Cleanup: Animation, split `graph_edit.c` into separate files

Split some of the code of `graph_edit.c` into:
* `graph_view.c`: preview range, view all, view selected etc.
* `graph_slider_ops.c`: the decimate modal operator code.

The latter file will be extended later with more slider-based operators.

Maniphest Tasks: T81785

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D9312

4 files changed, 1070 insertions, 967 deletions

diff --git a/source/blender/editors/space_graph/CMakeLists.txt b/source/blender/editors/space_graph/CMakeLists.txt
index fd5c5863608..414e5c87f5a 100644
--- a/source/blender/editors/space_graph/CMakeLists.txt
+++ b/source/blender/editors/space_graph/CMakeLists.txt
@@ -34,8 +34,10 @@ set(SRC
   graph_draw.c
   graph_edit.c
   graph_ops.c
+  graph_slider_ops.c
   graph_select.c
   graph_utils.c
+  graph_view.c
   space_graph.c
 
   graph_intern.h
diff --git a/source/blender/editors/space_graph/graph_edit.c b/source/blender/editors/space_graph/graph_edit.c
index bcd3adec1ab..1647fd4a6a6 100644
--- a/source/blender/editors/space_graph/graph_edit.c
+++ b/source/blender/editors/space_graph/graph_edit.c
@@ -61,7 +61,6 @@
 #include "ED_keyframes_edit.h"
 #include "ED_keyframing.h"
 #include "ED_markers.h"
-#include "ED_numinput.h"
 #include "ED_screen.h"
 #include "ED_transform.h"
 
@@ -71,497 +70,7 @@
 #include "graph_intern.h"
 
