anim_draw.cc

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/* SPDX-FileCopyrightText: 2008 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
#include "BLI_sys_types.h"
 
#include "DNA_anim_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_userdef_types.h"
 
#include "BLI_listbase.h"
#include "BLI_math_rotation.h"
#include "BLI_math_vector.h"
#include "BLI_rect.h"
#include "BLI_utildefines.h"
 
#include "BKE_context.hh"
#include "BKE_curve.hh"
#include "BKE_fcurve.hh"
#include "BKE_global.hh"
#include "BKE_mask.h"
#include "BKE_nla.hh"
 
#include "ED_anim_api.hh"
#include "ED_keyframes_edit.hh"
#include "ED_keyframes_keylist.hh"
 
#include "RNA_access.hh"
#include "RNA_path.hh"
 
#include "UI_resources.hh"
#include "UI_view2d.hh"
 
#include "GPU_immediate.hh"
#include "GPU_state.hh"
 
/* *************************************************** */
/* CURRENT FRAME DRAWING */
 
void ANIM_draw_cfra(const bContext *C, View2D *v2d, short flag)
{
  Scene *scene = CTX_data_scene(C);
 
  const float time = scene->r.cfra + scene->r.subframe;
  const float x = float(time * scene->r.framelen);
 
  GPU_line_width((flag & DRAWCFRA_WIDE) ? 3.0 : 2.0);
 
  GPUVertFormat *format = immVertexFormat();
  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
  immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
 
  /* Draw a light green line to indicate current frame */
  immUniformThemeColor(TH_CFRAME);
 
  immBegin(GPU_PRIM_LINES, 2);
  immVertex2f(pos, x, v2d->cur.ymin - 500.0f); /* XXX arbitrary... want it go to bottom */
  immVertex2f(pos, x, v2d->cur.ymax);
  immEnd();
  immUnbindProgram();
}
 
/* *************************************************** */
/* PREVIEW RANGE 'CURTAINS' */
/* NOTE: 'Preview Range' tools are defined in `anim_ops.cc`. */
 
void ANIM_draw_previewrange(const Scene *scene, View2D *v2d, int end_frame_width)
{
  /* Only draw this if preview range is set. */
  if (PRVRANGEON) {
    GPU_blend(GPU_BLEND_ALPHA);
 
    GPUVertFormat *format = immVertexFormat();
    uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
    immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
    immUniformThemeColorShadeAlpha(TH_ANIM_PREVIEW_RANGE, -25, -30);
 
    /* Only draw two separate 'curtains' if there's no overlap between them. */
    if (scene->r.psfra < scene->r.pefra + end_frame_width) {
      immRectf(pos, v2d->cur.xmin, v2d->cur.ymin, float(scene->r.psfra), v2d->cur.ymax);
      immRectf(pos,
               float(scene->r.pefra + end_frame_width),
               v2d->cur.ymin,
               v2d->cur.xmax,
               v2d->cur.ymax);
    }
    else {
      immRectf(pos, v2d->cur.xmin, v2d->cur.ymin, v2d->cur.xmax, v2d->cur.ymax);
    }
 
    immUnbindProgram();
 
    GPU_blend(GPU_BLEND_NONE);
  }
}
 
/* *************************************************** */
/* SCENE FRAME RANGE */
 
void ANIM_draw_framerange(Scene *scene, View2D *v2d)
{
  /* draw darkened area outside of active timeline frame range */
  GPU_blend(GPU_BLEND_ALPHA);
 
  GPUVertFormat *format = immVertexFormat();
  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
  immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
  immUniformThemeColorShadeAlpha(TH_BACK, -25, -100);
 
  if (scene->r.sfra < scene->r.efra) {
    immRectf(pos, v2d->cur.xmin, v2d->cur.ymin, float(scene->r.sfra), v2d->cur.ymax);
    immRectf(pos, float(scene->r.efra), v2d->cur.ymin, v2d->cur.xmax, v2d->cur.ymax);
  }
  else {
    immRectf(pos, v2d->cur.xmin, v2d->cur.ymin, v2d->cur.xmax, v2d->cur.ymax);
  }
 
