Tool System: experimental fallback tool support

Implement T66304 as an experimental option,
available under the preferences "Experimental" section.

- When enabled most tools in the 3D view have a gizmo.
- Dragging outside the gizmo uses the 'fallback' tool.
- The fallback tool can be changed or disabled in the tool options
  or from a pie menu (Alt-W).

4 files changed, 241 insertions, 0 deletions

diff --git a/source/blender/editors/space_view3d/CMakeLists.txt b/source/blender/editors/space_view3d/CMakeLists.txt
index 7c75f0ea907..2feef9e0c9a 100644
--- a/source/blender/editors/space_view3d/CMakeLists.txt
+++ b/source/blender/editors/space_view3d/CMakeLists.txt
@@ -61,6 +61,7 @@ set(SRC
   view3d_gizmo_preselect.c
   view3d_gizmo_preselect_type.c
   view3d_gizmo_ruler.c
+  view3d_gizmo_tool_generic.c
   view3d_header.c
   view3d_iterators.c
   view3d_ops.c
diff --git a/source/blender/editors/space_view3d/space_view3d.c b/source/blender/editors/space_view3d/space_view3d.c
index 5c7263d458d..7db1a6123e8 100644
--- a/source/blender/editors/space_view3d/space_view3d.c
+++ b/source/blender/editors/space_view3d/space_view3d.c
@@ -626,6 +626,8 @@ static void view3d_widgets(void)
   WM_gizmogrouptype_append(VIEW3D_GGT_xform_extrude);
   WM_gizmogrouptype_append(VIEW3D_GGT_mesh_preselect_elem);
   WM_gizmogrouptype_append(VIEW3D_GGT_mesh_preselect_edgering);
+  WM_gizmogrouptype_append(VIEW3D_GGT_tool_generic_handle_normal);
+  WM_gizmogrouptype_append(VIEW3D_GGT_tool_generic_handle_free);
 