 /* ************************************************************************** */
-/* KEYFRAME-RANGE STUFF */
-
-/* *************************** Calculate Range ************************** */
-
-/* Get the min/max keyframes. */
-/* Note: it should return total boundbox, filter for selection only can be argument... */
-void get_graph_keyframe_extents(bAnimContext *ac,
-                                float *xmin,
-                                float *xmax,
-                                float *ymin,
-                                float *ymax,
-                                const bool do_sel_only,
-                                const bool include_handles)
-{
-  Scene *scene = ac->scene;
-  SpaceGraph *sipo = (SpaceGraph *)ac->sl;
-
-  ListBase anim_data = {NULL, NULL};
-  bAnimListElem *ale;
-  int filter;
-
-  /* Get data to filter, from Dopesheet. */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
-  if (sipo->flag & SIPO_SELCUVERTSONLY) {
-    filter |= ANIMFILTER_SEL;
-  }
-
-  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
-
-  /* Set large values initial values that will be easy to override. */
-  if (xmin) {
-    *xmin = 999999999.0f;
-  }
-  if (xmax) {
-    *xmax = -999999999.0f;
-  }
-  if (ymin) {
-    *ymin = 999999999.0f;
-  }
-  if (ymax) {
-    *ymax = -999999999.0f;
-  }
-
-  /* Check if any channels to set range with. */
-  if (anim_data.first) {
-    bool foundBounds = false;
-
-    /* Go through channels, finding max extents. */
-    for (ale = anim_data.first; ale; ale = ale->next) {
-      AnimData *adt = ANIM_nla_mapping_get(ac, ale);
-      FCurve *fcu = (FCurve *)ale->key_data;
-      float txmin, txmax, tymin, tymax;
-      float unitFac, offset;
-
-      /* Get range. */
-      if (BKE_fcurve_calc_bounds(
-              fcu, &txmin, &txmax, &tymin, &tymax, do_sel_only, include_handles)) {
-        short mapping_flag = ANIM_get_normalization_flags(ac);
-
-        /* Apply NLA scaling. */
-        if (adt) {
-          txmin = BKE_nla_tweakedit_remap(adt, txmin, NLATIME_CONVERT_MAP);
-          txmax = BKE_nla_tweakedit_remap(adt, txmax, NLATIME_CONVERT_MAP);
-        }
-
-        /* Apply unit corrections. */
-        unitFac = ANIM_unit_mapping_get_factor(ac->scene, ale->id, fcu, mapping_flag, &offset);
-        tymin += offset;
-        tymax += offset;
-        tymin *= unitFac;
-        tymax *= unitFac;
-
-        /* Try to set cur using these values, if they're more extreme than previously set values.
-         */
-        if ((xmin) && (txmin < *xmin)) {
-          *xmin = txmin;
-        }
-        if ((xmax) && (txmax > *xmax)) {
-          *xmax = txmax;
-        }
-        if ((ymin) && (tymin < *ymin)) {
-          *ymin = tymin;
-        }
-        if ((ymax) && (tymax > *ymax)) {
-          *ymax = tymax;
-        }
-
-        foundBounds = true;
-      }
-    }
-
-    /* Ensure that the extents are not too extreme that view implodes...*/
-    if (foundBounds) {
-      if ((xmin && xmax) && (fabsf(*xmax - *xmin) < 0.001f)) {
-        *xmin -= 0.0005f;
-        *xmax += 0.0005f;
-      }
-      if ((ymin && ymax) && (fabsf(*ymax - *ymin) < 0.001f)) {
-        *ymax -= 0.0005f;
-        *ymax += 0.0005f;
-      }
-    }
-    else {
-      if (xmin) {
-        *xmin = (float)PSFRA;
-      }
-      if (xmax) {
-        *xmax = (float)PEFRA;
-      }
-      if (ymin) {
-        *ymin = -5;
-      }
-      if (ymax) {
-        *ymax = 5;
-      }
-    }
-
-    /* Free memory. */
-    ANIM_animdata_freelist(&anim_data);
-  }
-  else {
-    /* Set default range. */
-    if (ac->scene) {
-      if (xmin) {
-        *xmin = (float)PSFRA;
-      }
-      if (xmax) {
-        *xmax = (float)PEFRA;
-      }
-    }
-    else {
-      if (xmin) {
-        *xmin = -5;
-      }
-      if (xmax) {
-        *xmax = 100;
-      }
-    }
-
-    if (ymin) {
-      *ymin = -5;
-    }
-    if (ymax) {
-      *ymax = 5;
-    }
-  }
-}
-
-/* ****************** Automatic Preview-Range Operator ****************** */
-
-static int graphkeys_previewrange_exec(bContext *C, wmOperator *UNUSED(op))
-{
-  bAnimContext ac;
-  Scene *scene;
-  float min, max;
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &ac) == 0) {
-    return OPERATOR_CANCELLED;
-  }
-  if (ac.scene == NULL) {
-    return OPERATOR_CANCELLED;
-  }
-
-  scene = ac.scene;
-
-  /* Set the range directly. */
-  get_graph_keyframe_extents(&ac, &min, &max, NULL, NULL, false, false);
-  scene->r.flag |= SCER_PRV_RANGE;
-  scene->r.psfra = round_fl_to_int(min);
-  scene->r.pefra = round_fl_to_int(max);
-
-  /* Set notifier that things have changed. */
-  // XXX Err... there's nothing for frame ranges yet, but this should do fine too.
-  WM_event_add_notifier(C, NC_SCENE | ND_FRAME, ac.scene);
-
-  return OPERATOR_FINISHED;
-}
-
-void GRAPH_OT_previewrange_set(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Auto-Set Preview Range";
-  ot->idname = "GRAPH_OT_previewrange_set";
-  ot->description = "Automatically set Preview Range based on range of keyframes";
-
-  /* API callbacks */
-  ot->exec = graphkeys_previewrange_exec;
-  /* XXX: unchecked poll to get fsamples working too, but makes modifier damage trickier. */
-  ot->poll = ED_operator_graphedit_active;
-
-  /* Flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-}
-
-/* ****************** View-All Operator ****************** */
-
-static int graphkeys_viewall(bContext *C,
-                             const bool do_sel_only,
-                             const bool include_handles,
-                             const int smooth_viewtx)
-{
-  bAnimContext ac;
-  rctf cur_new;
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &ac) == 0) {
-    return OPERATOR_CANCELLED;
-  }
-
-  /* Set the horizontal range, with an extra offset so that the extreme keys will be in view. */
-  get_graph_keyframe_extents(&ac,
-                             &cur_new.xmin,
-                             &cur_new.xmax,
-                             &cur_new.ymin,
-                             &cur_new.ymax,
-                             do_sel_only,
-                             include_handles);
-
-  /* Give some more space at the borders. */
-  BLI_rctf_scale(&cur_new, 1.1f);
-
-  /* Take regions into account, that could block the view.
-   * Marker region is supposed to be larger than the scroll-bar, so prioritize it.*/
-  float pad_top = UI_TIME_SCRUB_MARGIN_Y;
-  float pad_bottom = BLI_listbase_is_empty(ED_context_get_markers(C)) ? V2D_SCROLL_HANDLE_HEIGHT :
-                                                                        UI_MARKER_MARGIN_Y;
-  BLI_rctf_pad_y(&cur_new, ac.region->winy, pad_bottom, pad_top);
-
-  UI_view2d_smooth_view(C, ac.region, &cur_new, smooth_viewtx);
-  return OPERATOR_FINISHED;
-}
-
-/* ......... */
-
-static int graphkeys_viewall_exec(bContext *C, wmOperator *op)
-{
-  const bool include_handles = RNA_boolean_get(op->ptr, "include_handles");
-  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
-
-  /* Whole range */
-  return graphkeys_viewall(C, false, include_handles, smooth_viewtx);
-}
-
-static int graphkeys_view_selected_exec(bContext *C, wmOperator *op)
-{
-  const bool include_handles = RNA_boolean_get(op->ptr, "include_handles");
-  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
-
-  /* Only selected. */
