/*
 * 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) 2009 Blender Foundation, Joshua Leung
 * All rights reserved.
 */

/** \file
 * \ingroup edanimation
 */

/* System includes ----------------------------------------------------- */

#include <float.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

#include "MEM_guardedalloc.h"

#include "BLI_dlrbTree.h"
#include "BLI_listbase.h"
#include "BLI_math.h"
#include "BLI_rect.h"
#include "BLI_utildefines.h"

#include "DNA_anim_types.h"
#include "DNA_brush_types.h"
#include "DNA_cachefile_types.h"
#include "DNA_gpencil_types.h"
#include "DNA_mask_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"

#include "BKE_fcurve.h"

#include "GPU_immediate.h"
#include "GPU_state.h"

#include "UI_interface.h"
#include "UI_resources.h"
#include "UI_view2d.h"

#include "ED_anim_api.h"
#include "ED_keyframes_draw.h"

/* *************************** Keyframe Processing *************************** */

/* ActKeyColumns (Keyframe Columns) ------------------------------------------ */

BLI_INLINE bool is_cfra_eq(float a, float b)
{
  return IS_EQT(a, b, BEZT_BINARYSEARCH_THRESH);
}

BLI_INLINE bool is_cfra_lt(float a, float b)
{
  return (b - a) > BEZT_BINARYSEARCH_THRESH;
}

/* Comparator callback used for ActKeyColumns and cframe float-value pointer */
/* NOTE: this is exported to other modules that use the ActKeyColumns for finding keyframes */
short compare_ak_cfraPtr(void *node, void *data)
{
  ActKeyColumn *ak = (ActKeyColumn *)node;
  const float *cframe = data;
  float val = *cframe;

  if (is_cfra_eq(val, ak->cfra)) {
    return 0;
  }

  if (val < ak->cfra) {
    return -1;
  }
  return 1;
}

/* --------------- */

/* Set of references to three logically adjacent keys. */
typedef struct BezTripleChain {
  /* Current keyframe. */
  BezTriple *cur;

  /* Logical neighbors. May be NULL. */
  BezTriple *prev, *next;
} BezTripleChain;

/* Categorize the interpolation & handle type of the keyframe. */
static eKeyframeHandleDrawOpts bezt_handle_type(BezTriple *bezt)
{
  if (bezt->h1 == HD_AUTO_ANIM && bezt->h2 == HD_AUTO_ANIM) {
    return KEYFRAME_HANDLE_AUTO_CLAMP;
  }
  if (ELEM(bezt->h1, HD_AUTO_ANIM, HD_AUTO) && ELEM(bezt->h2, HD_AUTO_ANIM, HD_AUTO)) {
    return KEYFRAME_HANDLE_AUTO;
  }
  if (bezt->h1 == HD_VECT && bezt->h2 == HD_VECT) {
    return KEYFRAME_HANDLE_VECTOR;
  }
  if (ELEM(HD_FREE, bezt->h1, bezt->h2)) {
    return KEYFRAME_HANDLE_FREE;
  }
  return KEYFRAME_HANDLE_ALIGNED;
}

/* Determine if the keyframe is an extreme by comparing with neighbors.
 * Ends of fixed-value sections and of the whole curve are also marked.
 */
static eKeyframeExtremeDrawOpts bezt_extreme_type(BezTripleChain *chain)
{
  if (chain->prev == NULL && chain->next == NULL) {
    return KEYFRAME_EXTREME_NONE;
  }

  /* Keyframe values for the current one and neighbors. */
  float cur_y = chain->cur->vec[1][1];
  float prev_y = cur_y, next_y = cur_y;

  if (chain->prev && !IS_EQF(cur_y, chain->prev->vec[1][1])) {
    prev_y = chain->prev->vec[1][1];
  }
  if (chain->next && !IS_EQF(cur_y, chain->next->vec[1][1])) {
    next_y = chain->next->vec[1][1];
  }

  /* Static hold. */
  if (prev_y == cur_y && next_y == cur_y) {
    return KEYFRAME_EXTREME_FLAT;
  }

  /* Middle of an incline. */
  if ((prev_y < cur_y && next_y > cur_y) || (prev_y > cur_y && next_y < cur_y)) {
    return KEYFRAME_EXTREME_NONE;
  }

  /* Bezier handle values for the overshoot check. */
  bool l_bezier = chain->prev && chain->prev->ipo == BEZT_IPO_BEZ;
  bool r_bezier = chain->next && chain->cur->ipo == BEZT_IPO_BEZ;
  float handle_l = l_bezier ? chain->cur->vec[0][1] : cur_y;
  float handle_r = r_bezier ? chain->cur->vec[2][1] : cur_y;

  /* Detect extremes. One of the neighbors is allowed to be equal to current. */
  if (prev_y < cur_y || next_y < cur_y) {
    bool is_overshoot = (handle_l > cur_y || handle_r > cur_y);

    return KEYFRAME_EXTREME_MAX | (is_overshoot ? KEYFRAME_EXTREME_MIXED : 0);
  }

  if (prev_y > cur_y || next_y > cur_y) {
    bool is_overshoot = (handle_l < cur_y || handle_r < cur_y);

    return KEYFRAME_EXTREME_MIN | (is_overshoot ? KEYFRAME_EXTREME_MIXED : 0);
  }

  return KEYFRAME_EXTREME_NONE;
}

/* Comparator callback used for ActKeyColumns and BezTripleChain */
static short compare_ak_bezt(void *node, void *data)
{
  BezTripleChain *chain = data;

  return compare_ak_cfraPtr(node, &chain->cur->vec[1][0]);
}

/* New node callback used for building ActKeyColumns from BezTripleChain */
static DLRBT_Node *nalloc_ak_bezt(void *data)
{
  ActKeyColumn *ak = MEM_callocN(sizeof(ActKeyColumn), "ActKeyColumn");
  BezTripleChain *chain = data;
  BezTriple *bezt = chain->cur;

