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, 29 insertions, 27 deletions

diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index a4f69b24351..6927e2dbc14 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -76,6 +76,7 @@
 #include "BKE_context.h"
 #include "BKE_depsgraph.h"
 #include "BKE_global.h"
+#include "BKE_library.h"
 #include "BKE_main.h"
 #include "BKE_packedFile.h"
 #include "BKE_report.h"
@@ -864,11 +865,11 @@ static void wm_history_file_update(void)
 
 
 /* screen can be NULL */
-static ImBuf *blend_file_thumb(Scene *scene, bScreen *screen, int **thumb_pt)
+static ImBuf *blend_file_thumb(Scene *scene, bScreen *screen, BlendThumbnail **thumb_pt)
 {
 	/* will be scaled down, but gives some nice oversampling */
 	ImBuf *ibuf;
-	int *thumb;
+	BlendThumbnail *thumb;
 	char err_out[256] = "unknown";
 
 	/* screen if no camera found */
@@ -876,7 +877,11 @@ static ImBuf *blend_file_thumb(Scene *scene, bScreen *screen, int **thumb_pt)
 	ARegion *ar = NULL;
 	View3D *v3d = NULL;
 
-	*thumb_pt = NULL;
+	/* In case we are given a valid thumbnail data, just generate image from it. */
+	if (*thumb_pt) {
+		thumb = *thumb_pt;
+		return BKE_main_thumbnail_to_imbuf(NULL, thumb);
+	}
 
 	/* scene can be NULL if running a script at startup and calling the save operator */
 	if (G.background || scene == NULL)
@@ -914,13 +919,7 @@ static ImBuf *blend_file_thumb(Scene *scene, bScreen *screen, int **thumb_pt)
 		/* add pretty overlay */
 		IMB_thumb_overlay_blend(ibuf->rect, ibuf->x, ibuf->y, aspect);
 		
-		/* first write into thumb buffer */
-		thumb = MEM_mallocN(((2 + (BLEN_THUMB_SIZE * BLEN_THUMB_SIZE))) * sizeof(int), "write_file thumb");
-
-		thumb[0] = BLEN_THUMB_SIZE;
-		thumb[1] = BLEN_THUMB_SIZE;
-
-		memcpy(thumb + 2, ibuf->rect, BLEN_THUMB_SIZE * BLEN_THUMB_SIZE * sizeof(int));
+		thumb = BKE_main_thumbnail_from_imbuf(NULL, ibuf);
 	}
 	else {
 		/* '*thumb_pt' needs to stay NULL to prevent a bad thumbnail from being handled */
@@ -959,25 +958,26 @@ int wm_file_write(bContext *C, const char *filepath, int fileflags, ReportList *
 {
 	Library *li;
 	int len;
-	int *thumb = NULL;
+	int ret = -1;
+	BlendThumbnail *thumb, *main_thumb;
 	ImBuf *ibuf_thumb = NULL;
 
 	len = strlen(filepath);
 	
 	if (len == 0) {
 		BKE_report(reports, RPT_ERROR, "Path is empty, cannot save");
-		return -1;
+		return ret;
 	}
 
 	if (len >= FILE_MAX) {
 		BKE_report(reports, RPT_ERROR, "Path too long, cannot save");
-		return -1;
+		return ret;
 	}
 	
 	/* Check if file write permission is ok */
 	if (BLI_exists(filepath) && !BLI_file_is_writable(filepath)) {
 		BKE_reportf(reports, RPT_ERROR, "Cannot save blend file, path '%s' is not writable", filepath);
-		return -1;
+		return ret;
 	}
  
 	/* note: used to replace the file extension (to ensure '.blend'),
@@ -988,18 +988,21 @@ int wm_file_write(bContext *C, const char *filepath, int fileflags, ReportList *
 	for (li = G.main->library.first; li; li = li->id.next) {
 		if (BLI_path_cmp(li->filepath, filepath) == 0) {
 			BKE_reportf(reports, RPT_ERROR, "Cannot overwrite used library '%.240s'", filepath);
-			return -1;
+			return ret;
 		}
 	}
 
+	/* Call pre-save callbacks befores writing preview, that way you can generate custom file thumbnail... */
+	BLI_callback_exec(G.main, NULL, BLI_CB_EVT_SAVE_PRE);
+
 	/* blend file thumbnail */
 	/* save before exit_editmode, otherwise derivedmeshes for shared data corrupt #27765) */
+	/* Main now can store a .blend thumbnail, usefull for background mode or thumbnail customization. */
+	main_thumb = thumb = CTX_data_main(C)->blen_thumb;
 	if ((U.flag & USER_SAVE_PREVIEWS) && BLI_thread_is_main()) {
 		ibuf_thumb = blend_file_thumb(CTX_data_scene(C), CTX_wm_screen(C), &thumb);
 	}
 
-	BLI_callback_exec(G.main, NULL, BLI_CB_EVT_SAVE_PRE);
-
 	/* operator now handles overwrite checks */
 
 	if (G.fileflags & G_AUTOPACK) {
@@ -1044,22 +1047,21 @@ int wm_file_write(bContext *C, const char *filepath, int fileflags, ReportList *
 		if (ibuf_thumb) {
 			IMB_thumb_delete(filepath, THB_FAIL); /* without this a failed thumb overrides */
 			ibuf_thumb = IMB_thumb_create(filepath, THB_LARGE, THB_SOURCE_BLEND, ibuf_thumb);
-			IMB_freeImBuf(ibuf_thumb);
 		}
 
-		if (thumb) MEM_freeN(thumb);
+		ret = 0;  /* Success. */
 	}
-	else {
-		if (ibuf_thumb) IMB_freeImBuf(ibuf_thumb);
-		if (thumb) MEM_freeN(thumb);
-		
-		WM_cursor_wait(0);
-		return -1;
+
+	if (ibuf_thumb) {
+		IMB_freeImBuf(ibuf_thumb);
+	}
+	if (thumb && thumb != main_thumb) {
+		MEM_freeN(thumb);
 	}
 
 	WM_cursor_wait(0);
-	
-	return 0;
+
+	return ret;
 }
 
 /**