add Support PNG 1/2/4/8-bit 256 INDEX Color Palette

README

@@ -32,7 +32,7 @@ Features
 uPNG supports loading and decoding PNG images into a simple byte buffer, suitable
 for passing directly to OpenGL as texture data.
 
-uPNG does NOT support interlaced images, paletted images, and fixed-transparency.
+uPNG does NOT support interlaced images, and fixed-transparency.
 Checksums are NOT verified and corrupt image data may be undetected.
 
 It DOES support RGB, RGBA, greyscale, and greyscale-with-alpha images.  RGB and
@@ -106,8 +106,16 @@ The formats supported are:
   UPNG_RGB16        48-bit RGB
   UPNG_RGBA8        32-bit RGBA
   UPNG_RGBA16       64-bit RGBA
+  UPNG_LUMINANCE1   1-bit Greyscale
+  UPNG_LUMINANCE2   2-bit Greyscale
+  UPNG_LUMINANCE4   4-bit Greyscale
   UPNG_LUMINANCE8   8-bit Greyscale
   UPNG_LUMINANCEA8  8-bit Greyscale w/ 8-bit Alpha
+  UPNG_INDEX1       1-bit 2 Color RGB INDEX Color Palette
+  UPNG_INDEX2       2-bit 4 Color RGB INDEX Color Palette
+  UPNG_INDEX4       4-bit 16 Color RGB INDEX Color Palette
+  UPNG_INDEX8       8-bit 256 Color RGB INDEX Color Palette
+  (Now uPNG support paletted images !)
 
 Possible error states are:
 

upng.c

@@ -38,6 +38,7 @@ freely, subject to the following restrictions:
 #define CHUNK_IHDR MAKE_DWORD('I','H','D','R')
 #define CHUNK_IDAT MAKE_DWORD('I','D','A','T')
 #define CHUNK_IEND MAKE_DWORD('I','E','N','D')
+#define CHUNK_PLTE MAKE_DWORD('P','L','T','E')
 
 #define FIRST_LENGTH_CODE_INDEX 257
 #define LAST_LENGTH_CODE_INDEX 285
@@ -72,6 +73,7 @@ typedef enum upng_state {
 typedef enum upng_color {
 	UPNG_LUM		= 0,
 	UPNG_RGB		= 2,
+	UPNG_INDX		= 3,
 	UPNG_LUMA		= 4,
 	UPNG_RGBA		= 6
 } upng_color;
@@ -93,6 +95,8 @@ struct upng_t {
 	unsigned char*	buffer;
 	unsigned long	size;
 
+	unsigned char*	palette;
+
 	upng_error		error;
 	unsigned		error_line;
 
@@ -876,6 +880,19 @@ static upng_format determine_format(upng_t* upng) {
 		default:
 			return UPNG_BADFORMAT;
 		}
+	case UPNG_INDX:
+		switch (upng->color_depth) {
+		case 1:
+			return UPNG_INDEX1;
+		case 2:
+			return UPNG_INDEX2;
+		case 4:
+			return UPNG_INDEX4;
+		case 8:
+			return UPNG_INDEX8;
+		default:
+			return UPNG_BADFORMAT;
+		}
 	default:
 		return UPNG_BADFORMAT;
 	}
@@ -966,7 +983,9 @@ upng_error upng_decode(upng_t* upng)
 	const unsigned char *chunk;
 	unsigned char* compressed;
 	unsigned char* inflated;
+	unsigned char* palette = NULL;
 	unsigned long compressed_size = 0, compressed_index = 0;
+	unsigned long palette_size = 0;
 	unsigned long inflated_size;
 	upng_error error;
 
@@ -1000,7 +1019,7 @@ upng_error upng_decode(upng_t* upng)
 	 * verify general well-formed-ness */
 	while (chunk < upng->source.buffer + upng->source.size) {
 		unsigned long length;
-		const unsigned char *data;	/*the data in the chunk */
+		// const unsigned char *data;	/*the data in the chunk */
 
 		/* make sure chunk header is not larger than the total compressed */
 		if ((unsigned long)(chunk - upng->source.buffer + 12) > upng->source.size) {
@@ -1022,19 +1041,21 @@ upng_error upng_decode(upng_t* upng)
 		}
 
 		/* get pointer to payload */
-		data = chunk + 8;
+		// data = chunk + 8;
 
 		/* parse chunks */
 		if (upng_chunk_type(chunk) == CHUNK_IDAT) {
 			compressed_size += length;
+		} else if (upng_chunk_type(chunk) == CHUNK_PLTE) {
+			palette_size = length;
 		} else if (upng_chunk_type(chunk) == CHUNK_IEND) {
 			break;
 		} else if (upng_chunk_critical(chunk)) {
 			SET_ERROR(upng, UPNG_EUNSUPPORTED);
 			return upng->error;
 		}
 