  /* store settings based on state of BezTriple */
  ak->cfra = bezt->vec[1][0];
  ak->sel = BEZT_ISSEL_ANY(bezt) ? SELECT : 0;
  ak->key_type = BEZKEYTYPE(bezt);
  ak->handle_type = bezt_handle_type(bezt);
  ak->extreme_type = bezt_extreme_type(chain);

  /* count keyframes in this column */
  ak->totkey = 1;

  return (DLRBT_Node *)ak;
}

/* Node updater callback used for building ActKeyColumns from BezTripleChain */
static void nupdate_ak_bezt(void *node, void *data)
{
  ActKeyColumn *ak = node;
  BezTripleChain *chain = data;
  BezTriple *bezt = chain->cur;

  /* set selection status and 'touched' status */
  if (BEZT_ISSEL_ANY(bezt)) {
    ak->sel = SELECT;
  }

  /* count keyframes in this column */
  ak->totkey++;

  /* For keyframe type, 'proper' keyframes have priority over breakdowns
   * (and other types for now). */
  if (BEZKEYTYPE(bezt) == BEZT_KEYTYPE_KEYFRAME) {
    ak->key_type = BEZT_KEYTYPE_KEYFRAME;
  }

  /* For interpolation type, select the highest value (enum is sorted). */
  ak->handle_type = MAX2(ak->handle_type, bezt_handle_type(bezt));

  /* For extremes, detect when combining different states. */
  char new_extreme = bezt_extreme_type(chain);

  if (new_extreme != ak->extreme_type) {
    /* Replace the flat status without adding mixed. */
    if (ak->extreme_type == KEYFRAME_EXTREME_FLAT) {
      ak->extreme_type = new_extreme;
    }
    else if (new_extreme != KEYFRAME_EXTREME_FLAT) {
      ak->extreme_type |= (new_extreme | KEYFRAME_EXTREME_MIXED);
    }
  }
}

/* ......... */

/* Comparator callback used for ActKeyColumns and GPencil frame */
static short compare_ak_gpframe(void *node, void *data)
{
  bGPDframe *gpf = (bGPDframe *)data;

  float frame = gpf->framenum;
  return compare_ak_cfraPtr(node, &frame);
}

/* New node callback used for building ActKeyColumns from GPencil frames */
static DLRBT_Node *nalloc_ak_gpframe(void *data)
{
  ActKeyColumn *ak = MEM_callocN(sizeof(ActKeyColumn), "ActKeyColumnGPF");
  bGPDframe *gpf = (bGPDframe *)data;

  /* store settings based on state of BezTriple */
  ak->cfra = gpf->framenum;
  ak->sel = (gpf->flag & GP_FRAME_SELECT) ? SELECT : 0;
  ak->key_type = gpf->key_type;

  /* count keyframes in this column */
  ak->totkey = 1;
  /* Set as visible block. */
  ak->totblock = 1;
  ak->block.sel = ak->sel;
  ak->block.flag |= ACTKEYBLOCK_FLAG_GPENCIL;

  return (DLRBT_Node *)ak;
}

/* Node updater callback used for building ActKeyColumns from GPencil frames */
static void nupdate_ak_gpframe(void *node, void *data)
{
  ActKeyColumn *ak = (ActKeyColumn *)node;
  bGPDframe *gpf = (bGPDframe *)data;

  /* set selection status and 'touched' status */
  if (gpf->flag & GP_FRAME_SELECT) {
    ak->sel = SELECT;
  }

  /* count keyframes in this column */
  ak->totkey++;

  /* for keyframe type, 'proper' keyframes have priority over breakdowns
   * (and other types for now). */
  if (gpf->key_type == BEZT_KEYTYPE_KEYFRAME) {
    ak->key_type = BEZT_KEYTYPE_KEYFRAME;
  }
}

/* ......... */

/* Comparator callback used for ActKeyColumns and GPencil frame */
static short compare_ak_masklayshape(void *node, void *data)
{
  MaskLayerShape *masklay_shape = (MaskLayerShape *)data;

  float frame = masklay_shape->frame;
  return compare_ak_cfraPtr(node, &frame);
}

/* New node callback used for building ActKeyColumns from GPencil frames */
static DLRBT_Node *nalloc_ak_masklayshape(void *data)
{
  ActKeyColumn *ak = MEM_callocN(sizeof(ActKeyColumn), "ActKeyColumnGPF");
  MaskLayerShape *masklay_shape = (MaskLayerShape *)data;

  /* store settings based on state of BezTriple */
  ak->cfra = masklay_shape->frame;
  ak->sel = (masklay_shape->flag & MASK_SHAPE_SELECT) ? SELECT : 0;

  /* count keyframes in this column */
  ak->totkey = 1;

  return (DLRBT_Node *)ak;
}

/* Node updater callback used for building ActKeyColumns from GPencil frames */
static void nupdate_ak_masklayshape(void *node, void *data)
{
  ActKeyColumn *ak = (ActKeyColumn *)node;
  MaskLayerShape *masklay_shape = (MaskLayerShape *)data;

  /* set selection status and 'touched' status */
  if (masklay_shape->flag & MASK_SHAPE_SELECT) {
    ak->sel = SELECT;
  }

