按钮隐藏TextFormField

点击txt7按钮保存隐藏字段后,我在底部工作表中有按钮保存。我总是想在页面上显示“保存”按钮。

  Scaffold(
    bottomSheet: SAVE_BUTTON here
    ),
    body: SingleChildScrollView(
      scrollDirection: Axis.vertical,
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Form(
              key: _formKey,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.start,
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Text(
                    'Label 1',
                    style: TextStyle(
                      fontSize: 16,
                      fontWeight: FontWeight.normal,
                    ),
                  ),
                  MyTextInputChange(
                    controller: txt1,
                    keyboardType: TextInputType.number,
                    enable: true,
                    autofocus: false,
                    required: false,
                    onChange: (value) {
                      setState(() {});
                    },
                  ),
                  .............
                      

任何解决方案,如何将txt7推到上方按钮SAVE的高度?