"how to create converter to work like "findancestor" for checking istypefound?" Code Answer

declare a type to contain converter parameters:

public sealed class myconverterparameter
{
    public type ancestortype { get; set; }
    public int ancestorlevel { get; set; }
}

re-write converter to use this type:

public sealed class myconverter : ivalueconverter
{
    public object convert(object value, type targettype, object parameter, cultureinfo culture)
    {
        var myparameter = (myconverterparameter)parameter;

        // other converter stuff here
    }

    public object convertback(object value, type targettype, object parameter, cultureinfo culture)
    {
        var myparameter = (myconverterparameter)parameter;

        // other converter stuff here
    }
}

declare additional resource in xaml, e.g.:

        <datatemplate>
            <datatemplate.resources>
                <local:myconverter x:key="myconverterkey"/>
                <local:myconverterparameter x:key="myconverterparameterkey" ancestortype="{x:type type-to-find}" ancestorlevel="1"/>
            </datatemplate.resources>

            <!-- datatemplate tree -->

            <datatemplate.triggers>
                <datatrigger binding="{binding path-to-bind-to, converter={staticresource myconverterkey}, converterparameter={staticresource myconverterparameterkey}}" value="value-to-fire-trigger">
                    <!-- setters -->
                </datatrigger>
            </datatemplate.triggers>
        </datatemplate>

p.s. why findancestor mode for realtivesource doesn't suits you?

By prasopes on September 25 2022