text: /*
   * 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) 2008 Blender Foundation.
   * All rights reserved.
   */
  
  /** \file
   * \ingroup edscr
   */
  
  #include <math.h>
  #include <string.h>
  
  #include "MEM_guardedalloc.h"
  
  #include "DNA_object_types.h"
  #include "DNA_scene_types.h"
  #include "DNA_userdef_types.h"
  #include "DNA_workspace_types.h"
  
  #include "BLI_blenlib.h"
  #include "BLI_utildefines.h"
  
  #include "BKE_context.h"
  #include "BKE_global.h"
  #include "BKE_icons.h"
  #include "BKE_image.h"
  #include "BKE_layer.h"
  #include "BKE_lib_id.h"
  #include "BKE_main.h"
  #include "BKE_scene.h"
  #include "BKE_screen.h"
  #include "BKE_sound.h"
  #include "BKE_workspace.h"
  
  #include "WM_api.h"
  #include "WM_types.h"
  
  #include "ED_clip.h"
  #include "ED_node.h"
  #include "ED_screen.h"
  #include "ED_screen_types.h"
  
  #include "UI_interface.h"
  
  #include "WM_message.h"
  
  #include "DEG_depsgraph_query.h"
  
  #include "screen_intern.h" /* own module include */
  
  /* adds no space data */
  static ScrArea *screen_addarea_ex(ScrAreaMap *area_map,
                                    ScrVert *bottom_left,
                                    ScrVert *top_left,
                                    ScrVert *top_right,
                                    ScrVert *bottom_right,
                                    short spacetype)
  {
    ScrArea *area = MEM_callocN(sizeof(ScrArea), "addscrarea");
  
    area->v1 = bottom_left;
    area->v2 = top_left;
    area->v3 = top_right;
    area->v4 = bottom_right;
    area->spacetype = spacetype;
  
    BLI_addtail(&area_map->areabase, area);
  
    return area;
  }
  static ScrArea *screen_addarea(bScreen *screen,
                                 ScrVert *left_bottom,
                                 ScrVert *left_top,
                                 ScrVert *right_top,
                                 ScrVert *right_bottom,
                                 short spacetype)
  {
    return screen_addarea_ex(
        AREAMAP_FROM_SCREEN(screen), left_bottom, left_top, right_top, right_bottom, spacetype);
  }
  
  static void screen_delarea(bContext *C, bScreen *screen, ScrArea *area)
  {
  
    ED_area_exit(C, area);
  
    BKE_screen_area_free(area);
  
    BLI_remlink(&screen->areabase, area);
    MEM_freeN(area);
  }
  
  ScrArea *area_split(
      const wmWindow *win, bScreen *screen, ScrArea *area, char dir, float fac, int merge)
  {
    ScrArea *newa = NULL;
    ScrVert *sv1, *sv2;
    short split;
    rcti window_rect;
  
    if (area == NULL) {
      return NULL;
    }
  
    WM_window_rect_calc(win, &window_rect);
  
    split = screen_geom_find_area_split_point(area, &window_rect, dir, fac);
    if (split == 0) {
      return NULL;
    }
  
    /* note regarding (fac > 0.5f) checks below.
     * normally it shouldn't matter which is used since the copy should match the original
     * however with viewport rendering and python console this isn't the case. - campbell */
  
    if (dir == 'h') {
      /* new vertices */
      sv1 = screen_geom_vertex_add(screen, area->v1->vec.x, split);
      sv2 = screen_geom_vertex_add(screen, area->v4->vec.x, split);
  
      /* new edges */
      screen_geom_edge_add(screen, area->v1, sv1);
      screen_geom_edge_add(screen, sv1, area->v2);
      screen_geom_edge_add(screen, area->v3, sv2);
      screen_geom_edge_add(screen, sv2, area->v4);
      screen_geom_edge_add(screen, sv1, sv2);
  
      if (fac > 0.5f) {
        /* new areas: top */
        newa = screen_addarea(screen, sv1, area->v2, area->v3, sv2, area->spacetype);
  
        /* area below */
        area->v2 = sv1;
        area->v3 = sv2;
      }
      else {
        /* new areas: bottom */
        newa = screen_addarea(screen, area->v1, sv1, sv2, area->v4, area->spacetype);
  
        /* area above */
        area->v1 = sv1;
        area->v4 = sv2;
      }
  
      ED_area_data_copy(newa, area, true);
    }
    else {
      /* new vertices */
      sv1 = screen_geom_vertex_add(screen, split, area->v1->vec.y);
      sv2 = screen_geom_vertex_add(screen, split, area->v2->vec.y);
  
      /* new edges */
      screen_geom_edge_add(screen, area->v1, sv1);
      screen_geom_edge_add(screen, sv1, area->v4);
      screen_geom_edge_add(screen, area->v2, sv2);
      screen_geom_edge_add(screen, sv2, area->v3);
      screen_geom_edge_add(screen, sv1, sv2);
  
      if (fac > 0.5f) {
        /* new areas: right */
        newa = screen_addarea(screen, sv1, sv2, area->v3, area->v4, area->spacetype);
  
        /* area left */
        area->v3 = sv2;
        area->v4 = sv1;
      }
      else {
        /* new areas: left */
        newa = screen_addarea(screen, area->v1, area->v2, sv2, sv1, area->spacetype);
  
        /* area right */
        area->v1 = sv1;
        area->v2 = sv2;
      }
  
      ED_area_data_copy(newa, area, true);
    }
  
    /* remove double vertices en edges */
    if (merge) {
      BKE_screen_remove_double_scrverts(screen);
    }
    BKE_screen_remove_double_scredges(screen);
    BKE_screen_remove_unused_scredges(screen);
  
    return newa;
  }
  
  /**
   * Empty screen, with 1 dummy area without spacedata. Uses window size.
   */
  bScreen *screen_add(Main *bmain, const char *name, const rcti *rect)
  {
    bScreen *screen;
    ScrVert *sv1, *sv2, *sv3, *sv4;
  
    screen = BKE_libblock_alloc(bmain, ID_SCR, name, 0);
    screen->do_refresh = true;
    screen->redraws_flag = TIME_ALL_3D_WIN | TIME_ALL_ANIM_WIN;
  
    sv1 = screen_geom_vertex_add(screen, rect->xmin, rect->ymin);
    sv2 = screen_geom_vertex_add(screen, rect->xmin, rect->ymax - 1);
    sv3 = screen_geom_vertex_add(screen, rect->xmax - 1, rect->ymax - 1);
    sv4 = screen_geom_vertex_add(screen, rect->xmax - 1, rect->ymin);
  
    screen_geom_edge_add(screen, sv1, sv2);
    screen_geom_edge_add(screen, sv2, sv3);
    screen_geom_edge_add(screen, sv3, sv4);
    screen_geom_edge_add(screen, sv4, sv1);
  
    /* dummy type, no spacedata */
    screen_addarea(screen, sv1, sv2, sv3, sv4, SPACE_EMPTY);
  
    return screen;
  }
  
  void screen_data_copy(bScreen *to, bScreen *from)
  {
    ScrVert *s1, *s2;
    ScrEdge *se;
    ScrArea *area, *saf;
  
