GPencil: Cleanup of function names, variables and comments

Also some code reorganization.

1 files changed, 285 insertions, 302 deletions

diff --git a/source/blender/editors/gpencil/gpencil_asset.c b/source/blender/editors/gpencil/gpencil_asset.c
index 85c7a6e7b33..96fc91f6a0d 100644
--- a/source/blender/editors/gpencil/gpencil_asset.c
+++ b/source/blender/editors/gpencil/gpencil_asset.c
@@ -13,9 +13,6 @@
  * 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) 2021, Blender Foundation
- * This is a new part of Blender
- * Operators for editing Grease Pencil strokes
  */
 
 /** \file
@@ -108,36 +105,40 @@ typedef struct tGPDasset {
   rctf rect_cage;
   /** 2D cage center. */
   float cage_center[2];
-  /** Transform centerr. */
+  /** Normal vector for cage. */
+  float cage_normal[3];
+  /** Transform center. */
   float transform_center[2];
+
   /** 2D cage manipulator points *
    *
-   *   8             9 (Rotation)
+   * NW-R             NE-R (Rotation)
    *    \           /
-   *     0----1----2
-   *     |         |
-   *     7         3
-   *     |         |
-   *     6----5----4
+   *     NW----N----NE
+   *     |          |
+   *     W          E
+   *     |          |
+   *     SW----S----SE
    *    /           \
-   *   11            10
+   * SW-R             SE-R
    */
   float manipulator[12][2];
   /** Manipulator index (-1 means not set). */
   int manipulator_index;
   /** Manipulator vector used to determine the effect. */
   float manipulator_vector[3];
-  /** Normal vector for cage. */
-  float normal_vec[3];
   /** Vector with the original orientation for rotation. */
   float vinit_rotation[2];
 
+  /* All the hash below are used to keep a reference of the asset data inserted in the target
+   * object. */
+
   /** Hash of new created layers. */
   struct GHash *asset_layers;
   /** Hash of new created frames. */
   struct GHash *asset_frames;
-  /** Hash of new created strokes. */
-  struct GHash *asset_strokes;
+  /** Hash of new created strokes linked to frame. */
+  struct GHash *asset_strokes_frame;
   /** Hash of new created strokes linked to layer. */
   struct GHash *asset_strokes_layer;
   /** Hash of new created materials. */
@@ -318,8 +319,8 @@ void GPENCIL_OT_asset_create(wmOperatorType *ot)
   RNA_def_boolean(ot->srna,
                   "reset_origin",
                   1,
-                  "Reset Origin to Strokes",
-                  "Set origin of the strokes in the center of the bounding box");
+                  "Reset Origin to Geometry",
+                  "Set origin of the asset in the center of the strokes bounding box");
 }
 
 /** \} */
@@ -336,177 +337,6 @@ static void gpencil_asset_import_update_strokes(bContext *C, tGPDasset *tgpa)
   WM_event_add_notifier(C, NC_GPENCIL | NA_EDITED, NULL);
 }
 
