spngsave: Don't shift indexed pixels (#3101)

DarthSim · web-flow · commit 982a835eedb6 · 2022-10-19T17:34:43.000+01:00
diff --git a/libvips/foreign/spngsave.c b/libvips/foreign/spngsave.c
@@ -270,7 +270,7 @@ vips_foreign_save_spng_pack( VipsForeignSaveSpng *spng,
 	VipsPel *q, VipsPel *p, size_t n )
 {
         int pixel_mask = 8 / spng->bitdepth - 1;
-	int shift = 8 - spng->bitdepth;
+	int shift = spng->palette ? 0 : 8 - spng->bitdepth;
 
         VipsPel bits;
         size_t x;

Original file line number	Diff line number	Diff line change
`@@ -270,7 +270,7 @@ vips_foreign_save_spng_pack( VipsForeignSaveSpng *spng,`
`270`	`270`	`VipsPel q, VipsPel p, size_t n )`
`271`	`271`	`{`
`272`	`272`	`int pixel_mask = 8 / spng->bitdepth - 1;`
`273`		`- int shift = 8 - spng->bitdepth;`
	`273`	`+ int shift = spng->palette ? 0 : 8 - spng->bitdepth;`
`274`	`274`
`275`	`275`	`VipsPel bits;`
`276`	`276`	`size_t x;`