awesome-uiwidgets/AwesomeUIWidgets/Assets/Scripts/Widgets/attachment_button.cs

using Unity.UIWidgets.foundation;
using Unity.UIWidgets.material;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;
using UnityEngine;
using Image = Unity.UIWidgets.widgets.Image;

namespace UIWidgetsSample
{
    public delegate void OnPressed();

    internal class AttachmentButton : StatelessWidget
    {
        /// Callback for attachment button tap event
        public readonly OnPressed onPressed;

        /// Creates attachment button widget
        public AttachmentButton(
            OnPressed onPressed,
            Key key = null
        ) : base(key)
        {
            this.onPressed = onPressed;
        }

        public override Widget build(BuildContext context)
        {
            var test = InheritedChatTheme.of(context).theme.inputTextColor;
            return new Container(
                height: 14,
                margin: EdgeInsets.only(right: 16),
                width: 24,
                child: new IconButton(
                    icon: InheritedChatTheme.of(context).theme.attachmentButtonIcon != null
                        ? InheritedChatTheme.of(context).theme.attachmentButtonIcon
                        : Image.file(
                            "assets/icon-attachment.png",
                            color: InheritedChatTheme.of(context).theme.inputTextColor,
                            //package: "flutter_chat_ui",
                            scale: 1
                        ),
                    onPressed: ()=>
                    {
                        Debug.Log("add file , not available yet");
                        //onPressed();
                    },
                    padding: EdgeInsets.zero,
                    tooltip:
                    InheritedL10n.of(context)?.l10n?.attachmentButtonAccessibilityLabel
                )
            );
        }
    }
}