-  return graphkeys_viewall(C, true, include_handles, smooth_viewtx);
-}
-
-/* ......... */
-
-void GRAPH_OT_view_all(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Frame All";
-  ot->idname = "GRAPH_OT_view_all";
-  ot->description = "Reset viewable area to show full keyframe range";
-
-  /* API callbacks */
-  ot->exec = graphkeys_viewall_exec;
-  /* XXX: Unchecked poll to get fsamples working too, but makes modifier damage trickier... */
-  ot->poll = ED_operator_graphedit_active;
-
-  /* Flags */
-  ot->flag = 0;
-
-  /* Props */
-  ot->prop = RNA_def_boolean(ot->srna,
-                             "include_handles",
-                             true,
-                             "Include Handles",
-                             "Include handles of keyframes when calculating extents");
-}
-
-void GRAPH_OT_view_selected(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Frame Selected";
-  ot->idname = "GRAPH_OT_view_selected";
-  ot->description = "Reset viewable area to show selected keyframe range";
-
-  /* API callbacks */
-  ot->exec = graphkeys_view_selected_exec;
-  /* XXX: Unchecked poll to get fsamples working too, but makes modifier damage trickier... */
-  ot->poll = ED_operator_graphedit_active;
-
-  /* Flags */
-  ot->flag = 0;
-
-  /* Props */
-  ot->prop = RNA_def_boolean(ot->srna,
-                             "include_handles",
-                             true,
-                             "Include Handles",
-                             "Include handles of keyframes when calculating extents");
-}
-
-/* ********************** View Frame Operator ****************************** */
-
-static int graphkeys_view_frame_exec(bContext *C, wmOperator *op)
-{
-  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
-  ANIM_center_frame(C, smooth_viewtx);
-  return OPERATOR_FINISHED;
-}
-
-void GRAPH_OT_view_frame(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Go to Current Frame";
-  ot->idname = "GRAPH_OT_view_frame";
-  ot->description = "Move the view to the current frame";
-
-  /* API callbacks */
-  ot->exec = graphkeys_view_frame_exec;
-  ot->poll = ED_operator_graphedit_active;
-
-  /* Flags */
-  ot->flag = 0;
-}
-
-/* ******************** Create Ghost-Curves Operator *********************** */
-/* This operator samples the data of the selected F-Curves to F-Points, storing them
- * as 'ghost curves' in the active Graph Editor.
- */
-
-/* Bake each F-Curve into a set of samples, and store as a ghost curve. */
-static void create_ghost_curves(bAnimContext *ac, int start, int end)
-{
-  SpaceGraph *sipo = (SpaceGraph *)ac->sl;
-  ListBase anim_data = {NULL, NULL};
-  bAnimListElem *ale;
-  int filter;
-
-  /* Free existing ghost curves. */
-  BKE_fcurves_free(&sipo->runtime.ghost_curves);
-
-  /* Sanity check. */
-  if (start >= end) {
-    printf("Error: Frame range for Ghost F-Curve creation is inappropriate\n");
-    return;
-  }
-
-  /* Filter data. */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_SEL |
-            ANIMFILTER_NODUPLIS);
-  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
-
-  /* Loop through filtered data and add keys between selected keyframes on every frame . */
-  for (ale = anim_data.first; ale; ale = ale->next) {
-    FCurve *fcu = (FCurve *)ale->key_data;
-    FCurve *gcu = BKE_fcurve_create();
-    AnimData *adt = ANIM_nla_mapping_get(ac, ale);
-    ChannelDriver *driver = fcu->driver;
-    FPoint *fpt;
-    float unitFac, offset;
-    int cfra;
-    short mapping_flag = ANIM_get_normalization_flags(ac);
-
-    /* Disable driver so that it don't muck up the sampling process. */
-    fcu->driver = NULL;
-
-    /* Calculate unit-mapping factor. */
-    unitFac = ANIM_unit_mapping_get_factor(ac->scene, ale->id, fcu, mapping_flag, &offset);
-
-    /* Create samples, but store them in a new curve
-     * - we cannot use fcurve_store_samples() as that will only overwrite the original curve.
-     */
-    gcu->fpt = fpt = MEM_callocN(sizeof(FPoint) * (end - start + 1), "Ghost FPoint Samples");
-    gcu->totvert = end - start + 1;
-
-    /* Use the sampling callback at 1-frame intervals from start to end frames. */
-    for (cfra = start; cfra <= end; cfra++, fpt++) {
-      float cfrae = BKE_nla_tweakedit_remap(adt, cfra, NLATIME_CONVERT_UNMAP);
-
-      fpt->vec[0] = cfrae;
-      fpt->vec[1] = (fcurve_samplingcb_evalcurve(fcu, NULL, cfrae) + offset) * unitFac;
-    }
-
-    /* Set color of ghost curve
-     * - make the color slightly darker.
-     */
-    gcu->color[0] = fcu->color[0] - 0.07f;
-    gcu->color[1] = fcu->color[1] - 0.07f;
-    gcu->color[2] = fcu->color[2] - 0.07f;
-
-    /* Store new ghost curve. */
-    BLI_addtail(&sipo->runtime.ghost_curves, gcu);
-
-    /* Restore driver. */
-    fcu->driver = driver;
-  }
-
-  /* Admin and redraws. */
-  ANIM_animdata_freelist(&anim_data);
-}
-
-/* ------------------- */
-
-static int graphkeys_create_ghostcurves_exec(bContext *C, wmOperator *UNUSED(op))
-{
-  bAnimContext ac;
-  View2D *v2d;
-  int start, end;
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &ac) == 0) {
-    return OPERATOR_CANCELLED;
-  }
-
-  /* Ghost curves are snapshots of the visible portions of the curves,
-   * so set range to be the visible range. */
-  v2d = &ac.region->v2d;
-  start = (int)v2d->cur.xmin;
-  end = (int)v2d->cur.xmax;
-
-  /* Bake selected curves into a ghost curve. */
-  create_ghost_curves(&ac, start, end);
-
-  /* Update this editor only. */
-  ED_area_tag_redraw(CTX_wm_area(C));
-
-  return OPERATOR_FINISHED;
-}
-
-void GRAPH_OT_ghost_curves_create(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Create Ghost Curves";
-  ot->idname = "GRAPH_OT_ghost_curves_create";
-  ot->description =
-      "Create snapshot (Ghosts) of selected F-Curves as background aid for active Graph Editor";
-
-  /* API callbacks */
-  ot->exec = graphkeys_create_ghostcurves_exec;
-  ot->poll = graphop_visible_keyframes_poll;
-
-  /* Flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* TODO: add props for start/end frames */
-}
-
-/* ******************** Clear Ghost-Curves Operator *********************** */
-/* This operator clears the 'ghost curves' for the active Graph Editor */
-
-static int graphkeys_clear_ghostcurves_exec(bContext *C, wmOperator *UNUSED(op))
-{
-  bAnimContext ac;
-  SpaceGraph *sipo;
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &ac) == 0) {
-    return OPERATOR_CANCELLED;
-  }
-  sipo = (SpaceGraph *)ac.sl;
-
-  /* If no ghost curves, don't do anything. */
-  if (BLI_listbase_is_empty(&sipo->runtime.ghost_curves)) {
-    return OPERATOR_CANCELLED;
-  }
-  /* Free ghost curves. */
-  BKE_fcurves_free(&sipo->runtime.ghost_curves);
-
-  /* Update this editor only. */
-  ED_area_tag_redraw(CTX_wm_area(C));
-
-  return OPERATOR_FINISHED;
-}
-
-void GRAPH_OT_ghost_curves_clear(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Clear Ghost Curves";
-  ot->idname = "GRAPH_OT_ghost_curves_clear";
-  ot->description = "Clear F-Curve snapshots (Ghosts) for active Graph Editor";
-
-  /* API callbacks */
-  ot->exec = graphkeys_clear_ghostcurves_exec;
-  ot->poll = ED_operator_graphedit_active;
-
-  /* Flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-}
-
-/* ************************************************************************** */
-/* GENERAL STUFF */
+/* INSERT DUPLICATE AND BAKE KEYFRAMES */
 