-/* Helper: Draw status message while the user is running the operator */
-static void gpencil_asset_import_status_indicators(bContext *C, tGPDasset *tgpa)
-{
-  char status_str[UI_MAX_DRAW_STR];
-  char msg_str[UI_MAX_DRAW_STR];
-  bGPdata *gpd_asset = tgpa->gpd_asset;
-  const char *mode_txt[] = {"", "(Location)", "(Rotation)", "(Scale)"};
-
-  BLI_strncpy(msg_str, TIP_("Importing Asset"), UI_MAX_DRAW_STR);
-
-  BLI_snprintf(status_str,
-               sizeof(status_str),
-               "%s %s %s",
-               msg_str,
-               gpd_asset->id.name + 2,
-               mode_txt[tgpa->mode]);
-
-  ED_area_status_text(tgpa->area, status_str);
-  ED_workspace_status_text(
-      C, TIP_("ESC/RMB to cancel, Enter/LMB(outside cage) to confirm, Shift to Scale uniform"));
-}
-
-/* Update screen and stroke */
-static void gpencil_asset_import_update(bContext *C, wmOperator *op, tGPDasset *tgpa)
-{
-  /* Update shift indicator in header. */
-  gpencil_asset_import_status_indicators(C, tgpa);
-  /* Update points position. */
-  gpencil_asset_import_update_strokes(C, tgpa);
-}
-
-/* ----------------------- */
-
-/* Exit and free memory */
-static void gpencil_asset_import_exit(bContext *C, wmOperator *op)
-{
-  tGPDasset *tgpa = op->customdata;
-  bGPdata *gpd = tgpa->gpd;
-
-  /* don't assume that operator data exists at all */
-  if (tgpa) {
-    /* clear status message area */
-    ED_area_status_text(tgpa->area, NULL);
-    ED_workspace_status_text(C, NULL);
-
-    /* Clear any temp stroke. */
-    // TODO
-
-    /* Free Hash tablets. */
-    if (tgpa->asset_layers != NULL) {
-      BLI_ghash_free(tgpa->asset_layers, NULL, NULL);
-    }
-    if (tgpa->asset_frames != NULL) {
-      BLI_ghash_free(tgpa->asset_frames, NULL, NULL);
-    }
-    if (tgpa->asset_strokes != NULL) {
-      BLI_ghash_free(tgpa->asset_strokes, NULL, NULL);
-      BLI_ghash_free(tgpa->asset_strokes_layer, NULL, NULL);
-    }
-
-    if (tgpa->asset_materials != NULL) {
-      BLI_ghash_free(tgpa->asset_materials, NULL, NULL);
-    }
-
-    /* Remove drawing handler. */
-    if (tgpa->draw_handle_3d) {
-      ED_region_draw_cb_exit(tgpa->region->type, tgpa->draw_handle_3d);
-    }
-
-    MEM_SAFE_FREE(tgpa);
-  }
-  DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
-  WM_event_add_notifier(C, NC_GPENCIL | NA_EDITED, NULL);
-
-  /* clear pointer */
-  op->customdata = NULL;
-}
-
-/* Init new temporary interpolation data */
-static bool gpencil_asset_import_set_init_values(bContext *C,
-                                                 wmOperator *op,
-                                                 ID *id,
-                                                 tGPDasset *tgpa)
-{
-  /* Save current settings. */
-  tgpa->win = CTX_wm_window(C);
-  tgpa->bmain = CTX_data_main(C);
-  tgpa->depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
-  tgpa->scene = CTX_data_scene(C);
-  tgpa->area = CTX_wm_area(C);
-  tgpa->region = CTX_wm_region(C);
-  tgpa->rv3d = CTX_wm_region_view3d(C);
-  tgpa->ob = CTX_data_active_object(C);
-
-  /* Setup space conversions data. */
-  gpencil_point_conversion_init(C, &tgpa->gsc);
-
-  /* Save current frame number. */
-  tgpa->cframe = tgpa->scene->r.cfra;
-
-  /* Target GP datablock. */
-  tgpa->gpd = tgpa->ob->data;
-  /* Asset GP datablock. */
-  tgpa->gpd_asset = (bGPdata *)id;
-
-  tgpa->mode = GP_ASSET_TRANSFORM_LOC;
-  tgpa->flag |= GP_ASSET_FLAG_IDLE;
-
-  /* Manipulator point is not set yet. */
-  tgpa->manipulator_index = -1;
-
-  tgpa->asset_layers = NULL;
-  tgpa->asset_frames = NULL;
-  tgpa->asset_strokes = NULL;
-  tgpa->asset_strokes_layer = NULL;
-  tgpa->asset_materials = NULL;
-
-  return true;
-}
-
-/* Allocate memory and initialize values */
-static tGPDasset *gpencil_session_init_asset_import(bContext *C, wmOperator *op)
-{
-  Main *bmain = CTX_data_main(C);
-  ID *id = NULL;
-
-  PropertyRNA *prop_name = RNA_struct_find_property(op->ptr, "name");
-  PropertyRNA *prop_type = RNA_struct_find_property(op->ptr, "type");
-
-  /* These shouldn't fail when created by outliner dropping as it checks the ID is valid. */
-  if (!RNA_property_is_set(op->ptr, prop_name) || !RNA_property_is_set(op->ptr, prop_type)) {
-    return NULL;
-  }