  GPU_blend(GPU_BLEND_NONE);
 
  /* thin lines where the actual frames are */
  immUniformThemeColorShade(TH_BACK, -60);
 
  immBegin(GPU_PRIM_LINES, 4);
 
  immVertex2f(pos, float(scene->r.sfra), v2d->cur.ymin);
  immVertex2f(pos, float(scene->r.sfra), v2d->cur.ymax);
 
  immVertex2f(pos, float(scene->r.efra), v2d->cur.ymin);
  immVertex2f(pos, float(scene->r.efra), v2d->cur.ymax);
 
  immEnd();
  immUnbindProgram();
}
 
void ANIM_draw_action_framerange(
    AnimData *adt, bAction *action, View2D *v2d, float ymin, float ymax)
{
  if ((action->flag & ACT_FRAME_RANGE) == 0) {
    return;
  }
 
  /* Compute the dimensions. */
  CLAMP_MIN(ymin, v2d->cur.ymin);
  CLAMP_MAX(ymax, v2d->cur.ymax);
 
  if (ymin > ymax) {
    return;
  }
 
  const float sfra = BKE_nla_tweakedit_remap(adt, action->frame_start, NLATIME_CONVERT_MAP);
  const float efra = BKE_nla_tweakedit_remap(adt, action->frame_end, NLATIME_CONVERT_MAP);
 
  /* Diagonal stripe filled area outside of the frame range. */
  GPU_blend(GPU_BLEND_ALPHA);
 
  GPUVertFormat *format = immVertexFormat();
  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
  immBindBuiltinProgram(GPU_SHADER_2D_DIAG_STRIPES);
 
  float color[4];
  UI_GetThemeColorShadeAlpha4fv(TH_BACK, -40, -50, color);
 
  immUniform4f("color1", color[0], color[1], color[2], color[3]);
  immUniform4f("color2", 0.0f, 0.0f, 0.0f, 0.0f);
  immUniform1i("size1", 2 * UI_SCALE_FAC);
  immUniform1i("size2", 4 * UI_SCALE_FAC);
 
  if (sfra < efra) {
    immRectf(pos, v2d->cur.xmin, ymin, sfra, ymax);
    immRectf(pos, efra, ymin, v2d->cur.xmax, ymax);
  }
  else {
    immRectf(pos, v2d->cur.xmin, ymin, v2d->cur.xmax, ymax);
  }
 
  immUnbindProgram();
 
  GPU_blend(GPU_BLEND_NONE);
 
  /* Thin lines where the actual frames are. */
  immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
  immUniformThemeColorShade(TH_BACK, -60);
 
  GPU_line_width(1.0f);
 
  immBegin(GPU_PRIM_LINES, 4);
 
  immVertex2f(pos, sfra, ymin);
  immVertex2f(pos, sfra, ymax);
 
  immVertex2f(pos, efra, ymin);
  immVertex2f(pos, efra, ymax);
 
  immEnd();
  immUnbindProgram();
}
 
/* *************************************************** */
/* NLA-MAPPING UTILITIES (required for drawing and also editing keyframes). */
 
bool ANIM_nla_mapping_allowed(const bAnimListElem *ale)
{
  /* Historically, there was another check in the code that this function replaced:
   * if (!ELEM(ac->datatype,
   *           ANIMCONT_ACTION,
   *           ANIMCONT_SHAPEKEY,
   *           ANIMCONT_DOPESHEET,
   *           ANIMCONT_FCURVES,
   *           ANIMCONT_NLA,
   *           ANIMCONT_CHANNEL,
   *           ANIMCONT_TIMELINE))
   * {
   *   ... prevent NLA-remapping ...
   * }
   *
   * I (Sybren) suspect that this was actually hiding some animation type check. When that code was
   * written, I think there was no GreasePencil data showing in the regular Dope Sheet editor.
   */
 
