添加触控支持

要处理触控输入事件，请阅读游戏循环中的 motionEvents 数组。它们包含自上次清空这些数组以来发生的事件。所含事件的数量存储在 motionEventsCount 中。

1. 迭代和处理游戏循环中的每个事件。在此示例中，以下代码会迭代 motionEvents 并通过 handle_event 进行处理：

   for(size_t i = 0; i < mApp->motionEventsCount; ++i) {
     GameActivityMotionEvent* motionEvent = mApp->motionEvents[i];
   
     int action = motionEvent->action;
     int actionMasked = action & AMOTION_EVENT_ACTION_MASK;
     int ptrIndex = (action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK) >>
       AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
   
     struct CookedEvent ev;
     memset(&ev, 0, sizeof(ev));
   
     if (actionMasked == AMOTION_EVENT_ACTION_DOWN ||
       actionMasked == AMOTION_EVENT_ACTION_POINTER_DOWN) {
         ev.type = COOKED_EVENT_TYPE_POINTER_DOWN;
     } else if (actionMasked == AMOTION_EVENT_ACTION_UP ||
       actionMasked == AMOTION_EVENT_ACTION_POINTER_UP) {
         ev.type = COOKED_EVENT_TYPE_POINTER_UP;
     } else {
         ev.type = COOKED_EVENT_TYPE_POINTER_MOVE;
     }
   
     ev.motionPointerId = motionEvent->pointers[ptrIndex].id;
     ev.motionIsOnScreen = motionEvent->source == AINPUT_SOURCE_TOUCHSCREEN;
     ev.motionX = GameActivityPointerInfo_getX(
       &motionEvent->pointers[ptrIndex]);
     ev.motionY = GameActivityPointerInfo_getY(
       &motionEvent->pointers[ptrIndex]);
   
     if (ev.motionIsOnScreen) {
       // Use screen size as the motion range.
       ev.motionMinX = 0.0f;
       ev.motionMaxX = SceneManager::GetInstance()->GetScreenWidth();
       ev.motionMinY = 0.0f;
       ev.motionMaxY = SceneManager::GetInstance()->GetScreenHeight();
     }
   
     handle_event(&ev);
   }
   

2. 操作完成后，请记得清除刚刚处理的事件队列：

   android_app_clear_motion_events(mApp);