private void DrawBorder(ACanvas canvas, PancakeView control)
{
if (control.BorderThickness > 0)
{
var borderThickness = Context.ToPixels(control.BorderThickness);
var halfBorderThickness = borderThickness / 2;
bool hasShadowOrElevation = control.HasShadow || (Build.VERSION.SdkInt >= BuildVersionCodes.Lollipop && control.Elevation > 0);
// TODO: This doesn't look entirely right yet when using it with rounded corners.
using (var paint = new Paint {
AntiAlias = true
})
using (Path.Direction direction = Path.Direction.Cw)
using (Paint.Style style = Paint.Style.Stroke)
using (var rect = new RectF(control.BorderDrawingStyle == BorderDrawingStyle.Outside && !hasShadowOrElevation ? -halfBorderThickness : halfBorderThickness,
control.BorderDrawingStyle == BorderDrawingStyle.Outside && !hasShadowOrElevation ? -halfBorderThickness : halfBorderThickness,
control.BorderDrawingStyle == BorderDrawingStyle.Outside && !hasShadowOrElevation ? canvas.Width + halfBorderThickness : canvas.Width - halfBorderThickness,
control.BorderDrawingStyle == BorderDrawingStyle.Outside && !hasShadowOrElevation ? canvas.Height + halfBorderThickness : canvas.Height - halfBorderThickness))
{
Path path = null;
if (control.Sides != 4)
{
path = ShapeUtils.CreatePolygonPath(Width, Height, control.Sides, control.CornerRadius.TopLeft, control.OffsetAngle);
}
else
{
path = ShapeUtils.CreateRoundedRectPath(Width, Height,
Context.ToPixels(control.CornerRadius.TopLeft),
Context.ToPixels(control.CornerRadius.TopRight),
Context.ToPixels(control.CornerRadius.BottomRight),
Context.ToPixels(control.CornerRadius.BottomLeft));
}
if (control.BorderIsDashed)
{
// dashes merge when thickness is increased
// off-distance should be scaled according to thickness
paint.SetPathEffect(new DashPathEffect(new float[] { 10, 5 * control.BorderThickness }, 0));
}
if ((control.BorderGradientStartColor != default(Xamarin.Forms.Color) && control.BorderGradientEndColor != default(Xamarin.Forms.Color)) || (control.BorderGradientStops != null && control.BorderGradientStops.Any()))
{
var angle = control.BorderGradientAngle / 360.0;
// Calculate the new positions based on angle between 0-360.
var a = canvas.Width * Math.Pow(Math.Sin(2 * Math.PI * ((angle + 0.75) / 2)), 2);
var b = canvas.Height * Math.Pow(Math.Sin(2 * Math.PI * ((angle + 0.0) / 2)), 2);
var c = canvas.Width * Math.Pow(Math.Sin(2 * Math.PI * ((angle + 0.25) / 2)), 2);
var d = canvas.Height * Math.Pow(Math.Sin(2 * Math.PI * ((angle + 0.5) / 2)), 2);
if (control.BorderGradientStops != null && control.BorderGradientStops.Count > 0)
{
// A range of colors is given. Let's add them.
var orderedStops = control.BorderGradientStops.OrderBy(x => x.Offset).ToList();
var colors = orderedStops.Select(x => x.Color.ToAndroid().ToArgb()).ToArray();
var locations = orderedStops.Select(x => x.Offset).ToArray();
var shader = new LinearGradient(canvas.Width - (float)a, (float)b, canvas.Width - (float)c, (float)d, colors, locations, Shader.TileMode.Clamp);
paint.SetShader(shader);
}
else
{
// Only two colors provided, use that.
var shader = new LinearGradient(canvas.Width - (float)a, (float)b, canvas.Width - (float)c, (float)d, control.BorderGradientStartColor.ToAndroid(), control.BorderGradientEndColor.ToAndroid(), Shader.TileMode.Clamp);
paint.SetShader(shader);
}
}
else
{
paint.Color = control.BorderColor.ToAndroid();
}
paint.StrokeCap = Paint.Cap.Square;
paint.StrokeWidth = borderThickness;
paint.SetStyle(style);
canvas.DrawPath(path, paint);
}
}
}
