API: Add function to get global colour table.

2 files changed, 34 insertions, 3 deletions

diff --git a/include/nsgif.h b/include/nsgif.h
index bd0fd58..9eec0f8 100644
--- a/include/nsgif.h
+++ b/include/nsgif.h
@@ -23,6 +23,9 @@
 /** Representation of infinity. */
 #define NSGIF_INFINITE (UINT32_MAX)
 
+/** Maximum colour table size */
+#define NSGIF_MAX_COLOURS 256
+
 /**
  * Opaque type used by LibNSGIF to represent a GIF object in memory.
  */
@@ -428,6 +431,23 @@ const nsgif_frame_info_t *nsgif_get_frame_info(
 		uint32_t frame);
 
 /**
+ * Get the global colour palette.
+ *
+ * If the GIF has no global colour table, this will return the default
+ * colour palette.
+ *
+ * Colours in same pixel format as \ref nsgif_bitmap_t.
+ *
+ * \param[in]  gif      The \ref nsgif_t object.
+ * \param[out] table    Client buffer to hold the colour table.
+ * \param[out] entries  The number of used entries in the colour table.
+ */
+void nsgif_global_palette(
+		const nsgif_t *gif,
+		uint32_t table[NSGIF_MAX_COLOURS],
+		size_t *entries);
+
+/**
  * Configure handling of small frame delays.
  *
  * Historically people created GIFs with a tiny frame delay, however the slow
diff --git a/src/gif.c b/src/gif.c
index 038ebf9..34b4e58 100644
--- a/src/gif.c
+++ b/src/gif.c
@@ -17,9 +17,6 @@
 #include "lzw.h"
 #include "nsgif.h"
 
-/** Maximum colour table size */
-#define NSGIF_MAX_COLOURS 256
-
 /** Default minimum allowable frame delay in cs. */
 #define NSGIF_FRAME_DELAY_MIN 2
 
@@ -1672,6 +1669,8 @@ nsgif_error nsgif_data_scan(
 			entry[gif->colour_layout.g] = 0xFF;
 			entry[gif->colour_layout.b] = 0xFF;
 			entry[gif->colour_layout.a] = 0xFF;
+
+			gif->colour_table_size = 2;
 		}
 
 		if (gif->info.colour_table &&
@@ -1909,6 +1908,18 @@ const nsgif_frame_info_t *nsgif_get_frame_info(
 }
 
 /* exported function documented in nsgif.h */
+void nsgif_global_palette(
+		const nsgif_t *gif,
+		uint32_t table[NSGIF_MAX_COLOURS],
+		size_t *entries)
+{
+	size_t len = sizeof(*table) * NSGIF_MAX_COLOURS;
+
+	memcpy(table, gif->global_colour_table, len);
+	*entries = gif->colour_table_size;
+}
+
+/* exported function documented in nsgif.h */
 const char *nsgif_strerror(nsgif_error err)
 {
 	static const char *const str[] = {