如何将运行的背景画笔动态绑定到资源？

<Application.Resources>
    <SolidColorBrush x:Key=\"colorBrush1\" Color=\"Orange\" Opacity=\"1\"/>
    <SolidColorBrush x:Key=\"colorBrush2\" Color=\"Green\" Opacity=\"1\"/>
</Application.Resources>

Run run = new Run(\"My name is Bob!\");
run.SetResourceReference(ForegroundProperty, \"colorBrush1\");
run.SetResourceReference(BackgroundProperty, \"colorBrush2\");

Paragraph paragraph = new Paragraph(run);

this.flowDocument.Blocks.Add(paragraph);

        Run run = new Run(\"My name is Bob!\");
        run.SetResourceReference(Run.ForegroundProperty, \"colorBrush1\");
        run.SetResourceReference(Run.BackgroundProperty, \"colorBrush2\");