Old feature request: undo system now restores images without reloading.

Was surprisingly easy to add, compiant with file reading and undo code.

Currently only the Image->ibuf gets restored, and its opengl binding, so
for realtime texture it works nicely. Also texture images are not freed
inbetween undo steps

Notes:
- Painting textures will just keep the painted image, there's no undo
  yet for that
- If this works satisfying, I'll extend it to compositing previews

TEST IT WELL PLEASE! :)

source/blender/blenloader/intern/readblenentry.c

@@ -289,6 +289,7 @@ BlendFileData *BLO_read_from_memory(void *mem, int memsize, BlendReadError *erro
 	return bfd;	
 }
 
+
 BlendFileData *BLO_read_from_memfile(const char *filename, MemFile *memfile, BlendReadError *error_r) 
 {
 	BlendFileData *bfd = NULL;
@@ -297,11 +298,19 @@ BlendFileData *BLO_read_from_memfile(const char *filename, MemFile *memfile, Ble
 	fd = blo_openblendermemfile(memfile, error_r);
 	if (fd) {
 		strcpy(fd->filename, filename);
+		
+		/* makes lookup of existing images in G.main */
+		blo_make_image_pointer_map(fd);
+		
 		bfd= blo_read_file_internal(fd, error_r);
 		if (bfd) {
 			bfd->type= BLENFILETYPE_BLEND;
 			strcpy(bfd->main->name, "");
 		}
+		
+		/* ensures relinked images are not freed */
+		blo_end_image_pointer_map(fd);
+		
 		blo_freefiledata(fd);			
 	}
 

source/blender/blenloader/intern/readfile.c

@@ -983,6 +983,8 @@ void blo_freefiledata(FileData *fd)
 			oldnewmap_free(fd->datamap);
 		if (fd->globmap)
 			oldnewmap_free(fd->globmap);
+		if (fd->imamap)
+			oldnewmap_free(fd->imamap);
 		if (fd->libmap && !(fd->flags & FD_FLAGS_NOT_MY_LIBMAP))
 			oldnewmap_free(fd->libmap);
 
@@ -1009,6 +1011,14 @@ static void *newglobadr(FileData *fd, void *adr)		/* direct datablocks with glob
 	return oldnewmap_lookup_and_inc(fd->globmap, adr);
 }
 
+static void *newimaadr(FileData *fd, void *adr)		/* used to restore image data after undo */
+{
+	if(fd->imamap && adr)
+		return oldnewmap_lookup_and_inc(fd->imamap, adr);
+	return NULL;
+}
+
+
 static void *newlibadr(FileData *fd, void *lib, void *adr)		/* only lib data */
 {
 	return oldnewmap_liblookup(fd->libmap, adr, lib);
@@ -1056,6 +1066,42 @@ static void change_idid_adr(ListBase *mainlist, FileData *basefd, void *old, voi
 	}
 }
 
+/* assumed; G.main still exists */
+void blo_make_image_pointer_map(FileData *fd)
+{
+	Image *ima= G.main->image.first;
+	
+	fd->imamap= oldnewmap_new();
+	
+	for(;ima; ima= ima->id.next) {
+		if(ima->ibuf)
+			oldnewmap_insert(fd->imamap, ima->ibuf, ima->ibuf, 0);
+	}
+}
+
+/* set G.main image ibufs to zero if it has been restored */
+void blo_end_image_pointer_map(FileData *fd)
+{
+	OldNew *entry= fd->imamap->entries;
+	Image *ima= G.main->image.first;
+	int i;
+	
+	/* used entries were restored, so we put them to zero */
+	for (i=0; i<fd->imamap->nentries; i++, entry++) {
+	 	if (entry->nr>0)
+			entry->newp= NULL;
+	}
+	
+	for(;ima; ima= ima->id.next) {
+		if(ima->ibuf) {
+			ima->ibuf= newimaadr(fd, ima->ibuf);
+			/* this mirrors direct_link_image */
+			if(ima->ibuf==NULL)
+				ima->bindcode= 0;
+		}
+	}
+}
+
 /* ********** END OLD POINTERS ****************** */
 /* ********** READ FILE ****************** */
 
@@ -1977,11 +2023,15 @@ static void lib_link_image(FileData *fd, Main *main)
 
 static void direct_link_image(FileData *fd, Image *ima)
 {
-	ima->ibuf= NULL;
-	ima->anim= NULL;
+	/* for undo system, pointers could be restored */
+	ima->ibuf= newimaadr(fd, ima->ibuf);
+	/* if restored, we keep the binded opengl index */
+	if(ima->ibuf==NULL)
+		ima->bindcode= 0;
+	
 	memset(ima->mipmap, 0, sizeof(ima->mipmap));
-	ima->repbind= 0;
-	ima->bindcode= 0;
+	ima->anim= NULL;
+	ima->repbind= NULL;
 	
 	ima->packedfile = direct_link_packedfile(fd, ima->packedfile);
 	ima->preview = direct_link_preview_image(fd, ima->preview);

source/blender/blenloader/intern/readfile.h

@@ -73,6 +73,7 @@ typedef struct FileData {
 	struct OldNewMap *datamap;
 	struct OldNewMap *globmap;
 	struct OldNewMap *libmap;
+	struct OldNewMap *imamap;
 	
 	ListBase mainlist;
 	
@@ -108,8 +109,10 @@ FileData *blo_openblenderfile( char *name, BlendReadError *error_r);
 FileData *blo_openblendermemory( void *buffer, int buffersize, BlendReadError *error_r);
 FileData *blo_openblendermemfile(struct MemFile *memfile, BlendReadError *error_r);
 
-void blo_freefiledata( FileData *fd);
+void blo_make_image_pointer_map(FileData *fd);
+void blo_end_image_pointer_map(FileData *fd);
 
+void blo_freefiledata( FileData *fd);
 
 BHead *blo_firstbhead(FileData *fd);
 BHead *blo_nextbhead(FileData *fd, BHead *thisblock);

source/blender/src/drawmesh.c

@@ -474,7 +474,7 @@ void free_realtime_image(Image *ima)
 		glDeleteTextures(ima->totbind, (GLuint *)ima->repbind);
 	
 		MEM_freeN(ima->repbind);
-		ima->repbind= 0;
+		ima->repbind= NULL;
 	}
 }