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

4 files changed, 74 insertions, 4 deletions

diff --git a/shared-module/displayio/Bitmap.c b/shared-module/displayio/Bitmap.c
index f8dc24c15..59971d25c 100644
--- a/shared-module/displayio/Bitmap.c
+++ b/shared-module/displayio/Bitmap.c
@@ -63,6 +63,11 @@ void common_hal_displayio_bitmap_construct(displayio_bitmap_t *self, uint32_t wi
     }
     self->x_mask = (1 << self->x_shift) - 1; // Used as a modulus on the x value
     self->bitmask = (1 << bits_per_value) - 1;
+
+    self->dirty_area.x1 = 0;
+    self->dirty_area.x2 = width;
+    self->dirty_area.y1 = 0;
+    self->dirty_area.y2 = height;
 }
 
 uint16_t common_hal_displayio_bitmap_get_height(displayio_bitmap_t *self) {
@@ -104,6 +109,26 @@ void common_hal_displayio_bitmap_set_pixel(displayio_bitmap_t *self, int16_t x,
     if (self->read_only) {
         mp_raise_RuntimeError(translate("Read-only object"));
     }
+    // Update the dirty area.
+    if (self->dirty_area.x1 == self->dirty_area.x2) {
+        self->dirty_area.x1 = x;
+        self->dirty_area.x2 = x + 1;
+        self->dirty_area.y1 = y;
+        self->dirty_area.y2 = y + 1;
+    } else {
+        if (x < self->dirty_area.x1) {
+            self->dirty_area.x1 = x;
+        } else if (x >= self->dirty_area.x2) {
+            self->dirty_area.x2 = x + 1;
+        }
+        if (y < self->dirty_area.y1) {
+            self->dirty_area.y1 = y;
+        } else if (y >= self->dirty_area.y2) {
+            self->dirty_area.y2 = y + 1;
+        }
+    }
+
+    // Update our data
     int32_t row_start = y * self->stride;
     uint32_t bytes_per_value = self->bits_per_value / 8;
     if (bytes_per_value < 1) {
@@ -124,3 +149,16 @@ void common_hal_displayio_bitmap_set_pixel(displayio_bitmap_t *self, int16_t x,
         }
     }
 }
+
+displayio_area_t* displayio_bitmap_get_refresh_areas(displayio_bitmap_t *self, displayio_area_t* tail) {
+    if (self->dirty_area.x1 == self->dirty_area.x2) {
+        return tail;
+    }
+    self->dirty_area.next = tail;
+    return &self->dirty_area;
+}
+
+void displayio_bitmap_finish_refresh(displayio_bitmap_t *self) {
+    self->dirty_area.x1 = 0;
+    self->dirty_area.x2 = 0;
+}
diff --git a/shared-module/displayio/Bitmap.h b/shared-module/displayio/Bitmap.h
index 48ca9e2cf..f4bd7ce4d 100644
--- a/shared-module/displayio/Bitmap.h
+++ b/shared-module/displayio/Bitmap.h
@@ -31,6 +31,7 @@
 #include <stdint.h>
 
 #include "py/obj.h"
+#include "shared-module/displayio/area.h"
 
 typedef struct {
     mp_obj_base_t base;
@@ -41,8 +42,12 @@ typedef struct {
     uint8_t bits_per_value;
     uint8_t x_shift;
     size_t x_mask;
+    displayio_area_t dirty_area;
     uint16_t bitmask;
     bool read_only;
 } displayio_bitmap_t;
 
+void displayio_bitmap_finish_refresh(displayio_bitmap_t *self);
+displayio_area_t* displayio_bitmap_get_refresh_areas(displayio_bitmap_t *self, displayio_area_t* tail);
+
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_BITMAP_H
diff --git a/shared-module/displayio/TileGrid.c b/shared-module/displayio/TileGrid.c
index cdca45a29..31abfb712 100644
--- a/shared-module/displayio/TileGrid.c
+++ b/shared-module/displayio/TileGrid.c
@@ -26,6 +26,7 @@
 