  /* count keyframes in this column */
  ak->totkey++;
}

/* --------------- */

/* Add the given BezTriple to the given 'list' of Keyframes */
static void add_bezt_to_keycolumns_list(DLRBT_Tree *keys, BezTripleChain *bezt)
{
  if (ELEM(NULL, keys, bezt)) {
    return;
  }

  BLI_dlrbTree_add(keys, compare_ak_bezt, nalloc_ak_bezt, nupdate_ak_bezt, bezt);
}

/* Add the given GPencil Frame to the given 'list' of Keyframes */
static void add_gpframe_to_keycolumns_list(DLRBT_Tree *keys, bGPDframe *gpf)
{
  if (ELEM(NULL, keys, gpf)) {
    return;
  }

  BLI_dlrbTree_add(keys, compare_ak_gpframe, nalloc_ak_gpframe, nupdate_ak_gpframe, gpf);
}

/* Add the given MaskLayerShape Frame to the given 'list' of Keyframes */
static void add_masklay_to_keycolumns_list(DLRBT_Tree *keys, MaskLayerShape *masklay_shape)
{
  if (ELEM(NULL, keys, masklay_shape)) {
    return;
  }

  BLI_dlrbTree_add(keys,
                   compare_ak_masklayshape,
                   nalloc_ak_masklayshape,
                   nupdate_ak_masklayshape,
                   masklay_shape);
}

/* ActKeyBlocks (Long Keyframes) ------------------------------------------ */

static const ActKeyBlockInfo dummy_keyblock = {0};

static void compute_keyblock_data(ActKeyBlockInfo *info, BezTriple *prev, BezTriple *beztn)
{
  memset(info, 0, sizeof(ActKeyBlockInfo));

  if (BEZKEYTYPE(beztn) == BEZT_KEYTYPE_MOVEHOLD) {
    /* Animator tagged a "moving hold"
     *   - Previous key must also be tagged as a moving hold, otherwise
     *     we're just dealing with the first of a pair, and we don't
     *     want to be creating any phantom holds...
     */
    if (BEZKEYTYPE(prev) == BEZT_KEYTYPE_MOVEHOLD) {
      info->flag |= ACTKEYBLOCK_FLAG_MOVING_HOLD | ACTKEYBLOCK_FLAG_ANY_HOLD;
    }
  }

  /* Check for same values...
   *  - Handles must have same central value as each other
   *  - Handles which control that section of the curve must be constant
   */
  if (IS_EQF(beztn->vec[1][1], prev->vec[1][1])) {
    bool hold;

    /* Only check handles in case of actual bezier interpolation. */
    if (prev->ipo == BEZT_IPO_BEZ) {
      hold = IS_EQF(beztn->vec[1][1], beztn->vec[0][1]) &&
             IS_EQF(prev->vec[1][1], prev->vec[2][1]);
    }
    /* This interpolation type induces movement even between identical keys. */
    else {
      hold = !ELEM(prev->ipo, BEZT_IPO_ELASTIC);
    }

    if (hold) {
      info->flag |= ACTKEYBLOCK_FLAG_STATIC_HOLD | ACTKEYBLOCK_FLAG_ANY_HOLD;
    }
  }

  /* Remember non-bezier interpolation info. */
  if (prev->ipo != BEZT_IPO_BEZ) {
    info->flag |= ACTKEYBLOCK_FLAG_NON_BEZIER;
  }

  info->sel = BEZT_ISSEL_ANY(prev) || BEZT_ISSEL_ANY(beztn);
}

static void add_keyblock_info(ActKeyColumn *col, const ActKeyBlockInfo *block)
{
  /* New curve and block. */
  if (col->totcurve <= 1 && col->totblock == 0) {
    memcpy(&col->block, block, sizeof(ActKeyBlockInfo));
  }
  /* Existing curve. */
  else {
    col->block.conflict |= (col->block.flag ^ block->flag);
    col->block.flag |= block->flag;
    col->block.sel |= block->sel;
  }

  if (block->flag) {
    col->totblock++;
  }
}

static void add_bezt_to_keyblocks_list(DLRBT_Tree *keys, BezTriple *bezt, int bezt_len)
{
  ActKeyColumn *col = keys->first;

  if (bezt && bezt_len >= 2) {
    ActKeyBlockInfo block;

    /* Find the first key column while inserting dummy blocks. */
    for (; col != NULL && is_cfra_lt(col->cfra, bezt[0].vec[1][0]); col = col->next) {
      add_keyblock_info(col, &dummy_keyblock);
    }

    BLI_assert(col != NULL);

    /* Insert real blocks. */
    for (int v = 1; col != NULL && v < bezt_len; v++, bezt++) {
      /* Wrong order of bezier keys: resync position. */
      if (is_cfra_lt(bezt[1].vec[1][0], bezt[0].vec[1][0])) {
        /* Backtrack to find the right location. */
        if (is_cfra_lt(bezt[1].vec[1][0], col->cfra)) {
          ActKeyColumn *newcol = (ActKeyColumn *)BLI_dlrbTree_search_exact(
              keys, compare_ak_cfraPtr, &bezt[1].vec[1][0]);

          if (newcol != NULL) {
            col = newcol;