   WM_gizmogrouptype_append(VIEW3D_GGT_ruler);
   WM_gizmotype_append(VIEW3D_GT_ruler_item);
diff --git a/source/blender/editors/space_view3d/view3d_gizmo_tool_generic.c b/source/blender/editors/space_view3d/view3d_gizmo_tool_generic.c
new file mode 100644
index 00000000000..838abe46616
--- /dev/null
+++ b/source/blender/editors/space_view3d/view3d_gizmo_tool_generic.c
@@ -0,0 +1,236 @@
+/*
+ * 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.
+ */
+
+/** \file
+ * \ingroup spview3d
+ */
+
+#include "BLI_math.h"
+#include "BLI_utildefines.h"
+
+#include "BKE_context.h"
+
+#include "ED_screen.h"
+#include "ED_transform.h"
+#include "ED_gizmo_library.h"
+#include "ED_gizmo_utils.h"
+
+#include "UI_resources.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "WM_toolsystem.h"
+
+#include "RNA_access.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+#include "WM_toolsystem.h"
+#include "WM_message.h"
+
+#include "view3d_intern.h" /* own include */
+
+static const char *handle_normal_id;
+static const char *handle_free_id;
+
+/* -------------------------------------------------------------------- */
+/** \name Generic Tool
+ * \{ */
+
+static bool WIDGETGROUP_tool_generic_poll(const bContext *C, wmGizmoGroupType *gzgt)
+{
+  if (!U.experimental.use_tool_fallback) {
+    return false;
+  }
+
+  if (!ED_gizmo_poll_or_unlink_delayed_from_tool(C, gzgt)) {
+    return false;
+  }
+
+  View3D *v3d = CTX_wm_view3d(C);
+  if (v3d->gizmo_flag & (V3D_GIZMO_HIDE | V3D_GIZMO_HIDE_CONTEXT)) {
+    return false;
+  }
+
+  return true;
+}
+
+static wmGizmo *tool_generic_create_gizmo(const bContext *C, wmGizmoGroup *gzgroup)
+{
+  wmGizmo *gz;
+
+  if (gzgroup->type->idname == handle_normal_id) {
+    gz = WM_gizmo_new("GIZMO_GT_button_2d", gzgroup, NULL);
+
+    UI_GetThemeColor3fv(TH_GIZMO_PRIMARY, gz->color);
+    UI_GetThemeColor3fv(TH_GIZMO_HI, gz->color_hi);
+
+    unit_m4(gz->matrix_offset);
+
+    PropertyRNA *prop = RNA_struct_find_property(gz->ptr, "icon");
+    RNA_property_enum_set(gz->ptr, prop, ICON_NONE);
+
+    gz->scale_basis = 0.12f;
+    gz->matrix_offset[3][2] -= 12.0;
+    RNA_enum_set(gz->ptr,
+                 "draw_options",
+                 (ED_GIZMO_BUTTON_SHOW_BACKDROP | ED_GIZMO_BUTTON_SHOW_HELPLINE |
+                  ED_GIZMO_BUTTON_SHOW_OUTLINE));
+  }
+  else {
+    gz = WM_gizmo_new("GIZMO_GT_button_2d", gzgroup, NULL);
+
+    UI_GetThemeColor3fv(TH_GIZMO_PRIMARY, gz->color);
+    UI_GetThemeColor3fv(TH_GIZMO_HI, gz->color_hi);
+
+    unit_m4(gz->matrix_offset);
+    gz->scale_basis = 0.16f * 3;
+
+    PropertyRNA *prop = RNA_struct_find_property(gz->ptr, "icon");
+    RNA_property_enum_set(gz->ptr, prop, ICON_NONE);
+
+    RNA_enum_set(gz->ptr, "draw_options", ED_GIZMO_BUTTON_SHOW_BACKDROP);
+
+    /* Make the center low alpha. */
+    WM_gizmo_set_line_width(gz, 2.0f);
+    RNA_float_set(gz->ptr, "backdrop_fill_alpha", 0.125f);
+  }
+
+  bToolRef *tref = WM_toolsystem_ref_from_context((bContext *)C);
+  wmWindowManager *wm = CTX_wm_manager(C);
+  struct wmKeyConfig *kc = wm->defaultconf;
+
+  gz->keymap = WM_keymap_ensure(kc, tref->runtime->keymap, tref->space_type, RGN_TYPE_WINDOW);
+  return gz;
+}
+
+static void WIDGETGROUP_tool_generic_setup(const bContext *C, wmGizmoGroup *gzgroup)
+{
+  wmGizmoWrapper *wwrapper = MEM_mallocN(sizeof(wmGizmoWrapper), __func__);
+  wwrapper->gizmo = tool_generic_create_gizmo(C, gzgroup);
+  gzgroup->customdata = wwrapper;
+}
+
+static void WIDGETGROUP_tool_generic_refresh(const bContext *C, wmGizmoGroup *gzgroup)
+{
+  wmGizmoWrapper *wwrapper = gzgroup->customdata;
+  wmGizmo *gz = wwrapper->gizmo;
+
+  ToolSettings *ts = CTX_data_tool_settings(C);
+  if (ts->workspace_tool_type != SCE_WORKSPACE_TOOL_FALLBACK) {
+    gzgroup->use_fallback_keymap = false;
+    WM_gizmo_set_flag(gz, WM_GIZMO_HIDDEN, true);
+    return;
+  }
+  else {
+    gzgroup->use_fallback_keymap = true;
+  }
+
+  /* skip, we don't draw anything anyway */
+  {
+    int orientation;
