VSE: Slip keyframes with strip content

The "slip strip contents" operator in the VSE now can move the strip
keyframes. There is a property to enable keyframe slipping.
The property is disabled by default, mainly because animation is
often used for fade in/out, which would be annoying if it moved with
content.

Pull Request: https://projects.blender.org/blender/blender/pulls/136386

source/blender/editors/space_sequencer/sequencer_edit.cc

@@ -548,7 +548,8 @@ static wmOperatorStatus sequencer_slip_invoke(bContext *C, wmOperator *op, const
   return OPERATOR_RUNNING_MODAL;
 }
 
-static void sequencer_slip_strips(Scene *scene, SlipData *data, int delta, float subframe_delta)
+static void sequencer_slip_strips(
+    Scene *scene, SlipData *data, int delta, float subframe_delta, bool slip_keyframes)
 {
   for (int i = data->num_seq - 1; i >= 0; i--) {
     Strip *strip = data->strip_array[i];
@@ -558,7 +559,7 @@ static void sequencer_slip_strips(Scene *scene, SlipData *data, int delta, float
       continue;
     }
 
-    seq::time_slip_strip(scene, strip, delta, subframe_delta);
+    seq::time_slip_strip(scene, strip, delta, subframe_delta, slip_keyframes);
   }
 
   for (int i = data->num_seq - 1; i >= 0; i--) {
@@ -614,6 +615,7 @@ static wmOperatorStatus sequencer_slip_exec(bContext *C, wmOperator *op)
 
   slip_add_sequences(ed->seqbasep, data->strip_array);
 
+  bool slip_keyframes = RNA_boolean_get(op->ptr, "slip_keyframes");
   float offset_fl = RNA_float_get(op->ptr, "offset");
   int offset = round_fl_to_int(offset_fl);
 
@@ -624,7 +626,7 @@ static wmOperatorStatus sequencer_slip_exec(bContext *C, wmOperator *op)
   }
 
   sequencer_slip_apply_limits(scene, data, &offset);
-  sequencer_slip_strips(scene, data, offset, subframe_delta);
+  sequencer_slip_strips(scene, data, offset, subframe_delta, slip_keyframes);
 
   MEM_freeN(data->strip_array);
   MEM_freeN(data);
@@ -679,7 +681,9 @@ static void handle_number_input(
     data->subframe_restore += subframe_delta;
   }
   data->previous_subframe_offset = offset_fl;
-  sequencer_slip_strips(scene, data, delta_offset, subframe_delta);
+
+  bool slip_keyframes = RNA_boolean_get(op->ptr, "slip_keyframes");
+  sequencer_slip_strips(scene, data, delta_offset, subframe_delta, slip_keyframes);
 
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
 }
@@ -738,7 +742,9 @@ static wmOperatorStatus sequencer_slip_modal(bContext *C, wmOperator *op, const
           data->subframe_restore = 0.0f;
         }
         data->previous_subframe_offset = offset_fl;
-        sequencer_slip_strips(scene, data, delta_offset, subframe_delta);
+
+        bool slip_keyframes = RNA_boolean_get(op->ptr, "slip_keyframes");
+        sequencer_slip_strips(scene, data, delta_offset, subframe_delta, slip_keyframes);
 
         WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
       }
@@ -764,7 +770,8 @@ static wmOperatorStatus sequencer_slip_modal(bContext *C, wmOperator *op, const
     case RIGHTMOUSE: {
       int offset = data->previous_offset;
       float subframe_delta = data->subframe_restore;
-      sequencer_slip_strips(scene, data, -offset, -subframe_delta);
+      bool slip_keyframes = RNA_boolean_get(op->ptr, "slip_keyframes");
+      sequencer_slip_strips(scene, data, -offset, -subframe_delta, slip_keyframes);
 
       MEM_freeN(data->strip_array);
       MEM_freeN(data);
@@ -834,6 +841,11 @@ void SEQUENCER_OT_slip(wmOperatorType *ot)
                        -FLT_MAX,
                        FLT_MAX);
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 100, 0);
+  RNA_def_boolean(ot->srna,
+                  "slip_keyframes",
+                  false,
+                  "Slip Keyframes",
+                  "Move the keyframes alongside the media");
 }
 
 /** \} */

source/blender/sequencer/SEQ_animation.hh

@@ -16,13 +16,13 @@ struct ListBase;
 struct Scene;
 struct Strip;
 struct SeqAnimationBackup;
-
 namespace blender::seq {
 