 #include "shared-bindings/displayio/TileGrid.h"
 
+#include "py/runtime.h"
 #include "shared-bindings/displayio/Bitmap.h"
 #include "shared-bindings/displayio/ColorConverter.h"
 #include "shared-bindings/displayio/OnDiskBitmap.h"
@@ -33,7 +34,7 @@
 #include "shared-bindings/displayio/Shape.h"
 
 void common_hal_displayio_tilegrid_construct(displayio_tilegrid_t *self, mp_obj_t bitmap,
-        uint16_t bitmap_width_in_tiles,
+        uint16_t bitmap_width_in_tiles, uint16_t bitmap_height_in_tiles,
         mp_obj_t pixel_shader, uint16_t width, uint16_t height,
         uint16_t tile_width, uint16_t tile_height, uint16_t x, uint16_t y, uint8_t default_tile) {
     uint32_t total_tiles = width * height;
@@ -54,6 +55,7 @@ void common_hal_displayio_tilegrid_construct(displayio_tilegrid_t *self, mp_obj_
         self->inline_tiles = false;
     }
     self->bitmap_width_in_tiles = bitmap_width_in_tiles;
+    self->tiles_in_bitmap = bitmap_width_in_tiles * bitmap_height_in_tiles;
     self->width_in_tiles = width;
     self->height_in_tiles = height;
     self->x = x;
@@ -204,6 +206,9 @@ uint8_t common_hal_displayio_tilegrid_get_tile(displayio_tilegrid_t *self, uint1
 }
 
 void common_hal_displayio_tilegrid_set_tile(displayio_tilegrid_t *self, uint16_t x, uint16_t y, uint8_t tile_index) {
+    if (tile_index >= self->tiles_in_bitmap) {
+        mp_raise_ValueError(translate("Tile value out of bounds"));
+    }
     uint8_t* tiles = self->tiles;
     if (self->inline_tiles) {
         tiles = (uint8_t*) &self->tiles;
@@ -442,6 +447,14 @@ void displayio_tilegrid_finish_refresh(displayio_tilegrid_t *self) {
     } else if (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_colorconverter_type)) {
         displayio_colorconverter_finish_refresh(self->pixel_shader);
     }
+    if (MP_OBJ_IS_TYPE(self->bitmap, &displayio_bitmap_type)) {
+        displayio_bitmap_finish_refresh(self->bitmap);
+    } else if (MP_OBJ_IS_TYPE(self->bitmap, &displayio_shape_type)) {
+        // TODO: Support shape changes.
+    } else if (MP_OBJ_IS_TYPE(self->bitmap, &displayio_ondiskbitmap_type)) {
+        // OnDiskBitmap changes will trigger a complete reload so no need to
+        // track changes.
+    }
     // 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.
 }
@@ -458,8 +471,21 @@ displayio_area_t* displayio_tilegrid_get_refresh_areas(displayio_tilegrid_t *sel
         return &self->current_area;
     }
 
-    // We must recheck if our sources require a refresh because needs_refresh may or may not have
-    // been called.
+    // If we have an in-memory bitmap, then check it for modifications.
+    if (MP_OBJ_IS_TYPE(self->bitmap, &displayio_bitmap_type)) {
+        displayio_area_t* refresh_area = displayio_bitmap_get_refresh_areas(self->bitmap, tail);
+        if (refresh_area != tail) {
+            // Special case a TileGrid that shows a full bitmap and use it's
+            // dirty area. Copy it to ours so we can transform it.
+            if (self->tiles_in_bitmap == 1) {
+                displayio_area_copy(refresh_area, &self->dirty_area);
+                self->partial_change = true;
+            } else {
+                self->full_change = true;
+            }
+        }
+    }
+
     self->full_change = self->full_change ||
         (MP_OBJ_IS_TYPE(self->pixel_shader, &displayio_palette_type) &&
          displayio_palette_needs_refresh(self->pixel_shader)) ||
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;