add circuitpython code

1 files changed, 652 insertions, 0 deletions

diff --git a/circuitpython/shared-module/displayio/TileGrid.c b/circuitpython/shared-module/displayio/TileGrid.c
new file mode 100644
index 0000000..5c968c3
--- /dev/null
+++ b/circuitpython/shared-module/displayio/TileGrid.c
@@ -0,0 +1,652 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#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"
+#include "shared-bindings/displayio/Palette.h"
+#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_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;
+    // Sprites will only have one tile so save a little memory by inlining values in the pointer.
+    uint8_t inline_tiles = sizeof(uint8_t *);
+    if (total_tiles <= inline_tiles) {
+        self->tiles = 0;
+        // Pack values into the pointer since there are only a few.
+        for (uint32_t i = 0; i < inline_tiles; i++) {
+            ((uint8_t *)&self->tiles)[i] = default_tile;
+        }
+        self->inline_tiles = true;
+    } else {
+        self->tiles = (uint8_t *)m_malloc(total_tiles, false);
+        for (uint32_t i = 0; i < total_tiles; i++) {
+            self->tiles[i] = default_tile;
+        }
+        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;
+    self->y = y;
+    self->pixel_width = width * tile_width;
+    self->pixel_height = height * tile_height;
+    self->tile_width = tile_width;
+    self->tile_height = tile_height;
+    self->bitmap = bitmap;
+    self->pixel_shader = pixel_shader;
+    self->in_group = false;
+    self->hidden = false;
+    self->hidden_by_parent = false;
+    self->previous_area.x1 = 0xffff;
+    self->previous_area.x2 = self->previous_area.x1;
+    self->flip_x = false;
+    self->flip_y = false;
+    self->transpose_xy = false;
+    self->absolute_transform = NULL;
+}
+
+
+bool common_hal_displayio_tilegrid_get_hidden(displayio_tilegrid_t *self) {
+    return self->hidden;
+}
+
+void common_hal_displayio_tilegrid_set_hidden(displayio_tilegrid_t *self, bool hidden) {
+    self->hidden = hidden;
+    if (!hidden) {
+        self->full_change = true;
+    }
+}
+
+void displayio_tilegrid_set_hidden_by_parent(displayio_tilegrid_t *self, bool hidden) {
+    self->hidden_by_parent = hidden;
+    if (!hidden) {
+        self->full_change = true;
+    }
+}
+
+bool displayio_tilegrid_get_previous_area(displayio_tilegrid_t *self, displayio_area_t *area) {
+    if (self->previous_area.x1 == self->previous_area.x2) {
+        return false;
+    }
+    displayio_area_copy(&self->previous_area, area);
+    return true;
+}
+
+STATIC void _update_current_x(displayio_tilegrid_t *self) {
+    uint16_t width;
+    if (self->transpose_xy) {
+        width = self->pixel_height;
+    } else {
+        width = self->pixel_width;
+    }
+
+    // If there's no transform, substitute an identity transform so the calculations will work.
+    const displayio_buffer_transform_t *absolute_transform =
+        self->absolute_transform == NULL
+        ? &null_transform
+        : self->absolute_transform;
+
+    if (absolute_transform->transpose_xy) {
+        self->current_area.y1 = absolute_transform->y + absolute_transform->dy * self->x;
+        self->current_area.y2 = absolute_transform->y + absolute_transform->dy * (self->x + width);
+        if (self->current_area.y2 < self->current_area.y1) {
+            int16_t temp = self->current_area.y2;
+            self->current_area.y2 = self->current_area.y1;
+            self->current_area.y1 = temp;
+        }
+    } else {
+        self->current_area.x1 = absolute_transform->x + absolute_transform->dx * self->x;
+        self->current_area.x2 = absolute_transform->x + absolute_transform->dx * (self->x + width);
+        if (self->current_area.x2 < self->current_area.x1) {
+            int16_t temp = self->current_area.x2;
+            self->current_area.x2 = self->current_area.x1;
+            self->current_area.x1 = temp;
+        }
+    }
+}
+
+STATIC void _update_current_y(displayio_tilegrid_t *self) {
+    uint16_t height;
+    if (self->transpose_xy) {
+        height = self->pixel_width;
+    } else {
+        height = self->pixel_height;
+    }
+
+    // If there's no transform, substitute an identity transform so the calculations will work.
