Fix link in Readme

[hackapet/Adafruit_Blinka_Displayio.git] / displayio / tilegrid.py

diff --git a/displayio/tilegrid.py b/displayio/tilegrid.py
index c88498da33e94d2e11755c06ba0c51771b350169..2c815a4f9280e92558ffab6d70e4373327ab9076 100644 (file)
--- a/displayio/tilegrid.py
+++ b/displayio/tilegrid.py
@@ -99,14 +99,18 @@ class TileGrid:
         self._flip_y = False
         self._top_left_x = 0
         self._top_left_y = 0
-        if tile_width is None:
+        if tile_width is None or tile_width == 0:
             tile_width = bitmap_width
-        if tile_height is None:
+        if tile_height is None or tile_width == 0:
             tile_height = bitmap_height
-        if tile_width > 0 and bitmap_width % tile_width != 0:
+        if tile_width < 1:
+            tile_width = 1
+        if tile_height < 1:
+            tile_height = 1
+        if bitmap_width % tile_width != 0:
             raise ValueError("Tile width must exactly divide bitmap width")
         self._tile_width = tile_width
-        if tile_height > 0 and bitmap_height % tile_height != 0:
+        if bitmap_height % tile_height != 0:
             raise ValueError("Tile height must exactly divide bitmap height")
         self._tile_height = tile_height
         if not 0 <= default_tile <= 255:
@@ -211,12 +215,15 @@ class TileGrid:
         )
         image.putalpha(alpha.convert("L"))
 
-    # pylint: disable=too-many-locals
+    # pylint: disable=too-many-locals,too-many-branches
     def _fill_area(self, buffer):
         """Draw onto the image"""
         if self._hidden:
             return
 
+        if self._bitmap.width <= 0 or self._bitmap.height <= 0:
+            return
+
         image = Image.new(
             "RGBA",
             (self._width * self._tile_width, self._height * self._tile_height),
@@ -269,9 +276,27 @@ class TileGrid:
             y *= self._absolute_transform.dy
             x += self._absolute_transform.x
             y += self._absolute_transform.y
-        buffer.alpha_composite(image, (x, y))
 
-    # pylint: enable=too-many-locals
+        source_x = source_y = 0
+        if x < 0:
+            source_x = round(0 - x)
+            x = 0
+        if y < 0:
+            source_y = round(0 - y)
+            y = 0
+
+        x = round(x)
+        y = round(y)
+
+        if (
+            x <= buffer.width
+            and y <= buffer.height
+            and source_x <= image.width
+            and source_y <= image.height
+        ):
+            buffer.alpha_composite(image, (x, y), source=(source_x, source_y))
+
+    # pylint: enable=too-many-locals,too-many-branches
 
     @property
     def hidden(self):