Grease Pencil: Edit Mode Pen Tool

This adds the `Pen` tool to Grease Pencil Edit Mode.

With the pen tool you can:
- Extrude points by `Left Click`.
- Move the handles by dragging the mouse.
- Snap handles to 45 degree increments with `Shift`.
- Cycle through the handle types by `Double Clicking`.
- Add new point on segments by `Ctrl Clicking`.
- Remove existing point by `Ctrl Clicking`.
- Close a curve by clicking on one end while having the other selected.
- Move existing segment by clicking and dragging on the edge.
- Move points by clicking and dragging the mouse.

Some changes have been made compared to the legacy
curve object's pen tool:
- `Angle locking` with `Alt` was replaced with `Angle Snapping`
   using `Shift`. This was done to match the behavior of Grease Pencil
   primitive tools.
- `Move Entire Point` was changed from the `Space` key to `Alt`. This
   was done because some laptops can't move the mouse while
  `Space` is held.
- `Link Handles` and `Free Align Toggle` were not implemented.
- `Toggle Vector` and `Close Spline Method` were removed.
- `Close Spline` was removed and set to always be true.
- `Extrude Handle` type was removed as a option and was replaced
   by the `shift` modifier key when clicking.
- Newly created points are placed on the drawing plane, instead of
  the view plane.

When a new curve is created, the material will be the active material
and the radius will be set from the `radius` property.

Note: This tool is added to edit mode because it uses handle selection
and bézier overlays which currently don't exist in draw mode.
A future PR will implement a draw mode version.

Pull Request: https://projects.blender.org/blender/blender/pulls/142646

scripts/modules/bl_keymap_utils/keymap_hierarchy.py

@@ -108,6 +108,7 @@ _km_hierarchy = [
         ]),
 
         ('Primitive Tool Modal Map', 'EMPTY', 'WINDOW', []),
+        ('Pen Tool Modal Map', 'EMPTY', 'WINDOW', []),
         ('Knife Tool Modal Map', 'EMPTY', 'WINDOW', []),
         ('Custom Normals Modal Map', 'EMPTY', 'WINDOW', []),
         ('Bevel Modal Map', 'EMPTY', 'WINDOW', []),

scripts/presets/keyconfig/keymap_data/blender_default.py

@@ -8328,6 +8328,53 @@ def km_grease_pencil_interpolate_tool_modal_map(_params):
 
     return keymap
 
+
+def km_grease_pencil_pen_tool_modal_map(_params):
+    items = []
+    keymap = (
+        "Pen Tool Modal Map",
+        {"space_type": 'EMPTY', "region_type": 'WINDOW', "modal": True},
+        {"items": items},
+    )
+
+    items.extend([
+        ("MOVE_HANDLE", {"type": 'LEFT_CTRL', "value": 'ANY', "any": True}, None),
+        ("MOVE_ENTIRE", {"type": 'LEFT_ALT', "value": 'ANY', "any": True}, None),
+        ("SNAP_ANGLE", {"type": 'LEFT_SHIFT', "value": 'ANY', "any": True}, None),
+    ])
+
+    return keymap
+
+
+def km_3d_view_tool_edit_grease_pencil_pen(params):
+    return (
+        "3D View Tool: Edit Grease Pencil, Pen",
+        {"space_type": 'VIEW_3D', "region_type": 'WINDOW'},
+        {"items": [
+            ("grease_pencil.pen", {"type": params.tool_mouse, "value": 'PRESS'},
+             {"properties": [
+                 ("extrude_point", True),
+                 ("move_segment", True),
+                 ("select_point", True),
+                 ("move_point", True),
+                 ("extrude_handle", "VECTOR"),
+             ]}),
+            ("grease_pencil.pen", {"type": params.tool_mouse, "value": 'PRESS', "shift": True},
+             {"properties": [
+                 ("extrude_point", True),
+                 ("move_segment", True),
+                 ("select_point", True),
+                 ("move_point", True),
+                 ("extrude_handle", "AUTO"),
+             ]}),
+            ("grease_pencil.pen", {"type": params.tool_mouse, "value": 'PRESS', "ctrl": True},
+             {"properties": [("insert_point", True), ("delete_point", True)]}),
+            ("grease_pencil.pen", {"type": params.tool_mouse, "value": 'DOUBLE_CLICK'},
+             {"properties": [("cycle_handle_type", True)]}),
+        ]},
+    )
+
+
 # ------------------------------------------------------------------------------
 # Grease Pencil: Texture Gradient Tool
 
