UI/Assets: Operator to load custom preview images for data-blocks

No automatic preview generation will ever be good enough to cover all cases
well. So custom preview images are a must for a preview driven data-block
selection - like for asset browsing.

The operator simply allows selecting an image file, which will then be read and
copied into the data-blocks preview (resized if necessary).

There's no UI for this currently and the operator won't be available in the
search menu yet. It will later once the Asset Browser UI is merged.

Reviewed as part of https://developer.blender.org/D9719.
Reviewed by: Bastien Montagne, Brecht Van Lommel

1 files changed, 72 insertions, 0 deletions

diff --git a/source/blender/editors/util/ed_util.c b/source/blender/editors/util/ed_util.c
index 76c261c9cba..5e3f443ce9c 100644
--- a/source/blender/editors/util/ed_util.c
+++ b/source/blender/editors/util/ed_util.c
@@ -35,6 +35,7 @@
 #include "DNA_screen_types.h"
 #include "DNA_space_types.h"
 
+#include "BLI_fileops.h"
 #include "BLI_listbase.h"
 #include "BLI_path_util.h"
 #include "BLI_string.h"
@@ -44,6 +45,7 @@
 
 #include "BKE_context.h"
 #include "BKE_global.h"
+#include "BKE_icons.h"
 #include "BKE_layer.h"
 #include "BKE_main.h"
 #include "BKE_material.h"
@@ -51,6 +53,7 @@
 #include "BKE_object.h"
 #include "BKE_packedFile.h"
 #include "BKE_paint.h"
+#include "BKE_report.h"
 #include "BKE_screen.h"
 #include "BKE_undo_system.h"
 #include "BKE_workspace.h"
@@ -501,3 +504,72 @@ void ED_OT_flush_edits(wmOperatorType *ot)
   /* flags */
   ot->flag = OPTYPE_INTERNAL;
 }
+
+static bool lib_id_load_custom_preview_poll(bContext *C)
+{
+  const PointerRNA idptr = CTX_data_pointer_get(C, "active_id");
+  BLI_assert(!idptr.data || RNA_struct_is_ID(idptr.type));
+
+  const ID *id = idptr.data;
+  if (!id) {
+    return false;
+  }
+  if (ID_IS_LINKED(id)) {
+    CTX_wm_operator_poll_msg_set(C, TIP_("Can't edit external library data"));
+    return false;
+  }
+  if (ID_IS_OVERRIDE_LIBRARY(id)) {
+    CTX_wm_operator_poll_msg_set(C, TIP_("Can't edit previews of overridden library data"));
+    return false;
+  }
+  if (!BKE_previewimg_id_get_p(id)) {
+    CTX_wm_operator_poll_msg_set(C, TIP_("Data-block does not support previews"));
+    return false;
+  }
+
+  return true;
+}
+
+static int lib_id_load_custom_preview_exec(bContext *C, wmOperator *op)
+{
+  char path[FILE_MAX];
+
+  RNA_string_get(op->ptr, "filepath", path);
+
+  if (!BLI_is_file(path)) {
+    BKE_reportf(op->reports, RPT_ERROR, "File not found '%s'", path);
+    return OPERATOR_CANCELLED;
+  }
+
+  PointerRNA idptr = CTX_data_pointer_get(C, "active_id");
+  ID *id = idptr.data;
+
+  BKE_previewimg_id_custom_set(id, path);
+
+  // WM_event_add_notifier(C, NC_ASSET, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void ED_OT_lib_id_load_custom_preview(wmOperatorType *ot)
+{
+  ot->name = "Load Custom Preview";
+  ot->description = "Choose an image to help identify the data-block visually";
+  ot->idname = "ED_OT_lib_id_load_custom_preview";
+
+  /* api callbacks */
+  ot->poll = lib_id_load_custom_preview_poll;
+  ot->exec = lib_id_load_custom_preview_exec;
+  ot->invoke = WM_operator_filesel;
+
+  /* flags */
+  ot->flag = OPTYPE_INTERNAL;
+
+  WM_operator_properties_filesel(ot,
+                                 FILE_TYPE_FOLDER | FILE_TYPE_IMAGE,
+                                 FILE_SPECIAL,
+                                 FILE_OPENFILE,
+                                 WM_FILESEL_FILEPATH,
+                                 FILE_DEFAULTDISPLAY,
+                                 FILE_SORT_DEFAULT);
+}