  switch (ale->type) {
    case ANIMTYPE_NLACURVE:
      /* NLA Control Curves occur on NLA strips,
       * and shouldn't be subjected to this kind of mapping. */
      return false;
    case ANIMTYPE_FCURVE: {
      /* The F-Curve data of a driver should never get NLA-remapped. */
      FCurve *fcurve = static_cast<FCurve *>(ale->key_data);
      return !fcurve->driver;
    }
    case ANIMTYPE_DSGPENCIL:
    case ANIMTYPE_GPLAYER:
    case ANIMTYPE_GREASE_PENCIL_DATABLOCK:
    case ANIMTYPE_GREASE_PENCIL_LAYER_GROUP:
    case ANIMTYPE_GREASE_PENCIL_LAYER:
      /* Grease Pencil doesn't use the NLA, so don't bother remapping. */
      return false;
    case ANIMTYPE_MASKDATABLOCK:
    case ANIMTYPE_MASKLAYER:
      /* I (Sybren) don't _think_ masks can use the NLA. */
      return false;
    case ANIMTYPE_SUMMARY:
      /* The summary line cannot do NLA remapping since it may contain multiple actions. */
      return false;
    default:
      /* NLA time remapping is the default behavior, and only should be
       * prohibited for the above types. */
      return true;
  }
}
 
float ANIM_nla_tweakedit_remap(bAnimListElem *ale,
                               const float cframe,
                               const eNlaTime_ConvertModes mode)
{
  if (!ANIM_nla_mapping_allowed(ale)) {
    return cframe;
  }
  return BKE_nla_tweakedit_remap(ale->adt, cframe, mode);
}
 
/* ------------------- */
 
/* Helper function for ANIM_nla_mapping_apply_fcurve() -> "restore",
 * i.e. mapping points back to action-time. */
static short bezt_nlamapping_restore(KeyframeEditData *ked, BezTriple *bezt)
{
  /* AnimData block providing scaling is stored in 'data', only_keys option is stored in i1 */
  AnimData *adt = static_cast<AnimData *>(ked->data);
  short only_keys = short(ked->i1);
 
  /* adjust BezTriple handles only if allowed to */
  if (only_keys == 0) {
    bezt->vec[0][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[0][0], NLATIME_CONVERT_UNMAP);
    bezt->vec[2][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[2][0], NLATIME_CONVERT_UNMAP);
  }
 
  bezt->vec[1][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[1][0], NLATIME_CONVERT_UNMAP);
 
  return 0;
}
 
/* helper function for ANIM_nla_mapping_apply_fcurve() -> "apply",
 * i.e. mapping points to NLA-mapped global time */
static short bezt_nlamapping_apply(KeyframeEditData *ked, BezTriple *bezt)
{
  /* AnimData block providing scaling is stored in 'data', only_keys option is stored in i1 */
  AnimData *adt = static_cast<AnimData *>(ked->data);
  short only_keys = short(ked->i1);
 
  /* adjust BezTriple handles only if allowed to */
  if (only_keys == 0) {
    bezt->vec[0][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[0][0], NLATIME_CONVERT_MAP);
    bezt->vec[2][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[2][0], NLATIME_CONVERT_MAP);
  }
 
  bezt->vec[1][0] = BKE_nla_tweakedit_remap(adt, bezt->vec[1][0], NLATIME_CONVERT_MAP);
 
  return 0;
}
 
void ANIM_nla_mapping_apply_fcurve(AnimData *adt, FCurve *fcu, bool restore, bool only_keys)
{
  if (adt == nullptr || BLI_listbase_is_empty(&adt->nla_tracks)) {
    return;
  }
  KeyframeEditData ked = {{nullptr}};
  KeyframeEditFunc map_cb;
 
  /* init edit data
   * - AnimData is stored in 'data'
   * - only_keys is stored in 'i1'
   */
  ked.data = (void *)adt;
  ked.i1 = int(only_keys);
 
  /* get editing callback */
  if (restore) {
    map_cb = bezt_nlamapping_restore;
  }
  else {
    map_cb = bezt_nlamapping_apply;
  }
 