@@ -8648,6 +8695,7 @@ def generate_keymaps(params=None):
         km_node_link_modal_map(params),
         km_node_resize_modal_map(params),
         km_grease_pencil_primitive_tool_modal_map(params),
+        km_grease_pencil_pen_tool_modal_map(params),
         km_grease_pencil_fill_tool_modal_map(params),
         km_grease_pencil_interpolate_tool_modal_map(params),
         km_sequencer_slip_modal_map(params),
@@ -8796,6 +8844,7 @@ def generate_keymaps(params=None):
         km_sequencer_preview_tool_move(params),
         km_sequencer_preview_tool_rotate(params),
         km_sequencer_preview_tool_scale(params),
+        km_3d_view_tool_edit_grease_pencil_pen(params),
         km_3d_view_tool_edit_grease_pencil_interpolate(params),
         km_3d_view_tool_paint_grease_pencil_interpolate(params),
         km_3d_view_tool_paint_grease_pencil_eyedropper(params),

scripts/startup/bl_ui/space_toolsystem_toolbar.py

@@ -2426,6 +2426,41 @@ class _defs_grease_pencil_edit:
             keymap=(),
         )
 
+    @ToolDef.from_fn
+    def pen():
+        def draw_settings(context, layout, tool):
+            props = tool.operator_properties("grease_pencil.pen")
+            layout.prop(props, "radius")
+
+            layout.separator()
+            tool_settings = context.tool_settings
+
+            sub = layout.row(align=True)
+            sub.prop_with_popover(
+                tool_settings,
+                "gpencil_stroke_placement_view3d",
+                text="",
+                panel="VIEW3D_PT_grease_pencil_origin",
+            )
+
+            sub = layout.row(align=True)
+            sub.active = tool_settings.gpencil_stroke_placement_view3d != 'SURFACE'
+            sub.prop_with_popover(
+                tool_settings.gpencil_sculpt,
+                "lock_axis",
+                text="",
+                panel="VIEW3D_PT_grease_pencil_lock",
+            )
+        return dict(
+            idname="builtin.pen",
+            label="Pen",
+            cursor='CROSSHAIR',
+            icon="ops.curve.pen",
+            widget=None,
+            keymap=(),
+            draw_settings=draw_settings,
+        )
+
 
 class _defs_image_generic:
 
@@ -3659,6 +3694,8 @@ class VIEW3D_PT_tools_active(ToolSelectPanelHelper, Panel):
             None,
             *_tools_transform,
             None,
+            _defs_grease_pencil_edit.pen,
+            None,
             _defs_edit_curve.curve_radius,
             _defs_transform.bend,
             (

source/blender/editors/grease_pencil/CMakeLists.txt

@@ -29,6 +29,7 @@ set(SRC
   intern/grease_pencil_merge.cc
   intern/grease_pencil_modes.cc
   intern/grease_pencil_ops.cc
+  intern/grease_pencil_pen.cc
   intern/grease_pencil_primitive.cc
   intern/grease_pencil_randomize.cc
   intern/grease_pencil_select.cc

source/blender/editors/grease_pencil/intern/grease_pencil_ops.cc

@@ -320,6 +320,7 @@ void ED_operatortypes_grease_pencil()
   ED_operatortypes_grease_pencil_lineart();
   ED_operatortypes_grease_pencil_trace();
   ED_operatortypes_grease_pencil_bake_animation();
+  ED_operatortypes_grease_pencil_pen();
 }
 
 void ED_operatormacros_grease_pencil()
@@ -370,6 +371,7 @@ void ED_keymap_grease_pencil(wmKeyConfig *keyconf)
   keymap_grease_pencil_fill_tool(keyconf);
 
   ED_primitivetool_modal_keymap(keyconf);
+  ED_pentool_modal_keymap(keyconf);
   ED_filltool_modal_keymap(keyconf);
   ED_interpolatetool_modal_keymap(keyconf);
 }

source/blender/editors/include/ED_grease_pencil.hh

@@ -72,6 +72,7 @@ void ED_operatortypes_grease_pencil_edit();
 void ED_operatortypes_grease_pencil_join();
 void ED_operatortypes_grease_pencil_material();
 void ED_operatortypes_grease_pencil_modes();
+void ED_operatortypes_grease_pencil_pen();
 void ED_operatortypes_grease_pencil_primitives();
 void ED_operatortypes_grease_pencil_weight_paint();
 void ED_operatortypes_grease_pencil_vertex_paint();
@@ -84,6 +85,7 @@ void ED_keymap_grease_pencil(wmKeyConfig *keyconf);
 void ED_primitivetool_modal_keymap(wmKeyConfig *keyconf);
 void ED_filltool_modal_keymap(wmKeyConfig *keyconf);
 void ED_interpolatetool_modal_keymap(wmKeyConfig *keyconf);
+void ED_pentool_modal_keymap(wmKeyConfig *keyconf);
 
 void GREASE_PENCIL_OT_stroke_trim(wmOperatorType *ot);