-  const short id_type = RNA_property_enum_get(op->ptr, prop_type);
-  char name[MAX_ID_NAME - 2];
-  RNA_property_string_get(op->ptr, prop_name, name);
-  id = BKE_libblock_find_name(bmain, id_type, name);
-  if (id == NULL) {
-    return NULL;
-  }
-  const int object_type = BKE_object_obdata_to_type(id);
-  if (object_type == -1) {
-    return NULL;
-  }
-
-  tGPDasset *tgpa = MEM_callocN(sizeof(tGPDasset), "GPencil Asset Import Data");
-
-  /* Save initial values. */
-  gpencil_asset_import_set_init_values(C, op, id, tgpa);
-
-  /* return context data for running operator */
-  return tgpa;
-}
-
-/* Init interpolation: Allocate memory and set init values */
-static int gpencil_asset_import_init(bContext *C, wmOperator *op)
-{
-  tGPDasset *tgpa;
-
-  /* check context */
-  tgpa = op->customdata = gpencil_session_init_asset_import(C, op);
-  if (tgpa == NULL) {
-    /* something wasn't set correctly in context */
-    gpencil_asset_import_exit(C, op);
-    return 0;
-  }
-
-  /* everything is now setup ok */
-  return 1;
-}
-
 /* Helper: Compute 2D cage size in screen pixels. */
 static void gpencil_2d_cage_calc(tGPDasset *tgpa)
 {
@@ -592,9 +422,85 @@ static void gpencil_2d_cage_calc(tGPDasset *tgpa)
   gpencil_point_xy_to_3d(&tgpa->gsc, tgpa->scene, tgpa->manipulator[CAGE_CORNER_SW], co3);
   sub_v3_v3v3(vec1, co2, co1);
   sub_v3_v3v3(vec2, co3, co2);
+
   /* Vector orthogonal to polygon plane. */
-  cross_v3_v3v3(tgpa->normal_vec, vec1, vec2);
-  normalize_v3(tgpa->normal_vec);
+  cross_v3_v3v3(tgpa->cage_normal, vec1, vec2);
+  normalize_v3(tgpa->cage_normal);
+}
+
+/* Draw a cage for manipulate asset */
+static void gpencil_2d_cage_draw(tGPDasset *tgpa)
+{
+  GPUVertFormat *format = immVertexFormat();
+  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+
+  GPU_blend(GPU_BLEND_ALPHA);
+
+  /* Draw dash box. */
+  immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_UNIFORM_COLOR);
+  GPU_line_width(1.0f);
+
+  float viewport_size[4];
+  GPU_viewport_size_get_f(viewport_size);
+  immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
+
+  immUniform1i("colors_len", 0); /* "simple" mode */
+  immUniform1f("dash_width", 6.0f);
+  immUniform1f("dash_factor", 0.5f);
+
+  float box_color[4];
+  UI_GetThemeColor4fv(TH_VERTEX_SELECT, box_color);
+  immUniformColor4fv(box_color);
+
+  immBegin(GPU_PRIM_LINE_LOOP, 4);
+  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_NW][0], tgpa->manipulator[CAGE_CORNER_NW][1]);
+  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_NE][0], tgpa->manipulator[CAGE_CORNER_NE][1]);
+  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_SE][0], tgpa->manipulator[CAGE_CORNER_SE][1]);
+  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_SW][0], tgpa->manipulator[CAGE_CORNER_SW][1]);
+  immEnd();
+
+  /* Rotation box */
+  const float gap = 2.0f;
+  for (int i = 0; i < 4; i++) {
+    imm_draw_box_wire_2d(pos,
+                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][0] - gap,
+                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][1] - gap,
+                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][0] + gap,
+                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][1] + gap);
+  }
+
+  /* Draw a line while is doing a transform. */
+  if ((tgpa->flag & GP_ASSET_FLAG_TRANSFORMING) && (tgpa->mode == GP_ASSET_TRANSFORM_ROT)) {
+    const float line_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+    immUniformColor4fv(line_color);
+    immBegin(GPU_PRIM_LINES, 2);
+    immVertex2f(pos, tgpa->transform_center[0], tgpa->transform_center[1]);
+    immVertex2f(pos, tgpa->mouse[0], tgpa->mouse[1]);
+    immEnd();
+  }
+
+  immUnbindProgram();
+
+  /* Draw Points. */
+  GPU_program_point_size(true);
+
+  immBindBuiltinProgram(GPU_SHADER_2D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_AA);
+
+  float point_color[4];
+  UI_GetThemeColor4fv(TH_SELECT, point_color);
+  immUniformColor4fv(point_color);
+
+  immUniform1f("size", UI_GetThemeValuef(TH_VERTEX_SIZE) * 1.5f * U.dpi_fac);
+
+  immBegin(GPU_PRIM_POINTS, 8);
+  for (int i = 0; i < 8; i++) {
+    immVertex2fv(pos, tgpa->manipulator[i]);
+  }
+  immEnd();
+  immUnbindProgram();
+  GPU_program_point_size(false);
+
+  GPU_blend(GPU_BLEND_NONE);
 }
 
