private static TextureFilter RenderBrushToTextureFilter(LinearGradientBrush brush, Point uvMin, Point uvMax)
{
// 0-255 spread for each color pass
int size = (brush.GradientStops.Count - 1) * 256;
if (brush.MappingMode == BrushMappingMode.Absolute)
{
// Convert to relative
Matrix scale = GetConversionToRelative(uvMin, uvMax);
brush.MappingMode = BrushMappingMode.RelativeToBoundingBox;
brush.StartPoint *= scale;
brush.EndPoint *= scale;
}
BilinearTextureFilter filter = new BilinearTextureFilter(RenderBrushToImageData(brush, size, size));
filter.HasErrorEstimation = false;
return(filter);
}
private static TextureFilter RenderBrushToTextureFilter(RadialGradientBrush brush, Point uvMin, Point uvMax)
{
if (brush.MappingMode == BrushMappingMode.Absolute)
{
// Convert to relative
Matrix scale = GetConversionToRelative(uvMin, uvMax);
brush.MappingMode = BrushMappingMode.RelativeToBoundingBox;
brush.Center *= scale;
brush.GradientOrigin *= scale;
brush.RadiusX *= scale.M11;
brush.RadiusY *= scale.M22;
}
#if HIGH_RES
// How close is the GradientOrigin to the edge of the ellipse defined by Center and RadiusX/Y ?
// The gradient has the least room to interpolate between o and c+r.
// We need to draw the gradient large enough to allow 256 color values for the shortest segment.
//
// ,,-----,,
// ,' ',
// / \ c == Center
// ; ; o == GradientOrigin
// | c | c+r == Center + RadiusX/Y
// ; o ;
// \ /
// ", ,"
// ''-----''
//
// c------o----c+r x is the thin area between the GradientOrigin and the edge of the ellipse
// x 512 * r/x is how we scale that area into an acceptable rendering space
//
// o--1--2---3-c+r But we must also note that x may be subdivided by GradientStops...
// x1 x2 x3 x4 512 * r/xn is the actual scale we want (xn is the shortest GradientStop segment)
//
double x = brush.RadiusX - Math.Abs(brush.Center.X - brush.GradientOrigin.X);
double y = brush.RadiusY - Math.Abs(brush.Center.Y - brush.GradientOrigin.Y);
x = Math.Max(x, 0);
y = Math.Max(y, 0);
SortedList <int, double> list = new SortedList <int, double>();
foreach (GradientStop stop in brush.GradientStops)
{
list.Add(list.Count, stop.Offset);
}
double shortest = 1.0;
for (int n = 1; n < list.Count; n++)
{
double offset = Math.Abs(list.Values[n] - list.Values[n - 1]);
// We can't do anything with 0, so skip it if it shows up.
if (MathEx.NotCloseEnough(offset, 0))
{
shortest = Math.Min(shortest, offset);
}
}
double w = 512 * brush.RadiusX / (x * shortest);
double h = 512 * brush.RadiusY / (y * shortest);
#endif
double w = brush.GradientStops.Count * 256 * 2;
double h = w;
BilinearTextureFilter filter = new BilinearTextureFilter(RenderBrushToImageData(brush, (int)w, (int)h));
filter.HasErrorEstimation = false;
return(filter);
}
