Drawing Outlines in a GPU Drawing Plugin

// No Selection Clipping
protected override unsafe void OnDraw(IDeviceContext deviceContext)
{
    // preserve background
    deviceContext.DrawImage(Environment.SourceImage);

    // get current selection as a geometry object
    IGeometry outlineGeometry = Environment.Selection.Geometry;

    // create a Direct2D factory
    IDirect2DFactory d2dFactory = this.Services.GetService<IDirect2DFactory>();

    // describe the type of line we will render
    IStrokeStyle myStrokeStyle = d2dFactory.CreateStrokeStyle(
        new StrokeStyleProperties(
            CapStyle.Flat, // start end cap
            CapStyle.Flat, // end end cap
            CapStyle.Flat, // dash end cap
            LineJoin.Miter, // corner type
            10f, // miter limit
            DashStyle.Solid, // line type
            0f, // dash offset
            StrokeTransformType.Normal));

    // make our line 5px wide and apply our selected style
    outlineGeometry = outlineGeometry.Widen(5, myStrokeStyle);

    // create a red brush for drawing our line
    ISolidColorBrush brush = deviceContext.CreateSolidColorBrush(LinearColors.Red);

    // make sure the line is antialiased
    deviceContext.AntialiasMode = AntialiasMode.PerPrimitive; // .Aliased

    // draw the actual line
    deviceContext.FillGeometry(outlineGeometry, brush);
}

#region UICode
MultiLineTextboxControl Amount1 = "Paint.NET Rocks!!!"; // [32767] Text
FontFamily Amount2 = "Arial"; // Font
ColorWheelControl Amount3 = ColorBgra.FromBgr(0, 0, 255); // [Red!] Fill Color
ColorWheelControl Amount4 = ColorBgra.FromBgr(0, 0, 0); // [Black!] Outline Color
#endregion
protected override unsafe void OnDraw(IDeviceContext deviceContext)
{
    // preserve background
    deviceContext.DrawImage(Environment.SourceImage);

    // create a Direct2D factory and a Text factory
    IDirect2DFactory d2dFactory = this.Services.GetService<IDirect2DFactory>();
    IDirectWriteFactory textFactory = this.Services.GetService<IDirectWriteFactory>();

    // describe the text we want to render
    ITextFormat textFormat = textFactory.CreateTextFormat(
        Amount2, 
        null, 
        FontWeight.Normal,
        FontStyle.Normal,
        FontStretch.Normal, 
        72);

    ITextLayout textLayout = textFactory.CreateTextLayout(
        Amount1, 
        textFormat, 
        TextLayoutConstants.DefaultMaxWidth, 
        TextLayoutConstants.DefaultMaxHeight);

    IStrokeStyle myStrokeStyle = d2dFactory.CreateStrokeStyle(
        new StrokeStyleProperties(
            CapStyle.Flat, // start end cap
            CapStyle.Flat, // end end cap
            CapStyle.Flat, // dash end cap
            LineJoin.Miter, // corner type
            10f, // miter limit
            DashStyle.Solid, // line type
            0f, // dash offset
            StrokeTransformType.Normal));

    // create a geometry object from our text
    IGeometry textGeometry = d2dFactory.CreateGeometryFromTextLayout(textLayout, 80, 50);

    // create a red brush for drawing our text
    ISolidColorBrush fillBrush = deviceContext.CreateSolidColorBrush(Amount3);

    // create a black brush for drawing the outline
    ISolidColorBrush outlineBrush = deviceContext.CreateSolidColorBrush(Amount4);

    // make sure the line is anti-aliased
    deviceContext.AntialiasMode = AntialiasMode.PerPrimitive; // .Aliased

    // draw the actual outline of the text
    deviceContext.DrawGeometry(textGeometry, outlineBrush, 4, myStrokeStyle);

    // fill the text
    deviceContext.FillGeometry(textGeometry, fillBrush);

    // you can do the last two lines in opposite order for fatter outlines
}