masks_history.c

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/*
    This file is part of Ansel
    Copyright (C) 2026 Guillaume Stutin.
 
    Ansel 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 3 of the License, or
    (at your option) any later version.
 
    Ansel 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 darktable.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "develop/masks/masks_history.h"
 
#include "common/atomic.h"
#include "develop/develop.h"
 
dt_masks_form_t *dt_masks_form_ref(dt_masks_form_t *form)
{
  if(IS_NULL_PTR(form)) return NULL;
  dt_atomic_add_int(&form->refcount, 1);
  return form;
}
 
void dt_masks_form_unref(dt_masks_form_t *form)
{
  if(IS_NULL_PTR(form)) return;
  // dt_atomic_sub_int returns the value *before* the decrement.
  if(dt_atomic_sub_int(&form->refcount, 1) == 1) dt_masks_free_form(form);
}
 
dt_masks_form_t *dt_masks_cow_touch(dt_develop_t *dev, dt_masks_form_t *form)
{
  if(IS_NULL_PTR(dev) || IS_NULL_PTR(form)) return form;
  if(dt_atomic_get_int(&form->refcount) <= 1) return form;
 
  dt_pthread_rwlock_wrlock(&dev->masks_mutex);
 
  GList *node = g_list_find(dev->forms, form);
  if(IS_NULL_PTR(node))
  {
    // Not (yet) a member of dev->forms: e.g. a transient in-creation shape.
    // Nothing to splice, leave it alone.
    dt_pthread_rwlock_unlock(&dev->masks_mutex);
    return form;
  }
 
  dt_masks_form_t *clone = dt_masks_dup_masks_form(form);
  node->data = clone;
 
  dt_pthread_rwlock_unlock(&dev->masks_mutex);
 
  if(!IS_NULL_PTR(dev->form_gui) && dev->form_gui->form_visible == form)
    dev->form_gui->form_visible = clone;
 
  dt_masks_form_unref(form);
 
  return clone;
}
 
void dt_masks_replace_current_forms(dt_develop_t *dev, GList *forms)
{
  dt_pthread_rwlock_wrlock(&dev->masks_mutex);
 
  GList *forms_shared = g_list_copy(forms);
  for(GList *node = forms_shared; node; node = g_list_next(node))
    dt_masks_form_ref((dt_masks_form_t *)node->data);
 
  GList *old_forms = dev->forms;
  dev->forms = forms_shared;
 
  dt_pthread_rwlock_unlock(&dev->masks_mutex);
 
  // form_visible is a raw pointer cached outside dev->forms (dt_masks_form_gui_t::form_visible).
  // If it pointed at an object we're about to release below, re-resolve it by formid in the new
  // dev->forms (or drop it if that formid is gone) before old_forms is freed -- otherwise the
  // very next mask interaction (mouse move, scroll...) dereferences freed memory.
  if(!IS_NULL_PTR(dev->form_gui) && !IS_NULL_PTR(dev->form_gui->form_visible)
     && g_list_find(old_forms, dev->form_gui->form_visible))
  {
    const int visible_formid = dev->form_gui->form_visible->formid;
    dev->form_gui->form_visible = dt_masks_get_from_id_ext(dev->forms, visible_formid);
  }
 
  g_list_free_full(old_forms, (void (*)(void *))dt_masks_form_unref);
 
  // Don't recompute gravity_center/area for every form here: this runs on every history
  // load, undo/redo and history navigation, for every mask of every module in the image,
  // whether or not the mask editor is even open. Just invalidate -- the one GUI hit-testing
  // read site (masks.c, group member selection) recomputes lazily on first actual use.
  for(GList *form_node = dev->forms; form_node; form_node = g_list_next(form_node))
    dt_masks_form_invalidate_gravity_center((dt_masks_form_t *)form_node->data);
}
 
GList *dt_masks_snapshot_current_forms(dt_develop_t *dev, gboolean reset_changed)
{
  dt_pthread_rwlock_rdlock(&dev->masks_mutex);
 
  GList *forms_snapshot = g_list_copy(dev->forms);
  for(GList *node = forms_snapshot; node; node = g_list_next(node))
    dt_masks_form_ref((dt_masks_form_t *)node->data);
 
  dt_pthread_rwlock_unlock(&dev->masks_mutex);
 
  if(reset_changed) dev->forms_changed = FALSE;
  return forms_snapshot;
}