Simple previewer for texture properties in Unity

PreviewTexture2D.cs

using UnityEngine;

public class PreviewTexture2D : PropertyAttribute
{
    public PreviewTexture2D()
    { }
}

PreviewTexture2DDrawer.cs

using UnityEngine;
using UnityEditor;

[CustomPropertyDrawer(typeof(PreviewTexture2D))]
public class PreviewTexture2DDrawer : PropertyDrawer
{
    static private int  BorderWidth = 8;
    static private bool SwitchAlpha = false;

    public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
    {
        EditorGUI.BeginProperty(position, label, property);

        var buttonName = SwitchAlpha ? "Alpha" : "RGB";

        if (GUILayout.Button (buttonName, "MiniButton"))
        {
            SwitchAlpha = !SwitchAlpha;
        }

        var rect = GUILayoutUtility.GetAspectRect (1.0f);

        rect.x      += BorderWidth;
        rect.y      += BorderWidth;
        rect.width  -= BorderWidth * 2;
        rect.height -= BorderWidth * 2;

        var texture = property.objectReferenceValue as Texture;

        if (SwitchAlpha)
        {
            EditorGUI.DrawTextureAlpha(rect, texture);
        }
        else
        {
            EditorGUI.DrawPreviewTexture(rect, texture);
        }
        EditorGUI.EndProperty();
    }
}