public override void SetAsSource(Context ctx, Rectangle bounds = default(Rectangle))
{
Cairo.Gradient grad = null;
switch (GradientType)
{
case Type.Vertical:
grad = new Cairo.LinearGradient(bounds.Left, bounds.Top, bounds.Left, bounds.Bottom);
break;
case Type.Horizontal:
grad = new Cairo.LinearGradient(bounds.Left, bounds.Top, bounds.Right, bounds.Top);
break;
case Type.Oblic:
grad = new Cairo.LinearGradient(bounds.Left, bounds.Top, bounds.Right, bounds.Bottom);
break;
case Type.Radial:
throw new NotImplementedException();
}
foreach (ColorStop cs in Stops)
{
grad.AddColorStop(cs.Offset, cs.Color);
}
ctx.SetSource(grad);
grad.Dispose();
}
static void ShadowGradient(Cairo.Gradient lg, double strength)
{
lg.AddColorStop(0, new Cairo.Color(0, 0, 0, strength));
lg.AddColorStop(1.0 / 6.0, new Cairo.Color(0, 0, 0, .85 * strength));
lg.AddColorStop(2.0 / 6.0, new Cairo.Color(0, 0, 0, .54 * strength));
lg.AddColorStop(3.0 / 6.0, new Cairo.Color(0, 0, 0, .24 * strength));
lg.AddColorStop(4.0 / 6.0, new Cairo.Color(0, 0, 0, .07 * strength));
lg.AddColorStop(5.0 / 6.0, new Cairo.Color(0, 0, 0, .01 * strength));
lg.AddColorStop(1, new Cairo.Color(0, 0, 0, 0));
}
static void GetShadowPattern(Cairo.Gradient shadow, ShadowParameters shadowParams)
{
double denLog = Math.Log(1.0f / shadowParams.shadowRadius);
shadow.AddColorStop(0.0, new Cairo.Color(0, 0, 0, shadowParams.shadowAlpha));
for (int i = 2; i <= shadowParams.shadowRadius; i++)
{
double step = i / shadowParams.shadowRadius;
shadow.AddColorStop(step, new Cairo.Color(0, 0, 0, shadowParams.shadowAlpha * (Math.Log(step) / denLog)));
}
}
static void FillShadowPattern(Cairo.Context cairo, Cairo.Gradient shadow, ShadowParameters shadowParams)
{
GetShadowPattern(shadow, shadowParams);
cairo.SetSource(shadow);
cairo.Fill();
}
