前言
很多时候我们需要知道软键盘是否打开和关闭，从而处理一些需求。之前在做shou app的时候，由于交互比较复杂，需要知道软键盘是开启或者关闭，决定是否让视频全屏，还是让聊天室全屏，或者是正常显示(上面是视频，下面是聊天室)
ViewTreeObserver.OnGlobalLayoutListener
OnGlobalLayoutListener 是ViewTreeObserver的内部类，当一个视图树的布局发生改变时，可以被ViewTreeObserver监听到，这是一个注册监听视图树的观察者(observer)，在视图树的全局事件改变时得到通知。ViewTreeObserver不能直接实例化，而是通过getViewTreeObserver()获得。
以上是说明，摘抄自http://www.cnblogs.com/superle/p/4567400.html这篇文章，也就是说，通过这个api，我们可以知道view的布局状态变化
如何监听软键盘
KeyboardChangeListener github上有这样的一个轮子，测试了下，的确有效，思路是，对android.R.id.content所对应的view设置监听，监听它的高度变化，计算比较，来确定软件盘是否弹起或者收拢了。这种模式需要设置activity
android:windowSoftInputMode="adjustResize"
full screen模式下如何监听软件盘
在full screen 状态上，发现，以上的方案完全不起作用了。在https://pspdfkit.com/blog/2016/keyboard-handling-on-android/ 上找到了解决办法。
大致上说的是full screen模式下，adjustResize不会生效了，window不会resize的。
getWindowVisibleDisplayFrame(Rect)这个api可以获取到view所在的区域，通过它比较每次区域的变化，可以实现监听软键盘是否可见
完整代码为:
public class KeyBoardChangeListener implements ViewTreeObserver.OnGlobalLayoutListener {
private static final String TAG = "KeyBoardChangeListener";
// Threshold for minimal keyboard height.
final int MIN_KEYBOARD_HEIGHT_PX = 150;
private final Rect windowVisibleDisplayFrame = new Rect();
// Top-level window decor view.
private View decorView;
private int lastVisibleDecorViewHeight;
private KeyBoardListener keyBoardListener;
KeyBoardChangeListener(Activity activity) {
if (activity == null) {
Log.e(TAG, "activity is null");
return;
}
decorView = activity.getWindow().getDecorView();
decorView.getViewTreeObserver().addOnGlobalLayoutListener(this);
}
public void setKeyBoardListener(KeyBoardListener keyBoardListener) {
this.keyBoardListener = keyBoardListener;
}
@Override
public void onGlobalLayout() {
// Retrieve visible rectangle inside window.
decorView.getWindowVisibleDisplayFrame(windowVisibleDisplayFrame);
final int visibleDecorViewHeight = windowVisibleDisplayFrame.height();
// Decide whether keyboard is visible from changing decor view height.
if (lastVisibleDecorViewHeight != 0) {
if (lastVisibleDecorViewHeight > visibleDecorViewHeight + MIN_KEYBOARD_HEIGHT_PX) {
// Calculate current keyboard height (this includes also navigation bar height when in fullscreen mode).
int currentKeyboardHeight = decorView.getHeight() - windowVisibleDisplayFrame.bottom;
// Notify listener about keyboard being shown.
if (keyBoardListener != null) {
keyBoardListener.onKeyboardChange(true, currentKeyboardHeight);
}
} else if (lastVisibleDecorViewHeight + MIN_KEYBOARD_HEIGHT_PX < visibleDecorViewHeight) {
// Notify listener about keyboard being hidden.
if (keyBoardListener != null) {
keyBoardListener.onKeyboardChange(false, 0);
}
}
}
// Save current decor view height for the next call.
lastVisibleDecorViewHeight = visibleDecorViewHeight;
}
public interface KeyBoardListener {
/**
* call back
*
* @param isShow true is show else hidden
* @param keyboardHeight keyboard height
*/
void onKeyboardChange(boolean isShow, int keyboardHeight);
}
}
相关参考
https://pspdfkit.com/blog/2016/keyboard-handling-on-android/
KeyboardChangeListener
https://gist.github.com/xingstarx/7a535fdda432e7678b53c628099c96ab