            /* The previous keyblock is garbage too. */
            if (col->prev != NULL) {
              add_keyblock_info(col->prev, &dummy_keyblock);
            }
          }
          else {
            BLI_assert(false);
          }
        }

        continue;
      }

      /* Normal sequence */
      BLI_assert(is_cfra_eq(col->cfra, bezt[0].vec[1][0]));

      compute_keyblock_data(&block, bezt, bezt + 1);

      for (; col != NULL && is_cfra_lt(col->cfra, bezt[1].vec[1][0]); col = col->next) {
        add_keyblock_info(col, &block);
      }

      BLI_assert(col != NULL);
    }
  }

  /* Insert dummy blocks at the end. */
  for (; col != NULL; col = col->next) {
    add_keyblock_info(col, &dummy_keyblock);
  }
}

/* Walk through columns and propagate blocks and totcurve.
 *
 * This must be called even by animation sources that don't generate
 * keyblocks to keep the data structure consistent after adding columns.
 */
static void update_keyblocks(DLRBT_Tree *keys, BezTriple *bezt, int bezt_len)
{
  /* Recompute the prev/next linked list. */
  BLI_dlrbTree_linkedlist_sync(keys);

  /* Find the curve count */
  int max_curve = 0;

  LISTBASE_FOREACH (ActKeyColumn *, col, keys) {
    max_curve = MAX2(max_curve, col->totcurve);
  }

  /* Propagate blocks to inserted keys */
  ActKeyColumn *prev_ready = NULL;

  LISTBASE_FOREACH (ActKeyColumn *, col, keys) {
    /* Pre-existing column. */
    if (col->totcurve > 0) {
      prev_ready = col;
    }
    /* Newly inserted column, so copy block data from previous. */
    else if (prev_ready != NULL) {
      col->totblock = prev_ready->totblock;
      memcpy(&col->block, &prev_ready->block, sizeof(ActKeyBlockInfo));
    }

    col->totcurve = max_curve + 1;
  }

  /* Add blocks on top */
  add_bezt_to_keyblocks_list(keys, bezt, bezt_len);
}

/* --------- */

bool actkeyblock_is_valid(ActKeyColumn *ac)
{
  return ac != NULL && ac->next != NULL && ac->totblock > 0;
}

/* Checks if ActKeyBlock should exist... */
int actkeyblock_get_valid_hold(ActKeyColumn *ac)
{
  /* check that block is valid */
  if (!actkeyblock_is_valid(ac)) {
    return 0;
  }

  const int hold_mask = (ACTKEYBLOCK_FLAG_ANY_HOLD | ACTKEYBLOCK_FLAG_STATIC_HOLD);
  return (ac->block.flag & ~ac->block.conflict) & hold_mask;
}

/* *************************** Keyframe Drawing *************************** */

void draw_keyframe_shape(float x,
                         float y,
                         float size,
                         bool sel,
                         short key_type,
                         short mode,
                         float alpha,
                         uint pos_id,
                         uint size_id,
                         uint color_id,
                         uint outline_color_id,
                         uint flags_id,
                         short handle_type,
                         short extreme_type)
{
  bool draw_fill = ELEM(mode, KEYFRAME_SHAPE_INSIDE, KEYFRAME_SHAPE_BOTH);
  bool draw_outline = ELEM(mode, KEYFRAME_SHAPE_FRAME, KEYFRAME_SHAPE_BOTH);

  BLI_assert(draw_fill || draw_outline);

  /* tweak size of keyframe shape according to type of keyframe
   * - 'proper' keyframes have key_type = 0, so get drawn at full size
   */
  switch (key_type) {
    case BEZT_KEYTYPE_KEYFRAME: /* must be full size */
      break;

    case BEZT_KEYTYPE_BREAKDOWN: /* slightly smaller than normal keyframe */
      size *= 0.85f;
      break;

    case BEZT_KEYTYPE_MOVEHOLD: /* Slightly smaller than normal keyframes
                                 * (but by less than for breakdowns). */
      size *= 0.925f;
      break;

    case BEZT_KEYTYPE_EXTREME: /* slightly larger */
      size *= 1.2f;
      break;

    default:
      size -= 0.8f * key_type;
  }

  uchar fill_col[4];
  uchar outline_col[4];
  uint flags = 0;

  /* draw! */
  if (draw_fill) {
    /* get interior colors from theme (for selected and unselected only) */
    switch (key_type) {
      case BEZT_KEYTYPE_BREAKDOWN: /* bluish frames (default theme) */
        UI_GetThemeColor4ubv(sel ? TH_KEYTYPE_BREAKDOWN_SELECT : TH_KEYTYPE_BREAKDOWN, fill_col);
        break;
      case BEZT_KEYTYPE_EXTREME: /* reddish frames (default theme) */
        UI_GetThemeColor4ubv(sel ? TH_KEYTYPE_EXTREME_SELECT : TH_KEYTYPE_EXTREME, fill_col);
        break;
      case BEZT_KEYTYPE_JITTER: /* greenish frames (default theme) */
        UI_GetThemeColor4ubv(sel ? TH_KEYTYPE_JITTER_SELECT : TH_KEYTYPE_JITTER, fill_col);
        break;
      case BEZT_KEYTYPE_MOVEHOLD: /* similar to traditional keyframes, but different... */
        UI_GetThemeColor4ubv(sel ? TH_KEYTYPE_MOVEHOLD_SELECT : TH_KEYTYPE_MOVEHOLD, fill_col);
        break;
      case BEZT_KEYTYPE_KEYFRAME: /* traditional yellowish frames (default theme) */
      default:
        UI_GetThemeColor4ubv(sel ? TH_KEYTYPE_KEYFRAME_SELECT : TH_KEYTYPE_KEYFRAME, fill_col);
    }

