setPressed(...); - 这将更新按钮状态。
• 注意隐藏弹出窗口的不同情况。