GPencil: Merge GSoC curve edit mode

Differential Revision: https://developer.blender.org/D8660

This patch is the result of the GSoC 2020 "Editing Grease Pencil Strokes
Using Curves" project. It adds a submode to greasepencil edit mode that
allows for the transformation of greasepencil strokes using bezier
curves. More information about the project can be found
here: https://wiki.blender.org/wiki/User:Filedescriptor/GSoC_2020.

1 files changed, 214 insertions, 0 deletions

diff --git a/source/blender/editors/gpencil/gpencil_edit_curve.c b/source/blender/editors/gpencil/gpencil_edit_curve.c
new file mode 100644
index 00000000000..60d1d2169b4
--- /dev/null
+++ b/source/blender/editors/gpencil/gpencil_edit_curve.c
@@ -0,0 +1,214 @@
+/*
+ * 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
+ * This is a new part of Blender
+ * Operators for editing Grease Pencil strokes
+ */
+
+/** \file
+ * \ingroup edgpencil
+ */
+
+#include <math.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "DNA_gpencil_types.h"
+#include "DNA_view3d_types.h"
+
+#include "BKE_context.h"
+#include "BKE_curve.h"
+#include "BKE_gpencil.h"
+#include "BKE_gpencil_curve.h"
+#include "BKE_gpencil_geom.h"
+
+#include "BLI_listbase.h"
+#include "BLI_math.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "ED_gpencil.h"
+
+#include "DEG_depsgraph.h"
+
+#include "gpencil_intern.h"
+
+/* Poll callback for checking if there is an active layer and we are in curve edit mode. */
+static bool gpencil_curve_edit_mode_poll(bContext *C)
+{
+  Object *ob = CTX_data_active_object(C);
+  if ((ob == NULL) || (ob->type != OB_GPENCIL)) {
+    return false;
+  }
+  bGPdata *gpd = (bGPdata *)ob->data;
+  if (!GPENCIL_CURVE_EDIT_SESSIONS_ON(gpd)) {
+    return false;
+  }
+
+  bGPDlayer *gpl = BKE_gpencil_layer_active_get(gpd);
+  return (gpl != NULL);
+}
+
+static int gpencil_stroke_enter_editcurve_mode_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = ob->data;
+
+  float error_threshold = RNA_float_get(op->ptr, "error_threshold");
+  gpd->curve_edit_threshold = error_threshold;
+
+  if (ELEM(NULL, gpd)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  LISTBASE_FOREACH (bGPDlayer *, gpl, &gpd->layers) {
+    LISTBASE_FOREACH (bGPDframe *, gpf, &gpl->frames) {
+      if (gpf == gpl->actframe) {
+        LISTBASE_FOREACH (bGPDstroke *, gps, &gpf->strokes) {
+          /* only allow selected and non-converted strokes to be transformed */
+          if ((gps->flag & GP_STROKE_SELECT && gps->editcurve == NULL) ||
+              (gps->editcurve != NULL && gps->editcurve->flag & GP_CURVE_NEEDS_STROKE_UPDATE)) {
+            BKE_gpencil_stroke_editcurve_update(gpd, gpl, gps);
+            /* Update the selection from the stroke to the curve. */
+            BKE_gpencil_editcurve_stroke_sync_selection(gps, gps->editcurve);
+            gps->flag |= GP_STROKE_NEEDS_CURVE_UPDATE;
+            BKE_gpencil_stroke_geometry_update(gpd, gps);
+          }
+        }
+      }
+    }
+  }
+
+  gpd->flag |= GP_DATA_CURVE_EDIT_MODE;
+
+  /* notifiers */
+  DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GPENCIL_OT_stroke_enter_editcurve_mode(wmOperatorType *ot)
+{
+  PropertyRNA *prop;
+
+  /* identifiers */
+  ot->name = "Enter curve edit mode";
+  ot->idname = "GPENCIL_OT_stroke_enter_editcurve_mode";
+  ot->description = "Called to transform a stroke into a curve";
+
+  /* api callbacks */
+  ot->exec = gpencil_stroke_enter_editcurve_mode_exec;
+  ot->poll = gpencil_active_layer_poll;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* properties */
+  prop = RNA_def_float(ot->srna,
+                       "error_threshold",
+                       0.1f,
+                       FLT_MIN,
+                       100.0f,
+                       "Error Threshold",
+                       "Threshold on the maximum deviation from the actual stroke",
+                       FLT_MIN,
+                       10.f);
+  RNA_def_property_ui_range(prop, FLT_MIN, 10.0f, 0.1f, 5);
+}
+
+static int gpencil_editcurve_set_handle_type_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = ob->data;
+  const int handle_type = RNA_enum_get(op->ptr, "type");
+
+  if (ELEM(NULL, gpd)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  GP_EDITABLE_CURVES_BEGIN(gps_iter, C, gpl, gps, gpc)
+  {
+    for (int i = 0; i < gpc->tot_curve_points; i++) {
+      bGPDcurve_point *gpc_pt = &gpc->curve_points[i];
+
+      if (gpc_pt->flag & GP_CURVE_POINT_SELECT) {
+        BezTriple *bezt = &gpc_pt->bezt;
+
+        if (bezt->f2 & SELECT) {
+          bezt->h1 = handle_type;
+          bezt->h2 = handle_type;
+        }
+        else {
+          if (bezt->f1 & SELECT) {
+            bezt->h1 = handle_type;
+          }
+          if (bezt->f3 & SELECT) {
+            bezt->h2 = handle_type;
+          }
+        }
+      }
+    }
+
+    BKE_gpencil_editcurve_recalculate_handles(gps);
+    gps->flag |= GP_STROKE_NEEDS_CURVE_UPDATE;
+    BKE_gpencil_stroke_geometry_update(gpd, gps);
+  }
+  GP_EDITABLE_CURVES_END(gps_iter);
+
+  /* notifiers */
+  DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GPENCIL_OT_stroke_editcurve_set_handle_type(wmOperatorType *ot)
+{
+  static const EnumPropertyItem editcurve_handle_type_items[] = {
+      {HD_FREE, "FREE", 0, "Free", ""},
+      {HD_AUTO, "AUTOMATIC", 0, "Automatic", ""},
+      {HD_VECT, "VECTOR", 0, "Vector", ""},
+      {HD_ALIGN, "ALIGNED", 0, "Aligned", ""},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  /* identifiers */
+  ot->name = "Set handle type";
+  ot->idname = "GPENCIL_OT_stroke_editcurve_set_handle_type";
+  ot->description = "Set the type of a edit curve handle";
+
+  /* api callbacks */
+  ot->invoke = WM_menu_invoke;
+  ot->exec = gpencil_editcurve_set_handle_type_exec;
+  ot->poll = gpencil_curve_edit_mode_poll;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* properties */
+  ot->prop = RNA_def_enum(ot->srna, "type", editcurve_handle_type_items, 1, "Type", "Spline type");
+}
+
+/** \} */