    /* free contents of 'to', is from blenkernel screen.c */
    BKE_screen_free(to);
  
    to->flag = from->flag;
  
    BLI_duplicatelist(&to->vertbase, &from->vertbase);
    BLI_duplicatelist(&to->edgebase, &from->edgebase);
    BLI_duplicatelist(&to->areabase, &from->areabase);
    BLI_listbase_clear(&to->regionbase);
  
    s2 = to->vertbase.first;
    for (s1 = from->vertbase.first; s1; s1 = s1->next, s2 = s2->next) {
      s1->newv = s2;
    }
  
    for (se = to->edgebase.first; se; se = se->next) {
      se->v1 = se->v1->newv;
      se->v2 = se->v2->newv;
      BKE_screen_sort_scrvert(&(se->v1), &(se->v2));
    }
  
    saf = from->areabase.first;
    for (area = to->areabase.first; area; area = area->next, saf = saf->next) {
      area->v1 = area->v1->newv;
      area->v2 = area->v2->newv;
      area->v3 = area->v3->newv;
      area->v4 = area->v4->newv;
  
      BLI_listbase_clear(&area->spacedata);
      BLI_listbase_clear(&area->regionbase);
      BLI_listbase_clear(&area->actionzones);
      BLI_listbase_clear(&area->handlers);
  
      ED_area_data_copy(area, saf, true);
    }
  
    /* put at zero (needed?) */
    for (s1 = from->vertbase.first; s1; s1 = s1->next) {
      s1->newv = NULL;
    }
  }
  
  /**
   * Prepare a newly created screen for initializing it as active screen.
   */
  void screen_new_activate_prepare(const wmWindow *win, bScreen *screen_new)
  {
    screen_new->winid = win->winid;
    screen_new->do_refresh = true;
    screen_new->do_draw = true;
  }
  
  /* with area as center, sb is located at: 0=W, 1=N, 2=E, 3=S */
  /* -1 = not valid check */
  /* used with join operator */
  int area_getorientation(ScrArea *area, ScrArea *sb)
  {
    if (area == NULL || sb == NULL) {
      return -1;
    }
  
    ScrVert *saBL = area->v1;
    ScrVert *saTL = area->v2;
    ScrVert *saTR = area->v3;
    ScrVert *saBR = area->v4;
  
    ScrVert *sbBL = sb->v1;
    ScrVert *sbTL = sb->v2;
    ScrVert *sbTR = sb->v3;
    ScrVert *sbBR = sb->v4;
  
    int tolerance = U.pixelsize * 4;
  
    if (saBL->vec.x == sbBR->vec.x && saTL->vec.x == sbTR->vec.x) { /* area to right of sb = W */
      if ((abs(saBL->vec.y - sbBR->vec.y) <= tolerance) &&
          (abs(saTL->vec.y - sbTR->vec.y) <= tolerance)) {
        return 0;
      }
    }
    else if (saTL->vec.y == sbBL->vec.y &&
             saTR->vec.y == sbBR->vec.y) { /* area to bottom of sb = N */
      if ((abs(saTL->vec.x - sbBL->vec.x) <= tolerance) &&
          (abs(saTR->vec.x - sbBR->vec.x) <= tolerance)) {
        return 1;
      }
    }
    else if (saTR->vec.x == sbTL->vec.x && saBR->vec.x == sbBL->vec.x) { /* area to left of sb = E */
      if ((abs(saTR->vec.y - sbTL->vec.y) <= tolerance) &&
          (abs(saBR->vec.y - sbBL->vec.y) <= tolerance)) {
        return 2;
      }
    }
    else if (saBL->vec.y == sbTL->vec.y && saBR->vec.y == sbTR->vec.y) { /* area on top of sb = S*/
      if ((abs(saBL->vec.x - sbTL->vec.x) <= tolerance) &&
          (abs(saBR->vec.x - sbTR->vec.x) <= tolerance)) {
        return 3;
      }
    }
  
    return -1;
  }
  
  /* Helper function to join 2 areas, it has a return value, 0=failed 1=success
   * used by the split, join operators
   */
  int screen_area_join(bContext *C, bScreen *screen, ScrArea *sa1, ScrArea *sa2)
  {
    int dir = area_getorientation(sa1, sa2);
  
    if (dir == -1) {
      return 0;
    }
  
    /* Align areas if they are not. Do sanity checking before getting here. */
  
    if (dir == 0 || dir == 2) {
      /* horizontal join, so vertically align source vert to target */
      sa2->v1->vec.y = sa1->v1->vec.y; /* vertical align sa1 BL */
      sa2->v2->vec.y = sa1->v2->vec.y; /* vertical align sa1 TL */
      sa2->v3->vec.y = sa1->v3->vec.y; /* vertical align sa1 TR */
      sa2->v4->vec.y = sa1->v4->vec.y; /* vertical align sa1 BR */
    }
    else {
      /* vertical join, so horizontally align source verts to target */
      sa2->v1->vec.x = sa1->v1->vec.x; /* vertical align sa1 BL */
      sa2->v2->vec.x = sa1->v2->vec.x; /* vertical align sa1 TL */
      sa2->v3->vec.x = sa1->v3->vec.x; /* vertical align sa1 TR */
      sa2->v4->vec.x = sa1->v4->vec.x; /* vertical align sa1 BR */
    }
  
    if (dir == 0) {      /* sa1 to right of sa2 = W */
      sa1->v1 = sa2->v1; /* BL */
      sa1->v2 = sa2->v2; /* TL */
      screen_geom_edge_add(screen, sa1->v2, sa1->v3);
      screen_geom_edge_add(screen, sa1->v1, sa1->v4);
    }
    else if (dir == 1) { /* sa1 to bottom of sa2 = N */
      sa1->v2 = sa2->v2; /* TL */
      sa1->v3 = sa2->v3; /* TR */
      screen_geom_edge_add(screen, sa1->v1, sa1->v2);
      screen_geom_edge_add(screen, sa1->v3, sa1->v4);
    }
    else if (dir == 2) { /* sa1 to left of sa2 = E */
      sa1->v3 = sa2->v3; /* TR */
      sa1->v4 = sa2->v4; /* BR */
      screen_geom_edge_add(screen, sa1->v2, sa1->v3);
      screen_geom_edge_add(screen, sa1->v1, sa1->v4);
    }
    else if (dir == 3) { /* sa1 on top of sa2 = S */
      sa1->v1 = sa2->v1; /* BL */
      sa1->v4 = sa2->v4; /* BR */
      screen_geom_edge_add(screen, sa1->v1, sa1->v2);
      screen_geom_edge_add(screen, sa1->v3, sa1->v4);
    }
  
    screen_delarea(C, screen, sa2);
    BKE_screen_remove_double_scrverts(screen);
    /* Update preview thumbnail */
    BKE_icon_changed(screen->id.icon_id);
  
    return 1;
  }
  
  /* ****************** EXPORTED API TO OTHER MODULES *************************** */
  
  /* screen sets cursor based on active region */
  static void region_cursor_set_ex(wmWindow *win, ScrArea *area, ARegion *region, bool swin_changed)
  {
    BLI_assert(WM_window_get_active_screen(win)->active_region == region);
    if (win->tag_cursor_refresh || swin_changed || (region->type && region->type->event_cursor)) {
      win->tag_cursor_refresh = false;
      ED_region_cursor_set(win, area, region);
    }
  }
  
  static void region_cursor_set(wmWindow *win, bool swin_changed)
  {
    bScreen *screen = WM_window_get_active_screen(win);
  