-bool animation_keyframes_exist(Scene *scene);
+bool animation_keyframes_exist(const Scene *scene);
 bool animation_drivers_exist(Scene *scene);
 void free_animdata(Scene *scene, Strip *strip);
-void offset_animdata(Scene *scene, Strip *strip, int ofs);
+void offset_animdata(const Scene *scene, Strip *strip, float ofs);
+
 /**
  * Return whether the fcurve targets the given sequence.
  */

source/blender/sequencer/SEQ_time.hh

@@ -125,7 +125,8 @@ void time_update_meta_strip_range(const Scene *scene, Strip *strip_meta);
 /**
  * Move contents of a strip without moving the strip handles.
  */
-void time_slip_strip(const Scene *scene, Strip *strip, int delta, float subframe_delta);
+void time_slip_strip(
+    const Scene *scene, Strip *strip, int delta, float subframe_delta, bool slip_keyframes);
 /**
  * Get difference between scene and movie strip frame-rate.
  */

source/blender/sequencer/intern/animation.cc

@@ -22,7 +22,7 @@
 
 namespace blender::seq {
 
-bool animation_keyframes_exist(Scene *scene)
+bool animation_keyframes_exist(const Scene *scene)
 {
   return scene->adt != nullptr && scene->adt->action != nullptr &&
          scene->adt->action->wrap().has_keyframes(scene->adt->slot_handle);
@@ -39,9 +39,9 @@ bool fcurve_matches(const Strip &strip, const FCurve &fcurve)
       fcurve, "sequence_editor.strips_all[", strip.name + 2);
 }
 
-void offset_animdata(Scene *scene, Strip *strip, int ofs)
+void offset_animdata(const Scene *scene, Strip *strip, float ofs)
 {
-  if (!animation_keyframes_exist(scene) || ofs == 0) {
+  if (!animation_keyframes_exist(scene) || ofs == 0.0f) {
     return;
   }
 

source/blender/sequencer/intern/strip_time.cc

@@ -23,6 +23,7 @@
 
 #include "MOV_read.hh"
 
+#include "SEQ_animation.hh"
 #include "SEQ_channels.hh"
 #include "SEQ_iterator.hh"
 #include "SEQ_render.hh"
@@ -551,14 +552,18 @@ void strip_time_translate_handles(const Scene *scene, Strip *strip, const int of
   time_update_meta_strip_range(scene, lookup_meta_by_strip(scene->ed, strip));
 }
 
-static void strip_time_slip_strip_ex(
-    const Scene *scene, Strip *strip, int delta, float subframe_delta, bool recursed)
+static void strip_time_slip_strip_ex(const Scene *scene,
+                                     Strip *strip,
+                                     int delta,
+                                     float subframe_delta,
+                                     bool slip_keyframes,
+                                     bool recursed)
 {
   if (strip->type == STRIP_TYPE_SOUND_RAM && subframe_delta != 0.0f) {
     strip->sound_offset += subframe_delta / FPS;
   }
 
-  if (delta == 0) {
+  if (delta == 0 && (!slip_keyframes || subframe_delta == 0.0f)) {
     return;
   }
 
@@ -580,12 +585,23 @@ static void strip_time_slip_strip_ex(
     if (BLI_listbase_is_empty(&strip->seqbase)) {
       return;
     }
+
     LISTBASE_FOREACH (Strip *, strip_child, &strip->seqbase) {
-      strip_time_slip_strip_ex(scene, strip_child, delta, subframe_delta, true);
+      /* The keyframes of strips inside meta strips should always be moved. */
+      strip_time_slip_strip_ex(scene, strip_child, delta, subframe_delta, true, true);
     }
   }
 
   strip->start = strip->start + delta;
+
+  if (slip_keyframes) {
+    float anim_offset = delta;
+    if (strip->type == STRIP_TYPE_SOUND_RAM) {
+      anim_offset += subframe_delta;
+    }
+    offset_animdata(scene, strip, anim_offset);
+  }
+
   if (!recursed) {
     strip->startofs = strip->startofs - delta;
     strip->endofs = strip->endofs + delta;
@@ -599,9 +615,10 @@ static void strip_time_slip_strip_ex(
   strip_time_update_effects_strip_range(scene, effects);
 }
 
-void time_slip_strip(const Scene *scene, Strip *strip, int delta, float subframe_delta)
+void time_slip_strip(
+    const Scene *scene, Strip *strip, int delta, float subframe_delta, bool slip_keyframes)
 {
-  strip_time_slip_strip_ex(scene, strip, delta, subframe_delta, false);
+  strip_time_slip_strip_ex(scene, strip, delta, subframe_delta, slip_keyframes, false);
 }
 
 int time_get_rounded_sound_offset(const Strip *strip, const float frames_per_second)