private static unsafe void GetMaskAlphaRow(int y, DecodeContext layerContext, MaskDecodeContext maskContext, ref NativeArray <byte> alphaBuffer)
{
if (maskContext == null)
{
return;
}
var mask = maskContext.Mask;
// Background color for areas not covered by the mask
byte backgroundColor = mask.InvertOnBlend
? (byte)(255 - mask.BackgroundColor)
: mask.BackgroundColor;
{
var alphaBufferPtr = NativeArrayUnsafeUtility.GetUnsafeBufferPointerWithoutChecks(alphaBuffer);
UnsafeUtility.MemSet(alphaBufferPtr, backgroundColor, alphaBuffer.Length);
}
if (maskContext.IsRowEmpty(y))
{
return;
}
//////////////////////////////////////
// Transfer mask into the alpha array
var pMaskData = mask.ImageData;
{
// Get pointers to starting positions
int alphaColumn = maskContext.Rectangle.X - layerContext.Rectangle.X;
var pAlpha = alphaColumn;
var pAlphaEnd = pAlpha + maskContext.Rectangle.Width;
int maskRow = y - mask.Rect.Y;
int maskColumn = maskContext.Rectangle.X - mask.Rect.X;
int idxMaskPixel = (maskRow * mask.Rect.Width) + maskColumn;
var pMask = idxMaskPixel * layerContext.ByteDepth;
// Take the high-order byte if values are 16-bit (little-endian)
if (layerContext.ByteDepth == 2)
{
pMask++;
}
// Decode mask into the alpha array.
if (layerContext.ByteDepth == 4)
{
DecodeMaskAlphaRow32(alphaBuffer, pAlpha, pAlphaEnd, pMaskData, pMask);
}
else
{
DecodeMaskAlphaRow(alphaBuffer, pAlpha, pAlphaEnd, pMaskData, pMask, layerContext.ByteDepth);
}
// Obsolete since Photoshop CS6, but retained for compatibility with
// older versions. Note that the background has already been inverted.
if (mask.InvertOnBlend)
{
Util.Invert(alphaBuffer, pAlpha, pAlphaEnd);
}
}
}
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Gets one row of alpha values from the mask.
/// </summary>
/// <param name="y">The y-coordinate of the row.</param>
/// <param name="layerContext">The decode context for the layer containing
/// the mask.</param>
/// <param name="maskContext">The decode context for the mask.</param>
/// <returns>An array of alpha values for the row, corresponding to the
/// width of the layer decode context.</returns>
unsafe private static byte[] GetMaskAlphaRow(
int y, DecodeContext layerContext, MaskDecodeContext maskContext)
{
if (maskContext == null)
{
return(null);
}
var mask = maskContext.Mask;
// Background color for areas not covered by the mask
byte backgroundColor = mask.InvertOnBlend
? (byte)(255 - mask.BackgroundColor)
: mask.BackgroundColor;
fixed(byte *pAlpha = &maskContext.AlphaBuffer[0])
{
Util.Fill(pAlpha, pAlpha + maskContext.AlphaBuffer.Length,
backgroundColor);
}
if (maskContext.IsRowEmpty(y))
{
return(maskContext.AlphaBuffer);
}
//////////////////////////////////////
// Transfer mask into the alpha array
fixed(byte *pAlphaRow = &maskContext.AlphaBuffer[0],
pMaskData = &mask.ImageData[0])
{
// Get pointers to starting positions
int alphaColumn = maskContext.Rectangle.X - layerContext.Rectangle.X;
byte *pAlpha = pAlphaRow + alphaColumn;
byte *pAlphaEnd = pAlpha + maskContext.Rectangle.Width;
int maskRow = y - maskContext.Mask.Rect.Y;
int maskColumn = maskContext.Rectangle.X - maskContext.Mask.Rect.X;
int idxMaskPixel = (maskRow * mask.Rect.Width) + maskColumn;
byte *pMask = pMaskData + idxMaskPixel * layerContext.ByteDepth;
// Take the high-order byte if values are 16-bit (little-endian)
if (layerContext.ByteDepth == 2)
{
pMask++;
}
// Decode mask into the alpha array.
if (layerContext.ByteDepth == 4)
{
DecodeMaskAlphaRow32(pAlpha, pAlphaEnd, pMask);
}
else
{
DecodeMaskAlphaRow(pAlpha, pAlphaEnd, pMask, layerContext.ByteDepth);
}
// Obsolete since Photoshop CS6, but retained for compatibility with
// older versions. Note that the background has already been inverted.
if (mask.InvertOnBlend)
{
Util.Invert(pAlpha, pAlphaEnd);
}
}
return(maskContext.AlphaBuffer);
}