    ED_screen_areas_iter (win, screen, area) {
      LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
        if (region == screen->active_region) {
          region_cursor_set_ex(win, area, region, swin_changed);
          return;
        }
      }
    }
  }
  
  void ED_screen_do_listen(bContext *C, wmNotifier *note)
  {
    wmWindow *win = CTX_wm_window(C);
    bScreen *screen = CTX_wm_screen(C);
  
    /* generic notes */
    switch (note->category) {
      case NC_WM:
        if (note->data == ND_FILEREAD) {
          screen->do_draw = true;
        }
        break;
      case NC_WINDOW:
        screen->do_draw = true;
        break;
      case NC_SCREEN:
        if (note->action == NA_EDITED) {
          screen->do_draw = screen->do_refresh = true;
        }
        break;
      case NC_SCENE:
        if (note->data == ND_MODE) {
          region_cursor_set(win, true);
        }
        break;
    }
  }
  
  /* make this screen usable */
  /* for file read and first use, for scaling window, area moves */
  void ED_screen_refresh(wmWindowManager *wm, wmWindow *win)
  {
    bScreen *screen = WM_window_get_active_screen(win);
  
    /* exception for bg mode, we only need the screen context */
    if (!G.background) {
      /* header size depends on DPI, let's verify */
      WM_window_set_dpi(win);
  
      ED_screen_global_areas_refresh(win);
  
      screen_geom_vertices_scale(win, screen);
  
      ED_screen_areas_iter (win, screen, area) {
        /* set spacetype and region callbacks, calls init() */
        /* sets subwindows for regions, adds handlers */
        ED_area_initialize(wm, win, area);
      }
  
      /* wake up animtimer */
      if (screen->animtimer) {
        WM_event_timer_sleep(wm, win, screen->animtimer, false);
      }
    }
  
    if (G.debug & G_DEBUG_EVENTS) {
      printf("%s: set screen\n", __func__);
    }
    screen->do_refresh = false;
    /* prevent multiwin errors */
    screen->winid = win->winid;
  
    screen->context = ed_screen_context;
  }
  
  /* file read, set all screens, ... */
  void ED_screens_initialize(Main *bmain, wmWindowManager *wm)
  {
    wmWindow *win;
  
    for (win = wm->windows.first; win; win = win->next) {
      if (BKE_workspace_active_get(win->workspace_hook) == NULL) {
        BKE_workspace_active_set(win->workspace_hook, bmain->workspaces.first);
      }
  
      ED_screen_refresh(wm, win);
      if (win->eventstate) {
        ED_screen_set_active_region(NULL, win, &win->eventstate->x);
      }
    }
  
    if (U.uiflag & USER_HEADER_FROM_PREF) {
      for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
        BKE_screen_header_alignment_reset(screen);
      }
    }
  }
  
  void ED_screen_ensure_updated(wmWindowManager *wm, wmWindow *win, bScreen *screen)
  {
    if (screen->do_refresh) {
      ED_screen_refresh(wm, win);
    }
  }
  
  /**
   * Utility to exit and free an area-region. Screen level regions (menus/popups) need to be treated
   * slightly differently, see #ui_region_temp_remove().
   */
  void ED_region_remove(bContext *C, ScrArea *area, ARegion *region)
  {
    ED_region_exit(C, region);
    BKE_area_region_free(area->type, region);
    BLI_freelinkN(&area->regionbase, region);
  }
  
  /* *********** exit calls are for closing running stuff ******** */
  
  void ED_region_exit(bContext *C, ARegion *region)
  {
    wmWindowManager *wm = CTX_wm_manager(C);
    wmWindow *win = CTX_wm_window(C);
    ARegion *prevar = CTX_wm_region(C);
  
    if (region->type && region->type->exit) {
      region->type->exit(wm, region);
    }
  
    CTX_wm_region_set(C, region);
  
    WM_event_remove_handlers(C, &region->handlers);
    WM_event_modal_handler_region_replace(win, region, NULL);
    WM_draw_region_free(region, true);
  
    if (region->headerstr) {
      MEM_freeN(region->headerstr);
      region->headerstr = NULL;
    }
  
    if (region->regiontimer) {
      WM_event_remove_timer(wm, win, region->regiontimer);
      region->regiontimer = NULL;
    }
  
    WM_msgbus_clear_by_owner(wm->message_bus, region);
  
    CTX_wm_region_set(C, prevar);
  }
  
  void ED_area_exit(bContext *C, ScrArea *area)
  {
    wmWindowManager *wm = CTX_wm_manager(C);
    wmWindow *win = CTX_wm_window(C);
    ScrArea *prevsa = CTX_wm_area(C);
    ARegion *region;
  
    if (area->type && area->type->exit) {
      area->type->exit(wm, area);
    }
  
    CTX_wm_area_set(C, area);
  
    for (region = area->regionbase.first; region; region = region->next) {
      ED_region_exit(C, region);
    }
  
    WM_event_remove_handlers(C, &area->handlers);
    WM_event_modal_handler_area_replace(win, area, NULL);
  
    CTX_wm_area_set(C, prevsa);
  }
  
  void ED_screen_exit(bContext *C, wmWindow *window, bScreen *screen)
  {
    wmWindowManager *wm = CTX_wm_manager(C);
    wmWindow *prevwin = CTX_wm_window(C);
  
    CTX_wm_window_set(C, window);
  
    if (screen->animtimer) {
      WM_event_remove_timer(wm, window, screen->animtimer);
  
      Depsgraph *depsgraph = CTX_data_depsgraph_pointer(C);
      Scene *scene = WM_window_get_active_scene(prevwin);
      Scene *scene_eval = (Scene *)DEG_get_evaluated_id(depsgraph, &scene->id);
      BKE_sound_stop_scene(scene_eval);
    }
    screen->animtimer = NULL;
    screen->scrubbing = false;
  
    screen->active_region = NULL;
  
    LISTBASE_FOREACH (ARegion *, region, &screen->regionbase) {
      ED_region_exit(C, region);
    }
    LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
      ED_area_exit(C, area);
    }
    /* Don't use ED_screen_areas_iter here, it skips hidden areas. */
    LISTBASE_FOREACH (ScrArea *, area, &window->global_areas.areabase) {
      ED_area_exit(C, area);
    }
  
    /* mark it available for use for other windows */
    screen->winid = 0;
  
    if (!WM_window_is_temp_screen(prevwin)) {
      /* use previous window if possible */
      CTX_wm_window_set(C, prevwin);
    }
    else {
      /* none otherwise */
      CTX_wm_window_set(C, NULL);
    }
  }
  
