Fragment消失時

1. 使用的viewpager or something 使用錯誤的getFragmentManager() or getChildFragmentManager()

2. 該頁Fragment layout可能有異常，嘗試使用ViewGroup包妥善

Android Focus一些概念

android提供了一些焦点相关的属性，在现有的框架层下通过设置View的属性来获得焦点：

• android:focusable：设置一个控件能否获得焦点
• android:nextFocusDown：(当按下键时)下一个获得焦点的控件
• android:nextFocusDown：(当按下键时)下一个获得焦点的控件
• android:nextFocusLeft：(当按下键时)下一个获得焦点的控件
• android:nextFocusRight：(当按下键时)下一个获得焦点的控 **注意：**如果按下某个方向键时，想让焦点停留在自身，可以使用android:nextFocusRight:"@null"或者android:nextFocusRight:"@id/自身id"

這只有在對view是有效的，對viewgroup等類是無效的 原因在於

private View findNextUserSpecifiedFocus(ViewGroup root, View focused, int direction) {
// check for user specified next focus
View userSetNextFocus = focused.findUserSetNextFocus(root, direction);
View cycleCheck = userSetNextFocus;
boolean cycleStep = true; // we want the first toggle to yield false
while (userSetNextFocus != null) {
if (userSetNextFocus.isFocusable()
&& userSetNextFocus.getVisibility() == View.VISIBLE
&& (!userSetNextFocus.isInTouchMode()
|| userSetNextFocus.isFocusableInTouchMode())) {
return userSetNextFocus;
}
userSetNextFocus = userSetNextFocus.findUserSetNextFocus(root, direction);
if (cycleStep = !cycleStep) {
cycleCheck = cycleCheck.findUserSetNextFocus(root, direction);
if (cycleCheck == userSetNextFocus) {
// found a cycle, user-specified focus forms a loop and none of the views
// are currently focusable.
break;
}
}
}
return null;
} 他在搜尋usersetnextfocus是用該focus view去找的 viewgroup自然對於該function就無作用。

一般來說focusSearch是focus主要的來源，如果都不override他就是一路找到decorView?或許吧，使用FocusSearchInstance來找，那個Util會把子Views focusable的全找出來作排序用rect的方式去找最靠近的focus, 除非你有指定id. 原生的四大主件LinearLayout RelativeLayout ...全都沒有複寫這method. 只有Leanback library的元件才有，所以客製化的頁面UI幾乎全都要自己override這method來控制focus。至少我認為是這樣。

@Overridepublic View focusSearch(View focused, int direction) {
    View returnView = null;
    ViewParent trace = focused.getParent();
    while (trace != null) {
        if (trace instanceof SlidingTabLayout) {
            returnView = FocusFinder.getInstance().findNextFocus((ViewGroup) trace, focused, direction);            break;        } else if (trace instanceof ViewPager) {
            returnView = FocusFinder.getInstance().findNextFocus((ViewGroup) trace, focused, direction);            break;        }
        trace = trace.getParent();    }

    if (trace instanceof SlidingTabLayout && direction == View.FOCUS_DOWN) {
        return pager;    }

    if (trace instanceof ViewPager && direction == View.FOCUS_UP) {
        return tabs.getSelectedView();    }

    return returnView == null ? super.focusSearch(focused, direction) : returnView;}

以上是一些客製化的範例。

The concept of using Google api using javascript.

There are 2 stand ways to call the google-apis,

https://developers.google.com/identity/protocols/OAuth2

1. Use oauth client
2. Use oauth server-to server applications

Concept.

For 1. The oauth flows are pretty standard for any oauth2 applications.
First you ask permission to the user that granted you to access the calendar.
Then there is a access_token and a refresh_token.
So that you can access user’s calendar via that access_token.

For 2. This is under the G-suite admin authority to manipulating G-suite users data
using a delegated account.
Create a service account and let that account has access to the data you want to manipulate.

The flow charts are

For 1.
Get token using oauth2  => Initialize an google-apis client with token and scopes =>
Use client to send the api

For 2.
Create Service Account Client in the google console =>
Create Security in G-suite app using G-suite admin account =>
JWT can make request to access G-suite users

There are 3  approach ways.

1. Using javascript under the react app. https://developers.google.com/identity/protocols/OAuth2UserAgent
2. Using JWT in node.js.
   https://neal.codes/blog/google-calendar-api-on-g-suite/
   
3. Using googleapis in could-functions in node.js.

Implementation details.

For 2.

1. To create a service account as a delegate.
2. Use the credential to authorize the JWTclient.
3. Add that service account to the calendar you want to manipulate.
4. Manipulate calendar using AWT like google apis.

Reference of creating google calendar, setup gcp project.

https://dev.to/megazear7/google-calendar-api-integration-made-easy-2a68