vectorio: clean up after group removal

VectorShape tells the Group to redraw whatever it left behind when it is removed now.

Author: kvc0

shared-module/displayio/Group.c

@@ -250,6 +250,8 @@ static void _remove_layer(displayio_group_t* self, size_t index) {
     bool rendered_last_frame = false;
 #if CIRCUITPY_VECTORIO
     if (MP_OBJ_IS_TYPE(layer, &vectorio_vector_shape_type)) {
+        bool has_dirty_area = vectorio_vector_shape_get_dirty_area(layer, &layer_area);
+        rendered_last_frame = has_dirty_area;
         vectorio_vector_shape_update_transform(layer, NULL);
     }
     else

shared-module/vectorio/VectorShape.c

@@ -64,6 +64,13 @@ static void _get_screen_area(vectorio_vector_shape_t *self, displayio_area_t *ou
 }
 
 
+// For use by Group to know where it needs to redraw on layer removal.
+bool vectorio_vector_shape_get_dirty_area(vectorio_vector_shape_t *self, displayio_area_t *out_area) {
+    displayio_area_copy(&self->ephemeral_dirty_area, out_area);
+    return true; // For now just always redraw.
+}
+
+
 // This must be invoked each time a shape changes its position or its shape in any way.
 void common_hal_vectorio_vector_shape_set_dirty(void *vector_shape) {
     vectorio_vector_shape_t *self = vector_shape;

shared-module/vectorio/VectorShape.h

@@ -38,7 +38,9 @@ typedef struct {
     displayio_area_t ephemeral_dirty_area;
 } vectorio_vector_shape_t;
 
-displayio_area_t* vectorio_vector_shape_get_refresh_areas(vectorio_vector_shape_t *self, displayio_area_t* tail);
+displayio_area_t* vectorio_vector_shape_get_refresh_areas(vectorio_vector_shape_t *self, displayio_area_t *tail);
+
+bool vectorio_vector_shape_get_dirty_area(vectorio_vector_shape_t *self, displayio_area_t *current_dirty_area);
 
 // Area is always in absolute screen coordinates.
 bool vectorio_vector_shape_fill_area(vectorio_vector_shape_t *self, const _displayio_colorspace_t *colorspace, const displayio_area_t *area, uint32_t *mask, uint32_t *buffer);