  /* *********************************** */
  
  /* case when on area-edge or in azones, or outside window */
  static void screen_cursor_set(wmWindow *win, const int xy[2])
  {
    const bScreen *screen = WM_window_get_active_screen(win);
    AZone *az = NULL;
    ScrArea *area;
  
    for (area = screen->areabase.first; area; area = area->next) {
      if ((az = ED_area_actionzone_find_xy(area, xy))) {
        break;
      }
    }
  
    if (area) {
      if (az->type == AZONE_AREA) {
        WM_cursor_set(win, WM_CURSOR_EDIT);
      }
      else if (az->type == AZONE_REGION) {
        if (az->edge == AE_LEFT_TO_TOPRIGHT || az->edge == AE_RIGHT_TO_TOPLEFT) {
          WM_cursor_set(win, WM_CURSOR_X_MOVE);
        }
        else {
          WM_cursor_set(win, WM_CURSOR_Y_MOVE);
        }
      }
    }
    else {
      ScrEdge *actedge = screen_geom_find_active_scredge(win, screen, xy[0], xy[1]);
  
      if (actedge) {
        if (screen_geom_edge_is_horizontal(actedge)) {
          WM_cursor_set(win, WM_CURSOR_Y_MOVE);
        }
        else {
          WM_cursor_set(win, WM_CURSOR_X_MOVE);
        }
      }
      else {
        WM_cursor_set(win, WM_CURSOR_DEFAULT);
      }
    }
  }
  
  /**
   * Called in wm_event_system.c. sets state vars in screen, cursors.
   * event type is mouse move.
   */
  void ED_screen_set_active_region(bContext *C, wmWindow *win, const int xy[2])
  {
    bScreen *screen = WM_window_get_active_screen(win);
    if (screen == NULL) {
      return;
    }
  
    ScrArea *area = NULL;
    ARegion *region;
    ARegion *region_prev = screen->active_region;
  
    ED_screen_areas_iter (win, screen, area_iter) {
      if (xy[0] > area_iter->totrct.xmin && xy[0] < area_iter->totrct.xmax) {
        if (xy[1] > area_iter->totrct.ymin && xy[1] < area_iter->totrct.ymax) {
          if (ED_area_azones_update(area_iter, xy) == NULL) {
            area = area_iter;
            break;
          }
        }
      }
    }
    if (area) {
      /* Make overlap active when mouse over. */
      for (region = area->regionbase.first; region; region = region->next) {
        if (ED_region_contains_xy(region, xy)) {
          screen->active_region = region;
          break;
        }
      }
    }
    else {
      screen->active_region = NULL;
    }
  
    /* Check for redraw headers. */
    if (region_prev != screen->active_region) {
  
      ED_screen_areas_iter (win, screen, area_iter) {
        bool do_draw = false;
  
        for (region = area_iter->regionbase.first; region; region = region->next) {
  
          /* Call old area's deactivate if assigned. */
          if (region == region_prev && area_iter->type->deactivate) {
            area_iter->type->deactivate(area_iter);
          }
  
          if (region == region_prev && region != screen->active_region) {
            wmGizmoMap *gzmap = region_prev->gizmo_map;
            if (gzmap) {
              if (WM_gizmo_highlight_set(gzmap, NULL)) {
                ED_region_tag_redraw_no_rebuild(region_prev);
              }
            }
          }
  
          if (region == region_prev || region == screen->active_region) {
            do_draw = true;
          }
        }
  
        if (do_draw) {
          for (region = area_iter->regionbase.first; region; region = region->next) {
            if (ELEM(region->regiontype, RGN_TYPE_HEADER, RGN_TYPE_TOOL_HEADER)) {
              ED_region_tag_redraw_no_rebuild(region);
            }
          }
        }
      }
    }
  
    /* Cursors, for time being set always on edges,
     * otherwise the active region doesn't switch. */
    if (screen->active_region == NULL) {
      screen_cursor_set(win, xy);
    }
    else {
      /* Notifier invokes freeing the buttons... causing a bit too much redraws. */
      region_cursor_set_ex(win, area, screen->active_region, region_prev != screen->active_region);
  
      if (region_prev != screen->active_region) {
        /* This used to be a notifier, but needs to be done immediate
         * because it can undo setting the right button as active due
         * to delayed notifier handling. */
        if (C) {
          UI_screen_free_active_but(C, screen);
        }
      }
    }
  }
  
  int ED_screen_area_active(const bContext *C)
  {
    wmWindow *win = CTX_wm_window(C);
    bScreen *screen = CTX_wm_screen(C);
    ScrArea *area = CTX_wm_area(C);
  
    if (win && screen && area) {
      AZone *az = ED_area_actionzone_find_xy(area, &win->eventstate->x);
      ARegion *region;
  
      if (az && az->type == AZONE_REGION) {
        return 1;
      }
  
      for (region = area->regionbase.first; region; region = region->next) {
        if (region == screen->active_region) {
          return 1;
        }
      }
    }
    return 0;
  }
  
  /**
   * Add an area and geometry (screen-edges and -vertices) for it to \a area_map,
   * with coordinates/dimensions matching \a rect.
   */
  static ScrArea *screen_area_create_with_geometry(ScrAreaMap *area_map,
                                                   const rcti *rect,
                                                   short spacetype)
  {
    ScrVert *bottom_left = screen_geom_vertex_add_ex(area_map, rect->xmin, rect->ymin);
    ScrVert *top_left = screen_geom_vertex_add_ex(area_map, rect->xmin, rect->ymax);
    ScrVert *top_right = screen_geom_vertex_add_ex(area_map, rect->xmax, rect->ymax);
    ScrVert *bottom_right = screen_geom_vertex_add_ex(area_map, rect->xmax, rect->ymin);
  
    screen_geom_edge_add_ex(area_map, bottom_left, top_left);
    screen_geom_edge_add_ex(area_map, top_left, top_right);
    screen_geom_edge_add_ex(area_map, top_right, bottom_right);
    screen_geom_edge_add_ex(area_map, bottom_right, bottom_left);
  
    return screen_addarea_ex(area_map, bottom_left, top_left, top_right, bottom_right, spacetype);
  }
  
  static void screen_area_set_geometry_rect(ScrArea *area, const rcti *rect)
  {
    area->v1->vec.x = rect->xmin;
    area->v1->vec.y = rect->ymin;
    area->v2->vec.x = rect->xmin;
    area->v2->vec.y = rect->ymax;
    area->v3->vec.x = rect->xmax;
    area->v3->vec.y = rect->ymax;
    area->v4->vec.x = rect->xmax;
    area->v4->vec.y = rect->ymin;
  }
  
  static void screen_global_area_refresh(wmWindow *win,
                                         bScreen *screen,
                                         eSpace_Type space_type,
                                         GlobalAreaAlign align,
                                         const rcti *rect,
                                         const short height_cur,
                                         const short height_min,
                                         const short height_max)
  {
    ScrArea *area;
  
    for (area = win->global_areas.areabase.first; area; area = area->next) {
      if (area->spacetype == space_type) {
        break;
      }
    }
  
    if (area) {
      screen_area_set_geometry_rect(area, rect);
    }
    else {
      area = screen_area_create_with_geometry(&win->global_areas, rect, space_type);
      SpaceType *stype = BKE_spacetype_from_id(space_type);
      SpaceLink *slink = stype->new (area, WM_window_get_active_scene(win));
  
      area->regionbase = slink->regionbase;
  
