GPencil: fix separate points/strokes freezing with empty selection

Code would still create an object (without setting up materials), code
for removing unused material slots would then freeze.

Now return/cancel early in case of empty selection.

This came up in T88269 [which is still not fully fixed, transforming
curve edit points clear their GP_STROKE_SELECT flag which now results in
the early exit, should be looked at separately]

Maniphest Tasks: T88269

Differential Revision: https://developer.blender.org/D11252

1 files changed, 32 insertions, 0 deletions

diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index 8d42024a518..9fba2ce5902 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -543,6 +543,38 @@ bool gpencil_stroke_inside_circle(const float mval[2], int rad, int x0, int y0,
 }
 
 /* ******************************************************** */
+/* Selection Validity Testing */
+
+bool ED_gpencil_frame_has_selected_stroke(const bGPDframe *gpf)
+{
+  LISTBASE_FOREACH (bGPDstroke *, gps, &gpf->strokes) {
+    if (gps->flag & GP_STROKE_SELECT) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool ED_gpencil_layer_has_selected_stroke(const bGPDlayer *gpl, const bool is_multiedit)
+{
+  bGPDframe *init_gpf = (is_multiedit) ? gpl->frames.first : gpl->actframe;
+  for (bGPDframe *gpf = init_gpf; gpf; gpf = gpf->next) {
+    if ((gpf == gpl->actframe) || ((gpf->flag & GP_FRAME_SELECT) && (is_multiedit))) {
+      if (ED_gpencil_frame_has_selected_stroke(gpf)) {
+        return true;
+      }
+    }
+    /* If not multiedit, exit loop. */
+    if (!is_multiedit) {
+      break;
+    }
+  }
+
+  return false;
+}
+
+/* ******************************************************** */
 /* Stroke Validity Testing */
 
 /* Check whether given stroke can be edited given the supplied context */