Merge pull request #31 from makermelissa/pwm

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

diff --git a/displayio/display.py b/displayio/display.py
index 84cdc25ee985d0c51755db33d06b32687024527f..1ea5d5555d5911a4d0b127af498e3d129ede13ff 100644 (file)
--- a/displayio/display.py
+++ b/displayio/display.py
@@ -155,9 +155,19 @@ class Display:
 
         self._backlight_type = None
         if backlight_pin is not None:
-            self._backlight_type = BACKLIGHT_IN_OUT
-            self._backlight = digitalio.DigitalInOut(backlight_pin)
-            self._backlight.switch_to_output()
+            try:
+                from pulseio import PWMOut  # pylint: disable=import-outside-toplevel
+
+                # 100Hz looks decent and doesn't keep the CPU too busy
+                self._backlight = PWMOut(backlight_pin, frequency=100, duty_cycle=0)
+                self._backlight_type = BACKLIGHT_PWM
+            except ImportError:
+                # PWMOut not implemented on this platform
+                pass
+            if self._backlight_type is None:
+                self._backlight_type = BACKLIGHT_IN_OUT
+                self._backlight = digitalio.DigitalInOut(backlight_pin)
+                self._backlight.switch_to_output()
             self.brightness = brightness
 
     # pylint: enable=too-many-locals
@@ -192,7 +202,7 @@ class Display:
         self._bus.end_transaction()
 
     def _release(self):
-        self._bus.release()
+        self._bus._release()  # pylint: disable=protected-access
         self._bus = None
 
     def show(self, group):
@@ -213,6 +223,8 @@ class Display:
         When auto refresh is on, updates the display immediately. (The display will also
         update without calls to this.)
         """
+        self._subrectangles = []
+
         # Go through groups and and add each to buffer
         if self._current_group is not None:
             buffer = Image.new("RGBA", (self._width, self._height))
@@ -221,8 +233,9 @@ class Display:
             # save image to buffer (or probably refresh buffer so we can compare)
             self._buffer.paste(buffer)
 
-        # Eventually calculate dirty rectangles here
-        self._subrectangles.append(Rectangle(0, 0, self._width, self._height))
+        if self._current_group is not None:
+            # Eventually calculate dirty rectangles here
+            self._subrectangles.append(Rectangle(0, 0, self._width, self._height))
 
         for area in self._subrectangles:
             self._refresh_display_area(area)
@@ -353,9 +366,11 @@ class Display:
         if 0 <= float(value) <= 1.0:
             self._brightness = value
             if self._backlight_type == BACKLIGHT_IN_OUT:
-                self._backlight.value = int(round(self._brightness))
-            # PWM not currently implemented
-            # Command-based brightness not implemented
+                self._backlight.value = round(self._brightness)
+            elif self._backlight_type == BACKLIGHT_PWM:
+                self._backlight.duty_cycle = self._brightness * 65535
+            elif self._brightness_command is not None:
+                self._write(self._brightness_command, round(value * 255))
         else:
             raise ValueError("Brightness must be between 0.0 and 1.0")