+    const displayio_buffer_transform_t *absolute_transform =
+        self->absolute_transform == NULL
+        ? &null_transform
+        : self->absolute_transform;
+
+    if (absolute_transform->transpose_xy) {
+        self->current_area.x1 = absolute_transform->x + absolute_transform->dx * self->y;
+        self->current_area.x2 = absolute_transform->x + absolute_transform->dx * (self->y + height);
+        if (self->current_area.x2 < self->current_area.x1) {
+            int16_t temp = self->current_area.x2;
+            self->current_area.x2 = self->current_area.x1;
+            self->current_area.x1 = temp;
+        }
+    } else {
+        self->current_area.y1 = absolute_transform->y + absolute_transform->dy * self->y;
+        self->current_area.y2 = absolute_transform->y + absolute_transform->dy * (self->y + height);
+        if (self->current_area.y2 < self->current_area.y1) {
+            int16_t temp = self->current_area.y2;
+            self->current_area.y2 = self->current_area.y1;
+            self->current_area.y1 = temp;
+        }
+    }
+}
+
+void displayio_tilegrid_update_transform(displayio_tilegrid_t *self,
+    const displayio_buffer_transform_t *absolute_transform) {
+    self->in_group = absolute_transform != NULL;
+    self->absolute_transform = absolute_transform;
+    if (absolute_transform != NULL) {
+        self->moved = true;
+
+        _update_current_x(self);
+        _update_current_y(self);
+    }
+}
+
+mp_int_t common_hal_displayio_tilegrid_get_x(displayio_tilegrid_t *self) {
+    return self->x;
+}
+void common_hal_displayio_tilegrid_set_x(displayio_tilegrid_t *self, mp_int_t x) {
+    if (self->x == x) {
+        return;
+    }
+
+    self->moved = true;
+
+    self->x = x;
+    if (self->absolute_transform != NULL) {
+        _update_current_x(self);
+    }
+}
+mp_int_t common_hal_displayio_tilegrid_get_y(displayio_tilegrid_t *self) {
+    return self->y;
+}
+
+void common_hal_displayio_tilegrid_set_y(displayio_tilegrid_t *self, mp_int_t y) {
+    if (self->y == y) {
+        return;
+    }
+    self->moved = true;
+    self->y = y;
+    if (self->absolute_transform != NULL) {
+        _update_current_y(self);
+    }
+}
+
+mp_obj_t common_hal_displayio_tilegrid_get_pixel_shader(displayio_tilegrid_t *self) {
+    return self->pixel_shader;
+}
+
+void common_hal_displayio_tilegrid_set_pixel_shader(displayio_tilegrid_t *self, mp_obj_t pixel_shader) {
+    self->pixel_shader = pixel_shader;
+    self->full_change = true;
+}
+
+mp_obj_t common_hal_displayio_tilegrid_get_bitmap(displayio_tilegrid_t *self) {
+    return self->bitmap;
+}
+
+void common_hal_displayio_tilegrid_set_bitmap(displayio_tilegrid_t *self, mp_obj_t bitmap) {
+    self->bitmap = bitmap;
+    self->full_change = true;
+}
+
+uint16_t common_hal_displayio_tilegrid_get_width(displayio_tilegrid_t *self) {
+    return self->width_in_tiles;
+}
+
+uint16_t common_hal_displayio_tilegrid_get_height(displayio_tilegrid_t *self) {
+    return self->height_in_tiles;
+}
+
+uint16_t common_hal_displayio_tilegrid_get_tile_width(displayio_tilegrid_t *self) {
+    return self->tile_width;
+}
+
+uint16_t common_hal_displayio_tilegrid_get_tile_height(displayio_tilegrid_t *self) {
+    return self->tile_height;
+}
+
+uint8_t common_hal_displayio_tilegrid_get_tile(displayio_tilegrid_t *self, uint16_t x, uint16_t y) {
+    uint8_t *tiles = self->tiles;
+    if (self->inline_tiles) {
+        tiles = (uint8_t *)&self->tiles;
+    }
+    if (tiles == NULL) {
+        return 0;
+    }
+    return tiles[y * self->width_in_tiles + x];
+}
+
