Fix: The bounding box gizmo breaks if transform pivot is set to cursor

The bounding box transform code assumed that the pivot would always be
the sequence object transform center.

Rework the code so that this assumption is true even if the general
transform pivot is set to be the 2D cursor.

1 files changed, 54 insertions, 25 deletions

diff --git a/source/blender/editors/transform/transform_gizmo_2d.c b/source/blender/editors/transform/transform_gizmo_2d.c
index 7a23a4a92ce..c3a0e4b1163 100644
--- a/source/blender/editors/transform/transform_gizmo_2d.c
+++ b/source/blender/editors/transform/transform_gizmo_2d.c
@@ -286,7 +286,14 @@ static bool gizmo2d_calc_bounds(const bContext *C, float *r_center, float *r_min
        * In addition to this, the rotation of the bounding box can not currently be hooked up
        * properly to read the result from the transform system (when transforming multiple strips).
        */
-      mid_v2_v2v2(r_center, r_min, r_max);
+      const int pivot_point = scene->toolsettings->sequencer_tool_settings->pivot_point;
+      if (pivot_point == V3D_AROUND_CURSOR) {
+        SpaceSeq *sseq = area->spacedata.first;
+        SEQ_image_preview_unit_to_px(scene, sseq->cursor, r_center);
+      }
+      else {
+        mid_v2_v2v2(r_center, r_min, r_max);
+      }
       zero_v2(r_min);
       zero_v2(r_max);
       return has_select;
@@ -353,39 +360,59 @@ static float gizmo2d_calc_rotation(const bContext *C)
   return 0.0f;
 }
 
-static bool gizmo2d_calc_center(const bContext *C, float r_center[2])
+static bool seq_get_strip_pivot_median(const Scene *scene, float r_pivot[2])
+{
+  zero_v2(r_pivot);
+
+  ListBase *seqbase = SEQ_active_seqbase_get(SEQ_editing_get(scene));
+  SeqCollection *strips = SEQ_query_rendered_strips(seqbase, scene->r.cfra, 0);
+  SEQ_filter_selected_strips(strips);
+  bool has_select = SEQ_collection_len(strips) != 0;
+
+  if (has_select) {
+    Sequence *seq;
+    SEQ_ITERATOR_FOREACH (seq, strips) {
+      float origin[2];
+      SEQ_image_transform_origin_offset_pixelspace_get(scene, seq, origin);
+      add_v2_v2(r_pivot, origin);
+    }
+    mul_v2_fl(r_pivot, 1.0f / SEQ_collection_len(strips));
+  }
+
+  SEQ_collection_free(strips);
+  return has_select;
+}
+
+static bool gizmo2d_calc_transform_pivot(const bContext *C, float r_pivot[2])
 {
   ScrArea *area = CTX_wm_area(C);
   Scene *scene = CTX_data_scene(C);
   bool has_select = false;
-  zero_v2(r_center);
+
   if (area->spacetype == SPACE_IMAGE) {
     SpaceImage *sima = area->spacedata.first;
     ViewLayer *view_layer = CTX_data_view_layer(C);
-    ED_uvedit_center_from_pivot_ex(sima, scene, view_layer, r_center, sima->around, &has_select);
+    ED_uvedit_center_from_pivot_ex(sima, scene, view_layer, r_pivot, sima->around, &has_select);
   }
   else if (area->spacetype == SPACE_SEQ) {
     SpaceSeq *sseq = area->spacedata.first;
     const int pivot_point = scene->toolsettings->sequencer_tool_settings->pivot_point;
-    ListBase *seqbase = SEQ_active_seqbase_get(SEQ_editing_get(scene));
-    SeqCollection *strips = SEQ_query_rendered_strips(seqbase, scene->r.cfra, 0);
-    SEQ_filter_selected_strips(strips);
-    has_select = SEQ_collection_len(strips) != 0;
 