    /* NOTE: we don't use the straight alpha from the theme, or else effects such as
     * graying out protected/muted channels doesn't work correctly!
     */
    fill_col[3] *= alpha;

    if (!draw_outline) {
      /* force outline color to match */
      outline_col[0] = fill_col[0];
      outline_col[1] = fill_col[1];
      outline_col[2] = fill_col[2];
      outline_col[3] = fill_col[3];
    }
  }

  if (draw_outline) {
    /* exterior - black frame */
    UI_GetThemeColor4ubv(sel ? TH_KEYBORDER_SELECT : TH_KEYBORDER, outline_col);
    outline_col[3] *= alpha;

    if (!draw_fill) {
      /* fill color needs to be (outline.rgb, 0) */
      fill_col[0] = outline_col[0];
      fill_col[1] = outline_col[1];
      fill_col[2] = outline_col[2];
      fill_col[3] = 0;
    }

    /* Handle type to outline shape. */
    switch (handle_type) {
      case KEYFRAME_HANDLE_AUTO_CLAMP:
        flags = 0x2;
        break; /* circle */
      case KEYFRAME_HANDLE_AUTO:
        flags = 0x12;
        break; /* circle with dot */
      case KEYFRAME_HANDLE_VECTOR:
        flags = 0xC;
        break; /* square */
      case KEYFRAME_HANDLE_ALIGNED:
        flags = 0x5;
        break; /* clipped diamond */

      case KEYFRAME_HANDLE_FREE:
      default:
        flags = 1; /* diamond */
    }

    /* Extreme type to arrow-like shading. */
    if (extreme_type & KEYFRAME_EXTREME_MAX) {
      flags |= 0x100;
    }
    if (extreme_type & KEYFRAME_EXTREME_MIN) {
      flags |= 0x200;
    }
    if (extreme_type & KEYFRAME_EXTREME_MIXED) {
      flags |= 0x400;
    }
  }

  immAttr1f(size_id, size);
  immAttr4ubv(color_id, fill_col);
  immAttr4ubv(outline_color_id, outline_col);
  immAttr1u(flags_id, flags);
  immVertex2f(pos_id, x, y);
}

static void draw_keylist(View2D *v2d,
                         DLRBT_Tree *keys,
                         float ypos,
                         float yscale_fac,
                         bool channelLocked,
                         int saction_flag)
{
  if (keys == NULL) {
    return;
  }

  const float icon_sz = U.widget_unit * 0.5f * yscale_fac;
  const float half_icon_sz = 0.5f * icon_sz;
  const float smaller_sz = 0.35f * icon_sz;
  const float ipo_sz = 0.1f * icon_sz;
  const float gpencil_sz = smaller_sz * 0.8f;
  const float screenspace_margin = (0.35f * (float)UI_UNIT_X) / UI_view2d_scale_get_x(v2d);

  /* locked channels are less strongly shown, as feedback for locked channels in DopeSheet */
  /* TODO: allow this opacity factor to be themed? */
  float alpha = channelLocked ? 0.25f : 1.0f;

  /* Show interpolation and handle type? */
  bool show_ipo = (saction_flag & SACTION_SHOW_INTERPOLATION) != 0;
  /* draw keyblocks */
  float sel_color[4], unsel_color[4];
  float sel_mhcol[4], unsel_mhcol[4];
  float ipo_color[4], ipo_color_mix[4];

  /* cache colors first */
  UI_GetThemeColor4fv(TH_STRIP_SELECT, sel_color);
  UI_GetThemeColor4fv(TH_STRIP, unsel_color);
  UI_GetThemeColor4fv(TH_DOPESHEET_IPOLINE, ipo_color);

  sel_color[3] *= alpha;
  unsel_color[3] *= alpha;
  ipo_color[3] *= alpha;

  copy_v4_v4(sel_mhcol, sel_color);
  sel_mhcol[3] *= 0.8f;
  copy_v4_v4(unsel_mhcol, unsel_color);
  unsel_mhcol[3] *= 0.8f;
  copy_v4_v4(ipo_color_mix, ipo_color);
  ipo_color_mix[3] *= 0.5f;

  LISTBASE_FOREACH (ActKeyColumn *, ab, keys) {
    /* Draw grease pencil bars between keyframes. */
    if ((ab->next != NULL) && (ab->block.flag & ACTKEYBLOCK_FLAG_GPENCIL)) {
      UI_draw_roundbox_corner_set(UI_CNR_TOP_RIGHT | UI_CNR_BOTTOM_RIGHT);
      float size = 1.0f;
      switch (ab->next->key_type) {
        case BEZT_KEYTYPE_BREAKDOWN:
        case BEZT_KEYTYPE_MOVEHOLD:
        case BEZT_KEYTYPE_JITTER:
          size *= 0.5f;
          break;
        case BEZT_KEYTYPE_KEYFRAME:
          size *= 0.8f;
          break;
        default:
          break;
      }
      UI_draw_roundbox_4fv(
          &(const rctf){
              .xmin = ab->cfra,
              .xmax = min_ff(ab->next->cfra - (screenspace_margin * size), ab->next->cfra),
              .ymin = ypos - gpencil_sz,
              .ymax = ypos + gpencil_sz,
          },
          true,
          0.25f * (float)UI_UNIT_X,
          (ab->block.sel) ? sel_mhcol : unsel_mhcol);
    }
    else {
      /* Draw other types. */
      UI_draw_roundbox_corner_set(UI_CNR_NONE);

