Delphi Android程序启动过程

function android_app_entry(param: Pointer): Pointer; cdecl;
 
// Delphi: init system unit and RTL.
procedure SystemEntry;
type
TMainFunction = procedure;
var
DlsymPointer: Pointer;
EntryPoint: TMainFunction;
begin
DlsymPointer := dlsym(RTLD_DEFAULT, '_NativeMain');
if DlsymPointer <> nil then
begin
EntryPoint := TMainFunction(DlsymPointer);
EntryPoint;
end;
end;
 
var
android_app: Pandroid_app;
looper: PALooper;
begin
android_app := Pandroid_app(param);
android_app^.config := AConfiguration_new;//创建应用程序config
AConfiguration_fromAssetManager(android_app^.config, android_app^.activity^.assetManager);
 
 //从主线程获取消息用
android_app^.cmdPollSource.id := LOOPER_ID_MAIN;
android_app^.cmdPollSource.app := android_app;
android_app^.cmdPollSource.process := @process_cmd;//设置处理cmd的命令的函数
android_app^.inputPollSource.id := LOOPER_ID_INPUT;
android_app^.inputPollSource.app := android_app;
android_app^.inputPollSource.process := @process_input;//输入事件处理的函数
 
 //创建一个looper消息循环，用来抓取消息
looper := ALooper_prepare(ALOOPER_PREPARE_ALLOW_NON_CALLBACKS);
ALooper_addFd(looper, android_app^.msgread, LOOPER_ID_MAIN, ALOOPER_EVENT_INPUT, nil, @android_app^.cmdPollSource);
android_app^.looper := looper;
 
pthread_mutex_lock(android_app^.mutex);
android_app^.running := 1; //设置，让线程从等待开启运行中退出，也就是从android_app_create中退出
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
 
{ Delphi: this will initialize System and any RTL related functions, call unit initialization sections and then
project main code, which will enter application main loop. This call will block until the loop ends, which is
typically signalled by android_app^.destroyRequested. }
SystemEntry;//这里才是调用了工程文件的Begin End之间的代码，是Delphi的一个封装，实际上，在Android Native中调用的是android_main(android_app);然后再这里执行一些消息的处理，等待程序运行结束
{ This place would be ideal to call unit finalization, class destructors and so on. }
// Halt;
 
android_app_destroy(android_app);//销毁android_app退出线程。这里实际上才是Android程序的终结
 
Result := nil;
end;

function android_app_read_cmd(android_app: Pandroid_app): ShortInt; cdecl;
var
cmd: ShortInt;
begin
Result := -1;
if __read(android_app^.msgread, @cmd, sizeof(cmd)) = SizeOf(cmd) then
begin
case cmd of
APP_CMD_SAVE_STATE:
free_saved_state(android_app);//释放当前的保存状态
end;
Result := cmd;
end;
end;
 
procedure android_app_pre_exec_cmd(android_app: Pandroid_app; cmd: ShortInt); cdecl; //准备执行命令状态
begin
case cmd of
APP_CMD_INPUT_CHANGED:
begin
pthread_mutex_lock(android_app^.mutex);
if android_app^.inputQueue <> nil then
AInputQueue_detachLooper(android_app^.inputQueue);
android_app^.inputQueue := android_app^.pendingInputQueue;
if android_app^.inputQueue <> nil then
AInputQueue_attachLooper(android_app^.inputQueue, android_app^.looper, LOOPER_ID_INPUT, nil,
@android_app^.inputPollSource);
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
end;
 
APP_CMD_INIT_WINDOW:
begin
pthread_mutex_lock(android_app^.mutex);
android_app^.window := android_app^.pendingWindow;
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
end;
 
APP_CMD_TERM_WINDOW:
pthread_cond_broadcast(android_app^.cond);
 
APP_CMD_RESUME, APP_CMD_START, APP_CMD_PAUSE, APP_CMD_STOP:
begin
pthread_mutex_lock(android_app^.mutex);
android_app^.activityState := cmd;
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
end;
 
APP_CMD_CONFIG_CHANGED:
AConfiguration_fromAssetManager(android_app^.config, android_app^.activity^.assetManager);
 
APP_CMD_DESTROY:
android_app^.destroyRequested := 1;
end;
end;
 
procedure android_app_post_exec_cmd(android_app: Pandroid_app; cmd: ShortInt); cdecl;
begin
case cmd of
APP_CMD_TERM_WINDOW:
begin
pthread_mutex_lock(android_app^.mutex);
android_app^.window := nil;
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
end;
 
APP_CMD_SAVE_STATE:
begin
pthread_mutex_lock(android_app^.mutex);
android_app^.stateSaved := 1;
pthread_cond_broadcast(android_app^.cond);
pthread_mutex_unlock(android_app^.mutex);
end;
 
APP_CMD_RESUME:
{ Delphi: It is unclear why this line is necessary in original AppGlue, but it prevents FireMonkey applications
from recovering saved state. FireMonkey recovers saved state usually after APP_CMD_INIT_WINDOW, which happens
much later after CMD_RESUME. }
{ free_saved_state(android_app) };
end;
end;
 
procedure process_cmd(app: Pandroid_app; source: Pandroid_poll_source); cdecl;
var
cmd: ShortInt;
begin
cmd := android_app_read_cmd(app);//先读取命令
android_app_pre_exec_cmd(app, cmd);//准备命令
if Assigned(app^.onAppCmd) then //程序内部的指令处理
app^.onAppCmd(app, cmd);
android_app_post_exec_cmd(app, cmd);//执行处理
end;

procedure TApplication.Run;
var
AppService: IFMXApplicationService;
begin
{$IFNDEF ANDROID}
AddExitProc(DoneApplication);
{$ENDIF}
FRunning := True;
try
if TPlatformServices.Current.SupportsPlatformService(IFMXApplicationService, AppService) then
AppService.Run;
finally
FRunning := False;
end;
end;

procedure TPlatformAndroid.Run;
begin
{ Although calling this routine is not really necessary, but it is a way to ensure that "Androidapi.AppGlue.pas" is
kept in uses list, in order to export ANativeActivity_onCreate callback. }
app_dummy;
 
repeat
InternalProcessMessages;
until FAndroidApp^.destroyRequested <> 0;
end;