     if (pivot_point == V3D_AROUND_CURSOR) {
-      SEQ_image_preview_unit_to_px(scene, sseq->cursor, r_center);
+      SEQ_image_preview_unit_to_px(scene, sseq->cursor, r_pivot);
+
+      ListBase *seqbase = SEQ_active_seqbase_get(SEQ_editing_get(scene));
+      SeqCollection *strips = SEQ_query_rendered_strips(seqbase, scene->r.cfra, 0);
+      SEQ_filter_selected_strips(strips);
+      has_select = SEQ_collection_len(strips) != 0;
+      SEQ_collection_free(strips);
     }
-    else if (has_select) {
-      Sequence *seq;
-      SEQ_ITERATOR_FOREACH (seq, strips) {
-        float origin[2];
-        SEQ_image_transform_origin_offset_pixelspace_get(scene, seq, origin);
-        add_v2_v2(r_center, origin);
-      }
-      mul_v2_fl(r_center, 1.0f / SEQ_collection_len(strips));
+    else {
+      has_select = seq_get_strip_pivot_median(scene, r_pivot);
     }
-
-    SEQ_collection_free(strips);
+  }
+  else {
+    BLI_assert_msg(0, "Unhandled space type!");
   }
   return has_select;
 }
@@ -409,7 +436,7 @@ static int gizmo2d_modal(bContext *C,
   ARegion *region = CTX_wm_region(C);
   float origin[3];
 
-  gizmo2d_calc_center(C, origin);
+  gizmo2d_calc_transform_pivot(C, origin);
   gizmo2d_origin_to_region(region, origin);
   WM_gizmo_set_matrix_location(widget, origin);
 
@@ -541,7 +568,7 @@ static void gizmo2d_xform_refresh(const bContext *C, wmGizmoGroup *gzgroup)
   GizmoGroup2D *ggd = gzgroup->customdata;
   bool has_select;
   if (ggd->no_cage) {
-    has_select = gizmo2d_calc_center(C, ggd->origin);
+    has_select = gizmo2d_calc_transform_pivot(C, ggd->origin);
   }
   else {
     has_select = gizmo2d_calc_bounds(C, ggd->origin, ggd->min, ggd->max);
@@ -597,7 +624,8 @@ static void gizmo2d_xform_draw_prepare(const bContext *C, wmGizmoGroup *gzgroup)
   ScrArea *area = CTX_wm_area(C);
 
   if (area->spacetype == SPACE_SEQ) {
-    gizmo2d_calc_center(C, origin);
+    Scene *scene = CTX_data_scene(C);
+    seq_get_strip_pivot_median(scene, origin);
 
     float matrix_rotate[4][4];
     unit_m4(matrix_rotate);
@@ -660,7 +688,8 @@ static void gizmo2d_xform_invoke_prepare(const bContext *C,
 
   if (ggd->rotation != 0.0f && area->spacetype == SPACE_SEQ) {
     float origin[3];
-    gizmo2d_calc_center(C, origin);
+    Scene *scene = CTX_data_scene(C);
+    seq_get_strip_pivot_median(scene, origin);
     /* We need to rotate the cardinal points so they align with the rotated bounding box. */
 
     rotate_around_center_v2(n, origin, ggd->rotation);
@@ -781,7 +810,7 @@ static void gizmo2d_resize_refresh(const bContext *C, wmGizmoGroup *gzgroup)
 {
   GizmoGroup_Resize2D *ggd = gzgroup->customdata;
   float origin[3];
-  const bool has_select = gizmo2d_calc_center(C, origin);
+  const bool has_select = gizmo2d_calc_transform_pivot(C, origin);
 
   if (has_select == false) {
     for (int i = 0; i < ARRAY_SIZE(ggd->gizmo_xy); i++) {
@@ -941,7 +970,7 @@ static void gizmo2d_rotate_refresh(const bContext *C, wmGizmoGroup *gzgroup)
 {
   GizmoGroup_Rotate2D *ggd = gzgroup->customdata;
   float origin[3];
-  const bool has_select = gizmo2d_calc_center(C, origin);
+  const bool has_select = gizmo2d_calc_transform_pivot(C, origin);
 
   if (has_select == false) {
     ggd->gizmo->flag |= WM_GIZMO_HIDDEN;