Interface activity cycle

Before introducing the activity cycle of the interface, let's first understand the hierarchical relationship of the interface

First of all, after our application is started, we will first enter the interface corresponding to mainActivity which is the startup interface, and then open the interface corresponding to subActivity through the openActivity method, and then enter the interface corresponding to thirdActivity, It forms the hierarchical effect seen in the figure above;The interface opened later is at the upper level of the hierarchy, and a relationship of Stack is formed between them;

Activity flow when opening the interface

Let's take a look at the process of the program after calling the openActivity method. Here are two situations:

  • Does not exist the interface to be opened in the interface stack;

Let’s first take a look at in onUI_init function,Only when the interface does not exist in the interface stack, this function will be used when it is opened for the first time. Going here means that all control pointers are initialized. In this function, we can start to perform some operations on them. as follows:

static void onUI_init() {
    //Tips :Add the display code of UI initialization here, such as:mTextView1Ptr->setText("123");
    LOGD("sub onUI_init\n");

When the interface is opened, data is passed over and received and processed in the, onUI_intent callback function:

static void onUI_intent(const Intent *intentPtr) {
    LOGD("sub onUI_intent\n");
    // Judge not empty
    if (intentPtr) {
        // Key value analysis
        std::string cmd = intentPtr->getExtra("cmd");        // "open"
        std::string value = intentPtr->getExtra("value");    // "ok"

Interface display completion callback onUI_show function;

  • There is the interface to be opened in the interface stack;

In this case, only the corresponding interface in the interface stack is moved to the top level, and the onUI_init process is not followed;

Open to display an interface, which means that the previous top-level interface is hidden; assuming that The mainActivity interface opens the subActivity interface, and their activity flow is as follows:

Here we focus on the mainActivity interface hide ------> subActivity interface display process;

Activity flow when closing the interface

When we call the goBack() function, the top-level interface will pop up until the interface is started;

When the interface is closed, the onUI_quit function will be called back. If some resources are requested after the interface is opened, remember to release it here;

After exiting the top-level interface, the next-level interface will be displayed, that is, the onUI_show interface of the next-level interface will be called back;

When we call the goHome() function, we will directly go back to the startup interface and pop up all other interfaces;

When we call the closeActivity("xxx") function, we can remove any interface except the startup interface; when the interface is not the top-level interface, the next-level interface will not goonUI_show;

powered by Gitbooklast modified: 2021-05-28 12:00:31

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