PopupWindow返回键和点击外部无法消失

今天查看项目代码，看到这个PopupWindow 让我想起了当初碰到的一个坑：PopupWindow 点击外部和返回键无法消失。现在闲暇记录一下：为PopupWindow 设置一个背景

popupWindow.setBackgroundDrawable(drawable)；

就这么简单 -_-

从源码上分析一下：

先看看弹出框显示的时候代码showAsDropDown，里面有个preparePopup方法

public void showAsDropDown(View anchor, int xoff, int yoff, int gravity) {
if (isShowing() || mContentView == null) {
return;
}

registerForScrollChanged(anchor, xoff, yoff, gravity);

mIsShowing = true;
mIsDropdown = true;

WindowManager.LayoutParams p = createPopupLayout(anchor.getWindowToken());
preparePopup(p);

updateAboveAnchor(findDropDownPosition(anchor, p, xoff, yoff, gravity));

if (mHeightMode < 0) p.height = mLastHeight = mHeightMode;
if (mWidthMode < 0) p.width = mLastWidth = mWidthMode;

p.windowAnimations = computeAnimationResource();

invokePopup(p);
}

再看preparePopup方法

/**
* <p>Prepare the popup by embedding in into a new ViewGroup if the
* background drawable is not null. If embedding is required, the layout
* parameters' height is modified to take into account the background's
* padding.</p>
*
* @param p the layout parameters of the popup's content view
*/
private void preparePopup(WindowManager.LayoutParams p) {
if (mContentView == null || mContext == null || mWindowManager == null) {
throw new IllegalStateException("You must specify a valid content view by "
+ "calling setContentView() before attempting to show the popup.");
}

if (mBackground != null) {
final ViewGroup.LayoutParams layoutParams = mContentView.getLayoutParams();
int height = ViewGroup.LayoutParams.MATCH_PARENT;
if (layoutParams != null &&
layoutParams.height == ViewGroup.LayoutParams.WRAP_CONTENT) {
height = ViewGroup.LayoutParams.WRAP_CONTENT;
}

// when a background is available, we embed the content view
// within another view that owns the background drawable
PopupViewContainer popupViewContainer = new PopupViewContainer(m
4000
Context);
PopupViewContainer.LayoutParams listParams = new PopupViewContainer.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT, height
);
popupViewContainer.setBackground(mBackground);
popupViewContainer.addView(mContentView, listParams);

mPopupView = popupViewContainer;
} else {
mPopupView = mContentView;
}

mPopupView.setElevation(mElevation);
mPopupViewInitialLayoutDirectionInherited =
(mPopupView.getRawLayoutDirection() == View.LAYOUT_DIRECTION_INHERIT);
mPopupWidth = p.width;
mPopupHeight = p.height;
}

上面可以看到mBackground不为空的时候，会PopupViewContainer作为mContentView的Parent，下面看看PopupViewContainer到底干了什么

private class PopupViewContainer extends FrameLayout {
private static final String TAG = "PopupWindow.PopupViewContainer";

public PopupViewContainer(Context context) {
super(context);
}

@Override
protected int[] onCreateDrawableState(int extraSpace) {
if (mAboveAnchor) {
// 1 more needed for the above anchor state
final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
View.mergeDrawableStates(drawableState, ABOVE_ANCHOR_STATE_SET);
return drawableState;
} else {
return super.onCreateDrawableState(extraSpace);
}
}

@Override
public boolean dispatchKeyEvent(KeyEvent event) {　　// 这个方法里面实现了返回键处理逻辑，会调用dismiss
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
if (getKeyDispatcherState() == null) {
return super.dispatchKeyEvent(event);
}

if (event.getAction() == KeyEvent.ACTION_DOWN
&& event.getRepeatCount() == 0) {
KeyEvent.DispatcherState state = getKeyDispatcherState();
if (state != null) {
state.startTracking(event, this);
}
return true;
} else if (event.getAction() == KeyEvent.ACTION_UP) {
KeyEvent.DispatcherState state = getKeyDispatcherState();
if (state != null && state.isTracking(event) && !event.isCanceled()) {
dismiss();
return true;
}
}
return super.dispatchKeyEvent(event);
} else {
return super.dispatchKeyEvent(event);
}
}

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (mTouchInterceptor != null && mTouchInterceptor.onTouch(this, ev)) {
return true;
}
return super.dispatchTouchEvent(ev);
}

@Override
public boolean onTouchEvent(MotionEvent event) { // 这个方法里面实现点击消失逻辑
final int x = (int) event.getX();
final int y = (int) event.getY();

if ((event.getAction() == MotionEvent.ACTION_DOWN)
&& ((x < 0) || (x >= getWidth()) || (y < 0) || (y >= getHeight()))) {
dismiss();
return true;
} else if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
dismiss();
return true;
} else {
return super.onTouchEvent(event);
}
}

@Override
public void sendAccessibilityEvent(int eventType) {
// clinets are interested in the content not the container, make it event source
if (mContentView != null) {
mContentView.sendAccessibilityEvent(eventType);
} else {
super.sendAccessibilityEvent(eventType);
}
}
}

看到上面红色部分的标注可以看出，这个内部类里面封装了处理返回键退出和点击外部退出的逻辑，但是这个类对象的构造过程中（preparePopup方法中）却有个mBackground != null的条件才会创建

而mBackground对象在setBackgroundDrawable方法中被赋值，看到这里应该就明白一切了。