 /* Helper: Detect mouse over cage areas. */
@@ -602,7 +508,7 @@ static void gpencil_2d_cage_area_detect(tGPDasset *tgpa, const int mouse[2])
 {
   const float gap = 5.0f;
 
-  /* Check if over any of the corners for scale with a small gap. */
+  /* Check if mouse is over any of the manipualtor points with a small gap. */
   rctf rect_mouse = {
       (float)mouse[0] - gap, (float)mouse[0] + gap, (float)mouse[1] - gap, (float)mouse[1] + gap};
 
@@ -614,6 +520,7 @@ static void gpencil_2d_cage_area_detect(tGPDasset *tgpa, const int mouse[2])
       tgpa->mode = (tgpa->manipulator_index < 8) ? GP_ASSET_TRANSFORM_SCALE :
                                                    GP_ASSET_TRANSFORM_ROT;
 
+      /* For rotation don't need to do more. */
       if (tgpa->mode == GP_ASSET_TRANSFORM_ROT) {
         WM_cursor_modal_set(tgpa->win, WM_CURSOR_HAND);
         return;
@@ -637,6 +544,7 @@ static void gpencil_2d_cage_area_detect(tGPDasset *tgpa, const int mouse[2])
         default:
           break;
       }
+
       /* Determine the vector of the cage effect. For corners is always full effect. */
       if (ELEM(tgpa->manipulator_index,
                CAGE_CORNER_NW,
@@ -663,7 +571,7 @@ static void gpencil_2d_cage_area_detect(tGPDasset *tgpa, const int mouse[2])
     }
   }
 
-  /* Check if mouse is inside cage for Location. */
+  /* Check if mouse is inside cage for Location transform. */
   if (BLI_rctf_isect_pt(&tgpa->rect_cage, (float)mouse[0], (float)mouse[1])) {
     tgpa->mode = GP_ASSET_TRANSFORM_LOC;
     WM_cursor_modal_set(tgpa->win, WM_CURSOR_DEFAULT);
@@ -679,9 +587,9 @@ static void gpencil_asset_rotation_matrix_get(float angle,
                                               float axis[3],
                                               float rotation_matrix[4][4])
 {
-  float u2 = axis[0] * axis[0];
-  float v2 = axis[1] * axis[1];
-  float w2 = axis[2] * axis[2];
+  const float u2 = axis[0] * axis[0];
+  const float v2 = axis[1] * axis[1];
+  const float w2 = axis[2] * axis[2];
   const float length = (u2 + v2 + w2);
   const float length_sqr = sqrt(length);
   const float cos_value = cos(angle);
@@ -720,7 +628,7 @@ static void gpencil_asset_rotation_matrix_get(float angle,
   rotation_matrix[3][3] = 1.0f;
 }
 
-/* Helper: Transfrom the stroke with mouse movements. */
+/* Helper: Transform the stroke with mouse movements. */
 static void gpencil_asset_transform_strokes(tGPDasset *tgpa,
                                             const int mouse[2],
                                             const bool shift_key)
@@ -774,10 +682,11 @@ static void gpencil_asset_transform_strokes(tGPDasset *tgpa,
   sub_v2_v2v2(vr, vr, tgpa->transform_center);
   normalize_v2(vr);
   float angle = angle_signed_v2v2(tgpa->vinit_rotation, vr);
-  gpencil_asset_rotation_matrix_get(angle, tgpa->normal_vec, rot_matrix);
+  gpencil_asset_rotation_matrix_get(angle, tgpa->cage_normal, rot_matrix);
 
+  /* Loop all strokes and apply transformation. */
   GHashIterator gh_iter;
-  GHASH_ITER (gh_iter, tgpa->asset_strokes) {
+  GHASH_ITER (gh_iter, tgpa->asset_strokes_frame) {
     bGPDstroke *gps = (bGPDstroke *)BLI_ghashIterator_getKey(&gh_iter);
     bGPDspoint *pt;
     int i;
@@ -815,7 +724,7 @@ static void gpencil_asset_transform_strokes(tGPDasset *tgpa,
       }
     }
 
-    /* In scale mode recal geometry. */
+    /* In scale mode recal stroke geometry because fill triangulation can change. */
     if (tgpa->mode == GP_ASSET_TRANSFORM_SCALE) {
       BKE_gpencil_stroke_geometry_update(tgpa->gpd, gps);
     }
@@ -830,12 +739,13 @@ static void gpencil_asset_transform_strokes(tGPDasset *tgpa,
     add_v3_v3(tgpa->asset_center, vec);
   }
 
-  /* Update mouse position and transform data to avoid acumulation. */
+  /* Update mouse position and transform data to avoid acumulation for next transformation. */
   copy_v2_v2_int(tgpa->mouse, mouse);
   tgpa->initial_dist = dist;
   copy_v2_v2(tgpa->vinit_rotation, vr);
 }
 