      BLI_addhead(&area->spacedata, slink);
      BLI_listbase_clear(&slink->regionbase);
  
      /* Data specific to global areas. */
      area->global = MEM_callocN(sizeof(*area->global), __func__);
      area->global->size_max = height_max;
      area->global->size_min = height_min;
      area->global->align = align;
    }
  
    if (area->global->cur_fixed_height != height_cur) {
      /* Refresh layout if size changes. */
      area->global->cur_fixed_height = height_cur;
      screen->do_refresh = true;
    }
  }
  
  static int screen_global_header_size(void)
  {
    return (int)ceilf(ED_area_headersize() / UI_DPI_FAC);
  }
  
  static void screen_global_topbar_area_refresh(wmWindow *win, bScreen *screen)
  {
    const short size = screen_global_header_size();
    rcti rect;
  
    BLI_rcti_init(&rect, 0, WM_window_pixels_x(win) - 1, 0, WM_window_pixels_y(win) - 1);
    rect.ymin = rect.ymax - size;
  
    screen_global_area_refresh(
        win, screen, SPACE_TOPBAR, GLOBAL_AREA_ALIGN_TOP, &rect, size, size, size);
  }
  
  static void screen_global_statusbar_area_refresh(wmWindow *win, bScreen *screen)
  {
    const short size_min = 1;
    const short size_max = 0.8f * screen_global_header_size();
    const short size = (screen->flag & SCREEN_COLLAPSE_STATUSBAR) ? size_min : size_max;
    rcti rect;
  
    BLI_rcti_init(&rect, 0, WM_window_pixels_x(win) - 1, 0, WM_window_pixels_y(win) - 1);
    rect.ymax = rect.ymin + size_max;
  
    screen_global_area_refresh(
        win, screen, SPACE_STATUSBAR, GLOBAL_AREA_ALIGN_BOTTOM, &rect, size, size_min, size_max);
  }
  
  void ED_screen_global_areas_sync(wmWindow *win)
  {
    /* Update screen flags from height in window, this is weak and perhaps
     * global areas should just become part of the screen instead. */
    bScreen *screen = BKE_workspace_active_screen_get(win->workspace_hook);
  
    screen->flag &= ~SCREEN_COLLAPSE_STATUSBAR;
  
    LISTBASE_FOREACH (ScrArea *, area, &win->global_areas.areabase) {
      if (area->global->cur_fixed_height == area->global->size_min) {
        if (area->spacetype == SPACE_STATUSBAR) {
          screen->flag |= SCREEN_COLLAPSE_STATUSBAR;
        }
      }
    }
  }
  
  void ED_screen_global_areas_refresh(wmWindow *win)
  {
    /* Don't create global area for child and temporary windows. */
    bScreen *screen = BKE_workspace_active_screen_get(win->workspace_hook);
    if ((win->parent != NULL) || screen->temp) {
      if (win->global_areas.areabase.first) {
        screen->do_refresh = true;
        BKE_screen_area_map_free(&win->global_areas);
      }
      return;
    }
  
    screen_global_topbar_area_refresh(win, screen);
    screen_global_statusbar_area_refresh(win, screen);
  }
  
  /* -------------------------------------------------------------------- */
  /* Screen changing */
  
  static bScreen *screen_fullscreen_find_associated_normal_screen(const Main *bmain, bScreen *screen)
  {
    for (bScreen *screen_iter = bmain->screens.first; screen_iter;
         screen_iter = screen_iter->id.next) {
      if ((screen_iter != screen) && ELEM(screen_iter->state, SCREENMAXIMIZED, SCREENFULL)) {
        ScrArea *area = screen_iter->areabase.first;
        if (area && area->full == screen) {
          return screen_iter;
        }
      }
    }
  
    return screen;
  }
  
  /**
   * \return the screen to activate.
   * \warning The returned screen may not always equal \a screen_new!
   */
  bScreen *screen_change_prepare(
      bScreen *screen_old, bScreen *screen_new, Main *bmain, bContext *C, wmWindow *win)
  {
    /* validate screen, it's called with notifier reference */
    if (BLI_findindex(&bmain->screens, screen_new) == -1) {
      return NULL;
    }
  
    screen_new = screen_fullscreen_find_associated_normal_screen(bmain, screen_new);
  
    /* check for valid winid */
    if (!(screen_new->winid == 0 || screen_new->winid == win->winid)) {
      return NULL;
    }
  
    if (screen_old != screen_new) {
      wmTimer *wt = screen_old->animtimer;
  
      /* remove handlers referencing areas in old screen */
      LISTBASE_FOREACH (ScrArea *, area, &screen_old->areabase) {
        WM_event_remove_area_handler(&win->modalhandlers, area);
      }
  
      /* we put timer to sleep, so screen_exit has to think there's no timer */
      screen_old->animtimer = NULL;
      if (wt) {
        WM_event_timer_sleep(CTX_wm_manager(C), win, wt, true);
      }
      ED_screen_exit(C, win, screen_old);
  
      /* Same scene, "transfer" playback to new screen. */
      if (wt) {
        screen_new->animtimer = wt;
      }
  
      return screen_new;
    }
  
    return NULL;
  }
  
  void screen_change_update(bContext *C, wmWindow *win, bScreen *screen)
  {
    Scene *scene = WM_window_get_active_scene(win);
    WorkSpace *workspace = BKE_workspace_active_get(win->workspace_hook);
    WorkSpaceLayout *layout = BKE_workspace_layout_find(workspace, screen);
  
    CTX_wm_window_set(C, win); /* stores C->wm.screen... hrmf */
  
    ED_screen_refresh(CTX_wm_manager(C), win);
  
    BKE_screen_view3d_scene_sync(screen, scene); /* sync new screen with scene data */
    WM_event_add_notifier(C, NC_WINDOW, NULL);
    WM_event_add_notifier(C, NC_SCREEN | ND_LAYOUTSET, layout);
  
    /* makes button hilites work */
    WM_event_add_mousemove(win);
  }
  
  /**
   * \brief Change the active screen.
   *
   * Operator call, WM + Window + screen already existed before
   *
   * \warning Do NOT call in area/region queues!
   * \returns if screen changing was successful.
   */
  bool ED_screen_change(bContext *C, bScreen *screen)
  {
    Main *bmain = CTX_data_main(C);
    wmWindow *win = CTX_wm_window(C);
    bScreen *screen_old = CTX_wm_screen(C);
    bScreen *screen_new = screen_change_prepare(screen_old, screen, bmain, C, win);
  
    if (screen_new) {
      WorkSpace *workspace = BKE_workspace_active_get(win->workspace_hook);
      WM_window_set_active_screen(win, workspace, screen);
      screen_change_update(C, win, screen_new);
  
      return true;
    }
  
    return false;
  }
  
  static void screen_set_3dview_camera(Scene *scene,
                                       ViewLayer *view_layer,
                                       ScrArea *area,
                                       View3D *v3d)
  {
    /* fix any cameras that are used in the 3d view but not in the scene */
    BKE_screen_view3d_sync(v3d, scene);
  
    if (!v3d->camera || !BKE_view_layer_base_find(view_layer, v3d->camera)) {
      v3d->camera = BKE_view_layer_camera_find(view_layer);
      // XXX if (screen == curscreen) handle_view3d_lock();
      if (!v3d->camera) {
        ARegion *region;
        ListBase *regionbase;
  