  /* apply to F-Curve */
  ANIM_fcurve_keyframes_loop(&ked, fcu, nullptr, map_cb, nullptr);
}
 
void ANIM_nla_mapping_apply_if_needed_fcurve(bAnimListElem *ale,
                                             FCurve *fcu,
                                             const bool restore,
                                             const bool only_keys)
{
  if (!ANIM_nla_mapping_allowed(ale)) {
    return;
  }
  ANIM_nla_mapping_apply_fcurve(ale->adt, fcu, restore, only_keys);
}
 
/* *************************************************** */
/* UNITS CONVERSION MAPPING (required for drawing and editing keyframes) */
 
short ANIM_get_normalization_flags(SpaceLink *space_link)
{
  if (space_link->spacetype == SPACE_GRAPH) {
    SpaceGraph *sipo = reinterpret_cast<SpaceGraph *>(space_link);
    bool use_normalization = (sipo->flag & SIPO_NORMALIZE) != 0;
    bool freeze_normalization = (sipo->flag & SIPO_NORMALIZE_FREEZE) != 0;
    return use_normalization ? (ANIM_UNITCONV_NORMALIZE |
                                (freeze_normalization ? ANIM_UNITCONV_NORMALIZE_FREEZE : 0)) :
                               0;
  }
 
  return 0;
}
 
static void fcurve_scene_coord_range_get(Scene *scene,
                                         const FCurve *fcu,
                                         float *r_min_coord,
                                         float *r_max_coord)
{
  float min_coord = FLT_MAX;
  float max_coord = -FLT_MAX;
  const bool use_preview_only = PRVRANGEON;
 
  if (fcu->bezt || fcu->fpt) {
    int start = 0;
    int end = fcu->totvert;
 
    if (use_preview_only) {
      if (fcu->bezt) {
        /* Preview frame ranges need to be converted to bezt array indices. */
        bool replace = false;
        start = BKE_fcurve_bezt_binarysearch_index(
            fcu->bezt, scene->r.psfra, fcu->totvert, &replace);
 
        end = BKE_fcurve_bezt_binarysearch_index(
            fcu->bezt, scene->r.pefra + 1, fcu->totvert, &replace);
      }
      else if (fcu->fpt) {
        const int unclamped_start = int(scene->r.psfra - fcu->fpt[0].vec[0]);
        start = max_ii(unclamped_start, 0);
        end = min_ii(unclamped_start + (scene->r.pefra - scene->r.psfra) + 1, fcu->totvert);
      }
    }
 
    if (fcu->bezt) {
      const BezTriple *bezt = fcu->bezt + start;
      for (int i = start; i < end; i++, bezt++) {
 
        if (i == 0) {
          /* We ignore extrapolation flags and handle here, and use the
           * control point position only. so we normalize "interesting"
           * part of the curve.
           *
           * Here we handle left extrapolation.
           */
          max_coord = max_ff(max_coord, bezt->vec[1][1]);
          min_coord = min_ff(min_coord, bezt->vec[1][1]);
        }
        else {
          const BezTriple *prev_bezt = bezt - 1;
          if (!ELEM(prev_bezt->ipo, BEZT_IPO_BEZ, BEZT_IPO_BACK, BEZT_IPO_ELASTIC)) {
            /* The points on the curve will lie inside the start and end points.
             * Calculate min/max using both previous and current CV.
             */
            max_coord = max_ff(max_coord, bezt->vec[1][1]);
            min_coord = min_ff(min_coord, bezt->vec[1][1]);
            max_coord = max_ff(max_coord, prev_bezt->vec[1][1]);
            min_coord = min_ff(min_coord, prev_bezt->vec[1][1]);
          }
          else {
            const int resol = fcu->driver ?
                                  32 :
                                  min_ii(int(5.0f * len_v2v2(bezt->vec[1], prev_bezt->vec[1])),
                                         32);
            if (resol < 2) {
              max_coord = max_ff(max_coord, prev_bezt->vec[1][1]);
              min_coord = min_ff(min_coord, prev_bezt->vec[1][1]);
            }
            else {
              if (!ELEM(prev_bezt->ipo, BEZT_IPO_BACK, BEZT_IPO_ELASTIC)) {
                /* Calculate min/max using bezier forward differencing. */
                float data[120];
                float v1[2], v2[2], v3[2], v4[2];
 
                v1[0] = prev_bezt->vec[1][0];
                v1[1] = prev_bezt->vec[1][1];
                v2[0] = prev_bezt->vec[2][0];
                v2[1] = prev_bezt->vec[2][1];
 
                v3[0] = bezt->vec[0][0];
                v3[1] = bezt->vec[0][1];
                v4[0] = bezt->vec[1][0];
                v4[1] = bezt->vec[1][1];
 