+/* Helper: Get a material from the datablock */
 static Material *gpencil_asset_material_get_from_id(ID *id, const int slot_index)
 {
   const short *tot_slots_data_ptr = BKE_id_material_len_p(id);
@@ -851,7 +761,7 @@ static Material *gpencil_asset_material_get_from_id(ID *id, const int slot_index
   return material;
 }
 
-/* Helper: Load all strokes in the target datablock. */
+/* Helper: Add all strokes from the asset in the target datablock. */
 static void gpencil_asset_add_strokes(tGPDasset *tgpa)
 {
   bGPdata *gpd_target = tgpa->gpd;
@@ -877,7 +787,7 @@ static void gpencil_asset_add_strokes(tGPDasset *tgpa)
       if (tgpa->asset_layers == NULL) {
         tgpa->asset_layers = BLI_ghash_ptr_new(__func__);
       }
-      /* Add to the hash to remove if operator is canceled. */
+      /* Add layer to the hash to remove if operator is canceled. */
       BLI_ghash_insert(tgpa->asset_layers, gpl_target, gpl_target);
     }
 
@@ -893,15 +803,15 @@ static void gpencil_asset_add_strokes(tGPDasset *tgpa)
         if (tgpa->asset_frames == NULL) {
           tgpa->asset_frames = BLI_ghash_ptr_new(__func__);
         }
-        /* Add to the hash to remove if operator is canceled. */
+        /* Add frame to the hash to remove if operator is canceled. */
         if (!BLI_ghash_haskey(tgpa->asset_frames, gpf_target)) {
           /* Add the hash key with a reference to the layer. */
           BLI_ghash_insert(tgpa->asset_frames, gpf_target, gpl_target);
         }
       }
       /* Loop all strokes and duplicate. */
-      if (tgpa->asset_strokes == NULL) {
-        tgpa->asset_strokes = BLI_ghash_ptr_new(__func__);
+      if (tgpa->asset_strokes_frame == NULL) {
+        tgpa->asset_strokes_frame = BLI_ghash_ptr_new(__func__);
         tgpa->asset_strokes_layer = BLI_ghash_ptr_new(__func__);
       }
 
@@ -940,25 +850,26 @@ static void gpencil_asset_add_strokes(tGPDasset *tgpa)
         /* Update geometry. */
         BKE_gpencil_stroke_geometry_update(gpd_target, gps_target);
 
-        /* Add the hash key with a reference to the frame. */
-        BLI_ghash_insert(tgpa->asset_strokes, gps_target, gpf_target);
+        /* Add the hash key with a reference to the frame and layer. */
+        BLI_ghash_insert(tgpa->asset_strokes_frame, gps_target, gpf_target);
         BLI_ghash_insert(tgpa->asset_strokes_layer, gps_target, gpl_target);
       }
     }
   }
+
   /* Prepare 2D cage. */
   gpencil_2d_cage_calc(tgpa);
   BKE_gpencil_centroid_3d(tgpa->gpd_asset, tgpa->asset_center);
   add_v3_v3(tgpa->asset_center, vec);
 }
 
-/* Helper: Clean any temp data. */
-static void gpencil_asset_clean_data(tGPDasset *tgpa)
+/* Helper: Clean any temp added data when the operator is canceled. */
+static void gpencil_asset_clean_temp_data(tGPDasset *tgpa)
 {
   GHashIterator gh_iter;
   /* Clean Strokes. */
-  if (tgpa->asset_strokes != NULL) {
-    GHASH_ITER (gh_iter, tgpa->asset_strokes) {
+  if (tgpa->asset_strokes_frame != NULL) {
+    GHASH_ITER (gh_iter, tgpa->asset_strokes_frame) {
       bGPDstroke *gps = (bGPDstroke *)BLI_ghashIterator_getKey(&gh_iter);
       bGPDframe *gpf = (bGPDframe *)BLI_ghashIterator_getValue(&gh_iter);
       BLI_remlink(&gpf->strokes, gps);
@@ -993,79 +904,170 @@ static void gpencil_asset_clean_data(tGPDasset *tgpa)
   }
 }
 
-/* Draw a cage for manipulate asset */
-static void gpencil_draw_cage(tGPDasset *tgpa)
+/* Helper: Draw status message while the user is running the operator. */
+static void gpencil_asset_import_status_indicators(bContext *C, tGPDasset *tgpa)
 {
-  GPUVertFormat *format = immVertexFormat();
-  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  char status_str[UI_MAX_DRAW_STR];
+  char msg_str[UI_MAX_DRAW_STR];
+  bGPdata *gpd_asset = tgpa->gpd_asset;
+  const char *mode_txt[] = {"", "(Location)", "(Rotation)", "(Scale)"};
 
