ButtonThemeData does not define its colorScheme in the constructor

[Levi-Lesches]

When initializing a new ButtonThemeData, the colorScheme property is not automatically generated, which pretty much makes all other parameters useless in some cases. For example, I'm trying to get the text color of a RaisedButton in an AlertDialog.actions button bar, and I need to override the theme (actually a really bad issue, IMO, see #38646). So I am trying to do:

actions: [
  RaisedButton(
    child: Text ("OK", style: TextStyle(
      // see issue #38646 for why this is needed 
      color: Theme.of(context).buttonTheme.getTextColor(RaisedButton(onPressed: () {}))
    )
  )
]

But I get an error:

Logs

I/flutter ( 8467): The following NoSuchMethodError was thrown building NotesBuilder(dirty, dependencies:
I/flutter ( 8467): [_LocalizationsScope-[GlobalKey#19ae2], _InheritedTheme]):
I/flutter ( 8467): The getter 'secondary' was called on null.
I/flutter ( 8467): Receiver: null
I/flutter ( 8467): Tried calling: secondary
I/flutter ( 8467):
I/flutter ( 8467): When the exception was thrown, this was the stack:
I/flutter ( 8467): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:50:5)
I/flutter ( 8467): #1      ButtonThemeData.getTextColor (package:flutter/src/material/button_theme.dart:590:28)
I/flutter ( 8467): #2      NotesBuilder.build (package:ramaz/pages/notes_builder.dart:34:43)
I/flutter ( 8467): #3      StatelessElement.build (package:flutter/src/widgets/framework.dart:3974:28)

I noticed this was because of ButtonTheme.getTextColor:

Color getTextColor(MaterialButton button) {
    if (!button.enabled)
      return getDisabledTextColor(button);

    if (button.textColor != null)
      return button.textColor;

    switch (getTextTheme(button)) {
      case ButtonTextTheme.normal:
        return getBrightness(button) == Brightness.dark ? Colors.white : Colors.black87;

      case ButtonTextTheme.accent:
        return colorScheme.secondary;

      case ButtonTextTheme.primary: {
        final Color fillColor = getFillColor(button);
        final bool fillIsDark = fillColor != null
          ? ThemeData.estimateBrightnessForColor(fillColor) == Brightness.dark
          : getBrightness(button) == Brightness.dark;
        if (fillIsDark)
          return Colors.white;
        if (button is FlatButton || button is OutlineButton)
          return colorScheme.primary;
        return Colors.black;
      }
    }

    assert(false);
    return null;
  }

This fails on ButtonTextTheme.accent, and since the error is that colorScheme was never defined, I went to the constructor:

 const ButtonThemeData({
    this.textTheme = ButtonTextTheme.normal,
    this.minWidth = 88.0,
    this.height = 36.0,
    EdgeInsetsGeometry padding,
    ShapeBorder shape,
    this.layoutBehavior = ButtonBarLayoutBehavior.padded,
    this.alignedDropdown = false,
    Color buttonColor,
    Color disabledColor,
    Color focusColor,
    Color hoverColor,
    Color highlightColor,
    Color splashColor,
    this.colorScheme,
    MaterialTapTargetSize materialTapTargetSize,
  }) : assert(textTheme != null),
       assert(minWidth != null && minWidth >= 0.0),
       assert(height != null && height >= 0.0),
       assert(alignedDropdown != null),
       assert(layoutBehavior != null),
       _buttonColor = buttonColor,
       _disabledColor = disabledColor,
       _focusColor = focusColor,
       _hoverColor = hoverColor,
       _highlightColor = highlightColor,
       _splashColor = splashColor,
       _padding = padding,
       _shape = shape,
       _materialTapTargetSize = materialTapTargetSize;

So colorScheme is never actually defined if not explicitly passed in. And because of #38646, passing in any of the other parameters doesn't actually matter for AlertDialog.actions.

Output of flutter doctor -v:

[√] Flutter (Channel stable, v1.7.8+hotfix.4, on Microsoft Windows [Version
    10.0.18362.239], locale en-US)
    • Flutter version 1.7.8+hotfix.4 at C:\Users\levi\flutter
    • Framework revision 20e59316b8 (4 weeks ago), 2019-07-18 20:04:33 -0700
    • Engine revision fee001c93f
    • Dart version 2.4.0


[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at C:\Users\levi\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling
      support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
    • All Android licenses accepted.

[√] Android Studio (version 3.4)
    • Android Studio at C:\Program Files\Android
    • Flutter plugin version 35.3.1
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[√] Connected device (1 available)
    • SM G950U1 • 988861314d554d4f52 • android-arm64 • Android 9 (API 28)

• No issues found!

[keshava19]

Any update on the pull request ?

[shihaohong]

I'm closing the issue since #39627 fixes this

[shihaohong]

I'm reopening this issue since we had to revert the original PR (#42854). The existence of both ThemeData and ButtonThemeData's colorScheme makes it impossible to define a default color scheme value for ButtonTheme, since doing so will never allow the buttons to ever access ThemeData's colorScheme

[Levi-Lesches]

Why is that property even there? Isn't ThemeData.colorScheme enough?

[HansMuller]

@Levi-Lesches [sorry about the long (long) delay in responding. You're correct that it doesn't really make sense to have a ColorScheme just for the ButtonTheme. ButtonTheme has evolved in a way that has made it rather difficult to use. We're considering simplifying the way buttons are themed. Look for a concrete proposal early next year.

[Levi-Lesches]

That's good to hear. Just a polite reminder that this issue is actively making #38646 much harder to work around.

[HansMuller]

@Levi-Lesches As you may have already noticed, the long-promised proposal to remedy this problem, albeit by leaving it behind, has been published in #54776.

I'm going to close this issue in favor of #54776. If you have time, I'll hope you'll consider the proposal and add your feedback.

[Levi-Lesches]

Checked it out, looks great! Can't wait for it to hit stable, the theming as of now really does get quite confusing.

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.