Change: Support decoding NewGRFs with out-of-order v2 container.

OpenTTD · Dec 12, 2023 · ef78232 · ef78232
1 parent 13c2e81
commit ef78232
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Showing 3 changed files with 37 additions and 12 deletions.
diff --git a/src/grfcodec.cpp b/src/grfcodec.cpp
@@ -24,6 +24,7 @@
 #include <sys/stat.h>
 #include <getopt.h>
 #include <algorithm>
+#include <map>
 
 #ifdef __MINGW32__
 	#include <io.h>
@@ -651,6 +652,31 @@ static int encode(const char *file, const char *dir, int compress, int *colourma
 	return 0;
 }
 
+std::map<uint, off_t> _sprite_offsets{};
+
+static void read_grf_sprite_offsets(FILE *grf)
+{
+	_sprite_offsets.clear();
+
+	const char action[] = "Reading sprite offsets";
+	uint32_t offset = readdword(action, grf);
+	off_t pos = ftell(grf);
+	fseek(grf, offset, SEEK_CUR);
+
+	uint id = 0, count = 0;
+	while ((id = readdword(action, grf)) != 0) {
+		if (_sprite_offsets.count(id) == 0)
+			_sprite_offsets[id] = ftell(grf) - 4;
+
+		fseek(grf, readdword(action, grf), SEEK_CUR);
+		count++;
+	}
+
+	printf("Found %zu / %u container chunks\n", _sprite_offsets.size(), count);
+
+	fseek(grf, pos, SEEK_SET);
+}
+
 static int decode(const char *file, const char *dir, const U8 *palette, int box, int width, int height, int *colourmap, int useplaintext)
 {
 	int count, result, lastpct = -1;
@@ -694,14 +720,13 @@ static int decode(const char *file, const char *dir, const U8 *palette, int box,
 	cfread(action, buffer, 1, sizeof(buffer), grf);
 	int grfcontversion = memcmp(buffer, header, sizeof(header)) == 0 ? 2 : 1;
 
-	U32 dataoffset = 0;
+	printf("Found grf container version %d\n", grfcontversion);
 	if (grfcontversion == 1) {
 		fseek(grf, 0, SEEK_SET);
 	} else {
-		dataoffset = sizeof(header) + 4 + readdword(action, grf); // GRF data offset
+		read_grf_sprite_offsets(grf);
 		fgetc(grf); // Compression
 	}
-	printf("Found grf container version %d\n", grfcontversion);
 
 	// We do the 'file' and 'writer' seperate to make
 	//   this a little bit less messy
@@ -764,7 +789,7 @@ static int decode(const char *file, const char *dir, const U8 *palette, int box,
 		pcx->newsprite();
 		if (pcx32 != NULL) pcx32->newsprite();
 
-		result = decodesprite(grf, pcx, pcx32, &writer, count, &dataoffset, grfcontversion);
+		result = decodesprite(grf, pcx, pcx32, &writer, count, grfcontversion);
 		writer.flush();
 		count++;
 	} while (result);

diff --git a/src/sprites.cpp b/src/sprites.cpp
@@ -17,6 +17,7 @@
 \*****************************************/
 
 #include <stdlib.h>
+#include <map>
 
 #include "sprites.h"
 #include "grfcomm.h"
@@ -241,7 +242,9 @@ static void writesprite(bool first, spritestorage *image_writer, spriteinfowrite
 	image_writer->spritedone(info.xdim, info.ydim);
 }
 
-int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, spriteinfowriter *writer, int spriteno, U32 *dataoffset, int grfcontversion)
+extern std::map<uint, off_t> _sprite_offsets;
+
+int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, spriteinfowriter *writer, int spriteno, int grfcontversion)
 {
 	static const char *action = "decoding sprite";
 	unsigned long size, datasize, inbufsize, outbufsize, startpos, returnpos = 0;
@@ -268,7 +271,8 @@ int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, sprit
 		id = readdword(action, grf);
 		returnpos = ftell(grf);
 
-		fseek(grf, *dataoffset, SEEK_SET);
+		uint32_t dataoffset = _sprite_offsets[id];
+		fseek(grf, dataoffset, SEEK_SET);
 	}
 
 	long result;
@@ -302,7 +306,6 @@ int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, sprit
 			result = 1;
 
 			if (returnpos == 0) return result;
-			*dataoffset = startpos + size + 1;
 			break;
 		}
 
@@ -422,10 +425,7 @@ int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, sprit
 		free(outbuffer);
 		free(imgbuffer);
 
-		if (returnpos != 0) {
-			*dataoffset = startpos + inbufsize;
-			if (grfcontversion == 2 && HASTRANSPARENCY(info.info)) *dataoffset += 4;
-		} else {
+		if (returnpos == 0) {
 			returnpos = startpos + inbufsize;
 			break;
 		}

diff --git a/src/sprites.h b/src/sprites.h
@@ -91,7 +91,7 @@ class spritestorage {
 
 extern int maxx, maxy, maxs;
 
-int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, spriteinfowriter *writer, int spriteno, U32 *dataoffset, int grfcontversion);
+int decodesprite(FILE *grf, spritestorage *imgpal, spritestorage *imgrgba, spriteinfowriter *writer, int spriteno, int grfcontversion);
 
 long getlasttilesize();
 long encodetile(U8 **compressed_data, long *uncompressed_size, const CommonPixel *image, long imgsize, int sx, int sy, SpriteInfo inf, int docompress, int spriteno, bool has_mask, bool rgba, int grfcontversion);