+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 index out of bounds"));
+    }
+    uint8_t *tiles = self->tiles;
+    if (self->inline_tiles) {
+        tiles = (uint8_t *)&self->tiles;
+    }
+    if (tiles == NULL) {
+        return;
+    }
+    tiles[y * self->width_in_tiles + x] = tile_index;
+    displayio_area_t temp_area;
+    displayio_area_t *tile_area;
+    if (!self->partial_change) {
+        tile_area = &self->dirty_area;
+    } else {
+        tile_area = &temp_area;
+    }
+    int16_t tx = (x - self->top_left_x) % self->width_in_tiles;
+    if (tx < 0) {
+        tx += self->width_in_tiles;
+    }
+    tile_area->x1 = tx * self->tile_width;
+    tile_area->x2 = tile_area->x1 + self->tile_width;
+    int16_t ty = (y - self->top_left_y) % self->height_in_tiles;
+    if (ty < 0) {
+        ty += self->height_in_tiles;
+    }
+    tile_area->y1 = ty * self->tile_height;
+    tile_area->y2 = tile_area->y1 + self->tile_height;
+
+    if (self->partial_change) {
+        displayio_area_union(&self->dirty_area, &temp_area, &self->dirty_area);
+    }
+
+    self->partial_change = true;
+}
+
+bool common_hal_displayio_tilegrid_get_flip_x(displayio_tilegrid_t *self) {
+    return self->flip_x;
+}
+
+void common_hal_displayio_tilegrid_set_flip_x(displayio_tilegrid_t *self, bool flip_x) {
+    if (self->flip_x == flip_x) {
+        return;
+    }
+    self->flip_x = flip_x;
+    self->full_change = true;
+}
+
+bool common_hal_displayio_tilegrid_get_flip_y(displayio_tilegrid_t *self) {
+    return self->flip_y;
+}
+
+void common_hal_displayio_tilegrid_set_flip_y(displayio_tilegrid_t *self, bool flip_y) {
+    if (self->flip_y == flip_y) {
+        return;
+    }
+    self->flip_y = flip_y;
+    self->full_change = true;
+}
+
+bool common_hal_displayio_tilegrid_get_transpose_xy(displayio_tilegrid_t *self) {
+    return self->transpose_xy;
+}
+
+void common_hal_displayio_tilegrid_set_transpose_xy(displayio_tilegrid_t *self, bool transpose_xy) {
+    if (self->transpose_xy == transpose_xy) {
+        return;
+    }
+    self->transpose_xy = transpose_xy;
+
+    // Square TileGrids do not change dimensions when transposed.
+    if (self->pixel_width == self->pixel_height) {
+        self->full_change = true;
+        return;
+    }
+
+    _update_current_x(self);
+    _update_current_y(self);
+
+    self->moved = true;
+}
+
+void common_hal_displayio_tilegrid_set_top_left(displayio_tilegrid_t *self, uint16_t x, uint16_t y) {
+    self->top_left_x = x;
+    self->top_left_y = y;
+    self->full_change = true;
+}
+
+bool displayio_tilegrid_fill_area(displayio_tilegrid_t *self,
+    const _displayio_colorspace_t *colorspace, const displayio_area_t *area,
+    uint32_t *mask, uint32_t *buffer) {
+    // If no tiles are present we have no impact.
+    uint8_t *tiles = self->tiles;
+    if (self->inline_tiles) {
+        tiles = (uint8_t *)&self->tiles;
+    }
+    if (tiles == NULL) {
+        return false;
+    }
+
+    bool hidden = self->hidden || self->hidden_by_parent;
+    if (hidden) {
+        return false;
+    }
+
+    displayio_area_t overlap;
+    if (!displayio_area_compute_overlap(area, &self->current_area, &overlap)) {
+        return false;
+    }
+
+    int16_t x_stride = 1;
+    int16_t y_stride = displayio_area_width(area);
+
+    bool flip_x = self->flip_x;
+    bool flip_y = self->flip_y;
+    if (self->transpose_xy != self->absolute_transform->transpose_xy) {
+        bool temp_flip = flip_x;
+        flip_x = flip_y;
+        flip_y = temp_flip;
+    }
+
+    // How many pixels are outside of our area between us and the start of the row.
