Make .blend file thumbnail reading simpler and more coherent, read/store them when reading in background mode.

Primary goal of this commit is to fix an annoying issue - when processing and saving .blend
files in background mode you lose their thumbnails, since it can only be generated with
an OpenGL context.

Solution to that is to read .blend thumbnail while reading .blend file (only done in background
mode currently), and store it in Main struct.

Also, this lead to removing .blend file reading code from thumb_blend (no need to have doublons).
We now have a small interface in regular reading code area, which keeps it reasonbaly light
by only reading/parsing header info, and first few BHead blocks.

This makes code reading .blend thumbnail about 3 to 4 times slower than previous highly specialized
one in blend_thumb.c, but overall thumbnail generation of a big .blend files folder only grows
of about 1%, think we can bare with it.

Finally, since thumbnail is now optionally stored in Main struct, it makes it easy to allow user
to define their own custom one (instead of auto-generated one). RNA API for this was not added though,
accessing that kind of .blend meta-data has to be rethought a bit on a bigger level first.

Reviewers: sergey, campbellbarton

Subscribers: Severin, psy-fi

Differential Revision: https://developer.blender.org/D1469

1 files changed, 13 insertions, 96 deletions

diff --git a/source/blender/imbuf/intern/thumbs_blend.c b/source/blender/imbuf/intern/thumbs_blend.c
index 17d9f3d0735..b5c6deb6b01 100644
--- a/source/blender/imbuf/intern/thumbs_blend.c
+++ b/source/blender/imbuf/intern/thumbs_blend.c
@@ -28,8 +28,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "zlib.h"
-
 #include "BLI_utildefines.h"
 #include "BLI_endian_switch.h"
 #include "BLI_fileops.h"
@@ -41,6 +39,8 @@
 #include "BKE_global.h"
 #include "BKE_idcode.h"
 #include "BKE_icons.h"
+#include "BKE_library.h"
+#include "BKE_main.h"
 
 #include "DNA_ID.h"  /* For preview images... */
 
@@ -48,97 +48,20 @@
 #include "IMB_imbuf.h"
 #include "IMB_thumbs.h"
 
-/* extracts the thumbnail from between the 'REND' and the 'GLOB'
- * chunks of the header, don't use typical blend loader because its too slow */
-
-static ImBuf *loadblend_thumb(gzFile gzfile)
-{
-	char buf[12];
-	int bhead[24 / sizeof(int)]; /* max size on 64bit */
-	char endian, pointer_size;
-	char endian_switch;
-	int sizeof_bhead;
-
-	/* read the blend file header */
-	if (gzread(gzfile, buf, 12) != 12)
-		return NULL;
-	if (!STREQLEN(buf, "BLENDER", 7))
-		return NULL;
-
-	if (buf[7] == '-')
-		pointer_size = 8;
-	else if (buf[7] == '_')
-		pointer_size = 4;
-	else
-		return NULL;
-
-	sizeof_bhead = 16 + pointer_size;
-
-	if (buf[8] == 'V')
-		endian = B_ENDIAN;  /* big: PPC */
-	else if (buf[8] == 'v')
-		endian = L_ENDIAN;  /* little: x86 */
-	else
-		return NULL;
-
-	endian_switch = ((ENDIAN_ORDER != endian)) ? 1 : 0;
-
-	while (gzread(gzfile, bhead, sizeof_bhead) == sizeof_bhead) {
-		if (endian_switch)
-			BLI_endian_switch_int32(&bhead[1]);  /* length */
-
-		if (bhead[0] == REND) {
-			gzseek(gzfile, bhead[1], SEEK_CUR); /* skip to the next */
-		}
-		else {
-			break;
-		}
-	}
-
-	/* using 'TEST' since new names segfault when loading in old blenders */
-	if (bhead[0] == TEST) {
-		ImBuf *img = NULL;
-		int size[2];
-
-		if (gzread(gzfile, size, sizeof(size)) != sizeof(size))
-			return NULL;
-
-		if (endian_switch) {
-			BLI_endian_switch_int32(&size[0]);
-			BLI_endian_switch_int32(&size[1]);
-		}
-		/* length */
-		bhead[1] -= sizeof(int) * 2;
-
-		/* inconsistent image size, quit early */
-		if (bhead[1] != size[0] * size[1] * sizeof(int))
-			return NULL;
-	
-		/* finally malloc and read the data */
-		img = IMB_allocImBuf(size[0], size[1], 32, IB_rect | IB_metadata);
-	
-		if (gzread(gzfile, img->rect, bhead[1]) != bhead[1]) {
-			IMB_freeImBuf(img);
-			img = NULL;
-		}
-	
-		return img;
-	}
-	
-	return NULL;
-}
+#include "MEM_guardedalloc.h"
 
 ImBuf *IMB_thumb_load_blend(const char *blen_path, const char *blen_group, const char *blen_id)
 {
+	ImBuf *ima = NULL;
+
 	if (blen_group && blen_id) {
 		LinkNode *ln, *names, *lp, *previews = NULL;
 		struct BlendHandle *libfiledata = BLO_blendhandle_from_file(blen_path, NULL);
-		ImBuf *ima = NULL;
 		int idcode = BKE_idcode_from_name(blen_group);
 		int i, nprevs, nnames;
 
 		if (libfiledata == NULL) {
-			return NULL;
+			return ima;
 		}
 
 		/* Note: we should handle all previews for a same group at once, would avoid reopening .blend file
@@ -180,25 +103,19 @@ ImBuf *IMB_thumb_load_blend(const char *blen_path, const char *blen_group, const
 
 		BLI_linklist_free(previews, BKE_previewimg_freefunc);
 		BLI_linklist_free(names, free);
-		return ima;
 	}
 	else {
-		gzFile gzfile;
-		/* not necessarily a gzip */
-		gzfile = BLI_gzopen(blen_path, "rb");
+		BlendThumbnail *data;
 
-		if (NULL == gzfile) {
-			return NULL;
-		}
-		else {
-			ImBuf *img = loadblend_thumb(gzfile);
-
-			/* read ok! */
-			gzclose(gzfile);
+		data = BLO_thumbnail_from_file(blen_path);
+		ima = BKE_main_thumbnail_to_imbuf(NULL, data);
 
-			return img;
+		if (data) {
+			MEM_freeN(data);
 		}
 	}
+
+	return ima;
 }
 
 /* add a fake passepartout overlay to a byte buffer, use for blend file thumbnails */