                BKE_fcurve_correct_bezpart(v1, v2, v3, v4);
 
                BKE_curve_forward_diff_bezier(
                    v1[0], v2[0], v3[0], v4[0], data, resol, sizeof(float[3]));
                BKE_curve_forward_diff_bezier(
                    v1[1], v2[1], v3[1], v4[1], data + 1, resol, sizeof(float[3]));
 
                for (int j = 0; j <= resol; ++j) {
                  const float *fp = &data[j * 3];
                  max_coord = max_ff(max_coord, fp[1]);
                  min_coord = min_ff(min_coord, fp[1]);
                }
              }
              else {
                /* Calculate min/max using full fcurve evaluation.
                 * [slower than bezier forward differencing but evaluates Back/Elastic
                 * interpolation as well]. */
                float step_size = (bezt->vec[1][0] - prev_bezt->vec[1][0]) / resol;
                for (int j = 0; j <= resol; j++) {
                  float eval_time = prev_bezt->vec[1][0] + step_size * j;
                  float eval_value = evaluate_fcurve_only_curve(fcu, eval_time);
                  max_coord = max_ff(max_coord, eval_value);
                  min_coord = min_ff(min_coord, eval_value);
                }
              }
            }
          }
        }
      }
    }
    else if (fcu->fpt) {
      const FPoint *fpt = fcu->fpt + start;
      for (int i = start; i < end; ++i, ++fpt) {
        min_coord = min_ff(min_coord, fpt->vec[1]);
        max_coord = max_ff(max_coord, fpt->vec[1]);
      }
    }
  }
 
  if (r_min_coord) {
    *r_min_coord = min_coord;
  }
  if (r_max_coord) {
    *r_max_coord = max_coord;
  }
}
 
static float normalization_factor_get(Scene *scene, FCurve *fcu, short flag, float *r_offset)
{
  float factor = 1.0f, offset = 0.0f;
 
  if (flag & ANIM_UNITCONV_RESTORE) {
    if (r_offset) {
      *r_offset = fcu->prev_offset;
    }
 
    return 1.0f / fcu->prev_norm_factor;
  }
 
  if (flag & ANIM_UNITCONV_NORMALIZE_FREEZE) {
    if (r_offset) {
      *r_offset = fcu->prev_offset;
    }
    if (fcu->prev_norm_factor == 0.0f) {
      /* Happens when Auto Normalize was disabled before
       * any curves were displayed.
       */
      return 1.0f;
    }
    return fcu->prev_norm_factor;
  }
 
  if (G.moving & G_TRANSFORM_FCURVES) {
    if (r_offset) {
      *r_offset = fcu->prev_offset;
    }
    if (fcu->prev_norm_factor == 0.0f) {
      /* Same as above. */
      return 1.0f;
    }
    return fcu->prev_norm_factor;
  }
 
  fcu->prev_norm_factor = 1.0f;
 
  float max_coord = -FLT_MAX;
  float min_coord = FLT_MAX;
  fcurve_scene_coord_range_get(scene, fcu, &min_coord, &max_coord);
 
  /* We use an ULPS-based floating point comparison here, with the
   * rationale that if there are too few possible values between
   * `min_coord` and `max_coord`, then after display normalization it
   * will certainly be a weird quantized experience for the user anyway. */
  if (min_coord < max_coord && ulp_diff_ff(min_coord, max_coord) > 256) {
    /* Normalize. */
    const float range = max_coord - min_coord;
    factor = 2.0f / range;
    offset = -min_coord - range / 2.0f;
  }
  else {
    /* Skip normalization. */
    factor = 1.0f;
    offset = -min_coord;
  }
 
