rescaling of tilemap and game object sprites to grid context's cell size

nodes/Context.gd

@@ -1,3 +1,4 @@
+tool
 extends Node2D
 class_name TK_Context
 

nodes/FittingSprite.gd

@@ -10,8 +10,11 @@ export var target_size: Vector2 = NO_SIZE_SENTINEL setget _set_target_size
 
 # todo: Ask context about preferred sizing if there's any.
 func _enter_tree() -> void:
-    if target_size == NO_SIZE_SENTINEL:
-        self.target_size = texture.get_size()
+    # It's okay to fail here for non-grid contexts.
+    if get_parent().get_parent().connect("cell_size_changed", self, "_update_cell_size"):
+        _set_target_size(get_parent().get_parent().cell_size)
+    elif target_size == NO_SIZE_SENTINEL:
+        _set_target_size(texture.get_size())
 
 func _set_target_size(p_size: Vector2) -> void:
     target_size = p_size
@@ -19,3 +22,6 @@ func _set_target_size(p_size: Vector2) -> void:
 
 func _update_scale() -> void:
     scale = target_size / texture.get_size()
+
+func _update_cell_size(_p_old_cell_size: Vector2, p_new_cell_size: Vector2) -> void:
+    _set_target_size(p_new_cell_size)

nodes/GameObject.gd

@@ -0,0 +1,12 @@
+tool
+extends Node2D
+class_name TK_GameObject
+
+func _ready() -> void:
+    # It's okay to fail here for non-grid contexts.
+    if get_parent().connect("cell_size_changed", self, "_update_cell_size"):
+        pass
+
+func _update_cell_size(p_old_cell_size: Vector2, p_new_cell_size: Vector2) -> void:
+    var delta := p_new_cell_size / p_old_cell_size
+    position *= delta

nodes/GameObject.tscn

@@ -1,3 +1,6 @@
-[gd_scene format=2]
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://nodes/GameObject.gd" type="Script" id=1]
 
 [node name="GameObject" type="Node2D"]
+script = ExtResource( 1 )

nodes/GridContext.gd

@@ -1,10 +1,13 @@
+tool
 extends TK_Context
 class_name TK_GridContext
 
 ## todo: Cell visualization.
 ## todo: Integration of TileMap.
 
-export var cell_size: Vector2 = Vector2(64, 64)
+export var cell_size: Vector2 = Vector2(64, 64) setget _set_cell_size
+
+signal cell_size_changed(p_old_cell_size, p_new_cell_size)
 
 func local_position_to_context_position(p_position: Vector2) -> Vector2:
     return p_position / cell_size
@@ -19,3 +22,12 @@ func try_moving(p_game_object: Node2D, p_from: Vector2, p_to: Vector2) -> bool:
     
     p_game_object.position = cell_size * p_to
     return true
+
+func _set_cell_size(p_new_cell_size: Vector2) -> void:
+    if p_new_cell_size.x == 0 or p_new_cell_size.y == 0:
+        push_error("Cell size cannot be zero")
+        return
+
+    var cell_size_cache = cell_size
+    cell_size = p_new_cell_size
+    emit_signal("cell_size_changed", cell_size_cache, p_new_cell_size)

nodes/TileMapObject.gd

@@ -0,0 +1,17 @@
+tool
+extends TileMap
+
+## Dictates whether tileset collision information should be exposed to game context.
+export var expose_collisions: bool = true
+
+func _enter_tree() -> void:
+    # It's okay to fail here for non-grid contexts.
+    if get_parent().connect("cell_size_changed", self, "_update_cell_size"):
+        _update_cell_size(get_parent().cell_size, get_parent().cell_size)
+
+func _update_cell_size(_p_old_cell_size: Vector2, p_new_cell_size: Vector2) -> void:
+    # We're assuming that all tile textures are of same dimensions.
+    # todo: Diagnose mismatch by walking over all textures?
+    var tileset_texture_size := tile_set.tile_get_texture(0).get_size()
+    scale = p_new_cell_size / tileset_texture_size
+    cell_size = p_new_cell_size / scale