前言
平時我們對View的顯示判斷都是用簡要的方式去判斷，那么勃教，究竟是用view.isShown()去判斷還是用view.
getVisibility() == View.VISIBLE 判斷好呢？其實可以來看看源碼
源碼
- isShow()
/**
* Returns the visibility of this view and all of its ancestors
*
* @return True if this view and all of its ancestors are {@link #VISIBLE}
*/
public boolean isShown() {
View current = this;
//noinspection ConstantConditions
do {
if ((current.mViewFlags & VISIBILITY_MASK) != VISIBLE) {
return false;
}
ViewParent parent = current.mParent;
if (parent == null) {
return false; // We are not attached to the view root
}
if (!(parent instanceof View)) {
return true;
}
current = (View) parent;
} while (current != null);
return false;
}
可以看出注釋
只有當view本身以及它的所有祖先們都是visible時画恰，isShown()才返回TRUE证九。
- View.VISIBLE
/**
* This view is visible.
* Use with {@link #setVisibility} and <a href="#attr_android:visibility">{@code
* android:visibility}.
*/
public static final int VISIBLE = 0x00000000;
而平常我們調(diào)用if(view.getVisibility() == View.VISIBLE)只是對view本身而不對祖先的可見性進行判斷删豺。
總結(jié)
其實精煉總結(jié)成一句話就是共虑，要判斷用戶能否看見某個view愧怜，應(yīng)使用isShown()。