  BLI_assert(factor != 0.0f);
  if (r_offset) {
    *r_offset = offset;
  }
 
  fcu->prev_norm_factor = factor;
  fcu->prev_offset = offset;
  return factor;
}
 
float ANIM_unit_mapping_get_factor(Scene *scene, ID *id, FCurve *fcu, short flag, float *r_offset)
{
  if (flag & ANIM_UNITCONV_NORMALIZE) {
    return normalization_factor_get(scene, fcu, flag, r_offset);
  }
 
  if (r_offset) {
    *r_offset = 0.0f;
  }
 
  /* sanity checks */
  if (id && fcu && fcu->rna_path) {
    PointerRNA ptr;
    PropertyRNA *prop;
 
    /* get RNA property that F-Curve affects */
    PointerRNA id_ptr = RNA_id_pointer_create(id);
    if (RNA_path_resolve_property(&id_ptr, fcu->rna_path, &ptr, &prop)) {
      /* rotations: radians <-> degrees? */
      if (RNA_SUBTYPE_UNIT(RNA_property_subtype(prop)) == PROP_UNIT_ROTATION) {
        /* if the radians flag is not set, default to using degrees which need conversions */
        if ((scene) && (scene->unit.system_rotation == USER_UNIT_ROT_RADIANS) == 0) {
          if (flag & ANIM_UNITCONV_RESTORE) {
            return DEG2RADF(1.0f); /* degrees to radians */
          }
          return RAD2DEGF(1.0f); /* radians to degrees */
        }
      }
 
      /* TODO: other rotation types here as necessary */
    }
  }
 
  /* no mapping needs to occur... */
  return 1.0f;
}
 
static bool find_prev_next_keyframes(bContext *C, int *r_nextfra, int *r_prevfra)
{
  Scene *scene = CTX_data_scene(C);
  Object *ob = CTX_data_active_object(C);
  Mask *mask = CTX_data_edit_mask(C);
  bDopeSheet ads = {nullptr};
  AnimKeylist *keylist = ED_keylist_create();
  const ActKeyColumn *aknext, *akprev;
  float cfranext, cfraprev;
  bool donenext = false, doneprev = false;
  int nextcount = 0, prevcount = 0;
 
  cfranext = cfraprev = float(scene->r.cfra);
 
  /* Seed up dummy dope-sheet context with flags to perform necessary filtering. */
  if ((scene->flag & SCE_KEYS_NO_SELONLY) == 0) {
    /* only selected channels are included */
    ads.filterflag |= ADS_FILTER_ONLYSEL;
  }
 
  /* populate tree with keyframe nodes */
  scene_to_keylist(&ads, scene, keylist, 0, {-FLT_MAX, FLT_MAX});
  gpencil_to_keylist(&ads, scene->gpd, keylist, false);
 
  if (ob) {
    ob_to_keylist(&ads, ob, keylist, 0, {-FLT_MAX, FLT_MAX});
    gpencil_to_keylist(&ads, static_cast<bGPdata *>(ob->data), keylist, false);
  }
 
  if (mask) {
    MaskLayer *masklay = BKE_mask_layer_active(mask);
    mask_to_keylist(&ads, masklay, keylist);
  }
  ED_keylist_prepare_for_direct_access(keylist);
 
  /* TODO(jbakker): Key-lists are ordered, no need to do any searching at all. */
  /* find matching keyframe in the right direction */
  do {
    aknext = ED_keylist_find_next(keylist, cfranext);
 
    if (aknext) {
      if (scene->r.cfra == int(aknext->cfra)) {
        /* make this the new starting point for the search and ignore */
        cfranext = aknext->cfra;
      }
      else {
        /* this changes the frame, so set the frame and we're done */
        if (++nextcount == U.view_frame_keyframes) {
          donenext = true;
        }
      }
      cfranext = aknext->cfra;
    }
  } while ((aknext != nullptr) && (donenext == false));
 
  do {
    akprev = ED_keylist_find_prev(keylist, cfraprev);
 
    if (akprev) {
      if (scene->r.cfra == int(akprev->cfra)) {
        /* make this the new starting point for the search */
      }
      else {
        /* this changes the frame, so set the frame and we're done */
        if (++prevcount == U.view_frame_keyframes) {
          doneprev = true;
        }
      }
      cfraprev = akprev->cfra;
    }
  } while ((akprev != nullptr) && (doneprev == false));
 
