private void DrawBorder()
{
var pancake = Element as CanvasView;
var layerName = "borderLayer";
// remove previous background layer if any
var prevBorderLayer = _wrapperView.Layer.Sublayers?.FirstOrDefault(x => x.Name == layerName);
prevBorderLayer?.RemoveFromSuperLayer();
if (pancake.BorderThickness > 0)
{
var borderLayer = new CAShapeLayer
{
StrokeColor = pancake.BorderColor == Xamarin.Forms.Color.Default ? UIColor.Clear.CGColor : pancake.BorderColor.ToCGColor(),
FillColor = null,
LineWidth = pancake.BorderThickness,
Name = layerName
};
// Create arcs for the given corner radius.
bool hasShadowOrElevation = pancake.HasShadow || pancake.Elevation > 0;
borderLayer.Path = pancake.Sides != 4 ?
ShapeUtils.CreatePolygonPath(Bounds, pancake.Sides, pancake.CornerRadius.TopLeft, pancake.OffsetAngle).CGPath :
ShapeUtils.CreateRoundedRectPath(Bounds, pancake.CornerRadius).CGPath; // insetBounds?
var layerPosition = new CGPoint(borderLayer.Path.BoundingBox.Width / 2, borderLayer.Path.BoundingBox.Height / 2);
borderLayer.Frame = borderLayer.Path.BoundingBox;
borderLayer.Position = layerPosition;
// Dash pattern for the border.
if (pancake.BorderIsDashed)
{
borderLayer.LineDashPattern = new NSNumber[] { new NSNumber(6), new NSNumber(3) };
}
if ((pancake.BorderGradientStartColor != default(Xamarin.Forms.Color) && pancake.BorderGradientEndColor != default(Xamarin.Forms.Color)) || (pancake.BorderGradientStops != null && pancake.BorderGradientStops.Any()))
{
var gradientFrame = Bounds.Inset(-pancake.BorderThickness, -pancake.BorderThickness);
var gradientLayer = CreateGradientLayer(pancake.BorderGradientAngle, gradientFrame);
gradientLayer.Position = new CGPoint((gradientFrame.Width / 2) - (pancake.BorderThickness), (gradientFrame.Height / 2) - (pancake.BorderThickness));
// Create a clone from the border layer and use that one as the mask.
// Why? Because the mask and the border somehow can't be the same, so
// don't want to do adjustments to borderLayer because it would influence the border.
var maskLayer = new CAShapeLayer()
{
Path = borderLayer.Path,
Position = new CGPoint(pancake.BorderThickness, pancake.BorderThickness),
FillColor = null,
LineWidth = pancake.BorderThickness,
StrokeColor = UIColor.Red.CGColor,
LineDashPattern = borderLayer.LineDashPattern
};
gradientLayer.Mask = maskLayer;
gradientLayer.Name = layerName;
if (pancake.BorderGradientStops != null)
{
// A range of colors is given. Let's add them.
var orderedStops = pancake.BorderGradientStops.OrderBy(x => x.Offset).ToList();
gradientLayer.Colors = orderedStops.Select(x => x.Color.ToCGColor()).ToArray();
gradientLayer.Locations = orderedStops.Select(x => new NSNumber(x.Offset)).ToArray();
}
else
{
// Only two colors provided, use that.
gradientLayer.Colors = new CGColor[] { pancake.BorderGradientStartColor.ToCGColor(), pancake.BorderGradientEndColor.ToCGColor() };
}
AddLayer(gradientLayer, -1, _wrapperView);
}
else
{
AddLayer(borderLayer, -1, _wrapperView);
}
}
}