      int valid_hold = actkeyblock_get_valid_hold(ab);
      if (valid_hold != 0) {
        if ((valid_hold & ACTKEYBLOCK_FLAG_STATIC_HOLD) == 0) {
          /* draw "moving hold" long-keyframe block - slightly smaller */
          UI_draw_roundbox_4fv(
              &(const rctf){
                  .xmin = ab->cfra,
                  .xmax = ab->next->cfra,
                  .ymin = ypos - smaller_sz,
                  .ymax = ypos + smaller_sz,
              },
              true,
              3.0f,
              (ab->block.sel) ? sel_mhcol : unsel_mhcol);
        }
        else {
          /* draw standard long-keyframe block */
          UI_draw_roundbox_4fv(
              &(const rctf){
                  .xmin = ab->cfra,
                  .xmax = ab->next->cfra,
                  .ymin = ypos - half_icon_sz,
                  .ymax = ypos + half_icon_sz,
              },
              true,
              3.0f,
              (ab->block.sel) ? sel_color : unsel_color);
        }
      }
      if (show_ipo && actkeyblock_is_valid(ab) && (ab->block.flag & ACTKEYBLOCK_FLAG_NON_BEZIER)) {
        /* draw an interpolation line */
        UI_draw_roundbox_4fv(
            &(const rctf){
                .xmin = ab->cfra,
                .xmax = ab->next->cfra,
                .ymin = ypos - ipo_sz,
                .ymax = ypos + ipo_sz,
            },
            true,
            3.0f,
            (ab->block.conflict & ACTKEYBLOCK_FLAG_NON_BEZIER) ? ipo_color_mix : ipo_color);
      }
    }
  }

  GPU_blend(GPU_BLEND_ALPHA);

  /* count keys */
  uint key_len = 0;
  LISTBASE_FOREACH (ActKeyColumn *, ak, keys) {
    /* Optimization: if keyframe doesn't appear within 5 units (screenspace)
     * in visible area, don't draw.
     * This might give some improvements,
     * since we current have to flip between view/region matrices.
     */
    if (IN_RANGE_INCL(ak->cfra, v2d->cur.xmin, v2d->cur.xmax)) {
      key_len++;
    }
  }

  if (key_len > 0) {
    /* draw keys */
    GPUVertFormat *format = immVertexFormat();
    uint pos_id = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
    uint size_id = GPU_vertformat_attr_add(format, "size", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
    uint color_id = GPU_vertformat_attr_add(
        format, "color", GPU_COMP_U8, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
    uint outline_color_id = GPU_vertformat_attr_add(
        format, "outlineColor", GPU_COMP_U8, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
    uint flags_id = GPU_vertformat_attr_add(format, "flags", GPU_COMP_U32, 1, GPU_FETCH_INT);

    GPU_program_point_size(true);
    immBindBuiltinProgram(GPU_SHADER_KEYFRAME_DIAMOND);
    immUniform1f("outline_scale", 1.0f);
    immUniform2f("ViewportSize", BLI_rcti_size_x(&v2d->mask) + 1, BLI_rcti_size_y(&v2d->mask) + 1);
    immBegin(GPU_PRIM_POINTS, key_len);

    short handle_type = KEYFRAME_HANDLE_NONE, extreme_type = KEYFRAME_EXTREME_NONE;

    LISTBASE_FOREACH (ActKeyColumn *, ak, keys) {
      if (IN_RANGE_INCL(ak->cfra, v2d->cur.xmin, v2d->cur.xmax)) {
        if (show_ipo) {
          handle_type = ak->handle_type;
        }
        if (saction_flag & SACTION_SHOW_EXTREMES) {
          extreme_type = ak->extreme_type;
        }

        draw_keyframe_shape(ak->cfra,
                            ypos,
                            icon_sz,
                            (ak->sel & SELECT),
                            ak->key_type,
                            KEYFRAME_SHAPE_BOTH,
                            alpha,
                            pos_id,
                            size_id,
                            color_id,
                            outline_color_id,
                            flags_id,
                            handle_type,
                            extreme_type);
      }
    }

    immEnd();
    GPU_program_point_size(false);
    immUnbindProgram();
  }

  GPU_blend(GPU_BLEND_NONE);
}

/* *************************** Channel Drawing Funcs *************************** */

void draw_summary_channel(
    View2D *v2d, bAnimContext *ac, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  saction_flag &= ~SACTION_SHOW_EXTREMES;

  BLI_dlrbTree_init(&keys);

  summary_to_keylist(ac, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, false, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_scene_channel(
    View2D *v2d, bDopeSheet *ads, Scene *sce, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  saction_flag &= ~SACTION_SHOW_EXTREMES;

  BLI_dlrbTree_init(&keys);

  scene_to_keylist(ads, sce, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, false, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_object_channel(
    View2D *v2d, bDopeSheet *ads, Object *ob, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  saction_flag &= ~SACTION_SHOW_EXTREMES;

  BLI_dlrbTree_init(&keys);

  ob_to_keylist(ads, ob, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, false, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_fcurve_channel(
    View2D *v2d, AnimData *adt, FCurve *fcu, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  bool locked = (fcu->flag & FCURVE_PROTECTED) ||
                ((fcu->grp) && (fcu->grp->flag & AGRP_PROTECTED)) ||
                ((adt && adt->action) && ID_IS_LINKED(adt->action));

  BLI_dlrbTree_init(&keys);

  fcurve_to_keylist(adt, fcu, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, locked, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_agroup_channel(
    View2D *v2d, AnimData *adt, bActionGroup *agrp, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  bool locked = (agrp->flag & AGRP_PROTECTED) ||
                ((adt && adt->action) && ID_IS_LINKED(adt->action));