  /* free temp stuff */
  ED_keylist_free(keylist);
 
  /* any success? */
  if (doneprev || donenext) {
    if (doneprev) {
      *r_prevfra = cfraprev;
    }
    else {
      *r_prevfra = scene->r.cfra - (cfranext - scene->r.cfra);
    }
 
    if (donenext) {
      *r_nextfra = cfranext;
    }
    else {
      *r_nextfra = scene->r.cfra + (scene->r.cfra - cfraprev);
    }
 
    return true;
  }
 
  return false;
}
 
void ANIM_center_frame(bContext *C, int smooth_viewtx)
{
  ARegion *region = CTX_wm_region(C);
  Scene *scene = CTX_data_scene(C);
  float w = BLI_rctf_size_x(&region->v2d.cur);
  rctf newrct;
  int nextfra, prevfra;
 
  switch (U.view_frame_type) {
    case ZOOM_FRAME_MODE_SECONDS: {
      const float fps = FPS;
      newrct.xmax = scene->r.cfra + U.view_frame_seconds * fps + 1;
      newrct.xmin = scene->r.cfra - U.view_frame_seconds * fps - 1;
      newrct.ymax = region->v2d.cur.ymax;
      newrct.ymin = region->v2d.cur.ymin;
      break;
    }
 
    /* hardest case of all, look for all keyframes around frame and display those */
    case ZOOM_FRAME_MODE_KEYFRAMES:
      if (find_prev_next_keyframes(C, &nextfra, &prevfra)) {
        newrct.xmax = nextfra;
        newrct.xmin = prevfra;
        newrct.ymax = region->v2d.cur.ymax;
        newrct.ymin = region->v2d.cur.ymin;
        break;
      }
      /* else drop through, keep range instead */
      ATTR_FALLTHROUGH;
 
    case ZOOM_FRAME_MODE_KEEP_RANGE:
    default:
      newrct.xmax = scene->r.cfra + (w / 2);
      newrct.xmin = scene->r.cfra - (w / 2);
      newrct.ymax = region->v2d.cur.ymax;
      newrct.ymin = region->v2d.cur.ymin;
      break;
  }
 
  UI_view2d_smooth_view(C, region, &newrct, smooth_viewtx);
}
/* *************************************************** */
 
rctf ANIM_frame_range_view2d_add_xmargin(const View2D &view_2d, const rctf view_rect)
{
  /* Keyframe diamonds seem to be drawn at 10 pixels wide, multiplied by the UI scale. */
  const float keyframe_size = 10 * UI_SCALE_FAC;
  const float margin_in_px = 4 * keyframe_size;
 
  /* This cannot use UI_view2d_scale_get_x(view_2d) because that would use the
   * current scale of the view, and not the one we'd get once `view_rect` is
   * applied. And this function should not assume that view_2d.cur == view_rect.
   *
   * As an added bonus, the division is inverted (compared to
   * UI_view2d_scale_get_x()) so that we can multiply with the result instead of
   * doing yet another division. */
  const float target_scale = BLI_rctf_size_x(&view_rect) / BLI_rcti_size_x(&view_2d.mask);
  const float margin_in_frames = margin_in_px * target_scale;
 
  /* Limit the margin to a maximum of 12.5% of the available size. This will
   * make the margins smaller when the view gets smaller, but for large views
   * still retain the fixed size calculated above */
  const float margin_max = 0.125f * BLI_rctf_size_x(&view_rect);
  const float margin = std::min(margin_in_frames, margin_max);
 
  rctf rect_with_margin = view_rect;
  rect_with_margin.xmin -= margin;
  rect_with_margin.xmax += margin;
 
  return rect_with_margin;
}