 /* ******************** Insert Keyframes Operator ************************* */
 
@@ -1307,479 +816,6 @@ void GRAPH_OT_clean(wmOperatorType *ot)
   RNA_def_boolean(ot->srna, "channels", false, "Channels", "");
 }
 
-/* ******************** Decimate Keyframes Operator ************************* */
-
-static void decimate_graph_keys(bAnimContext *ac, float remove_ratio, float error_sq_max)
-{
-  ListBase anim_data = {NULL, NULL};
-  bAnimListElem *ale;
-  int filter;
-
-  /* Filter data. */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
-            ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
-  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
-
-  /* Loop through filtered data and clean curves. */
-  for (ale = anim_data.first; ale; ale = ale->next) {
-    if (!decimate_fcurve(ale, remove_ratio, error_sq_max)) {
-      /* The selection contains unsupported keyframe types! */
-      WM_report(RPT_WARNING, "Decimate: Skipping non linear/bezier keyframes!");
-    }
-
-    ale->update |= ANIM_UPDATE_DEFAULT;
-  }
-
-  ANIM_animdata_update(ac, &anim_data);
-  ANIM_animdata_freelist(&anim_data);
-}
-
-/* ------------------- */
-
-/* This data type is only used for modal operation. */
-typedef struct tDecimateGraphOp {
-  bAnimContext ac;
-  Scene *scene;
-  ScrArea *area;
-  ARegion *region;
-
-  /** A 0-1 value for determining how much we should decimate. */
-  PropertyRNA *percentage_prop;
-
-  /** The original bezt curve data (used for restoring fcurves).*/
-  ListBase bezt_arr_list;
-
-  NumInput num;
-} tDecimateGraphOp;
-
-typedef struct tBeztCopyData {
-  int tot_vert;
-  BezTriple *bezt;
-} tBeztCopyData;
-
-typedef enum tDecimModes {
-  DECIM_RATIO = 1,
-  DECIM_ERROR,
-} tDecimModes;
-
-/* Overwrite the current bezts arrays with the original data. */
-static void decimate_reset_bezts(tDecimateGraphOp *dgo)
-{
-  ListBase anim_data = {NULL, NULL};
-  LinkData *link_bezt;
-  bAnimListElem *ale;
-  int filter;
-
-  bAnimContext *ac = &dgo->ac;
-
-  /* Filter data. */
-  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
-            ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
-  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
-
-  /* Loop through filtered data and reset bezts. */
-  for (ale = anim_data.first, link_bezt = dgo->bezt_arr_list.first; ale; ale = ale->next) {
-    FCurve *fcu = (FCurve *)ale->key_data;
-
-    if (fcu->bezt == NULL) {
-      /* This curve is baked, skip it. */
-      continue;
-    }
-
-    tBeztCopyData *data = link_bezt->data;
-
-    const int arr_size = sizeof(BezTriple) * data->tot_vert;
-
-    MEM_freeN(fcu->bezt);
-
-    fcu->bezt = MEM_mallocN(arr_size, __func__);
-    fcu->totvert = data->tot_vert;
-
-    memcpy(fcu->bezt, data->bezt, arr_size);
-
-    link_bezt = link_bezt->next;
-  }
-
-  ANIM_animdata_freelist(&anim_data);
-}
-
-static void decimate_exit(bContext *C, wmOperator *op)
-{
-  tDecimateGraphOp *dgo = op->customdata;
-  wmWindow *win = CTX_wm_window(C);
-
-  /* If data exists, clear its data and exit. */
-  if (dgo == NULL) {
-    return;
-  }
-
-  ScrArea *area = dgo->area;
-  LinkData *link;
-
-  for (link = dgo->bezt_arr_list.first; link != NULL; link = link->next) {
-    tBeztCopyData *copy = link->data;
-    MEM_freeN(copy->bezt);
-    MEM_freeN(link->data);
-  }
-
-  BLI_freelistN(&dgo->bezt_arr_list);
-  MEM_freeN(dgo);
-
-  /* Return to normal cursor and header status. */
-  WM_cursor_modal_restore(win);
-  ED_area_status_text(area, NULL);
-
-  /* Cleanup. */
-  op->customdata = NULL;
-}
-
-/* Draw a percentage indicator in header. */
-static void decimate_draw_status_header(wmOperator *op, tDecimateGraphOp *dgo)
-{
-  char status_str[UI_MAX_DRAW_STR];
-  char mode_str[32];
-
-  strcpy(mode_str, TIP_("Decimate Keyframes"));
-
-  if (hasNumInput(&dgo->num)) {
-    char str_offs[NUM_STR_REP_LEN];
-
-    outputNumInput(&dgo->num, str_offs, &dgo->scene->unit);
-
-    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, str_offs);
-  }
-  else {
-    float percentage = RNA_property_float_get(op->ptr, dgo->percentage_prop);
-    BLI_snprintf(
-        status_str, sizeof(status_str), "%s: %d %%", mode_str, (int)(percentage * 100.0f));
-  }
-
-  ED_area_status_text(dgo->area, status_str);
-}
-
-/* Calculate percentage based on position of mouse (we only use x-axis for now.
- * Since this is more convenient for users to do), and store new percentage value.
- */
-static void decimate_mouse_update_percentage(tDecimateGraphOp *dgo,
-                                             wmOperator *op,
-                                             const wmEvent *event)
-{
-  float percentage = (event->x - dgo->region->winrct.xmin) / ((float)dgo->region->winx);
-  RNA_property_float_set(op->ptr, dgo->percentage_prop, percentage);
-}
-
-static int graphkeys_decimate_invoke(bContext *C, wmOperator *op, const wmEvent *event)
-{
-  tDecimateGraphOp *dgo;
-
-  WM_cursor_modal_set(CTX_wm_window(C), WM_CURSOR_EW_SCROLL);
-
-  /* Init slide-op data. */
-  dgo = op->customdata = MEM_callocN(sizeof(tDecimateGraphOp), "tDecimateGraphOp");
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &dgo->ac) == 0) {
-    decimate_exit(C, op);
-    return OPERATOR_CANCELLED;
-  }
-
-  dgo->percentage_prop = RNA_struct_find_property(op->ptr, "remove_ratio");
-
-  dgo->scene = CTX_data_scene(C);
-  dgo->area = CTX_wm_area(C);
-  dgo->region = CTX_wm_region(C);
-
-  /* Initialize percentage so that it will have the correct value before the first mouse move. */
-  decimate_mouse_update_percentage(dgo, op, event);
-
-  decimate_draw_status_header(op, dgo);
-
-  /* Construct a list with the original bezt arrays so we can restore them during modal operation.
-   */
-  {
-    ListBase anim_data = {NULL, NULL};
-    bAnimContext *ac = &dgo->ac;
-    bAnimListElem *ale;
-
-    int filter;
-
-    /* Filter data. */
-    filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
-              ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
-    ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
-
-    /* Loop through filtered data and copy the curves. */
-    for (ale = anim_data.first; ale; ale = ale->next) {
-      FCurve *fcu = (FCurve *)ale->key_data;
-
-      if (fcu->bezt == NULL) {
-        /* This curve is baked, skip it. */
-        continue;
-      }
-
-      const int arr_size = sizeof(BezTriple) * fcu->totvert;
-
-      tBeztCopyData *copy = MEM_mallocN(sizeof(tBeztCopyData), "bezts_copy");
-      BezTriple *bezts_copy = MEM_mallocN(arr_size, "bezts_copy_array");
-
-      copy->tot_vert = fcu->totvert;
-      memcpy(bezts_copy, fcu->bezt, arr_size);
-
-      copy->bezt = bezts_copy;
-
-      LinkData *link = NULL;
-
-      link = MEM_callocN(sizeof(LinkData), "Bezt Link");
-      link->data = copy;
-
-      BLI_addtail(&dgo->bezt_arr_list, link);
-    }
-
-    ANIM_animdata_freelist(&anim_data);
-  }
-
-  if (dgo->bezt_arr_list.first == NULL) {
-    WM_report(RPT_WARNING,
-              "Fcurve Decimate: Can't decimate baked channels. Unbake them and try again.");
-    decimate_exit(C, op);
-    return OPERATOR_CANCELLED;
-  }
-
-  WM_event_add_modal_handler(C, op);
-  return OPERATOR_RUNNING_MODAL;
-}
-
-static void graphkeys_decimate_modal_update(bContext *C, wmOperator *op)
-{
-  /* Perform decimate updates - in response to some user action
-   * (e.g. pressing a key or moving the mouse). */
-  tDecimateGraphOp *dgo = op->customdata;
-
-  decimate_draw_status_header(op, dgo);
-
-  /* Reset keyframe data (so we get back to the original state). */
-  decimate_reset_bezts(dgo);
-
-  /* Apply... */
-  float remove_ratio = RNA_property_float_get(op->ptr, dgo->percentage_prop);
-  /* We don't want to limit the decimation to a certain error margin. */
-  const float error_sq_max = FLT_MAX;
-  decimate_graph_keys(&dgo->ac, remove_ratio, error_sq_max);
-  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
-}
-
-static int graphkeys_decimate_modal(bContext *C, wmOperator *op, const wmEvent *event)
-{
-  /* This assumes that we are in "DECIM_RATIO" mode. This is because the error margin is very hard
-   * and finicky to control with this modal mouse grab method. Therefore, it is expected that the
-   * error margin mode is not adjusted by the modal operator but instead tweaked via the redo
-   * panel.*/
-  tDecimateGraphOp *dgo = op->customdata;
-
-  const bool has_numinput = hasNumInput(&dgo->num);
-
-  switch (event->type) {
-    case LEFTMOUSE: /* Confirm */
-    case EVT_RETKEY:
-    case EVT_PADENTER: {
-      if (event->val == KM_PRESS) {
-        decimate_exit(C, op);
-
-        return OPERATOR_FINISHED;
-      }
-      break;
-    }
-
-    case EVT_ESCKEY: /* Cancel */
-    case RIGHTMOUSE: {
-      if (event->val == KM_PRESS) {
-        decimate_reset_bezts(dgo);
-
-        WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
-
-        decimate_exit(C, op);
-
-        return OPERATOR_CANCELLED;
-      }
-      break;
-    }
-
-    /* Percentage Change... */
-    case MOUSEMOVE: /* Calculate new position. */
-    {
-      if (has_numinput == false) {
-        /* Update percentage based on position of mouse. */
-        decimate_mouse_update_percentage(dgo, op, event);
-
-        /* Update pose to reflect the new values. */
-        graphkeys_decimate_modal_update(C, op);
-      }
-      break;
-    }
-    default: {
-      if ((event->val == KM_PRESS) && handleNumInput(C, &dgo->num, event)) {
-        float value;
-        float percentage = RNA_property_float_get(op->ptr, dgo->percentage_prop);
-
-        /* Grab percentage from numeric input, and store this new value for redo
-         * NOTE: users see ints, while internally we use a 0-1 float.
-         */
-        value = percentage * 100.0f;
-        applyNumInput(&dgo->num, &value);
-
-        percentage = value / 100.0f;
-        RNA_property_float_set(op->ptr, dgo->percentage_prop, percentage);
-
-        /* Update decimate output to reflect the new values. */
-        graphkeys_decimate_modal_update(C, op);
-        break;
-      }
-
-      /* Unhandled event - maybe it was some view manip? */
-      /* Allow to pass through. */
-      return OPERATOR_RUNNING_MODAL | OPERATOR_PASS_THROUGH;
-    }
-  }
-
-  return OPERATOR_RUNNING_MODAL;
-}
-
-static int graphkeys_decimate_exec(bContext *C, wmOperator *op)
-{
-  bAnimContext ac;
-
-  /* Get editor data. */
-  if (ANIM_animdata_get_context(C, &ac) == 0) {
-    return OPERATOR_CANCELLED;
-  }
-
-  tDecimModes mode = RNA_enum_get(op->ptr, "mode");
-  /* We want to be able to work on all available keyframes. */
-  float remove_ratio = 1.0f;
-  /* We don't want to limit the decimation to a certain error margin. */
-  float error_sq_max = FLT_MAX;
-
-  switch (mode) {
-    case DECIM_RATIO:
-      remove_ratio = RNA_float_get(op->ptr, "remove_ratio");
-      break;
-    case DECIM_ERROR:
-      error_sq_max = RNA_float_get(op->ptr, "remove_error_margin");
-      /* The decimate algorithm expects the error to be squared. */
-      error_sq_max *= error_sq_max;
-
-      break;
-  }
-
-  if (remove_ratio == 0.0f || error_sq_max == 0.0f) {
-    /* Nothing to remove. */
-    return OPERATOR_FINISHED;
-  }
-
-  decimate_graph_keys(&ac, remove_ratio, error_sq_max);
-
-  /* Set notifier that keyframes have changed. */
-  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
-
-  return OPERATOR_FINISHED;
-}
-
-static bool graphkeys_decimate_poll_property(const bContext *UNUSED(C),
-                                             wmOperator *op,
-                                             const PropertyRNA *prop)
-{
-  const char *prop_id = RNA_property_identifier(prop);
-
-  if (STRPREFIX(prop_id, "remove")) {
-    int mode = RNA_enum_get(op->ptr, "mode");
-
-    if (STREQ(prop_id, "remove_ratio") && mode != DECIM_RATIO) {
-      return false;
-    }
-    if (STREQ(prop_id, "remove_error_margin") && mode != DECIM_ERROR) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-static char *graphkeys_decimate_desc(bContext *UNUSED(C),
-                                     wmOperatorType *UNUSED(op),
-                                     PointerRNA *ptr)
-{
-
-  if (RNA_enum_get(ptr, "mode") == DECIM_ERROR) {
-    return BLI_strdup(
-        "Decimate F-Curves by specifying how much it can deviate from the original curve");
-  }
-
-  /* Use default description. */
-  return NULL;
-}
-
-static const EnumPropertyItem decimate_mode_items[] = {
-    {DECIM_RATIO,
-     "RATIO",
-     0,
-     "Ratio",
-     "Use a percentage to specify how many keyframes you want to remove"},
-    {DECIM_ERROR,
-     "ERROR",
-     0,
-     "Error Margin",
-     "Use an error margin to specify how much the curve is allowed to deviate from the original "
-     "path"},
-    {0, NULL, 0, NULL, NULL},
-};
-
-void GRAPH_OT_decimate(wmOperatorType *ot)
-{
-  /* Identifiers */
-  ot->name = "Decimate Keyframes";
-  ot->idname = "GRAPH_OT_decimate";
-  ot->description =
-      "Decimate F-Curves by removing keyframes that influence the curve shape the least";
-
-  /* API callbacks */
-  ot->poll_property = graphkeys_decimate_poll_property;
-  ot->get_description = graphkeys_decimate_desc;
-  ot->invoke = graphkeys_decimate_invoke;
-  ot->modal = graphkeys_decimate_modal;
-  ot->exec = graphkeys_decimate_exec;
-  ot->poll = graphop_editable_keyframes_poll;
-
-  /* Flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* Properties */
-  RNA_def_enum(ot->srna,
-               "mode",
-               decimate_mode_items,
-               DECIM_RATIO,
-               "Mode",
-               "Which mode to use for decimation");
-
-  RNA_def_float_percentage(ot->srna,
-                           "remove_ratio",
-                           1.0f / 3.0f,
-                           0.0f,
-                           1.0f,
-                           "Remove",
-                           "The percentage of keyframes to remove",
-                           0.0f,
-                           1.0f);
-  RNA_def_float(ot->srna,
-                "remove_error_margin",
-                0.0f,
-                0.0f,
-                FLT_MAX,
-                "Max Error Margin",
-                "How much the new decimated curve is allowed to deviate from the original",
-                0.0f,
-                10.0f);
-}
-
 /* ******************** Bake F-Curve Operator *********************** */
 /* This operator bakes the data of the selected F-Curves to F-Points */
 
