好久没写博客了,来一篇有问题搞不懂就要看!源!码!系列
之前一直搞不懂为什么PopupWindow一定要设置Background才能实现点击其他地方消失的效果,后来在老师的带领下看了下源码,豁然开朗(虽然还有些地方搞不懂)。
在PopupWindow类里有一个方法叫preparePopup(),对mBackground做了判断,若其不为空,则将mContentView嵌入到一个PopupViewContainer中。否则不执行此操作。具体代码如下:
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/**
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* <p>Prepare the popup by embedding in into a new ViewGroup if the
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* background drawable is not null. If embedding is required, the layout
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* parameters' height is modified to take into account the background's
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* padding.</p>
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*
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* @param p the layout parameters of the popup's content view
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*/
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private void preparePopup(WindowManager.LayoutParams p) {
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if (mContentView == null || mContext == null || mWindowManager == null) {
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throw new IllegalStateException("You must specify a valid content view by "
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+ "calling setContentView() before attempting to show the popup.");
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}
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if (mBackground != null) {
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final ViewGroup.LayoutParams layoutParams = mContentView.getLayoutParams();
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int height = ViewGroup.LayoutParams.MATCH_PARENT;
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if (layoutParams != null &&
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layoutParams.height == ViewGroup.LayoutParams.WRAP_CONTENT) {
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height = ViewGroup.LayoutParams.WRAP_CONTENT;
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}
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// when a background is available, we embed the content view
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// within another view that owns the background drawable
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PopupViewContainer popupViewContainer = new PopupViewContainer(mContext);
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PopupViewContainer.LayoutParams listParams = new PopupViewContainer.LayoutParams(
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ViewGroup.LayoutParams.MATCH_PARENT, height
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);
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popupViewContainer.setBackground(mBackground);
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popupViewContainer.addView(mContentView, listParams);
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mPopupView = popupViewContainer;
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} else {
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mPopupView = mContentView;
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}
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mPopupView.setElevation(mElevation);
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mPopupViewInitialLayoutDirectionInherited =
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(mPopupView.getRawLayoutDirection() == View.LAYOUT_DIRECTION_INHERIT);
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mPopupWidth = p.width;
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mPopupHeight = p.height;
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}
再看下PopupViewContainer的代码:
它里面注册了Touch事件,这下就大概明白了。如果我们不设置background的话,mContentView就不会被放入PopupViewContainer,
自然响应不了触摸事件,也就不会消失了。具体还是看代码吧:
所以说,源码才是王道。但我搞不懂的地方是,为啥一定要设置了背景才把mContentView加到PopupViewContainer中,有了解的朋友们请指教。
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