Make alpha channel unmultiply and premultiply utility functions public.

1 files changed, 35 insertions, 0 deletions

diff --git a/source/fitz/colorspace.c b/source/fitz/colorspace.c
index 4a957d20..89e6b9be 100644
--- a/source/fitz/colorspace.c
+++ b/source/fitz/colorspace.c
@@ -145,6 +145,41 @@ void fz_cmm_fin_profile(fz_context *ctx, fz_iccprofile *profile)
 			ctx->colorspace->cmm->fin_profile(ctx->cmm_instance, profile);
 }
 
+void fz_premultiply_row(fz_context *ctx, int n, int c, int w, unsigned char *s)
+{
+	unsigned char a;
+	int k;
+	int n1 = n-1;
+
+	for (; w > 0; w--)
+	{
+		a = s[n1];
+		for (k = 0; k < c; k++)
+			s[k] = fz_mul255(s[k], a);
+		s += n;
+	}
+}
+
+void fz_unmultiply_row(fz_context *ctx, int n, int c, int w, unsigned char *s, const unsigned char *in)
+{
+	int a, inva;
+	int k;
+	int n1 = n-1;
+
+	for (; w > 0; w--)
+	{
+		a = in[n1];
+		inva = a ? 255 * 256 / a : 0;
+		for (k = 0; k < c; k++)
+			s[k] = (in[k] * inva) >> 8;
+		for (;k < n1; k++)
+			s[k] = in[k];
+		s[n1] = a;
+		s += n;
+		in += n;
+	}
+}
+
 #define SLOWCMYK
 
 #if FZ_ENABLE_ICC