+    uint16_t start = 0;
+    if ((self->absolute_transform->dx < 0) != flip_x) {
+        start += (area->x2 - area->x1 - 1) * x_stride;
+        x_stride *= -1;
+    }
+    if ((self->absolute_transform->dy < 0) != flip_y) {
+        start += (area->y2 - area->y1 - 1) * y_stride;
+        y_stride *= -1;
+    }
+
+    // Track if this layer finishes filling in the given area. We can ignore any remaining
+    // layers at that point.
+    bool full_coverage = displayio_area_equal(area, &overlap);
+
+    // TODO(tannewt): Skip coverage tracking if all pixels outside the overlap have already been
+    // set and our palette is all opaque.
+
+    // TODO(tannewt): Check to see if the pixel_shader has any transparency. If it doesn't then we
+    // can either return full coverage or bulk update the mask.
+    displayio_area_t transformed;
+    displayio_area_transform_within(flip_x != (self->absolute_transform->dx < 0), flip_y != (self->absolute_transform->dy < 0), self->transpose_xy != self->absolute_transform->transpose_xy,
+        &overlap,
+        &self->current_area,
+        &transformed);
+
+    int16_t start_x = (transformed.x1 - self->current_area.x1);
+    int16_t end_x = (transformed.x2 - self->current_area.x1);
+    int16_t start_y = (transformed.y1 - self->current_area.y1);
+    int16_t end_y = (transformed.y2 - self->current_area.y1);
+
+    int16_t y_shift = 0;
+    int16_t x_shift = 0;
+    if ((self->absolute_transform->dx < 0) != flip_x) {
+        x_shift = area->x2 - overlap.x2;
+    } else {
+        x_shift = overlap.x1 - area->x1;
+    }
+    if ((self->absolute_transform->dy < 0) != flip_y) {
+        y_shift = area->y2 - overlap.y2;
+    } else {
+        y_shift = overlap.y1 - area->y1;
+    }
+
+    // This untransposes x and y so it aligns with bitmap rows.
+    if (self->transpose_xy != self->absolute_transform->transpose_xy) {
+        int16_t temp_stride = x_stride;
+        x_stride = y_stride;
+        y_stride = temp_stride;
+        int16_t temp_shift = x_shift;
+        x_shift = y_shift;
+        y_shift = temp_shift;
+    }
+
+    uint8_t pixels_per_byte = 8 / colorspace->depth;
+
+    displayio_input_pixel_t input_pixel;
+    displayio_output_pixel_t output_pixel;
+
+    for (input_pixel.y = start_y; input_pixel.y < end_y; ++input_pixel.y) {
+        int16_t row_start = start + (input_pixel.y - start_y + y_shift) * y_stride; // in pixels
+        int16_t local_y = input_pixel.y / self->absolute_transform->scale;
+        for (input_pixel.x = start_x; input_pixel.x < end_x; ++input_pixel.x) {
+            // Compute the destination pixel in the buffer and mask based on the transformations.
+            int16_t offset = row_start + (input_pixel.x - start_x + x_shift) * x_stride; // in pixels
+
+            // This is super useful for debugging out of range accesses. Uncomment to use.
+            // if (offset < 0 || offset >= (int32_t) displayio_area_size(area)) {
+            //     asm("bkpt");
+            // }
+
+            // Check the mask first to see if the pixel has already been set.