-  GPU_blend(GPU_BLEND_ALPHA);
+  BLI_strncpy(msg_str, TIP_("Importing Asset"), UI_MAX_DRAW_STR);
 
-  /* Draw dash box. */
-  immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_UNIFORM_COLOR);
-  GPU_line_width(1.0f);
+  BLI_snprintf(status_str,
+               sizeof(status_str),
+               "%s %s %s",
+               msg_str,
+               gpd_asset->id.name + 2,
+               mode_txt[tgpa->mode]);
 
-  float viewport_size[4];
-  GPU_viewport_size_get_f(viewport_size);
-  immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
+  ED_area_status_text(tgpa->area, status_str);
+  ED_workspace_status_text(
+      C, TIP_("ESC/RMB to cancel, Enter/LMB(outside cage) to confirm, Shift to Scale uniform"));
+}
 
-  immUniform1i("colors_len", 0); /* "simple" mode */
-  immUniform1f("dash_width", 6.0f);
-  immUniform1f("dash_factor", 0.5f);
+/* Update screen and stroke. */
+static void gpencil_asset_import_update(bContext *C, wmOperator *op, tGPDasset *tgpa)
+{
+  /* Update shift indicator in header. */
+  gpencil_asset_import_status_indicators(C, tgpa);
+  /* Update points position. */
+  gpencil_asset_import_update_strokes(C, tgpa);
+}
 
-  float box_color[4];
-  UI_GetThemeColor4fv(TH_VERTEX_SELECT, box_color);
-  immUniformColor4fv(box_color);
+/* ----------------------- */
 
-  immBegin(GPU_PRIM_LINE_LOOP, 4);
-  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_NW][0], tgpa->manipulator[CAGE_CORNER_NW][1]);
-  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_NE][0], tgpa->manipulator[CAGE_CORNER_NE][1]);
-  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_SE][0], tgpa->manipulator[CAGE_CORNER_SE][1]);
-  immVertex2f(pos, tgpa->manipulator[CAGE_CORNER_SW][0], tgpa->manipulator[CAGE_CORNER_SW][1]);
-  immEnd();
+/* Exit and free memory */
+static void gpencil_asset_import_exit(bContext *C, wmOperator *op)
+{
+  tGPDasset *tgpa = op->customdata;
+  bGPdata *gpd = tgpa->gpd;
 
-  /* Rotation box */
-  const float gap = 2.0f;
-  for (int i = 0; i < 4; i++) {
-    imm_draw_box_wire_2d(pos,
-                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][0] - gap,
-                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][1] - gap,
-                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][0] + gap,
-                         tgpa->manipulator[CAGE_CORNER_ROT_NW + i][1] + gap);
+  if (tgpa) {
+    /* Clear status message area. */
+    ED_area_status_text(tgpa->area, NULL);
+    ED_workspace_status_text(C, NULL);
+
+    /* Free Hash tablets. */
+    if (tgpa->asset_layers != NULL) {
+      BLI_ghash_free(tgpa->asset_layers, NULL, NULL);
+    }
+    if (tgpa->asset_frames != NULL) {
+      BLI_ghash_free(tgpa->asset_frames, NULL, NULL);
+    }
+    if (tgpa->asset_strokes_frame != NULL) {
+      BLI_ghash_free(tgpa->asset_strokes_frame, NULL, NULL);
+      BLI_ghash_free(tgpa->asset_strokes_layer, NULL, NULL);
+    }
+
+    if (tgpa->asset_materials != NULL) {
+      BLI_ghash_free(tgpa->asset_materials, NULL, NULL);
+    }
+
+    /* Remove drawing handler. */
+    if (tgpa->draw_handle_3d) {
+      ED_region_draw_cb_exit(tgpa->region->type, tgpa->draw_handle_3d);
+    }
+
+    MEM_SAFE_FREE(tgpa);
   }
+  DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_GPENCIL | NA_EDITED, NULL);
 
