Given a LinearGradientBrush defined as follows:
<LinearGradientBrush x:Key="RedYellowGradient"> <GradientStop Color="Blue" Offset="0.01" /> <GradientStop Color="Purple" Offset="0.25"/> <GradientStop Color="Red" Offset="0.5"/> <GradientStop Color="Orange" Offset="0.75"/> <GradientStop Color="Yellow" Offset="1.0"/> </LinearGradientBrush>
What is required to take that definition and determine the color represented by a specific offset, such as 0.13 or 0.82 without rendering anything visible?
This would take the form of a function with a prototype something like this:
Function GetColorFromBrushOffset(br as LinearGradientBrush, offset as Single) as SomeColorDataStructure
What would need to go in the function body? I'm not looking for finished code (though I won't refuse it!) just some ideas about what data structures and system calls to use.
This class (from one of this question's answers by @JonnyPiazzi) appears to exactly address my question:
public static class GradientStopCollectionExtensions { public static Color GetRelativeColor(this GradientStopCollection gsc, double offset) { GradientStop before = gsc.Where(w => w.Offset == gsc.Min(m => m.Offset)).First(); GradientStop after = gsc.Where(w => w.Offset == gsc.Max(m => m.Offset)).First(); foreach (var gs in gsc) { if (gs.Offset < offset && gs.Offset > before.Offset) { before = gs; } if (gs.Offset > offset && gs.Offset < after.Offset) { after = gs; } } var color = new Color(); color.ScA = (float)((offset - before.Offset) * (after.Color.ScA - before.Color.ScA) / (after.Offset - before.Offset) + before.Color.ScA); color.ScR = (float)((offset - before.Offset) * (after.Color.ScR - before.Color.ScR) / (after.Offset - before.Offset) + before.Color.ScR); color.ScG = (float)((offset - before.Offset) * (after.Color.ScG - before.Color.ScG) / (after.Offset - before.Offset) + before.Color.ScG); color.ScB = (float)((offset - before.Offset) * (after.Color.ScB - before.Color.ScB) / (after.Offset - before.Offset) + before.Color.ScB); return color; } }
