Replaces the SpriteRenderer with an Image component when a Sprite asset is dragged under a Canvas

ImageByDefault.cs

using System;
using UnityEditor;
using UnityEngine;
using UnityEngine.UI;

/// <summary>
/// Replaces the SpriteRenderer with an Image component when a Sprite asset is dragged under a Canvas
/// </summary>
[InitializeOnLoad]
public static class ImageByDefault
{
    static ImageByDefault()
    {
        AssemblyReloadEvents.AssemblyReloadCallback beforeRelod = null;
        beforeRelod = () =>
        {
            ObjectFactory.componentWasAdded -= SwapSpriteRenderer;
            AssemblyReloadEvents.beforeAssemblyReload -= beforeRelod;
        };

        ObjectFactory.componentWasAdded += SwapSpriteRenderer;
        AssemblyReloadEvents.beforeAssemblyReload += beforeRelod;
    }

    private static void SwapSpriteRenderer(Component component)
    {
        if (component is SpriteRenderer spriteRenderer)
        {
            EditorApplication.CallbackFunction SwapComponent = null;
            SwapComponent = () =>
            {
                EditorApplication.delayCall -= SwapComponent;
                if (component.GetComponentsInParent<Canvas>(true).Length > 0)
                {
                    var gameObject = spriteRenderer.gameObject;
                    var sprite = spriteRenderer.sprite;
                    UnityEngine.Object.DestroyImmediate(spriteRenderer);
                    var image = gameObject.AddComponent<Image>();
                    image.sprite = sprite;
                    image.SetNativeSize();
                    EditorUtility.SetDirty(image);
                }
            };
            EditorApplication.delayCall += SwapComponent;            
        }
    }
}