@@ -2232,7 +1268,7 @@ void GRAPH_OT_sample(wmOperatorType *ot)
 }
 
 /* ************************************************************************** */
-/* SETTINGS STUFF */
+/* EXTRAPOLATION MODE AND KEYFRAME HANDLE SETTINGS */
 
 /* ******************** Set Extrapolation-Type Operator *********************** */
 
@@ -2589,7 +1625,7 @@ void GRAPH_OT_handle_type(wmOperatorType *ot)
 }
 
 /* ************************************************************************** */
-/* TRANSFORM STUFF */
+/* EULER FILTER */
 
 /* ***************** 'Euler Filter' Operator **************************** */
 /* Euler filter tools (as seen in Maya), are necessary for working with 'baked'
@@ -2919,6 +1955,9 @@ void GRAPH_OT_euler_filter(wmOperatorType *ot)
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
+/* ************************************************************************** */
+/* SNAPPING */
+
 /* ***************** Jump to Selected Frames Operator *********************** */
 
 static bool graphkeys_framejump_poll(bContext *C)
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
new file mode 100644
index 00000000000..4cda6b34a01
--- /dev/null
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -0,0 +1,526 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2020 Blender Foundation.
+ * All rights reserved.
+ */
+
+#include <float.h>
+#include <string.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_listbase.h"
+#include "BLI_string.h"
+
+#include "DNA_anim_types.h"
+#include "DNA_scene_types.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+
+#include "BLT_translation.h"
+
+#include "BKE_context.h"
+
+#include "UI_interface.h"
+
+#include "ED_anim_api.h"
+#include "ED_keyframes_edit.h"
+#include "ED_numinput.h"
+#include "ED_screen.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "graph_intern.h"
+
+/* ******************** GRAPH SLIDER OPERATORS ************************* */
+/* This file contains a collection of operators to modify keyframes in the graph editor. All
+ * operators are modal and use a slider that allows the user to define a percentage to modify the
+ * operator.*/
+
+/* ******************** Decimate Keyframes Operator ************************* */
+
+static void decimate_graph_keys(bAnimContext *ac, float remove_ratio, float error_sq_max)
+{
+  ListBase anim_data = {NULL, NULL};
+  bAnimListElem *ale;
+  int filter;
+
+  /* Filter data. */
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
+            ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
+  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
+
+  /* Loop through filtered data and clean curves. */
+  for (ale = anim_data.first; ale; ale = ale->next) {
+    if (!decimate_fcurve(ale, remove_ratio, error_sq_max)) {
+      /* The selection contains unsupported keyframe types! */
+      WM_report(RPT_WARNING, "Decimate: Skipping non linear/bezier keyframes!");
+    }
+
+    ale->update |= ANIM_UPDATE_DEFAULT;
+  }
+
+  ANIM_animdata_update(ac, &anim_data);
+  ANIM_animdata_freelist(&anim_data);
+}
+
+/* ------------------- */
+
+/* This data type is only used for modal operation. */
+typedef struct tDecimateGraphOp {
+  bAnimContext ac;
+  Scene *scene;
+  ScrArea *area;
+  ARegion *region;
+
+  /** A 0-1 value for determining how much we should decimate. */
+  PropertyRNA *percentage_prop;
+
+  /** The original bezt curve data (used for restoring fcurves).*/
+  ListBase bezt_arr_list;
+
+  NumInput num;
+} tDecimateGraphOp;
+
+typedef struct tBeztCopyData {
+  int tot_vert;
+  BezTriple *bezt;
+} tBeztCopyData;
+
+typedef enum tDecimModes {
+  DECIM_RATIO = 1,
+  DECIM_ERROR,
+} tDecimModes;
+
+/* Overwrite the current bezts arrays with the original data. */
+static void decimate_reset_bezts(tDecimateGraphOp *dgo)
+{
+  ListBase anim_data = {NULL, NULL};
+  LinkData *link_bezt;
+  bAnimListElem *ale;
+  int filter;
+
+  bAnimContext *ac = &dgo->ac;
+
+  /* Filter data. */
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
+            ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
+  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
+
+  /* Loop through filtered data and reset bezts. */
+  for (ale = anim_data.first, link_bezt = dgo->bezt_arr_list.first; ale; ale = ale->next) {
+    FCurve *fcu = (FCurve *)ale->key_data;
+
+    if (fcu->bezt == NULL) {
+      /* This curve is baked, skip it. */
+      continue;
+    }
+
+    tBeztCopyData *data = link_bezt->data;
+
+    const int arr_size = sizeof(BezTriple) * data->tot_vert;
+
+    MEM_freeN(fcu->bezt);
+
+    fcu->bezt = MEM_mallocN(arr_size, __func__);
+    fcu->totvert = data->tot_vert;
+
+    memcpy(fcu->bezt, data->bezt, arr_size);
+
+    link_bezt = link_bezt->next;
+  }
+
+  ANIM_animdata_freelist(&anim_data);
+}
+
+static void decimate_exit(bContext *C, wmOperator *op)
+{
+  tDecimateGraphOp *dgo = op->customdata;
+  wmWindow *win = CTX_wm_window(C);
+
+  /* If data exists, clear its data and exit. */
+  if (dgo == NULL) {
+    return;
+  }
+
+  ScrArea *area = dgo->area;
+  LinkData *link;
+
+  for (link = dgo->bezt_arr_list.first; link != NULL; link = link->next) {
+    tBeztCopyData *copy = link->data;
+    MEM_freeN(copy->bezt);
+    MEM_freeN(link->data);
+  }
+
+  BLI_freelistN(&dgo->bezt_arr_list);
+  MEM_freeN(dgo);
+
+  /* Return to normal cursor and header status. */
+  WM_cursor_modal_restore(win);
+  ED_area_status_text(area, NULL);
+
+  /* Cleanup. */
+  op->customdata = NULL;
+}
+
+/* Draw a percentage indicator in header. */
+static void decimate_draw_status_header(wmOperator *op, tDecimateGraphOp *dgo)
+{
+  char status_str[UI_MAX_DRAW_STR];
+  char mode_str[32];
+
+  strcpy(mode_str, TIP_("Decimate Keyframes"));
+
+  if (hasNumInput(&dgo->num)) {
+    char str_offs[NUM_STR_REP_LEN];
+
+    outputNumInput(&dgo->num, str_offs, &dgo->scene->unit);
+
+    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, str_offs);
+  }
+  else {
+    float percentage = RNA_property_float_get(op->ptr, dgo->percentage_prop);
+    BLI_snprintf(
+        status_str, sizeof(status_str), "%s: %d %%", mode_str, (int)(percentage * 100.0f));
+  }
+
+  ED_area_status_text(dgo->area, status_str);
+}
+
+/* Calculate percentage based on position of mouse (we only use x-axis for now.
+ * Since this is more convenient for users to do), and store new percentage value.
+ */
+static void decimate_mouse_update_percentage(tDecimateGraphOp *dgo,
+                                             wmOperator *op,
+                                             const wmEvent *event)
+{
+  float percentage = (event->x - dgo->region->winrct.xmin) / ((float)dgo->region->winx);
+  RNA_property_float_set(op->ptr, dgo->percentage_prop, percentage);
+}
+
+static int graphkeys_decimate_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  tDecimateGraphOp *dgo;
+
+  WM_cursor_modal_set(CTX_wm_window(C), WM_CURSOR_EW_SCROLL);
+
+  /* Init slide-op data. */
+  dgo = op->customdata = MEM_callocN(sizeof(tDecimateGraphOp), "tDecimateGraphOp");
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &dgo->ac) == 0) {
+    decimate_exit(C, op);
+    return OPERATOR_CANCELLED;
+  }
+
+  dgo->percentage_prop = RNA_struct_find_property(op->ptr, "remove_ratio");
+
+  dgo->scene = CTX_data_scene(C);
+  dgo->area = CTX_wm_area(C);
+  dgo->region = CTX_wm_region(C);
+
+  /* Initialize percentage so that it will have the correct value before the first mouse move. */
+  decimate_mouse_update_percentage(dgo, op, event);
+
+  decimate_draw_status_header(op, dgo);
+
+  /* Construct a list with the original bezt arrays so we can restore them during modal operation.
+   */
+  {
+    ListBase anim_data = {NULL, NULL};
+    bAnimContext *ac = &dgo->ac;
+    bAnimListElem *ale;
+
+    int filter;
+
+    /* Filter data. */
+    filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_FOREDIT |
