Second try to fix missing previews of mat/tex/etc. in .blend files.

This time, it's a dedicated operator user has to run before saving the file.

And it recursively check all IDs linked from each scene, therefore rendering
materials etc. previews using a scene they are used in.

Note the renderengine issue is not completely addressed this way
(existing code for icon previews seems to ignore completely other engines,
and IDs not linked anywhere (fake-user ones) will be rendered with current scene's engine
as fallback, also you can get a material linked to an hidden object in a scene, etc.).

Reviewers: sergey, campbellbarton

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D980

2 files changed, 88 insertions, 19 deletions

diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index fabb69b8eff..c1c31f6795d 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -101,7 +101,6 @@
 #include "GHOST_Path-api.h"
 
 #include "UI_interface.h"
-#include "UI_interface_icons.h"
 #include "UI_view2d.h"
 
 #include "GPU_draw.h"
@@ -895,24 +894,6 @@ bool write_crash_blend(void)
 	}
 }
 
-static void UNUSED_FUNCTION(wm_ensure_previews)(bContext *C, Main *mainvar)
-{
-	ListBase *lb[] = {&mainvar->mat, &mainvar->tex, &mainvar->image, &mainvar->world, &mainvar->lamp, NULL};
-	ID *id;
-	int i;
-
-	for (i = 0; lb[i]; i++) {
-		for (id = lb[i]->first; id; id = id->next) {
-			/* Only preview non-library datablocks, lib ones do not pertain to this .blend file!
-			 * Same goes for ID with no user. */
-			if (!id->lib && (id->us != 0)) {
-				UI_id_icon_render(C, id, false, false);
-				UI_id_icon_render(C, id, true, false);
-			}
-		}
-	}
-}
-
 /**
  * \see #wm_homefile_write_exec wraps #BLO_write_file in a similar way.
  */
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index 5b944a7b1ec..02a029fc3f3 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -61,6 +61,7 @@
 #include "BLI_blenlib.h"
 #include "BLI_dial.h"
 #include "BLI_dynstr.h" /*for WM_operator_pystring */
+#include "BLI_linklist_stack.h"
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 #include "BLI_ghash.h"
@@ -76,6 +77,7 @@
 #include "BKE_idprop.h"
 #include "BKE_image.h"
 #include "BKE_library.h"
+#include "BKE_library_query.h"
 #include "BKE_global.h"
 #include "BKE_main.h"
 #include "BKE_material.h"
@@ -105,6 +107,7 @@
 #include "RNA_enum_types.h"
 
 #include "UI_interface.h"
+#include "UI_interface_icons.h"
 #include "UI_resources.h"
 
 #include "WM_api.h"
@@ -4705,6 +4708,90 @@ static void WM_OT_dependency_relations(wmOperatorType *ot)
 	ot->exec = dependency_relations_exec;
 }
 
+/* *************************** Mat/tex/etc. previews generation ************* */
+
+typedef struct PreviewsIDEnsureStack {
+	Scene *scene;
+
+	BLI_LINKSTACK_DECLARE(id_stack, ID *);
+} PreviewsIDEnsureStack;
+
+static void previews_id_ensure(bContext *C, Scene *scene, ID *id)
+{
+	BLI_assert(ELEM(GS(id->name), ID_MA, ID_TE, ID_IM, ID_WO, ID_LA));
+
+	/* Only preview non-library datablocks, lib ones do not pertain to this .blend file!
+	 * Same goes for ID with no user. */
+	if (!id->lib && (id->us != 0)) {
+		UI_id_icon_render(C, scene, id, false, false);
+		UI_id_icon_render(C, scene, id, true, false);
+	}
+}
+
+static bool previews_id_ensure_callback(void *todo_v, ID **idptr, int UNUSED(cd_flag))
+{
+	PreviewsIDEnsureStack *todo = todo_v;
+	ID *id = *idptr;
+
+	if (id && (id->flag & LIB_DOIT)) {
+		if (ELEM(GS(id->name), ID_MA, ID_TE, ID_IM, ID_WO, ID_LA)) {
+			previews_id_ensure(NULL, todo->scene, id);
+		}
+		id->flag &= ~LIB_DOIT;  /* Tag the ID as done in any case. */
+		BLI_LINKSTACK_PUSH(todo->id_stack, id);
+	}
+
+	return true;
+}
+
+static int previews_ensure_exec(bContext *C, wmOperator *UNUSED(op))
+{
+	Main *bmain = CTX_data_main(C);
+	ListBase *lb[] = {&bmain->mat, &bmain->tex, &bmain->image, &bmain->world, &bmain->lamp, NULL};
+	PreviewsIDEnsureStack preview_id_stack;
+	Scene *scene;
+	ID *id;
+	int i;
+
+	/* We use LIB_DOIT to check whether we have already handled a given ID or not. */
+	BKE_main_id_flag_all(bmain, LIB_DOIT, true);
+
+	BLI_LINKSTACK_INIT(preview_id_stack.id_stack);
+
+	for (scene = bmain->scene.first; scene; scene = scene->id.next) {
+		preview_id_stack.scene = scene;
+		id = (ID *)scene;
+
+		do {
+			/* This will loop over all IDs linked by current one, render icons for them if needed,
+			 * and add them to 'todo' preview_id_stack. */
+			BKE_library_foreach_ID_link(id, previews_id_ensure_callback, &preview_id_stack, IDWALK_READONLY);
+		} while((id = BLI_LINKSTACK_POP(preview_id_stack.id_stack)));
+	}
+
+	BLI_LINKSTACK_FREE(preview_id_stack.id_stack);
+
+	/* Check a last time for ID not used (fake users only, in theory), and
+	 * do our best for those, using current scene... */
+	for (i = 0; lb[i]; i++) {
+		for (id = lb[i]->first; id; id = id->next) {
+			previews_id_ensure(C, NULL, id);
+		}
+	}
+
+	return OPERATOR_FINISHED;
+}
+
+static void WM_OT_previews_ensure(wmOperatorType *ot)
+{
+	ot->name = "Refresh DataBlock Previews";
+	ot->idname = "WM_OT_previews_ensure";
+	ot->description = "Ensure datablock previews are available and up-to-date "
+	                  "(to be saved in .blend file, only for some types like materials, textures, etc.)";
+
+	ot->exec = previews_ensure_exec;
+}
+
 /* ******************************************************* */
 
 static void operatortype_ghash_free_cb(wmOperatorType *ot)
@@ -4768,6 +4855,7 @@ void wm_operatortype_init(void)
 #if defined(WIN32)
 	WM_operatortype_append(WM_OT_console_toggle);
 #endif
+	WM_operatortype_append(WM_OT_previews_ensure);
 }
 
 /* circleselect-like modal operators */