  BLI_dlrbTree_init(&keys);

  agroup_to_keylist(adt, agrp, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, locked, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_action_channel(
    View2D *v2d, AnimData *adt, bAction *act, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  bool locked = (act && ID_IS_LINKED(act));

  saction_flag &= ~SACTION_SHOW_EXTREMES;

  BLI_dlrbTree_init(&keys);

  action_to_keylist(adt, act, &keys, saction_flag);

  draw_keylist(v2d, &keys, ypos, yscale_fac, locked, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_gpencil_channel(
    View2D *v2d, bDopeSheet *ads, bGPdata *gpd, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  saction_flag &= ~SACTION_SHOW_EXTREMES;

  BLI_dlrbTree_init(&keys);

  gpencil_to_keylist(ads, gpd, &keys, false);

  draw_keylist(v2d, &keys, ypos, yscale_fac, false, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_gpl_channel(
    View2D *v2d, bDopeSheet *ads, bGPDlayer *gpl, float ypos, float yscale_fac, int saction_flag)
{
  DLRBT_Tree keys;

  bool locked = (gpl->flag & GP_LAYER_LOCKED) != 0;

  BLI_dlrbTree_init(&keys);

  gpl_to_keylist(ads, gpl, &keys);

  draw_keylist(v2d, &keys, ypos, yscale_fac, locked, saction_flag);

  BLI_dlrbTree_free(&keys);
}

void draw_masklay_channel(View2D *v2d,
                          bDopeSheet *ads,
                          MaskLayer *masklay,
                          float ypos,
                          float yscale_fac,
                          int saction_flag)
{
  DLRBT_Tree keys;

  bool locked = (masklay->flag & MASK_LAYERFLAG_LOCKED) != 0;

  BLI_dlrbTree_init(&keys);

  mask_to_keylist(ads, masklay, &keys);

  draw_keylist(v2d, &keys, ypos, yscale_fac, locked, saction_flag);

  BLI_dlrbTree_free(&keys);
}

/* *************************** Keyframe List Conversions *************************** */

void summary_to_keylist(bAnimContext *ac, DLRBT_Tree *keys, int saction_flag)
{
  if (ac) {
    ListBase anim_data = {NULL, NULL};
    bAnimListElem *ale;
    int filter;

    /* get F-Curves to take keyframes from */
    filter = ANIMFILTER_DATA_VISIBLE;
    ANIM_animdata_filter(ac, &anim_data, filter, ac->data, ac->datatype);

    /* loop through each F-Curve, grabbing the keyframes */
    for (ale = anim_data.first; ale; ale = ale->next) {
      /* Why not use all #eAnim_KeyType here?
       * All of the other key types are actually "summaries" themselves,
       * and will just end up duplicating stuff that comes up through
       * standard filtering of just F-Curves. Given the way that these work,
       * there isn't really any benefit at all from including them. - Aligorith */

      switch (ale->datatype) {
        case ALE_FCURVE:
          fcurve_to_keylist(ale->adt, ale->data, keys, saction_flag);
          break;
        case ALE_MASKLAY:
          mask_to_keylist(ac->ads, ale->data, keys);
          break;
        case ALE_GPFRAME:
          gpl_to_keylist(ac->ads, ale->data, keys);
          break;
        default:
          // printf("%s: datatype %d unhandled\n", __func__, ale->datatype);
          break;
      }
    }

    ANIM_animdata_freelist(&anim_data);
  }
}

void scene_to_keylist(bDopeSheet *ads, Scene *sce, DLRBT_Tree *keys, int saction_flag)
{
  bAnimContext ac = {NULL};
  ListBase anim_data = {NULL, NULL};
  bAnimListElem *ale;
  int filter;

  bAnimListElem dummychan = {NULL};

  if (sce == NULL) {
    return;
  }

  /* create a dummy wrapper data to work with */
  dummychan.type = ANIMTYPE_SCENE;
  dummychan.data = sce;
  dummychan.id = &sce->id;
  dummychan.adt = sce->adt;

  ac.ads = ads;
  ac.data = &dummychan;
  ac.datatype = ANIMCONT_CHANNEL;

  /* get F-Curves to take keyframes from */
  filter = ANIMFILTER_DATA_VISIBLE; /* curves only */
  ANIM_animdata_filter(&ac, &anim_data, filter, ac.data, ac.datatype);

  /* loop through each F-Curve, grabbing the keyframes */
  for (ale = anim_data.first; ale; ale = ale->next) {
    fcurve_to_keylist(ale->adt, ale->data, keys, saction_flag);
  }

  ANIM_animdata_freelist(&anim_data);
}

void ob_to_keylist(bDopeSheet *ads, Object *ob, DLRBT_Tree *keys, int saction_flag)
{
  bAnimContext ac = {NULL};
  ListBase anim_data = {NULL, NULL};
  bAnimListElem *ale;
  int filter;

  bAnimListElem dummychan = {NULL};
  Base dummybase = {NULL};

  if (ob == NULL) {
    return;
  }

  /* create a dummy wrapper data to work with */
  dummybase.object = ob;

  dummychan.type = ANIMTYPE_OBJECT;
  dummychan.data = &dummybase;
  dummychan.id = &ob->id;
  dummychan.adt = ob->adt;

  ac.ads = ads;
  ac.data = &dummychan;
  ac.datatype = ANIMCONT_CHANNEL;

  /* get F-Curves to take keyframes from */
  filter = ANIMFILTER_DATA_VISIBLE; /* curves only */
  ANIM_animdata_filter(&ac, &anim_data, filter, ac.data, ac.datatype);

