xamarin - SkiaSharp ArcTo Method does not draw curve -

i trying draw arc on skiasharp canvas view using following code.

path3.arcto(new skpoint(0, h/2), 1.57f, skpatharcsize.large,             skpathdirection.clockwise, new skpoint(w/2, h)); 

but instead of curve, drawing straight line. how make curve?

complete code

 private void onpainting(object sender, skpaintsurfaceeventargs e)  {       var surface = e.surface;      var canvas = surface.canvas;      canvas.clear(skcolors.white);          var w = e.info.width;         var h = e.info.height;          var pathstroke3 = new skpaint         {             isantialias = true,             style = skpaintstyle.strokeandfill,             color = new skcolor(240, 0, 100, 250),             strokewidth = 5         };          var path3 = new skpath { filltype = skpathfilltype.evenodd };         path3.moveto(0, h/2);         path3.arcto(new skpoint(0, h/2), 1.57f, skpatharcsize.large, skpathdirection.clockwise, new skpoint(w/2, h));         path3.lineto(0, h);         path3.close();         canvas.drawpath(path3, pathstroke3);    } 

xaml

 <grid x:name="controlgrid" columnspacing="0" rowspacing="0" padding="0" backgroundcolor="white" >     <grid.rowdefinitions>         <rowdefinition height="4*" />         <rowdefinition height="6*" />     </grid.rowdefinitions>     <grid.columndefinitions>         <columndefinition width="*" />     </grid.columndefinitions>     <views:skcanvasview paintsurface="onpainting" enabletouchevents="true"       touch="ontouch" heightrequest="300" grid.row="0"/>  </grid> 

your x radius zero, arcto adds line path current point exit point.

arcto appends line xy if either radii zero, or if last path point equals (x, y). arcto scales radii r fit last path point , xy if both greater 0 small.

you can like:

path3.arcto(new skpoint(100, 100), 0, skpatharcsize.large, skpathdirection.clockwise, new skpoint(w / 2, h)); 

but not know drawing intent is; concave, convex, bounded, unbounded, etc... other examples using conicto might closer think intent might be:

path3.conicto(w / 3, h / 2, w / 2, h, 0.50f); 

path3.conicto(0, h - (h / 5), w / 2, h, 0.50f); 

you might want @ official docs understand how arcto resolves arcs, conics , moves:

• https://skia.org/user/api/bmh_skpath?cl=9919#arcto