[QUESTION] SkiaSharp vs System.Windows.Media.FormattedText

[InsomniumBR]

Hello Guys,

I am planning on moving an App from WPF to Xamarin, and I want to use SkiaSharp to accomplish a task that it is currently capable of.

This App generates a text based on TrueType fonts, after generating and presenting it to the screen, it sends commands to a device similar to a "3d printer" that engraves this text. And for doing that it reads all the glyphs inside the generated text based on the top left origin, and generates the g codes (movement codes) for the machine to write physically the text.

I am currently stuck on the FormattedText class to accomplish that, using the BuildGeometry method that returns a Geometry which has PathGeometry, PathFigure, with LineSegments, PolyBezierSegments and others, representing the build path for the font.

I just want your help to kindly advice if the SkiaSharp has all these details (or have something similar to that). I have already seen a class called SKPaint that has a MeasureText method, and some methods like GetGlyphs and GetGlyphsPosition that seems to help on that journey. But I don't see exactly the lines, beziercurves, etc. Could you please advice about it?

Thanks for your help,

Best,

[daltonks]

I haven't used it myself, but there is SKPaint.GetTextPath(). This returns an SKPath, which you can iterate over using SKPath.CreateIterator() or CreateRawIterator(). Tbh, I don't know the exact differences between the two, but CreateRawIterator() has worked fine for me.

Here is an example of iterating over a path and doing something with the information (duplicating the path in this case):

using var iterator = path.CreateRawIterator();
var points = new Span<SKPoint>(new SKPoint[4]);
var duplicatePath = new SKPath();
while (true)
{
    var verb = iterator.Next(points);
    var p0 = points[0];
    var p1 = points[1];
    var p2 = points[2];
    var p3 = points[3];
    switch (verb)
    {
        case SKPathVerb.Move:
            duplicatePath.MoveTo(p0.X, p0.Y);
            break;
        case SKPathVerb.Line:
            duplicatePath.LineTo(p1.X, p1.Y);
            break;
        case SKPathVerb.Quad:
            duplicatePath.QuadTo(p1.X, p1.Y, p2.X, p2.Y);
            break;
        case SKPathVerb.Conic:
            duplicatePath.ConicTo(p1.X, p1.Y, p2.X, p2.Y, iterator.ConicWeight());
            break;
        case SKPathVerb.Cubic:
            duplicatePath.CubicTo(p1.X, p1.Y, p2.X, p2.Y, p3.X, p3.Y);
            break;
        case SKPathVerb.Close:
            duplicatePath.Close();
            break;
        case SKPathVerb.Done:
            break;
        default:
            throw new ArgumentOutOfRangeException();
    }
}

[InsomniumBR]

Great @daltonks I think that if you can duplicate it, it is enough for me to convert that for physical engraving.
Thanks for your comment!

[daltonks]

Right on, good luck.
And oh yeah, you'll have to exit out of the while loop when you get the Done verb, but the rest of it should be good.