+              ANIMFILTER_SEL | ANIMFILTER_NODUPLIS);
+    ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
+
+    /* Loop through filtered data and copy the curves. */
+    for (ale = anim_data.first; ale; ale = ale->next) {
+      FCurve *fcu = (FCurve *)ale->key_data;
+
+      if (fcu->bezt == NULL) {
+        /* This curve is baked, skip it. */
+        continue;
+      }
+
+      const int arr_size = sizeof(BezTriple) * fcu->totvert;
+
+      tBeztCopyData *copy = MEM_mallocN(sizeof(tBeztCopyData), "bezts_copy");
+      BezTriple *bezts_copy = MEM_mallocN(arr_size, "bezts_copy_array");
+
+      copy->tot_vert = fcu->totvert;
+      memcpy(bezts_copy, fcu->bezt, arr_size);
+
+      copy->bezt = bezts_copy;
+
+      LinkData *link = NULL;
+
+      link = MEM_callocN(sizeof(LinkData), "Bezt Link");
+      link->data = copy;
+
+      BLI_addtail(&dgo->bezt_arr_list, link);
+    }
+
+    ANIM_animdata_freelist(&anim_data);
+  }
+
+  if (dgo->bezt_arr_list.first == NULL) {
+    WM_report(RPT_WARNING,
+              "Fcurve Decimate: Can't decimate baked channels. Unbake them and try again.");
+    decimate_exit(C, op);
+    return OPERATOR_CANCELLED;
+  }
+
+  WM_event_add_modal_handler(C, op);
+  return OPERATOR_RUNNING_MODAL;
+}
+
+static void graphkeys_decimate_modal_update(bContext *C, wmOperator *op)
+{
+  /* Perform decimate updates - in response to some user action
+   * (e.g. pressing a key or moving the mouse). */
+  tDecimateGraphOp *dgo = op->customdata;
+
+  decimate_draw_status_header(op, dgo);
+
+  /* Reset keyframe data (so we get back to the original state). */
+  decimate_reset_bezts(dgo);
+
+  /* Apply... */
+  float remove_ratio = RNA_property_float_get(op->ptr, dgo->percentage_prop);
+  /* We don't want to limit the decimation to a certain error margin. */
+  const float error_sq_max = FLT_MAX;
+  decimate_graph_keys(&dgo->ac, remove_ratio, error_sq_max);
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+}
+
+static int graphkeys_decimate_modal(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  /* This assumes that we are in "DECIM_RATIO" mode. This is because the error margin is very hard
+   * and finicky to control with this modal mouse grab method. Therefore, it is expected that the
+   * error margin mode is not adjusted by the modal operator but instead tweaked via the redo
+   * panel.*/
+  tDecimateGraphOp *dgo = op->customdata;
+
+  const bool has_numinput = hasNumInput(&dgo->num);
+
+  switch (event->type) {
+    case LEFTMOUSE: /* Confirm */
+    case EVT_RETKEY:
+    case EVT_PADENTER: {
+      if (event->val == KM_PRESS) {
+        decimate_exit(C, op);
+
+        return OPERATOR_FINISHED;
+      }
+      break;
+    }
+
+    case EVT_ESCKEY: /* Cancel */
+    case RIGHTMOUSE: {
+      if (event->val == KM_PRESS) {
+        decimate_reset_bezts(dgo);
+
+        WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+
+        decimate_exit(C, op);
+
+        return OPERATOR_CANCELLED;
+      }
+      break;
+    }
+
+    /* Percentage Change... */
+    case MOUSEMOVE: /* Calculate new position. */
+    {
+      if (has_numinput == false) {
+        /* Update percentage based on position of mouse. */
+        decimate_mouse_update_percentage(dgo, op, event);
+
+        /* Update pose to reflect the new values. */
+        graphkeys_decimate_modal_update(C, op);
+      }
+      break;
+    }
+    default: {
+      if ((event->val == KM_PRESS) && handleNumInput(C, &dgo->num, event)) {
+        float value;
+        float percentage = RNA_property_float_get(op->ptr, dgo->percentage_prop);
+
+        /* Grab percentage from numeric input, and store this new value for redo
+         * NOTE: users see ints, while internally we use a 0-1 float.
+         */
+        value = percentage * 100.0f;
+        applyNumInput(&dgo->num, &value);
+
+        percentage = value / 100.0f;
+        RNA_property_float_set(op->ptr, dgo->percentage_prop, percentage);
+
+        /* Update decimate output to reflect the new values. */
+        graphkeys_decimate_modal_update(C, op);
+        break;
+      }
+
+      /* Unhandled event - maybe it was some view manip? */
+      /* Allow to pass through. */
+      return OPERATOR_RUNNING_MODAL | OPERATOR_PASS_THROUGH;
+    }
+  }
+
+  return OPERATOR_RUNNING_MODAL;
+}
+
+static int graphkeys_decimate_exec(bContext *C, wmOperator *op)
+{
+  bAnimContext ac;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  tDecimModes mode = RNA_enum_get(op->ptr, "mode");
+  /* We want to be able to work on all available keyframes. */
+  float remove_ratio = 1.0f;
+  /* We don't want to limit the decimation to a certain error margin. */
+  float error_sq_max = FLT_MAX;
+
+  switch (mode) {
+    case DECIM_RATIO:
+      remove_ratio = RNA_float_get(op->ptr, "remove_ratio");
+      break;
+    case DECIM_ERROR:
+      error_sq_max = RNA_float_get(op->ptr, "remove_error_margin");
+      /* The decimate algorithm expects the error to be squared. */
+      error_sq_max *= error_sq_max;
+
+      break;
+  }
+
+  if (remove_ratio == 0.0f || error_sq_max == 0.0f) {
+    /* Nothing to remove. */
+    return OPERATOR_FINISHED;
+  }
+
+  decimate_graph_keys(&ac, remove_ratio, error_sq_max);
+
+  /* Set notifier that keyframes have changed. */
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+static bool graphkeys_decimate_poll_property(const bContext *UNUSED(C),
+                                             wmOperator *op,
+                                             const PropertyRNA *prop)
+{
+  const char *prop_id = RNA_property_identifier(prop);
+
+  if (STRPREFIX(prop_id, "remove")) {
+    int mode = RNA_enum_get(op->ptr, "mode");
+
+    if (STREQ(prop_id, "remove_ratio") && mode != DECIM_RATIO) {
+      return false;
+    }
+    if (STREQ(prop_id, "remove_error_margin") && mode != DECIM_ERROR) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static char *graphkeys_decimate_desc(bContext *UNUSED(C),
+                                     wmOperatorType *UNUSED(op),
+                                     PointerRNA *ptr)
+{
+
+  if (RNA_enum_get(ptr, "mode") == DECIM_ERROR) {
+    return BLI_strdup(
+        "Decimate F-Curves by specifying how much it can deviate from the original curve");
+  }
+
+  /* Use default description. */
+  return NULL;
+}
+
+static const EnumPropertyItem decimate_mode_items[] = {
+    {DECIM_RATIO,
+     "RATIO",
+     0,
+     "Ratio",
+     "Use a percentage to specify how many keyframes you want to remove"},
+    {DECIM_ERROR,
+     "ERROR",
+     0,
+     "Error Margin",
+     "Use an error margin to specify how much the curve is allowed to deviate from the original "
+     "path"},
+    {0, NULL, 0, NULL, NULL},
+};
+
+void GRAPH_OT_decimate(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Decimate Keyframes";
+  ot->idname = "GRAPH_OT_decimate";
+  ot->description =
+      "Decimate F-Curves by removing keyframes that influence the curve shape the least";
+
+  /* API callbacks */
+  ot->poll_property = graphkeys_decimate_poll_property;
+  ot->get_description = graphkeys_decimate_desc;
+  ot->invoke = graphkeys_decimate_invoke;
+  ot->modal = graphkeys_decimate_modal;
+  ot->exec = graphkeys_decimate_exec;
+  ot->poll = graphop_editable_keyframes_poll;
+
+  /* Flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* Properties */
+  RNA_def_enum(ot->srna,
+               "mode",
+               decimate_mode_items,
+               DECIM_RATIO,
+               "Mode",
+               "Which mode to use for decimation");
+
+  RNA_def_float_percentage(ot->srna,
+                           "remove_ratio",
+                           1.0f / 3.0f,
+                           0.0f,
+                           1.0f,
+                           "Remove",
+                           "The percentage of keyframes to remove",