+    if (gzgroup->type->idname == handle_normal_id) {
+      orientation = V3D_ORIENT_NORMAL;
+    }
+    else {
+      orientation = V3D_ORIENT_GLOBAL; /* dummy, use view. */
+    }
+
+    struct TransformBounds tbounds;
+    const bool hide = ED_transform_calc_gizmo_stats(C,
+                                                    &(struct TransformCalcParams){
+                                                        .use_only_center = true,
+                                                        .orientation_type = orientation + 1,
+                                                    },
+                                                    &tbounds) == 0;
+
+    WM_gizmo_set_flag(gz, WM_GIZMO_HIDDEN, hide);
+    if (hide) {
+      return;
+    }
+    copy_m4_m3(gz->matrix_basis, tbounds.axis);
+    copy_v3_v3(gz->matrix_basis[3], tbounds.center);
+    negate_v3(gz->matrix_basis[2]);
+  }
+
+  WM_gizmo_set_flag(gz, WM_GIZMO_DRAW_OFFSET_SCALE, true);
+}
+
+static void WIDGETGROUP_gizmo_message_subscribe(const bContext *C,
+                                                wmGizmoGroup *gzgroup,
+                                                struct wmMsgBus *mbus)
+{
+  ARegion *ar = CTX_wm_region(C);
+
+  wmMsgSubscribeValue msg_sub_value_gz_tag_refresh = {
+      .owner = ar,
+      .user_data = gzgroup->parent_gzmap,
+      .notify = WM_gizmo_do_msg_notify_tag_refresh,
+  };
+
+  {
+    extern PropertyRNA rna_ToolSettings_workspace_tool_type;
+    const PropertyRNA *props[] = {
+        &rna_ToolSettings_workspace_tool_type,
+    };
+
+    Scene *scene = CTX_data_scene(C);
+    PointerRNA toolsettings_ptr;
+    RNA_pointer_create(&scene->id, &RNA_ToolSettings, scene->toolsettings, &toolsettings_ptr);
+
+    for (int i = 0; i < ARRAY_SIZE(props); i++) {
+      WM_msg_subscribe_rna(
+          mbus, &toolsettings_ptr, props[i], &msg_sub_value_gz_tag_refresh, __func__);
+    }
+  }
+}
+
+static const char *handle_normal_id = "VIEW3D_GGT_tool_generic_handle_normal";
+static const char *handle_free_id = "VIEW3D_GGT_tool_generic_handle_free";
+
+void VIEW3D_GGT_tool_generic_handle_normal(wmGizmoGroupType *gzgt)
+{
+  gzgt->name = "Generic Tool Widget Normal";
+  gzgt->idname = handle_normal_id;
+
+  gzgt->flag |= (WM_GIZMOGROUPTYPE_3D | WM_GIZMOGROUPTYPE_TOOL_FALLBACK_KEYMAP);
+
+  gzgt->gzmap_params.spaceid = SPACE_VIEW3D;
+  gzgt->gzmap_params.regionid = RGN_TYPE_WINDOW;
+
+  gzgt->poll = WIDGETGROUP_tool_generic_poll;
+  gzgt->setup = WIDGETGROUP_tool_generic_setup;
+  gzgt->refresh = WIDGETGROUP_tool_generic_refresh;
+  gzgt->message_subscribe = WIDGETGROUP_gizmo_message_subscribe;
+}
+
+void VIEW3D_GGT_tool_generic_handle_free(wmGizmoGroupType *gzgt)
+{
+  gzgt->name = "Generic Tool Widget Free";
+  gzgt->idname = handle_free_id;
+
+  gzgt->flag |= (WM_GIZMOGROUPTYPE_3D | WM_GIZMOGROUPTYPE_TOOL_FALLBACK_KEYMAP);
+
+  gzgt->gzmap_params.spaceid = SPACE_VIEW3D;
+  gzgt->gzmap_params.regionid = RGN_TYPE_WINDOW;
+
+  gzgt->poll = WIDGETGROUP_tool_generic_poll;
+  gzgt->setup = WIDGETGROUP_tool_generic_setup;
+  gzgt->refresh = WIDGETGROUP_tool_generic_refresh;
+  gzgt->message_subscribe = WIDGETGROUP_gizmo_message_subscribe;
+}
+
+/** \} */
diff --git a/source/blender/editors/space_view3d/view3d_intern.h b/source/blender/editors/space_view3d/view3d_intern.h
index 6b5c27b68f4..ddbb64bf067 100644
--- a/source/blender/editors/space_view3d/view3d_intern.h
+++ b/source/blender/editors/space_view3d/view3d_intern.h
@@ -261,6 +261,8 @@ void VIEW3D_GGT_armature_spline(struct wmGizmoGroupType *gzgt);
 void VIEW3D_GGT_navigate(struct wmGizmoGroupType *gzgt);
 void VIEW3D_GGT_mesh_preselect_elem(struct wmGizmoGroupType *gzgt);
 void VIEW3D_GGT_mesh_preselect_edgering(struct wmGizmoGroupType *gzgt);
+void VIEW3D_GGT_tool_generic_handle_normal(struct wmGizmoGroupType *gzgt);
+void VIEW3D_GGT_tool_generic_handle_free(struct wmGizmoGroupType *gzgt);
 
 void VIEW3D_GGT_ruler(struct wmGizmoGroupType *gzgt);
 void VIEW3D_GT_ruler_item(struct wmGizmoType *gzt);