Animation: Add GP layers in regular Dopesheet

Grease Pencil animation channels are now also shown in the Dopesheet
mode of the Dopesheet editor and in the Timeline.

Grease pencil related events are now listened not only by container
`SACTCONT_GPENCIL` (Grease Pencil Dopesheet), but also
`SACTCONT_DOPESHEET` (main Dopesheet), and `SACTCONT_TIMELINE`
(timeline).

A new Animation Filter flag was added: `ANIMFILTER_FCURVESONLY`. For now
this only filters out Grease Pencil Layer channels.

**Implemented:**

- Preview range set: now only considers selected Grease Pencil keyframes
  when `onlySel` parameter is true. Not only this allows the operator to
  work with grease pencil keyframes in main dopesheet, but it also fixes
  the operator in the Grease Pencil dopesheet.
- Translation: allocation (and freeing) of specific memory for
  translation of Grease Pencil keyframes.
- Copy/Paste: call to both Fcurve and GPencil operators, to allow for
  mixed selection. Errors are only reported when both the FCurve and
  GPencil functions fail to paste anything.
- Keyframe Type change and Insert Keyframe: removed some code here to
  unify Grease Pencil dopesheet and main dopesheet code.

- Jump, Snap, Mirror, Select all/box/lasso/circle, Select left/right,
  Clickselect: account for Grease Pencil channels within the channels
  loop, no need for `ANIMFILTER_FCURVESONLY` there.

**Not Implemented:**

- Graph-related operators. The filter `ANIMFILTER_FCURVESONLY` is
  naively added to all graph-related operators, meaning more-or-less all
  operators that used `ANIMFILTER_CURVE_VISIBLE`.
- Select linked: is for F-curves channel only
- Select more/less: not yet implemented for grease pencil layers.
- Clean Keys, Sample, Extrapolation, Interpolation, Easing, and Handle
  type change: work on Fcurve-channels only, so the
  `ANIMFILTER_FCURVESONLY` filter is activated

Graying out these operators (when no fcurve keyframe is selected) can be
done with custom poll functions BUT may affect performance. This is NOT
done in this patch.

**Dopesheet Summary Selection:**

The main summary of the dopesheet now also takes into account Grease
Pencil keyframes, using some nasty copy/pasting of code, as explained
[on devtalk](https://devtalk.blender.org/t/gpencil-layers-integration-in-main-dopesheet-selection-issue/24527).
It works, but may be improved, providing some deeper changes.

Reviewed By: mendio, pepeland, sybren

Maniphest Tasks: T97477

Differential Revision: https://developer.blender.org/D15003

source/blender/editors/space_graph/graph_select.c

@@ -172,7 +172,8 @@ static void get_nearest_fcurve_verts_list(bAnimContext *ac, const int mval[2], L
    * - if the option to only show keyframes that belong to selected F-Curves is enabled,
    *   include the 'only selected' flag...
    */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS | ANIMFILTER_FCURVESONLY);
   if (sipo->flag &
       SIPO_SELCUVERTSONLY) { /* FIXME: this should really be check for by the filtering code... */
     filter |= ANIMFILTER_SEL;
@@ -342,7 +343,8 @@ void deselect_graph_keys(bAnimContext *ac, bool test, short sel, bool do_channel
   KeyframeEditFunc test_cb, sel_cb;
 
   /* determine type-based settings */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
 
   /* filter data */
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
@@ -498,7 +500,8 @@ static rctf initialize_box_select_coords(const bAnimContext *ac, const rctf *rec
 
 static int initialize_animdata_selection_filter(const SpaceGraph *sipo)
 {
-  int filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  int filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+                ANIMFILTER_NODUPLIS);
   if (sipo->flag & SIPO_SELCUVERTSONLY) {
     filter |= ANIMFILTER_FOREDIT | ANIMFILTER_SELEDIT;
   }
@@ -1150,7 +1153,8 @@ static void markers_selectkeys_between(bAnimContext *ac)
   ked.f2 = max;
 
   /* filter data */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
   /* select keys in-between */
@@ -1189,7 +1193,8 @@ static void columnselect_graph_keys(bAnimContext *ac, short mode)
   /* build list of columns */
   switch (mode) {
     case GRAPHKEYS_COLUMNSEL_KEYS: /* list of selected keys */
-      filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+      filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+                ANIMFILTER_NODUPLIS);
       ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
       for (ale = anim_data.first; ale; ale = ale->next) {
@@ -1222,7 +1227,8 @@ static void columnselect_graph_keys(bAnimContext *ac, short mode)
   /* loop through all of the keys and select additional keyframes
    * based on the keys found to be selected above
    */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
   for (ale = anim_data.first; ale; ale = ale->next) {
@@ -1314,7 +1320,8 @@ static int graphkeys_select_linked_exec(bContext *C, wmOperator *UNUSED(op))
   }
 
   /* loop through all of the keys and select additional keyframes based on these */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
   ANIM_animdata_filter(&ac, &anim_data, filter, ac.data, ac.datatype);
 
   for (ale = anim_data.first; ale; ale = ale->next) {
@@ -1372,7 +1379,8 @@ static void select_moreless_graph_keys(bAnimContext *ac, short mode)
   memset(&ked, 0, sizeof(KeyframeEditData));
 
   /* loop through all of the keys and select additional keyframes based on these */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
   for (ale = anim_data.first; ale; ale = ale->next) {
@@ -1521,7 +1529,7 @@ static void graphkeys_select_leftright(bAnimContext *ac, short leftright, short
   }
 
   /* filter data */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_NODUPLIS | ANIMFILTER_FCURVESONLY);
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
   /* select keys */
@@ -1797,7 +1805,8 @@ static int mouse_graph_keys(bAnimContext *ac,
    * otherwise the active flag won't be set T26452. */
   if (!run_modal && (nvi->fcu->flag & FCURVE_SELECTED) && something_was_selected) {
     /* NOTE: Sync the filter flags with findnearest_fcurve_vert. */
-    int filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+    int filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+                  ANIMFILTER_NODUPLIS);
     ANIM_set_active_channel(ac, ac->data, ac->datatype, filter, nvi->fcu, nvi->ctype);
   }
 
@@ -1873,7 +1882,8 @@ static int graphkeys_mselect_column(bAnimContext *ac,
   /* loop through all of the keys and select additional keyframes
    * based on the keys found to be selected above
    */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FCURVESONLY |
+            ANIMFILTER_NODUPLIS);
   ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
 
   for (ale = anim_data.first; ale; ale = ale->next) {