Flutter: Fix CupertinoAlertDialog Scrollbar With HintText

Hey guys, let's dive into a quirky issue I stumbled upon while working with Flutter, specifically when using CupertinoAlertDialog and the adaptive_dialog package. This bug specifically pops up when you throw a hintText into the mix with DialogTextField and it's causing a vertical scrollbar to appear where it shouldn't. I'm using Flutter 3.33 and adaptive_dialog version 2.4.2, so if you're on a similar setup, this might hit home.

The Problem: Unwanted Scrollbars with HintText

So, here's the deal. I've been loving the adaptive_dialog package – it's been a real lifesaver. But recently, I noticed something weird. When I use showTextInputDialog (the Cupertino version), and I include hintText in my DialogTextField, a vertical scrollbar magically appears. The kicker? If I remove the hintText, the scrollbar vanishes. It's like the hintText is playing some kind of layout Tetris, slightly shrinking the content area just enough to force a scroll. And trust me, it's not supposed to do that! When everything fits comfortably, there shouldn't be a scrollbar. This issue makes the dialog look a little off and disrupts the user experience, especially when you expect a clean, scroll-free interface. We're talking about making the user experience as smooth as butter, right? Now let's talk about the nitty-gritty details of the issue.

It's like this: you've got a simple DialogTextField with a hintText. You expect everything to fit nicely, but boom – a scrollbar. Without the hint, it's all good. It's as if adding that little hint makes the content area just a tad smaller, which triggers the scroll. I've provided a code snippet below, and images to better show what is going on.

Reproducing the Bug

Here's the simplified code that showcases the problem. I’ve stripped away everything unnecessary to focus on the core issue. This is a basic example that reproduces the error, making it easier to pinpoint the root cause. This way, you can quickly check if you're seeing the same behavior on your end. Basically, it shows a simple dialog with two text fields, one with a hintText and one without, to demonstrate the difference.

showTextInputDialog(
  textFields: [
    DialogTextField(
      //hintText: "Hint",
    ),
    DialogTextField(
      obscureText: true,
      autocorrect: false,
    )
  ],
  builder: (context, child) {
    return CupertinoTheme(
      data: CupertinoTheme.of(context).copyWith(
        primaryColor: Colors.black87, // OK·Cancel 글자색
      ),
      child: child,
    );
  },
  context: context,
  title: "Title",
  message: "Message"
);

If you uncomment the hintText: "Hint", line, the scrollbar shows up. Comment it out, and it's gone. The images above perfectly highlight the problem, clearly showing the scrollbar's unwanted presence when the hintText is active.

Expected vs. Actual Behavior

Let’s get this straight, the expected behavior is straightforward: providing a hintText shouldn't mess with the dialog's layout enough to force scrolling when content fits without it. The dialog should just size itself to fit the content neatly without any scrollbars. Ideally, adding a hintText to your text field should not change how your dialog looks or behaves. The appearance of the dialog shouldn't change, and it should fit everything without any scrollbars. The visual experience should be consistent regardless of whether you use hintText or not.

However, the actual behavior is different, the content area is reduced just enough to trigger an internal scroll view, and a vertical scrollbar appears. It's as if the dialog is miscalculating the space it needs when a hint is present. It does not matter the content length, if a hintText exists, the scrollbar will show up. This unexpected scrollbar disrupts the flow and makes the dialog less user-friendly. I'm hoping that the package maintainers can provide a fix.

Possible Root Cause and Workarounds

I'm not entirely sure what causes this issue, but it might be related to how the Cupertino widgets calculate their sizes or how adaptive_dialog handles the hintText within the layout. It could be a small calculation error that leads to this weird behavior. I haven’t dug deep enough to pinpoint the exact source, so it’s just a guess at this point.

As for workarounds, you could try to manually adjust the dialog's size or content padding to prevent the scrollbar from appearing. This is a quick fix that can potentially stop the scrollbar from showing up. However, this approach might not be ideal as it can create an extra step for the user. This solution is not ideal but can quickly resolve the issue.

Another idea is to customize the DialogTextField to use a different widget that doesn't trigger the scrollbar. Experimenting with custom widgets can help you find a workaround. For example, you could try replacing DialogTextField with a different widget.

I haven't found a perfect solution, but I am looking into these workarounds to see if I can find a solution. As a temporary measure, you could remove the hintText and add a label instead. However, it is not the same as the hintText. If I find something, I will update this article with more details. Ultimately, a proper fix from the package maintainers would be best.

Call for Help and Future Updates

If anyone else has encountered this issue or has a solution, please speak up! Any insights or workarounds would be greatly appreciated. This is a community effort, and your contributions can help solve this problem. This issue is not super critical, but it would be great to have this issue resolved. I'll be keeping an eye out for updates in the adaptive_dialog package and will update this post accordingly. Together, we can find a solution and make Flutter development smoother for everyone. I will keep you posted. Let's work together to fix this bug! The best thing is to file an issue on GitHub. This way, the developers know that this bug exists and work on it.