-		chunk += upng_chunk_length(chunk) + 12;
+		chunk += length + 12;
 	}
 
 	/* allocate enough space for the (compressed and filtered) image data */
@@ -1044,6 +1065,15 @@ upng_error upng_decode(upng_t* upng)
 		return upng->error;
 	}
 
+	if (palette_size) {
+		palette = (unsigned char*)malloc(palette_size);
+		if (palette == NULL) {
+			free(compressed);
+			SET_ERROR(upng, UPNG_ENOMEM);
+			return upng->error;
+		}
+	}
+
 	/* scan through the chunks again, this time copying the values into
 	 * our compressed buffer.  there's no reason to validate anything a second time. */
 	chunk = upng->source.buffer + 33;
@@ -1052,23 +1082,27 @@ upng_error upng_decode(upng_t* upng)
 		const unsigned char *data;	/*the data in the chunk */
 
 		length = upng_chunk_length(chunk);
-		data = chunk + 8;
 
 		/* parse chunks */
 		if (upng_chunk_type(chunk) == CHUNK_IDAT) {
+			data = chunk + 8;
 			memcpy(compressed + compressed_index, data, length);
 			compressed_index += length;
+		} else if (upng_chunk_type(chunk) == CHUNK_PLTE) {
+			data = chunk + 8;
+			memcpy(palette, data, palette_size);
 		} else if (upng_chunk_type(chunk) == CHUNK_IEND) {
 			break;
 		}
 
-		chunk += upng_chunk_length(chunk) + 12;
+		chunk += length + 12;
 	}
 
 	/* allocate space to store inflated (but still filtered) data */
 	inflated_size = ((upng->width * (upng->height * upng_get_bpp(upng) + 7)) / 8) + upng->height;
 	inflated = (unsigned char*)malloc(inflated_size);
 	if (inflated == NULL) {
+		free(palette);
 		free(compressed);
 		SET_ERROR(upng, UPNG_ENOMEM);
 		return upng->error;
@@ -1077,6 +1111,7 @@ upng_error upng_decode(upng_t* upng)
 	/* decompress image data */
 	error = uz_inflate(upng, inflated, inflated_size, compressed, compressed_size);
 	if (error != UPNG_EOK) {
+		free(palette);
 		free(compressed);
 		free(inflated);
 		return upng->error;
@@ -1089,6 +1124,7 @@ upng_error upng_decode(upng_t* upng)
 	upng->size = (upng->height * upng->width * upng_get_bpp(upng) + 7) / 8;
 	upng->buffer = (unsigned char*)malloc(upng->size);
 	if (upng->buffer == NULL) {
+		free(palette);
 		free(inflated);
 		upng->size = 0;
 		SET_ERROR(upng, UPNG_ENOMEM);
@@ -1100,10 +1136,13 @@ upng_error upng_decode(upng_t* upng)
 	free(inflated);
 
 	if (upng->error != UPNG_EOK) {
+		free(palette);
 		free(upng->buffer);
 		upng->buffer = NULL;
 		upng->size = 0;
 	} else {
+		/* palette */
+		upng->palette = palette;
 		upng->state = UPNG_DECODED;
 	}
 
@@ -1200,6 +1239,11 @@ upng_t* upng_new_from_file(const char *filename)
 
 void upng_free(upng_t* upng)
 {
+	/* deallocate palette */
+	if (upng->palette != NULL) {
+		free(upng->palette);
+	}
+
 	/* deallocate image buffer */
 	if (upng->buffer != NULL) {
 		free(upng->buffer);
@@ -1248,6 +1292,8 @@ unsigned upng_get_components(const upng_t* upng)
 		return 2;
 	case UPNG_RGBA:
 		return 4;
+	case UPNG_INDX:
+		return 1;
 	default:
 		return 0;
 	}
@@ -1279,3 +1325,8 @@ unsigned upng_get_size(const upng_t* upng)
 {
 	return upng->size;
 }
+
+const unsigned char* upng_get_palette(const upng_t* upng)
+{
+	return upng->palette;
+}

upng.h

@@ -52,7 +52,11 @@ typedef enum upng_format {
 	UPNG_LUMINANCE_ALPHA1,
 	UPNG_LUMINANCE_ALPHA2,
 	UPNG_LUMINANCE_ALPHA4,
-	UPNG_LUMINANCE_ALPHA8
+	UPNG_LUMINANCE_ALPHA8,
+	UPNG_INDEX1,
+	UPNG_INDEX2,
+	UPNG_INDEX4,
+	UPNG_INDEX8
 } upng_format;
 
 typedef struct upng_t upng_t;
@@ -77,5 +81,6 @@ upng_format	upng_get_format		(const upng_t* upng);
 
 const unsigned char*	upng_get_buffer		(const upng_t* upng);
 unsigned				upng_get_size		(const upng_t* upng);
+const unsigned char*	upng_get_palette	(const upng_t* upng);
 
 #endif /*defined(UPNG_H)*/