Missing DashOffset in Pen Style

Hi, I’m wondering why the DashOffset is not present in Mapsui.Styles.Pen. I need to create animations which uses XAML StrokeDashOffset or phase in SKPathEffect.CreateDash(dash, phase). Please let me know if you think there’s easier ways to accomplish the following or if you would like a PR 😉

Mapsui.Styles.Pen

Property

/// <summary>
/// Stroke dash offset (phase)
/// </summary>
public float DashOffset { get; set; }

Mapsui.Rendering.Skia.PenStyleExtension

Optional parameter to specify phase

public static SKPathEffect ToSkia(this PenStyle penStyle, float width, float[] dashArray = null, float phase = 0f)
{
    switch (penStyle)
    {
        case PenStyle.UserDefined:
            // If dashArray is empty or not even, create sold dash
            if (dashArray == null || dashArray.Length == 0 || dashArray.Length % 2 != 0)
                return SKPathEffect.CreateDash(new float[0], 0);
            // Multiply each dash entry with line width
            float[] dash = new float[dashArray.Length];
            for (var i = 0; i < dashArray.Length; i++)
            {
                dash[i] = dashArray[i] * width;
            }
            return SKPathEffect.CreateDash(dash, phase);
        case PenStyle.Dash:
            return SKPathEffect.CreateDash(new [] { width * 4f, width * 3f }, phase);
        case PenStyle.Dot:
            return SKPathEffect.CreateDash(new [] { width * 1f, width * 3f }, phase);
        case PenStyle.DashDot:
            return SKPathEffect.CreateDash(new [] { width * 4f, width * 3f, width * 1f, width * 3f }, phase);
        case PenStyle.DashDotDot:
            return SKPathEffect.CreateDash(new [] { width * 4f, width * 3f, width * 1f, width * 3f, width * 1f, width * 3f }, phase);
        case PenStyle.LongDash:
            return SKPathEffect.CreateDash(new [] { width * 8f, width * 3f }, phase);
        case PenStyle.LongDashDot:
            return SKPathEffect.CreateDash(new [] { width * 8f, width * 3f, width * 1f, width * 3f }, phase);
        case PenStyle.ShortDash:
            return SKPathEffect.CreateDash(new [] { width * 2f, width * 3f }, phase);
        case PenStyle.ShortDashDot:
            return SKPathEffect.CreateDash(new [] { width * 2f, width * 3f, width * 1f, width * 3f }, phase);
        case PenStyle.ShortDashDotDot:
            return SKPathEffect.CreateDash(new [] { width * 2f, width * 3f, width * 1f, width * 3f, width * 1f, width * 3f }, phase);
        case PenStyle.ShortDot:
            return SKPathEffect.CreateDash(new [] { width * 1f, width * 3f }, phase);
        default:
            return SKPathEffect.CreateDash(new float[0], phase);
    }
}
}

Mapsui.Rendering.Skia.LineStringRenderer

Inherits value from VectorStyle

public static void Draw(SKCanvas canvas, IReadOnlyViewport viewport, IStyle style, IFeature feature, IGeometry geometry,
    float opacity)
{
    if (style is LabelStyle labelStyle)
    {
        var worldCenter = geometry.BoundingBox.Centroid;
        var center = viewport.WorldToScreen(worldCenter);
        LabelRenderer.Draw(canvas, labelStyle, feature, center, opacity);
    }
    else
    {
        var lineString = ((LineString) geometry).Vertices;

        float lineWidth = 1;
        var lineColor = new Color();

        var vectorStyle = style as VectorStyle;
        var strokeCap = PenStrokeCap.Butt;
        var strokeJoin = StrokeJoin.Miter;
        var strokeMiterLimit = 4f;
        var strokeStyle = PenStyle.Solid;
        float[] dashArray = null;
        float dashOffset = 0f;

        if (vectorStyle != null)
        {
            lineWidth = (float) vectorStyle.Line.Width;
            lineColor = vectorStyle.Line.Color;
            strokeCap = vectorStyle.Line.PenStrokeCap;
            strokeJoin = vectorStyle.Line.StrokeJoin;
            strokeMiterLimit = vectorStyle.Line.StrokeMiterLimit;
            strokeStyle = vectorStyle.Line.PenStyle;
            dashArray = vectorStyle.Line.DashArray;
            dashOffset = vectorStyle.Line.DashOffset;
        }

        using (var path = lineString.ToSkiaPath(viewport, canvas.LocalClipBounds))
        using (var paint = new SKPaint { IsAntialias = true })
        {
            paint.IsStroke = true;
            paint.StrokeWidth = lineWidth;
            paint.Color = lineColor.ToSkia(opacity);
            paint.StrokeCap = strokeCap.ToSkia();
            paint.StrokeJoin = strokeJoin.ToSkia();
            paint.StrokeMiter = strokeMiterLimit;
            if (strokeStyle != PenStyle.Solid)
                paint.PathEffect = strokeStyle.ToSkia(lineWidth, dashArray, dashOffset);
            else
                paint.PathEffect = null;
            canvas.DrawPath(path, paint);
        }
    }
}

Mapsui.Rendering.Xaml.LineStringRenderer

Inherits value from VectorStyle

public static class LineStringRenderer
{
    public static System.Windows.Shapes.Shape RenderLineString(LineString lineString, IStyle style, IReadOnlyViewport viewport)
    {
        if (!(style is VectorStyle)) throw new ArgumentException("Style is not of type VectorStyle");
        var vectorStyle = style as VectorStyle;

        System.Windows.Shapes.Path path = CreateLineStringPath(vectorStyle);
        path.Data = lineString.ToXaml();
        path.RenderTransform = new MatrixTransform { Matrix = GeometryRenderer.CreateTransformMatrix(viewport) };
        GeometryRenderer.CounterScaleLineWidth(path, viewport.Resolution);
        return path;
    }

    public static System.Windows.Shapes.Path CreateLineStringPath(VectorStyle style)
    {
        var path = new System.Windows.Shapes.Path { Opacity = style.Opacity };
        if (style.Outline != null)
        {
            //todo: render an outline around the line. 
        }
        path.Stroke = new SolidColorBrush(style.Line.Color.ToXaml());
        path.StrokeDashArray = style.Line.PenStyle.ToXaml(style.Line.DashArray);
        path.StrokeDashOffset = style.Line.DashOffset;
        var penStrokeCap = style.Line.PenStrokeCap.ToXaml();
        path.StrokeEndLineCap = penStrokeCap;
        path.StrokeStartLineCap = penStrokeCap;
        path.StrokeLineJoin = style.Line.StrokeJoin.ToXaml();
        path.StrokeMiterLimit = style.Line.StrokeMiterLimit;
        path.Tag = style.Line.Width; // see #linewidthhack
        path.IsHitTestVisible = false;
        return path;
    }
}

[charlenni]

See #1157

[charlenni]

Is this issue is solved? If yes, can you close it?