-  /* Draw a line while is doing a transform. */
-  if ((tgpa->flag & GP_ASSET_FLAG_TRANSFORMING) && (tgpa->mode == GP_ASSET_TRANSFORM_ROT)) {
-    const float line_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
-    immUniformColor4fv(line_color);
-    immBegin(GPU_PRIM_LINES, 2);
-    immVertex2f(pos, tgpa->transform_center[0], tgpa->transform_center[1]);
-    immVertex2f(pos, tgpa->mouse[0], tgpa->mouse[1]);
-    immEnd();
+  /* Clear pointer. */
+  op->customdata = NULL;
+}
+
+/* Init new temporary data. */
+static bool gpencil_asset_import_set_init_values(bContext *C,
+                                                 wmOperator *op,
+                                                 ID *id,
+                                                 tGPDasset *tgpa)
+{
+  /* Save current settings. */
+  tgpa->win = CTX_wm_window(C);
+  tgpa->bmain = CTX_data_main(C);
+  tgpa->depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
+  tgpa->scene = CTX_data_scene(C);
+  tgpa->area = CTX_wm_area(C);
+  tgpa->region = CTX_wm_region(C);
+  tgpa->rv3d = CTX_wm_region_view3d(C);
+  tgpa->ob = CTX_data_active_object(C);
+
+  /* Setup space conversions data. */
+  gpencil_point_conversion_init(C, &tgpa->gsc);
+
+  /* Save current frame number. */
+  tgpa->cframe = tgpa->scene->r.cfra;
+
+  /* Target GP datablock. */
+  tgpa->gpd = tgpa->ob->data;
+  /* Asset GP datablock. */
+  tgpa->gpd_asset = (bGPdata *)id;
+
+  tgpa->mode = GP_ASSET_TRANSFORM_LOC;
+  tgpa->flag |= GP_ASSET_FLAG_IDLE;
+
+  /* Manipulator point is not set yet. */
+  tgpa->manipulator_index = -1;
+
+  tgpa->asset_layers = NULL;
+  tgpa->asset_frames = NULL;
+  tgpa->asset_strokes_frame = NULL;
+  tgpa->asset_strokes_layer = NULL;
+  tgpa->asset_materials = NULL;
+
+  return true;
+}
+
+/* Allocate memory and initialize values */
+static tGPDasset *gpencil_session_init_asset_import(bContext *C, wmOperator *op)
+{
+  Main *bmain = CTX_data_main(C);
+  ID *id = NULL;
+
+  PropertyRNA *prop_name = RNA_struct_find_property(op->ptr, "name");
+  PropertyRNA *prop_type = RNA_struct_find_property(op->ptr, "type");
+
+  /* These shouldn't fail when created by outliner dropping as it checks the ID is valid. */
+  if (!RNA_property_is_set(op->ptr, prop_name) || !RNA_property_is_set(op->ptr, prop_type)) {
+    return NULL;
+  }
+  const short id_type = RNA_property_enum_get(op->ptr, prop_type);
+  char name[MAX_ID_NAME - 2];
+  RNA_property_string_get(op->ptr, prop_name, name);
+  id = BKE_libblock_find_name(bmain, id_type, name);
+  if (id == NULL) {
+    return NULL;
+  }
+  const int object_type = BKE_object_obdata_to_type(id);
+  if (object_type == -1) {
+    return NULL;
   }
 
-  immUnbindProgram();
+  tGPDasset *tgpa = MEM_callocN(sizeof(tGPDasset), "GPencil Asset Import Data");
 
-  /* Draw Points. */
-  GPU_program_point_size(true);
+  /* Save initial values. */
+  gpencil_asset_import_set_init_values(C, op, id, tgpa);
 
-  immBindBuiltinProgram(GPU_SHADER_2D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_AA);
+  /* return context data for running operator */
+  return tgpa;
+}
 
-  float point_color[4];
-  UI_GetThemeColor4fv(TH_SELECT, point_color);
-  immUniformColor4fv(point_color);
+/* Init: Allocate memory and set init values */
+static bool gpencil_asset_import_init(bContext *C, wmOperator *op)
+{
+  tGPDasset *tgpa;
 
-  immUniform1f("size", UI_GetThemeValuef(TH_VERTEX_SIZE) * 1.5f * U.dpi_fac);
-  /* Draw points. */
-  immBegin(GPU_PRIM_POINTS, 8);
-  for (int i = 0; i < 8; i++) {
-    immVertex2fv(pos, tgpa->manipulator[i]);
+  /* check context */
+  tgpa = op->customdata = gpencil_session_init_asset_import(C, op);
+  if (tgpa == NULL) {
+    /* something wasn't set correctly in context */
+    gpencil_asset_import_exit(C, op);
+    return false;
   }
-  immEnd();
-  immUnbindProgram();
-  GPU_program_point_size(false);
 
-  GPU_blend(GPU_BLEND_NONE);
+  return true;
 }
 
 /* Drawing callback for modal operator. */
@@ -1077,17 +1079,16 @@ static void gpencil_asset_draw(const bContext *C, ARegion *UNUSED(region), void
   if (region != tgpa->region) {
     return;
   }
-  gpencil_draw_cage(tgpa);
+  gpencil_2d_cage_draw(tgpa);
 }
-/* ----------------------- */
 
