public void ScaleOpacity(double adjustment, OpacityStyle style)
{
if (adjustment == 0)
return;
if (style == OpacityStyle.Auto)
style = adjustment > 0 ? OpacityStyle.Additive : OpacityStyle.MoveEndpoint;
var lut = new byte[256];
for (int x = 0; x < 256; x++)
switch (style)
{
case OpacityStyle.MoveEndpoint:
if (adjustment < 0)
lut[x] = (byte) (x / (1.0 + -adjustment));
else
lut[x] = (byte) (255 - (255 - x) / (1.0 + adjustment));
break;
case OpacityStyle.MoveMidpoint:
lut[x] = (byte) (Math.Pow(x / 255.0, adjustment < 0 ? (1 - adjustment) : (1 / (1 + adjustment))) * 255);
break;
case OpacityStyle.Additive:
if (adjustment < 0)
lut[x] = (byte) Math.Max(0, 255 - (255 - x) * (1.0 - adjustment));
else
lut[x] = (byte) Math.Min(255, x * (1.0 + adjustment));
break;
default:
throw new Exception();
}
using (UseWrite())
{
for (int y = 0; y < Height; y++)
{
byte* ptr = Data + y * Stride + 3;
byte* end = ptr + Width * 4;
while (ptr < end)
{
*ptr = lut[*ptr];
ptr += 4;
}
}
}
}
public void ScaleOpacity(double adjustment, OpacityStyle style)
{
if (adjustment == 0)
{
return;
}
if (style == OpacityStyle.Auto)
{
style = adjustment > 0 ? OpacityStyle.Additive : OpacityStyle.MoveEndpoint;
}
var lut = new byte[256];
for (int x = 0; x < 256; x++)
{
switch (style)
{
case OpacityStyle.MoveEndpoint:
if (adjustment < 0)
{
lut[x] = (byte)(x / (1.0 + -adjustment));
}
else
{
lut[x] = (byte)(255 - (255 - x) / (1.0 + adjustment));
}
break;
case OpacityStyle.MoveMidpoint:
lut[x] = (byte)(Math.Pow(x / 255.0, adjustment < 0 ? (1 - adjustment) : (1 / (1 + adjustment))) * 255);
break;
case OpacityStyle.Additive:
if (adjustment < 0)
{
lut[x] = (byte)Math.Max(0, 255 - (255 - x) * (1.0 - adjustment));
}
else
{
lut[x] = (byte)Math.Min(255, x * (1.0 + adjustment));
}
break;
default:
throw new Exception();
}
}
using (UseWrite())
{
for (int y = 0; y < Height; y++)
{
byte *ptr = Data + y * Stride + 3;
byte *end = ptr + Width * 4;
while (ptr < end)
{
*ptr = lut[*ptr];
ptr += 4;
}
}
}
}
public OpacityEffect()
{
Opacity = -1.5;
Style = OpacityStyle.Auto;
}
