TileGrid: pixel_shader is not always a Palette

shared-module/displayio/ColorConverter.c

@@ -39,3 +39,11 @@ bool common_hal_displayio_colorconverter_convert(displayio_colorconverter_t *sel
     *output_color = __builtin_bswap16(packed);
     return true;
 }
+
+// Currently no refresh logic is needed for a ColorConverter.
+bool displayio_colorconverter_needs_refresh(displayio_colorconverter_t *self) {
+    return false;
+}
+
+void displayio_colorconverter_finish_refresh(displayio_colorconverter_t *self) {
+}

shared-module/displayio/ColorConverter.h

@@ -36,4 +36,7 @@ typedef struct {
     mp_obj_base_t base;
 } displayio_colorconverter_t;
 
+bool displayio_colorconverter_needs_refresh(displayio_colorconverter_t *self);
+void displayio_colorconverter_finish_refresh(displayio_colorconverter_t *self);
+
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_COLORCONVERTER_H

shared-module/displayio/TileGrid.c

@@ -170,12 +170,24 @@ bool displayio_tilegrid_get_pixel(displayio_tilegrid_t *self, int16_t x, int16_t
 }
 
 bool displayio_tilegrid_needs_refresh(displayio_tilegrid_t *self) {
-    return self->needs_refresh || displayio_palette_needs_refresh(self->pixel_shader);
+    if (self->needs_refresh) {
+        return true;
+    } else if (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_palette_type)) {
+        return displayio_palette_needs_refresh(self->pixel_shader);
+    } else if (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_colorconverter_type)) {
+        return displayio_colorconverter_needs_refresh(self->pixel_shader);
+    }
+
+    return false;
 }
 
 void displayio_tilegrid_finish_refresh(displayio_tilegrid_t *self) {
     self->needs_refresh = false;
-    displayio_palette_finish_refresh(self->pixel_shader);
+    if (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_palette_type)) {
+        displayio_palette_finish_refresh(self->pixel_shader);
+    } else if (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_colorconverter_type)) {
+        displayio_colorconverter_finish_refresh(self->pixel_shader);
+    }
     // TODO(tannewt): We could double buffer changes to position and move them over here.
     // That way they won't change during a refresh and tear.
 }