        /* regionbase is in different place depending if space is active */
        if (v3d == area->spacedata.first) {
          regionbase = &area->regionbase;
        }
        else {
          regionbase = &v3d->regionbase;
        }
  
        for (region = regionbase->first; region; region = region->next) {
          if (region->regiontype == RGN_TYPE_WINDOW) {
            RegionView3D *rv3d = region->regiondata;
            if (rv3d->persp == RV3D_CAMOB) {
              rv3d->persp = RV3D_PERSP;
            }
          }
        }
      }
    }
  }
  
  void ED_screen_scene_change(bContext *C, wmWindow *win, Scene *scene)
  {
  #if 0
    ViewLayer *view_layer_old = WM_window_get_active_view_layer(win);
  #endif
  
    /* Switch scene. */
    win->scene = scene;
    if (CTX_wm_window(C) == win) {
      CTX_data_scene_set(C, scene);
    }
  
    /* Ensure the view layer name is updated. */
    WM_window_ensure_active_view_layer(win);
    ViewLayer *view_layer = WM_window_get_active_view_layer(win);
  
  #if 0
    /* Mode Syncing. */
    if (view_layer_old) {
      WorkSpace *workspace = CTX_wm_workspace(C);
      Object *obact_new = OBACT(view_layer);
      UNUSED_VARS(obact_new);
      eObjectMode object_mode_old = workspace->object_mode;
      Object *obact_old = OBACT(view_layer_old);
      UNUSED_VARS(obact_old, object_mode_old);
    }
  #endif
  
    /* Update 3D view cameras. */
    const bScreen *screen = WM_window_get_active_screen(win);
    LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
      LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
        if (sl->spacetype == SPACE_VIEW3D) {
          View3D *v3d = (View3D *)sl;
          screen_set_3dview_camera(scene, view_layer, area, v3d);
        }
      }
    }
  }
  
  ScrArea *ED_screen_full_newspace(bContext *C, ScrArea *area, int type)
  {
    wmWindow *win = CTX_wm_window(C);
    ScrArea *newsa = NULL;
    SpaceLink *newsl;
  
    if (!area || area->full == NULL) {
      newsa = ED_screen_state_toggle(C, win, area, SCREENMAXIMIZED);
    }
  
    if (!newsa) {
      newsa = area;
    }
  
    BLI_assert(newsa);
    newsl = newsa->spacedata.first;
  
    /* Tag the active space before changing, so we can identify it when user wants to go back. */
    if ((newsl->link_flag & SPACE_FLAG_TYPE_TEMPORARY) == 0) {
      newsl->link_flag |= SPACE_FLAG_TYPE_WAS_ACTIVE;
    }
  
    ED_area_newspace(C, newsa, type, newsl->link_flag & SPACE_FLAG_TYPE_TEMPORARY);
  
    return newsa;
  }
  
  /**
   * \a was_prev_temp for the case previous space was a temporary fullscreen as well
   */
  void ED_screen_full_prevspace(bContext *C, ScrArea *area)
  {
    BLI_assert(area->full);
  
    if (area->flag & AREA_FLAG_STACKED_FULLSCREEN) {
      /* stacked fullscreen -> only go back to previous area and don't toggle out of fullscreen */
      ED_area_prevspace(C, area);
    }
    else {
      ED_screen_restore_temp_type(C, area);
    }
  }
  
  void ED_screen_restore_temp_type(bContext *C, ScrArea *area)
  {
    SpaceLink *sl = area->spacedata.first;
  
    /* In case nether functions below run. */
    ED_area_tag_redraw(area);
  
    if (sl->link_flag & SPACE_FLAG_TYPE_TEMPORARY) {
      ED_area_prevspace(C, area);
    }
  
    if (area->full) {
      ED_screen_state_toggle(C, CTX_wm_window(C), area, SCREENMAXIMIZED);
    }
  }
  
  /* restore a screen / area back to default operation, after temp fullscreen modes */
  void ED_screen_full_restore(bContext *C, ScrArea *area)
  {
    wmWindow *win = CTX_wm_window(C);
    SpaceLink *sl = area->spacedata.first;
    bScreen *screen = CTX_wm_screen(C);
    short state = (screen ? screen->state : SCREENMAXIMIZED);
  
    /* if fullscreen area has a temporary space (such as a file browser or fullscreen render
     * overlaid on top of an existing setup) then return to the previous space */
  
    if (sl->next) {
      if (sl->link_flag & SPACE_FLAG_TYPE_TEMPORARY) {
        ED_screen_full_prevspace(C, area);
      }
      else {
        ED_screen_state_toggle(C, win, area, state);
      }
      /* warning: 'area' may be freed */
    }
    /* otherwise just tile the area again */
    else {
      ED_screen_state_toggle(C, win, area, state);
    }
  }
  
  /**
   * this function toggles: if area is maximized/full then the parent will be restored
   *
   * \warning \a area may be freed.
   */
  ScrArea *ED_screen_state_toggle(bContext *C, wmWindow *win, ScrArea *area, const short state)
  {
    Main *bmain = CTX_data_main(C);
    wmWindowManager *wm = CTX_wm_manager(C);
    WorkSpace *workspace = WM_window_get_active_workspace(win);
    bScreen *screen, *oldscreen;
    ARegion *region;
  
    if (area) {
      /* ensure we don't have a button active anymore, can crash when
       * switching screens with tooltip open because region and tooltip
       * are no longer in the same screen */
      for (region = area->regionbase.first; region; region = region->next) {
        UI_blocklist_free(C, &region->uiblocks);
  
        if (region->regiontimer) {
          WM_event_remove_timer(wm, NULL, region->regiontimer);
          region->regiontimer = NULL;
        }
      }
  
      /* prevent hanging status prints */
      ED_area_status_text(area, NULL);
      ED_workspace_status_text(C, NULL);
    }
  
    if (area && area->full) {
      WorkSpaceLayout *layout_old = WM_window_get_active_layout(win);
      /* restoring back to SCREENNORMAL */
      screen = area->full;                          /* the old screen to restore */
      oldscreen = WM_window_get_active_screen(win); /* the one disappearing */
  
      BLI_assert(BKE_workspace_layout_screen_get(layout_old) != screen);
      BLI_assert(BKE_workspace_layout_screen_get(layout_old)->state != SCREENNORMAL);
  
      screen->state = SCREENNORMAL;
      screen->flag = oldscreen->flag;
  
      /* find old area to restore from */
      ScrArea *fullsa = NULL;
      LISTBASE_FOREACH (ScrArea *, old, &screen->areabase) {
        /* area to restore from is always first */
        if (old->full && !fullsa) {
          fullsa = old;
        }
  
