Fix T87489: Text Data-Blocks get deleted on Recursive Purge

Text data block were not considered special in the recursive purge
function.  So they would get deleted if they had no actual users.

To fix this we instead make text data block use "fake user" so that
addon authors can specify script files that should be removed if nothing
is using it anymore.

Per default, new text object have "fake user" set. So functionality
wise, the user has to explicitly specify that they want the text object
to be purge-able.

Reviewed By: Bastien

Differential Revision: http://developer.blender.org/D10983

6 files changed, 22 insertions, 12 deletions

diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 08aea043fc7..f74f7fe84de 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -39,7 +39,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 19
+#define BLENDER_FILE_SUBVERSION 20
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and show a warning if the file
diff --git a/source/blender/blenkernel/intern/text.c b/source/blender/blenkernel/intern/text.c
index 944e01321ce..27f5593c2ca 100644
--- a/source/blender/blenkernel/intern/text.c
+++ b/source/blender/blenkernel/intern/text.c
@@ -171,6 +171,9 @@ static void text_free_data(ID *id)
 
 static void text_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
+  if (id->us < 1 && !BLO_write_is_undo(writer)) {
+    return;
+  }
   Text *text = (Text *)id;
 
   /* Note: we are clearing local temp data here, *not* the flag in the actual 'real' ID. */
@@ -231,8 +234,6 @@ static void text_blend_read_data(BlendDataReader *reader, ID *id)
   }
 
   text->flags = (text->flags) & ~TXT_ISEXT;
-
-  id_us_ensure_real(&text->id);
 }
 
 IDTypeInfo IDType_ID_TXT = {
@@ -293,8 +294,10 @@ Text *BKE_text_add(Main *bmain, const char *name)
   Text *ta;
 
   ta = BKE_id_new(bmain, ID_TXT, name);
-  /* Texts always have 'real' user (see also read code). */
-  id_us_ensure_real(&ta->id);
+  /* Texts have no users by default... Set the fake user flag to ensure that this text block
+   * doesn't get deleted by default when cleaning up data blocks. */
+  id_us_min(&ta->id);
+  id_fake_user_set(&ta->id);
 
   return ta;
 }
@@ -468,7 +471,7 @@ bool BKE_text_reload(Text *text)
  * \param is_internal: If \a true, this text data-block only exists in memory,
  * not as a file on disk.
  *
- * \note text data-blocks have no user by default, only the 'real user' flag.
+ * \note text data-blocks have no real user but have 'fake user' enabled by default
  */
 Text *BKE_text_load_ex(Main *bmain, const char *file, const char *relpath, const bool is_internal)
 {
@@ -489,9 +492,8 @@ Text *BKE_text_load_ex(Main *bmain, const char *file, const char *relpath, const
   }
 
   ta = BKE_libblock_alloc(bmain, ID_TXT, BLI_path_basename(filepath_abs), 0);
-  /* Texts have no user by default... Only the 'real' user flag. */
-  id_us_ensure_real(&ta->id);
   id_us_min(&ta->id);
+  id_fake_user_set(&ta->id);
 
   BLI_listbase_clear(&ta->lines);
   ta->curl = ta->sell = NULL;
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 85cf45bd868..19ae0014bb8 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -2912,7 +2912,7 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
         else if (sl->spacetype == SPACE_TEXT) {
           SpaceText *st = (SpaceText *)sl;
 
-          st->text = restore_pointer_by_name(id_map, (ID *)st->text, USER_REAL);
+          st->text = restore_pointer_by_name(id_map, (ID *)st->text, USER_IGNORE);
           if (st->text == NULL) {
             st->text = newmain->texts.first;
           }
diff --git a/source/blender/blenloader/intern/versioning_290.c b/source/blender/blenloader/intern/versioning_290.c
index fe8e46e8928..97fe9fb04c4 100644
--- a/source/blender/blenloader/intern/versioning_290.c
+++ b/source/blender/blenloader/intern/versioning_290.c
@@ -48,6 +48,7 @@
 #include "DNA_screen_types.h"
 #include "DNA_shader_fx_types.h"
 #include "DNA_space_types.h"
+#include "DNA_text_types.h"
 #include "DNA_tracking_types.h"
 #include "DNA_workspace_types.h"
 
@@ -686,6 +687,15 @@ void do_versions_after_linking_290(Main *bmain, ReportList *UNUSED(reports))
     }
   }
 
+  if (!MAIN_VERSION_ATLEAST(bmain, 293, 20)) {
+    /* Set zero user text objects to have a fake user. */
+    LISTBASE_FOREACH (Text *, text, &bmain->texts) {
+      if (text->id.us == 0) {
+        id_fake_user_set(&text->id);
+      }
+    }
+  }
+
   /**
    * Versioning code until next subversion bump goes here.
    *
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index 760fbe75688..caeb52ab7e9 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -1110,7 +1110,7 @@ static void template_ID(const bContext *C,
       UI_but_flag_enable(but, UI_BUT_REDALERT);
     }
 
-    if (id->lib == NULL && !(ELEM(GS(id->name), ID_GR, ID_SCE, ID_SCR, ID_TXT, ID_OB, ID_WS)) &&
+    if (id->lib == NULL && !(ELEM(GS(id->name), ID_GR, ID_SCE, ID_SCR, ID_OB, ID_WS)) &&
         (hide_buttons == false)) {
       uiDefIconButR(block,
                     UI_BTYPE_ICON_TOGGLE,
diff --git a/source/blender/editors/space_text/text_ops.c b/source/blender/editors/space_text/text_ops.c
index e6803d12a42..9ec759ce4ae 100644
--- a/source/blender/editors/space_text/text_ops.c
+++ b/source/blender/editors/space_text/text_ops.c
@@ -266,8 +266,6 @@ static int text_new_exec(bContext *C, wmOperator *UNUSED(op))
   PropertyRNA *prop;
 
   text = BKE_text_add(bmain, "Text");
-  /* Texts have no user by default... Only the 'real' user flag. */
-  id_us_min(&text->id);
 
   /* hook into UI */
   UI_context_active_but_prop_get_templateID(C, &ptr, &prop);