blend file thumbnailing

- uses same thumbnail system as image browser
- blend files show thumbnails in ubuntu/gnome (freedesktop spec)
- 128x128 images are embedded into the blend file header, a simple loader avoids reading the entire blend file to extract it when generating thumbnails in the file selector.
  When the image browser reads a directory it loads images and creates thumbnails, blend files embedded images are treated just like loading an image.
- the thumbnail is created from the camera view in solid mode. (no camera == no thumbnal).
- readfile/writefile.c: had to use the 'TEST' code name to save thumbnails, anything else would segfault older blender versions on load. (its not used elsewhere).

3 files changed, 22 insertions, 8 deletions

diff --git a/source/blender/blenloader/BLO_writefile.h b/source/blender/blenloader/BLO_writefile.h
index a95e5867c7e..182c582cc0f 100644
--- a/source/blender/blenloader/BLO_writefile.h
+++ b/source/blender/blenloader/BLO_writefile.h
@@ -35,10 +35,12 @@ struct MemFile;
 struct Main;
 struct ReportList;
 
-extern int BLO_write_file(struct Main *mainvar, char *dir, int write_flags, struct ReportList *reports);
+extern int BLO_write_file(struct Main *mainvar, char *dir, int write_flags, struct ReportList *reports, int *thumb);
 extern int BLO_write_file_mem(struct Main *mainvar, struct MemFile *compare, struct MemFile *current, 
 							  int write_flags, struct ReportList *reports);
 extern int BLO_write_runtime(struct Main *mainvar, char *file, char *exename, struct ReportList *reports);
 
+#define BLEN_THUMB_SIZE 128
+
 #endif
 
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 381fc868a0d..8dbf2682bb6 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -10971,7 +10971,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filename)
 		switch(bhead->code) {
 		case DATA:
 		case DNA1:
-		case TEST:
+		case TEST: /* used as preview since 2.5x */
 		case REND:
 			bhead = blo_nextbhead(fd, bhead);
 			break;
diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index 5f2ee73e129..35fda1d8aa7 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -62,6 +62,7 @@ Any case: direct data is ALWAYS after the lib block
 	- write library block
 	- per LibBlock
 		- write the ID of LibBlock
+- write TEST (128x128, blend file preview, optional)
 - write FileGlobal (some global vars)
 - write SDNA
 - write USER if filename is ~/.B.blend
@@ -2390,9 +2391,19 @@ static void write_global(WriteData *wd, int fileflags, Main *mainvar)
 	writestruct(wd, GLOB, "FileGlobal", 1, &fg);
 }
 
+/* preview image, first 2 values are width and height
+ * second are an RGBA image (unsigned char)
+ * note, this uses 'TEST' since new types will segfault on file load for older blender versions.
+ */
+static void write_thumb(WriteData *wd, int *img)
+{
+	if(img)
+		writedata(wd, TEST, (2 + img[0] * img[1]) * sizeof(int), img);
+}
+
 /* if MemFile * there's filesave to memory */
 static int write_file_handle(Main *mainvar, int handle, MemFile *compare, MemFile *current, 
-							 int write_user_block, int write_flags)
+							 int write_user_block, int write_flags, int *thumb)
 {
 	BHead bhead;
 	ListBase mainlist;
@@ -2407,6 +2418,7 @@ static int write_file_handle(Main *mainvar, int handle, MemFile *compare, MemFil
 	mywrite(wd, buf, 12);
 
 	write_renderinfo(wd, mainvar);
+	write_thumb(wd, thumb);
 	write_global(wd, write_flags, mainvar);
 
 	/* no UI save in undo */
@@ -2458,7 +2470,7 @@ static int write_file_handle(Main *mainvar, int handle, MemFile *compare, MemFil
 }
 
 /* return: success (1) */
-int BLO_write_file(Main *mainvar, char *dir, int write_flags, ReportList *reports)
+int BLO_write_file(Main *mainvar, char *dir, int write_flags, ReportList *reports, int *thumb)
 {
 	char userfilename[FILE_MAXDIR+FILE_MAXFILE];
 	char tempname[FILE_MAXDIR+FILE_MAXFILE+1];
@@ -2497,7 +2509,7 @@ int BLO_write_file(Main *mainvar, char *dir, int write_flags, ReportList *report
 		makeFilesRelative(dir, NULL); /* note, making relative to something OTHER then G.sce */
 
 	/* actual file writing */
-	err= write_file_handle(mainvar, file, NULL,NULL, write_user_block, write_flags);
+	err= write_file_handle(mainvar, file, NULL,NULL, write_user_block, write_flags, thumb);
 	close(file);
 
 	/* rename/compress */
@@ -2550,7 +2562,7 @@ int BLO_write_file_mem(Main *mainvar, MemFile *compare, MemFile *current, int wr
 {
 	int err;
 
-	err= write_file_handle(mainvar, 0, compare, current, 0, write_flags);
+	err= write_file_handle(mainvar, 0, compare, current, 0, write_flags, NULL);
 	
 	if(err==0) return 1;
 	return 0;
@@ -2646,7 +2658,7 @@ int BLO_write_runtime(Main *mainvar, char *file, char *exename, ReportList *repo
 	outfd= open(gamename, O_BINARY|O_WRONLY|O_CREAT|O_TRUNC, 0777);
 	if (outfd != -1) {
 
-		write_file_handle(mainvar, outfd, NULL,NULL, 0, G.fileflags);
+		write_file_handle(mainvar, outfd, NULL,NULL, 0, G.fileflags, NULL);
 
 		if (write(outfd, " ", 1) != 1) {
 			BKE_report(reports, RPT_ERROR, "Unable to write to output file.");
@@ -2732,7 +2744,7 @@ int BLO_write_runtime(Main *mainvar, char *file, char *exename, ReportList *repo
 
 	datastart= lseek(outfd, 0, SEEK_CUR);
 
-	write_file_handle(mainvar, outfd, NULL,NULL, 0, G.fileflags);
+	write_file_handle(mainvar, outfd, NULL,NULL, 0, G.fileflags, NULL);
 
 	if (!handle_write_msb_int(outfd, datastart) || (write(outfd, "BRUNTIME", 8)!=8)) {
 		BKE_report(reports, RPT_ERROR, "Unable to write to output file.");