code: private void requestActivityTransparent() {
          try {
              Intent intent = getIntent();
              if (intent != null && intent.getBooleanExtra(EXTRA_IS_FULLSCREEN, false)) {
                  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
              }
              requestWindowFeature(Window.FEATURE_NO_TITLE);
              Window window = getWindow();
              if (window != null) {
                  window.addFlags(0x04000000);
              }
          } catch (Exception e) {
              HMSAgentLog.w("requestActivityTransparent exception:" + e.getMessage());
          }
      }
docs: 启用透明的跳板Activity