+                           0.0f,
+                           1.0f);
+  RNA_def_float(ot->srna,
+                "remove_error_margin",
+                0.0f,
+                0.0f,
+                FLT_MAX,
+                "Max Error Margin",
+                "How much the new decimated curve is allowed to deviate from the original",
+                0.0f,
+                10.0f);
+}
diff --git a/source/blender/editors/space_graph/graph_view.c b/source/blender/editors/space_graph/graph_view.c
new file mode 100644
index 00000000000..0b9ba3762a3
--- /dev/null
+++ b/source/blender/editors/space_graph/graph_view.c
@@ -0,0 +1,536 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2020 Blender Foundation.
+ * All rights reserved.
+ */
+
+#include <math.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_listbase.h"
+#include "BLI_math.h"
+#include "BLI_rect.h"
+
+#include "DNA_anim_types.h"
+#include "DNA_scene_types.h"
+#include "DNA_space_types.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+
+#include "BKE_context.h"
+#include "BKE_fcurve.h"
+#include "BKE_nla.h"
+
+#include "UI_interface.h"
+#include "UI_view2d.h"
+
+#include "ED_anim_api.h"
+#include "ED_markers.h"
+#include "ED_screen.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "graph_intern.h"
+
+/* *************************** Calculate Range ************************** */
+
+/* Get the min/max keyframes. */
+/* Note: it should return total boundbox, filter for selection only can be argument... */
+void get_graph_keyframe_extents(bAnimContext *ac,
+                                float *xmin,
+                                float *xmax,
+                                float *ymin,
+                                float *ymax,
+                                const bool do_sel_only,
+                                const bool include_handles)
+{
+  Scene *scene = ac->scene;
+  SpaceGraph *sipo = (SpaceGraph *)ac->sl;
+
+  ListBase anim_data = {NULL, NULL};
+  bAnimListElem *ale;
+  int filter;
+
+  /* Get data to filter, from Dopesheet. */
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_NODUPLIS);
+  if (sipo->flag & SIPO_SELCUVERTSONLY) {
+    filter |= ANIMFILTER_SEL;
+  }
+
+  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
+
+  /* Set large values initial values that will be easy to override. */
+  if (xmin) {
+    *xmin = 999999999.0f;
+  }
+  if (xmax) {
+    *xmax = -999999999.0f;
+  }
+  if (ymin) {
+    *ymin = 999999999.0f;
+  }
+  if (ymax) {
+    *ymax = -999999999.0f;
+  }
+
+  /* Check if any channels to set range with. */
+  if (anim_data.first) {
+    bool foundBounds = false;
+
+    /* Go through channels, finding max extents. */
+    for (ale = anim_data.first; ale; ale = ale->next) {
+      AnimData *adt = ANIM_nla_mapping_get(ac, ale);
+      FCurve *fcu = (FCurve *)ale->key_data;
+      float txmin, txmax, tymin, tymax;
+      float unitFac, offset;
+
+      /* Get range. */
+      if (BKE_fcurve_calc_bounds(
+              fcu, &txmin, &txmax, &tymin, &tymax, do_sel_only, include_handles)) {
+        short mapping_flag = ANIM_get_normalization_flags(ac);
+
+        /* Apply NLA scaling. */
+        if (adt) {
+          txmin = BKE_nla_tweakedit_remap(adt, txmin, NLATIME_CONVERT_MAP);
+          txmax = BKE_nla_tweakedit_remap(adt, txmax, NLATIME_CONVERT_MAP);
+        }
+
+        /* Apply unit corrections. */
+        unitFac = ANIM_unit_mapping_get_factor(ac->scene, ale->id, fcu, mapping_flag, &offset);
+        tymin += offset;
+        tymax += offset;
+        tymin *= unitFac;
+        tymax *= unitFac;
+
+        /* Try to set cur using these values, if they're more extreme than previously set values.
+         */
+        if ((xmin) && (txmin < *xmin)) {
+          *xmin = txmin;
+        }
+        if ((xmax) && (txmax > *xmax)) {
+          *xmax = txmax;
+        }
+        if ((ymin) && (tymin < *ymin)) {
+          *ymin = tymin;
+        }
+        if ((ymax) && (tymax > *ymax)) {
+          *ymax = tymax;
+        }
+
+        foundBounds = true;
+      }
+    }
+
+    /* Ensure that the extents are not too extreme that view implodes...*/
+    if (foundBounds) {
+      if ((xmin && xmax) && (fabsf(*xmax - *xmin) < 0.001f)) {
+        *xmin -= 0.0005f;
+        *xmax += 0.0005f;
+      }
+      if ((ymin && ymax) && (fabsf(*ymax - *ymin) < 0.001f)) {
+        *ymax -= 0.0005f;
+        *ymax += 0.0005f;
+      }
+    }
+    else {
+      if (xmin) {
+        *xmin = (float)PSFRA;
+      }
+      if (xmax) {
+        *xmax = (float)PEFRA;
+      }
+      if (ymin) {
+        *ymin = -5;
+      }
+      if (ymax) {
+        *ymax = 5;
+      }
+    }
+
+    /* Free memory. */
+    ANIM_animdata_freelist(&anim_data);
+  }
+  else {
+    /* Set default range. */
+    if (ac->scene) {
+      if (xmin) {
+        *xmin = (float)PSFRA;
+      }
+      if (xmax) {
+        *xmax = (float)PEFRA;
+      }
+    }
+    else {
+      if (xmin) {
+        *xmin = -5;
+      }
+      if (xmax) {
+        *xmax = 100;
+      }
+    }
+
+    if (ymin) {
+      *ymin = -5;
+    }
+    if (ymax) {
+      *ymax = 5;
+    }
+  }
+}
+
+/* ****************** Automatic Preview-Range Operator ****************** */
+
+static int graphkeys_previewrange_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  bAnimContext ac;
+  Scene *scene;
+  float min, max;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+  if (ac.scene == NULL) {
+    return OPERATOR_CANCELLED;
+  }
+
+  scene = ac.scene;
+
+  /* Set the range directly. */
+  get_graph_keyframe_extents(&ac, &min, &max, NULL, NULL, false, false);
+  scene->r.flag |= SCER_PRV_RANGE;
+  scene->r.psfra = round_fl_to_int(min);
+  scene->r.pefra = round_fl_to_int(max);
+
+  /* Set notifier that things have changed. */
+  // XXX Err... there's nothing for frame ranges yet, but this should do fine too.
+  WM_event_add_notifier(C, NC_SCENE | ND_FRAME, ac.scene);
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_previewrange_set(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Auto-Set Preview Range";
+  ot->idname = "GRAPH_OT_previewrange_set";
+  ot->description = "Automatically set Preview Range based on range of keyframes";
+
+  /* API callbacks */
+  ot->exec = graphkeys_previewrange_exec;
+  /* XXX: unchecked poll to get fsamples working too, but makes modifier damage trickier. */
+  ot->poll = ED_operator_graphedit_active;
+
+  /* Flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}
+
+/* ****************** View-All Operator ****************** */
+
+static int graphkeys_viewall(bContext *C,
+                             const bool do_sel_only,
+                             const bool include_handles,
+                             const int smooth_viewtx)
+{
+  bAnimContext ac;
+  rctf cur_new;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  /* Set the horizontal range, with an extra offset so that the extreme keys will be in view. */
+  get_graph_keyframe_extents(&ac,
+                             &cur_new.xmin,
+                             &cur_new.xmax,
+                             &cur_new.ymin,
+                             &cur_new.ymax,
+                             do_sel_only,
+                             include_handles);
+
+  /* Give some more space at the borders. */
+  BLI_rctf_scale(&cur_new, 1.1f);
+
+  /* Take regions into account, that could block the view.
+   * Marker region is supposed to be larger than the scroll-bar, so prioritize it.*/
+  float pad_top = UI_TIME_SCRUB_MARGIN_Y;
+  float pad_bottom = BLI_listbase_is_empty(ED_context_get_markers(C)) ? V2D_SCROLL_HANDLE_HEIGHT :
+                                                                        UI_MARKER_MARGIN_Y;
+  BLI_rctf_pad_y(&cur_new, ac.region->winy, pad_bottom, pad_top);
+
