Flutter TextFormField 为错误文本添加填充

Question

I have a Form elements like this

The error message stacks up like this

Is there any way to adding small padding around the error text?

This is the widget

 Card(
                              color: Colors.white.withOpacity(0.9),
                              shadowColor: Colors.grey.withOpacity(0.2),
                              elevation: 15,
                              child: TextFormField(
                                style: TextStyle(
                                  fontSize: _screenFontSize,
                                ),
                                decoration: InputDecoration(
                                    border: InputBorder.none,
                                    prefixIcon: Icon(
                                      Icons.email_outlined,
                                      color: Colors.grey,
                                    ),
                                    hintText: "example@website.com",
                                    labelText: "EMAIL",
                                    labelStyle: TextStyle(color: Colors.grey)),
                                keyboardType: TextInputType.emailAddress,
                                // The validator receives the text that the user has entered.
                                validator: (value) {
                                  if (value == null ||
                                      value.isEmpty ||
                                      !value.contains('@') ||
                                      !value.contains('.')) {
                                    return 'Please enter a valid Email';
                                  }
                                  return null;
                                },
                              ),
                            ),

Answer 1

UPDATE:

If you are fine with hacky approaches, use your error string like this,

return '    Please enter a valid Email\n';

Actual Explanation:

As per the current implementation, this is not possible in Flutter .

Explanation:

If you check the source code for TextFormField and find out the Widget responsible for rendering the error string, you will come to the following file.

flutter/lib/src/material/input_decorator.dart

Now, if you check how it renders the error message,

if (widget.errorText != null) {
  return Stack(
    children: <Widget>[
      Opacity(
        opacity: 1.0 - _controller.value,
        child: _helper,
      ),
      _buildError(),
    ],
  );
}

Here, _buildError is as such,

Widget _buildError() {
  assert(widget.errorText != null);
  return Semantics(
    container: true,
    liveRegion: true,
    child: Opacity(
      opacity: _controller.value,
      child: FractionalTranslation(
        translation: Tween<Offset>(
          begin: const Offset(0.0, -0.25),
          end: Offset.zero,
        ).evaluate(_controller.view),
        child: Text(
          widget.errorText!,
          style: widget.errorStyle,
          textAlign: widget.textAlign,
          overflow: TextOverflow.ellipsis,
          maxLines: widget.errorMaxLines,
        ),
      ),
    ),
  );
}

Now it you notice the actual Text widget being built, you will find that it is just wrapped inside an Opacity and FractionalTranslation .

Now, FractionalTranslation could've possibly allowed us to slightly alter the position of the Text widget, but if you notice, the translation is hardcoded to animate between a Tween and as such is not open to changes through any properties.

So, unfortunately, not possible.