/*
* public static void DrawGradientPath(Canvas canvas, List<TinyTypeLib.PointF> path, int gradientSize, Color color)
* {
* if (path.Count < 3)
* {
* throw new Exception("Path must have at least three points");
* }
*
* // Add the first two points to the end to make it easier to assess direction
* int originalCount = path.Count;
* path.Add(path[0]);
* path.Add(path[1]);
*
* for (int i = 0; i < originalCount; i++ )
* {
* Line line = new Line(path[i], path[i + 1]);
* DrawGradientLine(canvas, line, gradientSize, color);
* }
* }
*
* public static void DrawGradientCap(Canvas canvas, TinyTypeLib.Rect middleSquare, int quadrant, int gradientSize, Color color)
* {
* Paint paint = new Paint();
* paint.SetStyle(Paint.Style.Fill);
* Color transparent = color;
* transparent.A = 0;
*
* Point center = new Point(
* quadrant == 1 || quadrant == 4 ? middleSquare.Right : middleSquare.Left,
* quadrant == 1 || quadrant == 2 ? middleSquare.Top : middleSquare.Bottom);
*
* int startAngle = (4 - quadrant) * 90;
*
* paint.SetShader(new RadialGradient(center.X, center.Y, gradientSize, color, transparent, Shader.TileMode.Mirror));
* canvas.DrawArc(new RectF(
* center.X - gradientSize,
* center.Y - gradientSize,
* center.X + gradientSize,
* center.Y + gradientSize), startAngle, 90, true, paint);
*
* }
*/
// gradientSize is the distance from the line to half-way through the gradient's fade
// The direction of the gradient is controlled by the sign of signedGradientSize
public static void DrawGradientLine(Canvas canvas, Line line, int signedGradientSize, Color color, TinyTypeLib.Rect clipRect)
{
// Allow for a little overlap. For some reason, Android leaves a white line even though the clipRects were lining up.
clipRect = new TinyTypeLib.Rect(clipRect.Left - 1, clipRect.Top - 1, clipRect.Right + 1, clipRect.Bottom + 1);
int gradientSizeAbs = Math.Abs(signedGradientSize);
Line perpendicular = line.GetPerpendicular(gradientSizeAbs);
Paint paint = new Paint();
paint.SetStyle(Paint.Style.Stroke);
paint.StrokeCap = Paint.Cap.Butt;
// Here we need to solve for the gradient's start point, or the location of B. We'll solve for angle C and length a to find that out.
double c = line.Length;
double b = gradientSizeAbs;
/*
* B____c_____A
* \ /
* a\ /b
* \/
* C=90
*/
// Solve for angle B in radians. B = sin-1(b/c)
double B = Math.Asin(b / c);
// Solve for length a. a^2+b^2 = c^2, so a = sqrt(c^2-b^2)
double a = Math.Sqrt((c * c) - (b * b));
int direction = signedGradientSize > 0 ? -1 : 1;
double finalAngle = direction * B + line.Angle;
Line test = new Line(866, 313.5f, 678, 313.5f);
double ang = test.Angle; // should be 3.14
Line l = new Line(line.Start, finalAngle, a);
Line gradientLine = new Line(l.End, line.End);
canvas.ClipRect(AndroidUtil.GetRect(clipRect));
paint.StrokeWidth = gradientSizeAbs * 2;
paint.SetShader(new LinearGradient(gradientLine.Start.X, gradientLine.Start.Y, gradientLine.End.X, gradientLine.End.Y, color, AndroidUtil.GetTransparentColor(color), Shader.TileMode.Mirror));
canvas.DrawLine(l.Start.X, l.Start.Y, l.End.X, l.End.Y, paint);
}