-/* Invoke handler: Initialize the operator */
+/* Invoke handler: Initialize the operator. */
 static int gpencil_asset_import_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
   bGPdata *gpd = CTX_data_gpencil_data(C);
   tGPDasset *tgpa = NULL;
 
-  /* try to initialize context data needed */
+  /* Try to initialize context data needed. */
   if (!gpencil_asset_import_init(C, op)) {
     if (op->customdata) {
       MEM_freeN(op->customdata);
@@ -1106,18 +1107,19 @@ static int gpencil_asset_import_invoke(bContext *C, wmOperator *op, const wmEven
   tgpa->draw_handle_3d = ED_region_draw_cb_activate(
       tgpa->region->type, gpencil_asset_draw, tgpa, REGION_DRAW_POST_PIXEL);
 
-  /* update shift indicator in header */
+  /* Update screen. */
   gpencil_asset_import_status_indicators(C, tgpa);
+
   DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GPENCIL | NA_EDITED, NULL);
 
-  /* add a modal handler for this operator */
+  /* Add a modal handler for this operator. */
   WM_event_add_modal_handler(C, op);
 
   return OPERATOR_RUNNING_MODAL;
 }
 
-/* Modal handler: Events handling during interactive part */
+/* Modal handler: Events handling during interactive part. */
 static int gpencil_asset_import_modal(bContext *C, wmOperator *op, const wmEvent *event)
 {
   tGPDasset *tgpa = op->customdata;
@@ -1170,10 +1172,10 @@ static int gpencil_asset_import_modal(bContext *C, wmOperator *op, const wmEvent
         break;
       }
     }
-      /* Confirm */
+      /* Confirm. */
     case EVT_PADENTER:
     case EVT_RETKEY: {
-      /* return to normal cursor and header status */
+      /* Return to normal cursor and header status. */
       ED_area_status_text(tgpa->area, NULL);
       ED_workspace_status_text(C, NULL);
       WM_cursor_modal_restore(win);
@@ -1181,15 +1183,15 @@ static int gpencil_asset_import_modal(bContext *C, wmOperator *op, const wmEvent
       /* Clean up temp data. */
       gpencil_asset_import_exit(C, op);
 
-      /* done! */
+      /* Done! */
       return OPERATOR_FINISHED;
     }
 
-    case EVT_ESCKEY: /* cancel */
+    case EVT_ESCKEY: /* Cancel */
     case RIGHTMOUSE: {
       /* Delete temp strokes. */
-      gpencil_asset_clean_data(tgpa);
-      /* Return to normal cursor and header status */
+      gpencil_asset_clean_temp_data(tgpa);
+      /* Return to normal cursor and header status. */
       ED_area_status_text(tgpa->area, NULL);
       ED_workspace_status_text(C, NULL);
       WM_cursor_modal_restore(win);
@@ -1197,12 +1199,10 @@ static int gpencil_asset_import_modal(bContext *C, wmOperator *op, const wmEvent
       /* Clean up temp data. */
       gpencil_asset_import_exit(C, op);
 
-      /* canceled! */
+      /* Canceled! */
       return OPERATOR_CANCELLED;
     }
-
-    case MOUSEMOVE: /* calculate new position */
-    {
+    case MOUSEMOVE: {
       /* Apply transform. */
       if (tgpa->flag & GP_ASSET_FLAG_TRANSFORMING) {
         gpencil_asset_transform_strokes(tgpa, event->mval, event->shift);
@@ -1217,33 +1217,16 @@ static int gpencil_asset_import_modal(bContext *C, wmOperator *op, const wmEvent
       gpencil_asset_import_update(C, op, tgpa);
       break;
     }
-    case WHEELUPMOUSE: {
-      // Scale
-      // TODO
-
-      /* Update screen. */
-      gpencil_asset_import_update(C, op, tgpa);
-      break;
-    }
-    case WHEELDOWNMOUSE: {
-      // Scale
-      // TODO
-
-      /* Update screen. */
-      gpencil_asset_import_update(C, op, tgpa);
-      break;
-    }
-
     default: {
       /* Unhandled event - allow to pass through. */
       return OPERATOR_RUNNING_MODAL | OPERATOR_PASS_THROUGH;
     }
   }
-  /* still running... */
+  /* Still running... */
   return OPERATOR_RUNNING_MODAL;
 }
 
-/* Cancel handler */
+/* Cancel handler. */
 static void gpencil_asset_import_cancel(bContext *C, wmOperator *op)
 {
   /* this is just a wrapper around exit() */