+            if ((mask[offset / 32] & (1 << (offset % 32))) != 0) {
+                continue;
+            }
+            int16_t local_x = input_pixel.x / self->absolute_transform->scale;
+            uint16_t tile_location = ((local_y / self->tile_height + self->top_left_y) % self->height_in_tiles) * self->width_in_tiles + (local_x / self->tile_width + self->top_left_x) % self->width_in_tiles;
+            input_pixel.tile = tiles[tile_location];
+            input_pixel.tile_x = (input_pixel.tile % self->bitmap_width_in_tiles) * self->tile_width + local_x % self->tile_width;
+            input_pixel.tile_y = (input_pixel.tile / self->bitmap_width_in_tiles) * self->tile_height + local_y % self->tile_height;
+
+            output_pixel.pixel = 0;
+            input_pixel.pixel = 0;
+
+            // We always want to read bitmap pixels by row first and then transpose into the destination
+            // buffer because most bitmaps are row associated.
+            if (mp_obj_is_type(self->bitmap, &displayio_bitmap_type)) {
+                input_pixel.pixel = common_hal_displayio_bitmap_get_pixel(self->bitmap, input_pixel.tile_x, input_pixel.tile_y);
+            } else if (mp_obj_is_type(self->bitmap, &displayio_shape_type)) {
+                input_pixel.pixel = common_hal_displayio_shape_get_pixel(self->bitmap, input_pixel.tile_x, input_pixel.tile_y);
+            } else if (mp_obj_is_type(self->bitmap, &displayio_ondiskbitmap_type)) {
+                input_pixel.pixel = common_hal_displayio_ondiskbitmap_get_pixel(self->bitmap, input_pixel.tile_x, input_pixel.tile_y);
+            }
+
+            output_pixel.opaque = true;
+            if (self->pixel_shader == mp_const_none) {
+                output_pixel.pixel = input_pixel.pixel;
+            } else if (mp_obj_is_type(self->pixel_shader, &displayio_palette_type)) {
+                output_pixel.opaque = displayio_palette_get_color(self->pixel_shader, colorspace, input_pixel.pixel, &output_pixel.pixel);
+            } else if (mp_obj_is_type(self->pixel_shader, &displayio_colorconverter_type)) {
+                displayio_colorconverter_convert(self->pixel_shader, colorspace, &input_pixel, &output_pixel);
+            }
+            if (!output_pixel.opaque) {
+                // A pixel is transparent so we haven't fully covered the area ourselves.
+                full_coverage = false;
+            } else {
+                mask[offset / 32] |= 1 << (offset % 32);
+                if (colorspace->depth == 16) {
+                    *(((uint16_t *)buffer) + offset) = output_pixel.pixel;
+                } else if (colorspace->depth == 32) {
+                    *(((uint32_t *)buffer) + offset) = output_pixel.pixel;
+                } else if (colorspace->depth == 8) {
+                    *(((uint8_t *)buffer) + offset) = output_pixel.pixel;
+                } else if (colorspace->depth < 8) {
+                    // Reorder the offsets to pack multiple rows into a byte (meaning they share a column).
+                    if (!colorspace->pixels_in_byte_share_row) {
+                        uint16_t width = displayio_area_width(area);
+                        uint16_t row = offset / width;
+                        uint16_t col = offset % width;
+                        // Dividing by pixels_per_byte does truncated division even if we multiply it back out.
+                        offset = col * pixels_per_byte + (row / pixels_per_byte) * pixels_per_byte * width + row % pixels_per_byte;
+                        // Also useful for validating that the bitpacking worked correctly.
+                        // if (offset > displayio_area_size(area)) {
+                        //     asm("bkpt");
+                        // }
+                    }
+                    uint8_t shift = (offset % pixels_per_byte) * colorspace->depth;
+                    if (colorspace->reverse_pixels_in_byte) {
+                        // Reverse the shift by subtracting it from the leftmost shift.
+                        shift = (pixels_per_byte - 1) * colorspace->depth - shift;
+                    }
+                    ((uint8_t *)buffer)[offset / pixels_per_byte] |= output_pixel.pixel << shift;
+                }
+            }
+            (void)input_pixel;
+        }
+    }
+    return full_coverage;
+}
+
+void displayio_tilegrid_finish_refresh(displayio_tilegrid_t *self) {
+    bool first_draw = self->previous_area.x1 == self->previous_area.x2;
+    bool hidden = self->hidden || self->hidden_by_parent;
+    if (!first_draw && hidden) {
+        self->previous_area.x2 = self->previous_area.x1;
+    } else if (self->moved || first_draw) {
+        displayio_area_copy(&self->current_area, &self->previous_area);
+    }
+
+    self->moved = false;
+    self->full_change = false;
+    self->partial_change = false;
+    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);
+    }
+    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)) {
+        displayio_shape_finish_refresh(self->bitmap);
+    } 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.
