private void DrawEllipse(SKCanvas canvas, EllipseDrawingFigure ellipse)
{
_paint.Color = new SKColor(0, 0, 0);
canvas.DrawOval(ellipse.Rectangle.Margin(2), _paint);
_paint.Color = new SKColor(255, 255, 255);
canvas.DrawOval(ellipse.Rectangle, _paint);
_paint.Color = new SKColor(0, 0, 0);
_paint.TextAlign = SKTextAlign.Center;
_paint.TextSize = GridWidth;
canvas.DrawText(ellipse.Text, ellipse.Center, _paint);
}
private EllipseDrawingFigure[] CreateEllipses(SKPoint pt1, SKPoint pt2)
{
var left = Math.Min(pt1.X, pt2.X);
var top = Math.Min(pt1.Y, pt2.Y);
var right = Math.Max(pt1.X, pt2.X);
var bottom = Math.Max(pt1.Y, pt2.Y);
var ellipses = new List <EllipseDrawingFigure>();
for (var x = left; x <= right; x += EllipseWidth)
{
for (var y = top; y <= bottom; y += EllipseWidth)
{
var ellipse = new EllipseDrawingFigure
{
Center = new SKPoint(x, y),
Width = EllipseWidth,
Text = (_completedEllipses.Count + ellipses.Count + 1).ToString(),
};
ellipses.Add(ellipse);
}
}
return(ellipses.ToArray());
}
void OnTouchEffectAction(object sender, TouchActionEventArgs args)
{
switch (args.Type)
{
case TouchActionType.Pressed:
bool isDragOperation = false;
// Loop through the completed figures
foreach (EllipseDrawingFigure fig in completedFigures.Reverse <EllipseDrawingFigure>())
{
// Check if the finger is touching one of the ellipses
if (fig.IsInEllipse(ConvertToPixel(args.Location)))
{
// Tentatively assume this is a dragging operation
isDragOperation = true;
// Loop through all the figures currently being dragged
foreach (EllipseDrawingFigure draggedFigure in draggingFigures.Values)
{
// If there's a match, we'll need to dig deeper
if (fig == draggedFigure)
{
isDragOperation = false;
break;
}
}
if (isDragOperation)
{
fig.LastFingerLocation = args.Location;
draggingFigures.Add(args.Id, fig);
break;
}
}
}
if (isDragOperation)
{
// Move the dragged ellipse to the end of completedFigures so it's drawn on top
EllipseDrawingFigure fig = draggingFigures[args.Id];
completedFigures.Remove(fig);
completedFigures.Add(fig);
}
else // start making a new ellipse
{
// Random bytes for random color
byte[] buffer = new byte[4];
random.NextBytes(buffer);
EllipseDrawingFigure figure = new EllipseDrawingFigure
{
Color = new SKColor(buffer[0], buffer[1], buffer[2], buffer[3]),
StartPoint = ConvertToPixel(args.Location),
EndPoint = ConvertToPixel(args.Location)
};
inProgressFigures.Add(args.Id, figure);
}
canvasView.InvalidateSurface();
break;
case TouchActionType.Moved:
if (draggingFigures.ContainsKey(args.Id))
{
EllipseDrawingFigure figure = draggingFigures[args.Id];
SKRect rect = figure.Rectangle;
rect.Offset(ConvertToPixel(new Point(args.Location.X - figure.LastFingerLocation.X,
args.Location.Y - figure.LastFingerLocation.Y)));
figure.Rectangle = rect;
figure.LastFingerLocation = args.Location;
}
else if (inProgressFigures.ContainsKey(args.Id))
{
EllipseDrawingFigure figure = inProgressFigures[args.Id];
figure.EndPoint = ConvertToPixel(args.Location);
}
canvasView.InvalidateSurface();
break;
case TouchActionType.Released:
if (draggingFigures.ContainsKey(args.Id))
{
draggingFigures.Remove(args.Id);
}
else if (inProgressFigures.ContainsKey(args.Id))
{
EllipseDrawingFigure figure = inProgressFigures[args.Id];
figure.EndPoint = ConvertToPixel(args.Location);
completedFigures.Add(figure);
inProgressFigures.Remove(args.Id);
}
canvasView.InvalidateSurface();
break;
case TouchActionType.Cancelled:
if (draggingFigures.ContainsKey(args.Id))
{
draggingFigures.Remove(args.Id);
}
if (inProgressFigures.ContainsKey(args.Id))
{
inProgressFigures.Remove(args.Id);
}
canvasView.InvalidateSurface();
break;
}
}