Merge pull request #102 from FoamyGuy/set_root_group

root_group properties/functions on Display object and displaycore.

displayio/_display.py

@@ -23,7 +23,7 @@ import threading
 from typing import Optional
 from dataclasses import astuple
 import digitalio
-from PIL import Image
+from PIL import Image, ImageDraw
 import numpy
 import microcontroller
 import circuitpython_typing
@@ -158,7 +158,7 @@ class Display:
         self._buffer = Image.new("RGB", (width, height))
         self._subrectangles = []
         self._bounds_encoding = ">BB" if single_byte_bounds else ">HH"
-        self._current_group = None
+
         displays.append(self)
         self._refresh_thread = None
         if self._auto_refresh:
@@ -240,7 +240,7 @@ class Display:
         """Switches to displaying the given group of layers. When group is None, the
         default CircuitPython terminal will be shown.
         """
-        self._core.show(group)
+        self._core.set_root_group(group)
 
     def refresh(
         self,
@@ -263,6 +263,7 @@ class Display:
         if not self._core.start_refresh():
             return False
 
+        force_full_refresh = False
         # Go through groups and and add each to buffer
         if self._core._current_group is not None:
             buffer = Image.new("RGBA", (self._core._width, self._core._height))
@@ -272,11 +273,21 @@ class Display:
             )  # pylint: disable=protected-access
             # save image to buffer (or probably refresh buffer so we can compare)
             self._buffer.paste(buffer)
+        else:
+            # show nothing
+            buffer = Image.new("RGBA", (self._core._width, self._core._height))
+            draw = ImageDraw.Draw(buffer)
+            draw.rectangle([(0, 0), buffer.size], fill=(0, 0, 0))
+            self._buffer.paste(buffer)
+            force_full_refresh = True
 
-        self._subrectangles = self._core.get_refresh_areas()
-
-        for area in self._subrectangles:
-            self._refresh_display_area(area)
+        if force_full_refresh:
+            full_rect = RectangleStruct(0, 0, self._width, self._height)
+            self._refresh_display_area(full_rect)
+        else:
+            self._subrectangles = self._core.get_refresh_areas()
+            for area in self._subrectangles:
+                self._refresh_display_area(area)
 
         self._core.finish_refresh()
 
@@ -452,3 +463,15 @@ class Display:
     def bus(self) -> _DisplayBus:
         """Current Display Bus"""
         return self._core.get_bus()
+
+    @property
+    def root_group(self) -> Group:
+        """The root group on the display."""
+        return self._core.get_root_group()
+
+    @root_group.setter
+    def root_group(self, new_group):
+        """Switches to displaying the given group of layers. When group is None,
+        a blank screen will be shown.
+        """
+        self._core.set_root_group(new_group)

displayio/_displaycore.py

@@ -151,7 +151,11 @@ class _DisplayCore:
         if self._current_group is not None:
             self._current_group._update_transform(self._transform)
 
-    def show(self, root_group: Group) -> bool:
+    def get_root_group(self):
+        """The root group on the display."""
+        return self._current_group
+
+    def set_root_group(self, root_group: Group) -> bool:
         # pylint: disable=protected-access
 
         """