+}
+
+displayio_area_t *displayio_tilegrid_get_refresh_areas(displayio_tilegrid_t *self, displayio_area_t *tail) {
+    bool first_draw = self->previous_area.x1 == self->previous_area.x2;
+    bool hidden = self->hidden || self->hidden_by_parent;
+    // Check hidden first because it trumps all other changes.
+    if (hidden) {
+        if (!first_draw) {
+            self->previous_area.next = tail;
+            return &self->previous_area;
+        } else {
+            return tail;
+        }
+    } else if (self->moved && !first_draw) {
+        displayio_area_union(&self->previous_area, &self->current_area, &self->dirty_area);
+        if (displayio_area_size(&self->dirty_area) <= 2U * self->pixel_width * self->pixel_height) {
+            self->dirty_area.next = tail;
+            return &self->dirty_area;
+        }
+        self->previous_area.next = tail;
+        self->current_area.next = &self->previous_area;
+        return &self->current_area;
+    }
+
+    // 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 its
+            // 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;
+            }
+        }
+    } else if (mp_obj_is_type(self->bitmap, &displayio_shape_type)) {
+        displayio_area_t *refresh_area = displayio_shape_get_refresh_areas(self->bitmap, tail);
+        if (refresh_area != tail) {
+            displayio_area_copy(refresh_area, &self->dirty_area);
+            self->partial_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)) ||
+        (mp_obj_is_type(self->pixel_shader, &displayio_colorconverter_type) &&
+            displayio_colorconverter_needs_refresh(self->pixel_shader));
+    if (self->full_change || first_draw) {
+        self->current_area.next = tail;
+        return &self->current_area;
+    }
+
+    if (self->partial_change) {
+        int16_t x = self->x;
+        int16_t y = self->y;
+        if (self->absolute_transform->transpose_xy) {
+            int16_t temp = y;
+            y = x;
+            x = temp;
+        }
+        int16_t x1 = self->dirty_area.x1;
+        int16_t x2 = self->dirty_area.x2;
+        if (self->flip_x) {
+            x1 = self->pixel_width - x1;
+            x2 = self->pixel_width - x2;
+        }
+        int16_t y1 = self->dirty_area.y1;
+        int16_t y2 = self->dirty_area.y2;
+        if (self->flip_y) {
+            y1 = self->pixel_height - y1;
+            y2 = self->pixel_height - y2;
+        }
+        if (self->transpose_xy != self->absolute_transform->transpose_xy) {
+            int16_t temp1 = y1, temp2 = y2;
+            y1 = x1;
+            x1 = temp1;
+            y2 = x2;
+            x2 = temp2;
+        }
+        self->dirty_area.x1 = self->absolute_transform->x + self->absolute_transform->dx * (x + x1);
+        self->dirty_area.y1 = self->absolute_transform->y + self->absolute_transform->dy * (y + y1);
+        self->dirty_area.x2 = self->absolute_transform->x + self->absolute_transform->dx * (x + x2);
+        self->dirty_area.y2 = self->absolute_transform->y + self->absolute_transform->dy * (y + y2);
+        if (self->dirty_area.y2 < self->dirty_area.y1) {
+            int16_t temp = self->dirty_area.y2;
+            self->dirty_area.y2 = self->dirty_area.y1;
+            self->dirty_area.y1 = temp;
+        }
+        if (self->dirty_area.x2 < self->dirty_area.x1) {
+            int16_t temp = self->dirty_area.x2;
+            self->dirty_area.x2 = self->dirty_area.x1;
+            self->dirty_area.x1 = temp;
+        }
+
+        self->dirty_area.next = tail;
+        return &self->dirty_area;
+    }
+    return tail;
+}