  /* loop through each F-Curve, grabbing the keyframes */
  for (ale = anim_data.first; ale; ale = ale->next) {
    fcurve_to_keylist(ale->adt, ale->data, keys, saction_flag);
  }

  ANIM_animdata_freelist(&anim_data);
}

void cachefile_to_keylist(bDopeSheet *ads,
                          CacheFile *cache_file,
                          DLRBT_Tree *keys,
                          int saction_flag)
{
  if (cache_file == NULL) {
    return;
  }

  /* create a dummy wrapper data to work with */
  bAnimListElem dummychan = {NULL};
  dummychan.type = ANIMTYPE_DSCACHEFILE;
  dummychan.data = cache_file;
  dummychan.id = &cache_file->id;
  dummychan.adt = cache_file->adt;

  bAnimContext ac = {NULL};
  ac.ads = ads;
  ac.data = &dummychan;
  ac.datatype = ANIMCONT_CHANNEL;

  /* get F-Curves to take keyframes from */
  ListBase anim_data = {NULL, NULL};
  int filter = ANIMFILTER_DATA_VISIBLE; /* curves only */
  ANIM_animdata_filter(&ac, &anim_data, filter, ac.data, ac.datatype);

  /* loop through each F-Curve, grabbing the keyframes */
  LISTBASE_FOREACH (bAnimListElem *, ale, &anim_data) {
    fcurve_to_keylist(ale->adt, ale->data, keys, saction_flag);
  }

  ANIM_animdata_freelist(&anim_data);
}

void fcurve_to_keylist(AnimData *adt, FCurve *fcu, DLRBT_Tree *keys, int saction_flag)
{
  if (fcu && fcu->totvert && fcu->bezt) {
    /* apply NLA-mapping (if applicable) */
    if (adt) {
      ANIM_nla_mapping_apply_fcurve(adt, fcu, 0, 0);
    }

    /* Check if the curve is cyclic. */
    bool is_cyclic = BKE_fcurve_is_cyclic(fcu) && (fcu->totvert >= 2);
    bool do_extremes = (saction_flag & SACTION_SHOW_EXTREMES) != 0;

    /* loop through beztriples, making ActKeysColumns */
    BezTripleChain chain = {0};

    for (int v = 0; v < fcu->totvert; v++) {
      chain.cur = &fcu->bezt[v];

      /* Neighbor keys, accounting for being cyclic. */
      if (do_extremes) {
        chain.prev = (v > 0) ? &fcu->bezt[v - 1] : is_cyclic ? &fcu->bezt[fcu->totvert - 2] : NULL;
        chain.next = (v + 1 < fcu->totvert) ? &fcu->bezt[v + 1] : is_cyclic ? &fcu->bezt[1] : NULL;
      }

      add_bezt_to_keycolumns_list(keys, &chain);
    }

    /* Update keyblocks. */
    update_keyblocks(keys, fcu->bezt, fcu->totvert);

    /* unapply NLA-mapping if applicable */
    if (adt) {
      ANIM_nla_mapping_apply_fcurve(adt, fcu, 1, 0);
    }
  }
}

void agroup_to_keylist(AnimData *adt, bActionGroup *agrp, DLRBT_Tree *keys, int saction_flag)
{
  FCurve *fcu;

  if (agrp) {
    /* loop through F-Curves */
    for (fcu = agrp->channels.first; fcu && fcu->grp == agrp; fcu = fcu->next) {
      fcurve_to_keylist(adt, fcu, keys, saction_flag);
    }
  }
}

void action_to_keylist(AnimData *adt, bAction *act, DLRBT_Tree *keys, int saction_flag)
{
  FCurve *fcu;

  if (act) {
    /* loop through F-Curves */
    for (fcu = act->curves.first; fcu; fcu = fcu->next) {
      fcurve_to_keylist(adt, fcu, keys, saction_flag);
    }
  }
}

void gpencil_to_keylist(bDopeSheet *ads, bGPdata *gpd, DLRBT_Tree *keys, const bool active)
{
  bGPDlayer *gpl;

  if (gpd && keys) {
    /* for now, just aggregate out all the frames, but only for visible layers */
    for (gpl = gpd->layers.last; gpl; gpl = gpl->prev) {
      if ((gpl->flag & GP_LAYER_HIDE) == 0) {
        if ((!active) || ((active) && (gpl->flag & GP_LAYER_SELECT))) {
          gpl_to_keylist(ads, gpl, keys);
        }
      }
    }
  }
}

void gpl_to_keylist(bDopeSheet *UNUSED(ads), bGPDlayer *gpl, DLRBT_Tree *keys)
{
  bGPDframe *gpf;

  if (gpl && keys) {
    /* Although the frames should already be in an ordered list,
     * they are not suitable for displaying yet. */
    for (gpf = gpl->frames.first; gpf; gpf = gpf->next) {
      add_gpframe_to_keycolumns_list(keys, gpf);
    }

    update_keyblocks(keys, NULL, 0);
  }
}

void mask_to_keylist(bDopeSheet *UNUSED(ads), MaskLayer *masklay, DLRBT_Tree *keys)
{
  MaskLayerShape *masklay_shape;

  if (masklay && keys) {
    for (masklay_shape = masklay->splines_shapes.first; masklay_shape;
         masklay_shape = masklay_shape->next) {
      add_masklay_to_keycolumns_list(keys, masklay_shape);
    }

    update_keyblocks(keys, NULL, 0);
  }
}