Track a dirty area for in-memory bitmaps

This fixes the bug that bitmap changes do not cause screen updates
and optimizes the refresh when the bitmap is simply shown on the
screen. If the bitmap is used in tiles, then changing it will
cause all TileGrids using it to do a full refresh.

Fixes #1981

1 files changed, 2 insertions, 1 deletions

diff --git a/shared-module/displayio/TileGrid.h b/shared-module/displayio/TileGrid.h
index 4d97eccc2..160b920dd 100644
--- a/shared-module/displayio/TileGrid.h
+++ b/shared-module/displayio/TileGrid.h
@@ -41,7 +41,8 @@ typedef struct {
     int16_t y;
     uint16_t pixel_width;
     uint16_t pixel_height;
-    uint16_t bitmap_width_in_tiles;
+    uint16_t bitmap_width_in_tiles;;
+    uint8_t tiles_in_bitmap;
     uint16_t width_in_tiles;
     uint16_t height_in_tiles;
     uint16_t tile_width;