        /* clear full screen state */
        old->full = NULL;
      }
  
      area->full = NULL;
  
      if (fullsa == NULL) {
        if (G.debug & G_DEBUG) {
          printf("%s: something wrong in areafullscreen\n", __func__);
        }
        return NULL;
      }
  
      if (state == SCREENFULL) {
        /* unhide global areas */
        LISTBASE_FOREACH (ScrArea *, glob_area, &win->global_areas.areabase) {
          glob_area->global->flag &= ~GLOBAL_AREA_IS_HIDDEN;
        }
        /* restore the old side panels/header visibility */
        for (region = area->regionbase.first; region; region = region->next) {
          region->flag = region->flagfullscreen;
        }
      }
  
      ED_area_data_swap(fullsa, area);
  
      /* animtimer back */
      screen->animtimer = oldscreen->animtimer;
      oldscreen->animtimer = NULL;
  
      ED_screen_change(C, screen);
      ED_area_tag_refresh(fullsa);
  
      BKE_workspace_layout_remove(CTX_data_main(C), workspace, layout_old);
  
      /* After we've restored back to SCREENNORMAL, we have to wait with
       * screen handling as it uses the area coords which aren't updated yet.
       * Without doing so, the screen handling gets wrong area coords,
       * which in worst case can lead to crashes (see T43139) */
      screen->skip_handling = true;
    }
    else {
      /* change from SCREENNORMAL to new state */
      WorkSpaceLayout *layout_new;
      ScrArea *newa;
      char newname[MAX_ID_NAME - 2];
  
      BLI_assert(ELEM(state, SCREENMAXIMIZED, SCREENFULL));
  
      oldscreen = WM_window_get_active_screen(win);
  
      oldscreen->state = state;
      BLI_snprintf(newname, sizeof(newname), "%s-%s", oldscreen->id.name + 2, "nonnormal");
  
      layout_new = ED_workspace_layout_add(bmain, workspace, win, newname);
  
      screen = BKE_workspace_layout_screen_get(layout_new);
      screen->state = state;
      screen->redraws_flag = oldscreen->redraws_flag;
      screen->temp = oldscreen->temp;
      screen->flag = oldscreen->flag;
  
      /* timer */
      screen->animtimer = oldscreen->animtimer;
      oldscreen->animtimer = NULL;
  
      /* use random area when we have no active one, e.g. when the
       * mouse is outside of the window and we open a file browser */
      if (!area || area->global) {
        area = oldscreen->areabase.first;
      }
  
      newa = (ScrArea *)screen->areabase.first;
  
      /* copy area */
      ED_area_data_swap(newa, area);
      newa->flag = area->flag; /* mostly for AREA_FLAG_WASFULLSCREEN */
  
      if (state == SCREENFULL) {
        /* temporarily hide global areas */
        LISTBASE_FOREACH (ScrArea *, glob_area, &win->global_areas.areabase) {
          glob_area->global->flag |= GLOBAL_AREA_IS_HIDDEN;
        }
        /* temporarily hide the side panels/header */
        for (region = newa->regionbase.first; region; region = region->next) {
          region->flagfullscreen = region->flag;
  
          if (ELEM(region->regiontype,
                   RGN_TYPE_UI,
                   RGN_TYPE_HEADER,
                   RGN_TYPE_TOOL_HEADER,
                   RGN_TYPE_FOOTER,
                   RGN_TYPE_TOOLS,
                   RGN_TYPE_NAV_BAR,
                   RGN_TYPE_EXECUTE)) {
            region->flag |= RGN_FLAG_HIDDEN;
          }
        }
      }
  
      area->full = oldscreen;
      newa->full = oldscreen;
  
      ED_screen_change(C, screen);
    }
  
    /* XXX bad code: setscreen() ends with first area active. fullscreen render assumes this too */
    CTX_wm_area_set(C, screen->areabase.first);
  
    return screen->areabase.first;
  }
  
  /**
   * Wrapper to open a temporary space either as fullscreen space, or as separate window, as defined
   * by \a display_type.
   *
   * \param title: Title to set for the window, if a window is spawned.
   * \param x, y: Position of the window, if a window is spawned.
   * \param sizex, sizey: Dimensions of the window, if a window is spawned.
   */
  ScrArea *ED_screen_temp_space_open(bContext *C,
                                     const char *title,
                                     int x,
                                     int y,
                                     int sizex,
                                     int sizey,
                                     eSpace_Type space_type,
                                     int display_type,
                                     bool dialog)
  {
    ScrArea *area = NULL;
  
    switch (display_type) {
      case USER_TEMP_SPACE_DISPLAY_WINDOW:
        if (WM_window_open_temp(C, title, x, y, sizex, sizey, (int)space_type, dialog)) {
          area = CTX_wm_area(C);
        }
        break;
      case USER_TEMP_SPACE_DISPLAY_FULLSCREEN: {
        ScrArea *ctx_area = CTX_wm_area(C);
  
        if (ctx_area != NULL && ctx_area->full) {
          area = ctx_area;
          ED_area_newspace(C, ctx_area, space_type, true);
          area->flag |= AREA_FLAG_STACKED_FULLSCREEN;
          ((SpaceLink *)area->spacedata.first)->link_flag |= SPACE_FLAG_TYPE_TEMPORARY;
        }
        else if (ctx_area != NULL && ctx_area->spacetype == space_type) {
          area = ED_screen_state_toggle(C, CTX_wm_window(C), ctx_area, SCREENMAXIMIZED);
        }
        else {
          area = ED_screen_full_newspace(C, ctx_area, (int)space_type);
          ((SpaceLink *)area->spacedata.first)->link_flag |= SPACE_FLAG_TYPE_TEMPORARY;
        }
        break;
      }
    }
  
    return area;
  }
  
  /* update frame rate info for viewport drawing */
  void ED_refresh_viewport_fps(bContext *C)
  {
    wmTimer *animtimer = CTX_wm_screen(C)->animtimer;
    Scene *scene = CTX_data_scene(C);
  
    /* is anim playback running? */
    if (animtimer && (U.uiflag & USER_SHOW_FPS)) {
      ScreenFrameRateInfo *fpsi = scene->fps_info;
  
      /* if there isn't any info, init it first */
      if (fpsi == NULL) {
        fpsi = scene->fps_info = MEM_callocN(sizeof(ScreenFrameRateInfo),
                                             "refresh_viewport_fps fps_info");
      }
  
      /* update the values */
      fpsi->redrawtime = fpsi->lredrawtime;
      fpsi->lredrawtime = animtimer->ltime;
    }
    else {
      /* playback stopped or shouldn't be running */
      if (scene->fps_info) {
        MEM_freeN(scene->fps_info);
      }
      scene->fps_info = NULL;
    }
  }
  