+  UI_view2d_smooth_view(C, ac.region, &cur_new, smooth_viewtx);
+  return OPERATOR_FINISHED;
+}
+
+/* ......... */
+
+static int graphkeys_viewall_exec(bContext *C, wmOperator *op)
+{
+  const bool include_handles = RNA_boolean_get(op->ptr, "include_handles");
+  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
+
+  /* Whole range */
+  return graphkeys_viewall(C, false, include_handles, smooth_viewtx);
+}
+
+static int graphkeys_view_selected_exec(bContext *C, wmOperator *op)
+{
+  const bool include_handles = RNA_boolean_get(op->ptr, "include_handles");
+  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
+
+  /* Only selected. */
+  return graphkeys_viewall(C, true, include_handles, smooth_viewtx);
+}
+
+/* ......... */
+
+void GRAPH_OT_view_all(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Frame All";
+  ot->idname = "GRAPH_OT_view_all";
+  ot->description = "Reset viewable area to show full keyframe range";
+
+  /* API callbacks */
+  ot->exec = graphkeys_viewall_exec;
+  /* XXX: Unchecked poll to get fsamples working too, but makes modifier damage trickier... */
+  ot->poll = ED_operator_graphedit_active;
+
+  /* Flags */
+  ot->flag = 0;
+
+  /* Props */
+  ot->prop = RNA_def_boolean(ot->srna,
+                             "include_handles",
+                             true,
+                             "Include Handles",
+                             "Include handles of keyframes when calculating extents");
+}
+
+void GRAPH_OT_view_selected(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Frame Selected";
+  ot->idname = "GRAPH_OT_view_selected";
+  ot->description = "Reset viewable area to show selected keyframe range";
+
+  /* API callbacks */
+  ot->exec = graphkeys_view_selected_exec;
+  /* XXX: Unchecked poll to get fsamples working too, but makes modifier damage trickier... */
+  ot->poll = ED_operator_graphedit_active;
+
+  /* Flags */
+  ot->flag = 0;
+
+  /* Props */
+  ot->prop = RNA_def_boolean(ot->srna,
+                             "include_handles",
+                             true,
+                             "Include Handles",
+                             "Include handles of keyframes when calculating extents");
+}
+
+/* ********************** View Frame Operator ****************************** */
+
+static int graphkeys_view_frame_exec(bContext *C, wmOperator *op)
+{
+  const int smooth_viewtx = WM_operator_smooth_viewtx_get(op);
+  ANIM_center_frame(C, smooth_viewtx);
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_view_frame(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Go to Current Frame";
+  ot->idname = "GRAPH_OT_view_frame";
+  ot->description = "Move the view to the current frame";
+
+  /* API callbacks */
+  ot->exec = graphkeys_view_frame_exec;
+  ot->poll = ED_operator_graphedit_active;
+
+  /* Flags */
+  ot->flag = 0;
+}
+
+/* ******************** Create Ghost-Curves Operator *********************** */
+/* This operator samples the data of the selected F-Curves to F-Points, storing them
+ * as 'ghost curves' in the active Graph Editor.
+ */
+
+/* Bake each F-Curve into a set of samples, and store as a ghost curve. */
+static void create_ghost_curves(bAnimContext *ac, int start, int end)
+{
+  SpaceGraph *sipo = (SpaceGraph *)ac->sl;
+  ListBase anim_data = {NULL, NULL};
+  bAnimListElem *ale;
+  int filter;
+
+  /* Free existing ghost curves. */
+  BKE_fcurves_free(&sipo->runtime.ghost_curves);
+
+  /* Sanity check. */
+  if (start >= end) {
+    printf("Error: Frame range for Ghost F-Curve creation is inappropriate\n");
+    return;
+  }
+
+  /* Filter data. */
+  filter = (ANIMFILTER_DATA_VISIBLE | ANIMFILTER_CURVE_VISIBLE | ANIMFILTER_SEL |
+            ANIMFILTER_NODUPLIS);
+  ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);
+
+  /* Loop through filtered data and add keys between selected keyframes on every frame . */
+  for (ale = anim_data.first; ale; ale = ale->next) {
+    FCurve *fcu = (FCurve *)ale->key_data;
+    FCurve *gcu = BKE_fcurve_create();
+    AnimData *adt = ANIM_nla_mapping_get(ac, ale);
+    ChannelDriver *driver = fcu->driver;
+    FPoint *fpt;
+    float unitFac, offset;
+    int cfra;
+    short mapping_flag = ANIM_get_normalization_flags(ac);
+
+    /* Disable driver so that it don't muck up the sampling process. */
+    fcu->driver = NULL;
+
+    /* Calculate unit-mapping factor. */
+    unitFac = ANIM_unit_mapping_get_factor(ac->scene, ale->id, fcu, mapping_flag, &offset);
+
+    /* Create samples, but store them in a new curve
+     * - we cannot use fcurve_store_samples() as that will only overwrite the original curve.
+     */
+    gcu->fpt = fpt = MEM_callocN(sizeof(FPoint) * (end - start + 1), "Ghost FPoint Samples");
+    gcu->totvert = end - start + 1;
+
+    /* Use the sampling callback at 1-frame intervals from start to end frames. */
+    for (cfra = start; cfra <= end; cfra++, fpt++) {
+      float cfrae = BKE_nla_tweakedit_remap(adt, cfra, NLATIME_CONVERT_UNMAP);
+
+      fpt->vec[0] = cfrae;
+      fpt->vec[1] = (fcurve_samplingcb_evalcurve(fcu, NULL, cfrae) + offset) * unitFac;
+    }
+
+    /* Set color of ghost curve
+     * - make the color slightly darker.
+     */
+    gcu->color[0] = fcu->color[0] - 0.07f;
+    gcu->color[1] = fcu->color[1] - 0.07f;
+    gcu->color[2] = fcu->color[2] - 0.07f;
+
+    /* Store new ghost curve. */
+    BLI_addtail(&sipo->runtime.ghost_curves, gcu);
+
+    /* Restore driver. */
+    fcu->driver = driver;
+  }
+
+  /* Admin and redraws. */
+  ANIM_animdata_freelist(&anim_data);
+}
+
+/* ------------------- */
+
+static int graphkeys_create_ghostcurves_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  bAnimContext ac;
+  View2D *v2d;
+  int start, end;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  /* Ghost curves are snapshots of the visible portions of the curves,
+   * so set range to be the visible range. */
+  v2d = &ac.region->v2d;
+  start = (int)v2d->cur.xmin;
+  end = (int)v2d->cur.xmax;
+
+  /* Bake selected curves into a ghost curve. */
+  create_ghost_curves(&ac, start, end);
+
+  /* Update this editor only. */
+  ED_area_tag_redraw(CTX_wm_area(C));
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_ghost_curves_create(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Create Ghost Curves";
+  ot->idname = "GRAPH_OT_ghost_curves_create";
+  ot->description =
+      "Create snapshot (Ghosts) of selected F-Curves as background aid for active Graph Editor";
+
+  /* API callbacks */
+  ot->exec = graphkeys_create_ghostcurves_exec;
+  ot->poll = graphop_visible_keyframes_poll;
+
+  /* Flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* TODO: add props for start/end frames */
+}
+
+/* ******************** Clear Ghost-Curves Operator *********************** */
+/* This operator clears the 'ghost curves' for the active Graph Editor */
+
+static int graphkeys_clear_ghostcurves_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  bAnimContext ac;
+  SpaceGraph *sipo;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+  sipo = (SpaceGraph *)ac.sl;
+
+  /* If no ghost curves, don't do anything. */
+  if (BLI_listbase_is_empty(&sipo->runtime.ghost_curves)) {
+    return OPERATOR_CANCELLED;
+  }
+  /* Free ghost curves. */
+  BKE_fcurves_free(&sipo->runtime.ghost_curves);
+
+  /* Update this editor only. */
+  ED_area_tag_redraw(CTX_wm_area(C));
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_ghost_curves_clear(wmOperatorType *ot)
+{
+  /* Identifiers */
+  ot->name = "Clear Ghost Curves";
+  ot->idname = "GRAPH_OT_ghost_curves_clear";
+  ot->description = "Clear F-Curve snapshots (Ghosts) for active Graph Editor";
+
+  /* API callbacks */
+  ot->exec = graphkeys_clear_ghostcurves_exec;
+  ot->poll = ED_operator_graphedit_active;
+
+  /* Flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}
\ No newline at end of file