  /* redraws: uses defines from stime->redraws
   * enable: 1 - forward on, -1 - backwards on, 0 - off
   */
  void ED_screen_animation_timer(bContext *C, int redraws, int sync, int enable)
  {
    bScreen *screen = CTX_wm_screen(C);
    wmWindowManager *wm = CTX_wm_manager(C);
    wmWindow *win = CTX_wm_window(C);
    Scene *scene = CTX_data_scene(C);
    bScreen *stopscreen = ED_screen_animation_playing(wm);
  
    if (stopscreen) {
      WM_event_remove_timer(wm, win, stopscreen->animtimer);
      stopscreen->animtimer = NULL;
    }
  
    if (enable) {
      ScreenAnimData *sad = MEM_callocN(sizeof(ScreenAnimData), "ScreenAnimData");
  
      screen->animtimer = WM_event_add_timer(wm, win, TIMER0, (1.0 / FPS));
  
      sad->region = CTX_wm_region(C);
      /* if startframe is larger than current frame, we put currentframe on startframe.
       * note: first frame then is not drawn! (ton) */
      if (PRVRANGEON) {
        if (scene->r.psfra > scene->r.cfra) {
          sad->sfra = scene->r.cfra;
          scene->r.cfra = scene->r.psfra;
        }
        else {
          sad->sfra = scene->r.cfra;
        }
      }
      else {
        if (scene->r.sfra > scene->r.cfra) {
          sad->sfra = scene->r.cfra;
          scene->r.cfra = scene->r.sfra;
        }
        else {
          sad->sfra = scene->r.cfra;
        }
      }
      sad->redraws = redraws;
      sad->flag |= (enable < 0) ? ANIMPLAY_FLAG_REVERSE : 0;
      sad->flag |= (sync == 0) ? ANIMPLAY_FLAG_NO_SYNC : (sync == 1) ? ANIMPLAY_FLAG_SYNC : 0;
  
      ScrArea *area = CTX_wm_area(C);
  
      char spacetype = -1;
  
      if (area) {
        spacetype = area->spacetype;
      }
  
      sad->from_anim_edit = (ELEM(spacetype, SPACE_GRAPH, SPACE_ACTION, SPACE_NLA));
  
      screen->animtimer->customdata = sad;
    }
  
    /* notifier catched by top header, for button */
    WM_event_add_notifier(C, NC_SCREEN | ND_ANIMPLAY, NULL);
  }
  
  /* helper for screen_animation_play() - only to be used for TimeLine */
  static ARegion *time_top_left_3dwindow(bScreen *screen)
  {
    ARegion *aret = NULL;
    ScrArea *area;
    int min = 10000;
  
    for (area = screen->areabase.first; area; area = area->next) {
      if (area->spacetype == SPACE_VIEW3D) {
        ARegion *region;
        for (region = area->regionbase.first; region; region = region->next) {
          if (region->regiontype == RGN_TYPE_WINDOW) {
            if (region->winrct.xmin - region->winrct.ymin < min) {
              aret = region;
              min = region->winrct.xmin - region->winrct.ymin;
            }
          }
        }
      }
    }
  
    return aret;
  }
  
  void ED_screen_animation_timer_update(bScreen *screen, int redraws)
  {
    if (screen && screen->animtimer) {
      wmTimer *wt = screen->animtimer;
      ScreenAnimData *sad = wt->customdata;
  
      sad->redraws = redraws;
      sad->region = NULL;
      if (redraws & TIME_REGION) {
        sad->region = time_top_left_3dwindow(screen);
      }
    }
  }
  
  /* results in fully updated anim system */
  void ED_update_for_newframe(Main *bmain, Depsgraph *depsgraph)
  {
    Scene *scene = DEG_get_input_scene(depsgraph);
  
    DEG_id_tag_update_ex(bmain, &scene->id, ID_RECALC_TIME);
  
  #ifdef DURIAN_CAMERA_SWITCH
    void *camera = BKE_scene_camera_switch_find(scene);
    if (camera && scene->camera != camera) {
      bScreen *screen;
      scene->camera = camera;
      /* are there cameras in the views that are not in the scene? */
      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
        BKE_screen_view3d_scene_sync(screen, scene);
      }
      DEG_id_tag_update(&scene->id, ID_RECALC_COPY_ON_WRITE);
    }
  #endif
  
    ED_clip_update_frame(bmain, scene->r.cfra);
  
    /* this function applies the changes too */
    BKE_scene_graph_update_for_newframe(depsgraph, bmain);
  }
  
  /*
   * return true if any active area requires to see in 3D
   */
  bool ED_screen_stereo3d_required(const bScreen *screen, const Scene *scene)
  {
    ScrArea *area;
    const bool is_multiview = (scene->r.scemode & R_MULTIVIEW) != 0;
  
    for (area = screen->areabase.first; area; area = area->next) {
      switch (area->spacetype) {
        case SPACE_VIEW3D: {
          View3D *v3d;
  
          if (!is_multiview) {
            continue;
          }
  
          v3d = area->spacedata.first;
          if (v3d->camera && v3d->stereo3d_camera == STEREO_3D_ID) {
            ARegion *region;
            for (region = area->regionbase.first; region; region = region->next) {
              if (region->regiondata && region->regiontype == RGN_TYPE_WINDOW) {
                RegionView3D *rv3d = region->regiondata;
                if (rv3d->persp == RV3D_CAMOB) {
                  return true;
                }
              }
            }
          }
          break;
        }
        case SPACE_IMAGE: {
          SpaceImage *sima;
  
          /* images should always show in stereo, even if
           * the file doesn't have views enabled */
          sima = area->spacedata.first;
          if (sima->image && BKE_image_is_stereo(sima->image) &&
              (sima->iuser.flag & IMA_SHOW_STEREO)) {
            return true;
          }
          break;
        }
        case SPACE_NODE: {
          SpaceNode *snode;
  
          if (!is_multiview) {
            continue;
          }
  
          snode = area->spacedata.first;
          if ((snode->flag & SNODE_BACKDRAW) && ED_node_is_compositor(snode)) {
            return true;
          }
          break;
        }
        case SPACE_SEQ: {
          SpaceSeq *sseq;
  
          if (!is_multiview) {
            continue;
          }
  
          sseq = area->spacedata.first;
          if (ELEM(sseq->view, SEQ_VIEW_PREVIEW, SEQ_VIEW_SEQUENCE_PREVIEW)) {
            return true;
          }
  
          if (sseq->draw_flag & SEQ_DRAW_BACKDROP) {
            return true;
          }
  
          break;
        }
      }
    }
  
    return false;
  }
  
  /**
   * Find the scene displayed in \a screen.
   * \note Assumes \a screen to be visible/active!
   */
  
  Scene *ED_screen_scene_find_with_window(const bScreen *screen,
                                          const wmWindowManager *wm,
                                          struct wmWindow **r_window)
  {
    LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
      if (WM_window_get_active_screen(win) == screen) {
        if (r_window) {
          *r_window = win;
        }
        return WM_window_get_active_scene(win);
      }
    }
  
    /* Can by NULL when accessing a screen that isn't active. */
    return NULL;
  }
  
  ScrArea *ED_screen_area_find_with_spacedata(const bScreen *screen,
                                              const SpaceLink *sl,
                                              const bool only_visible)
  {
    if (only_visible) {
      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
        if (area->spacedata.first == sl) {
          return area;
        }
      }
    }
    else {
      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
        if (BLI_findindex(&area->spacedata, sl) != -1) {
          return area;
        }
      }
    }
    return NULL;
  }
  
  Scene *ED_screen_scene_find(const bScreen *screen, const wmWindowManager *wm)
  {
    return ED_screen_scene_find_with_window(screen, wm, NULL);
  }
  
  wmWindow *ED_screen_window_find(const bScreen *screen, const wmWindowManager *wm)
  {
    LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
      if (WM_window_get_active_screen(win) == screen) {
        return win;
      }
    }
    return NULL;
  }
  