Support & demo interrupt handlers for buttons

examples/pwm-backlight.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+import time
+from displayhatmini import DisplayHATMini
+
+try:
+    from PIL import Image, ImageDraw, ImageFont
+except ImportError:
+    print("""This example requires PIL/Pillow, try:
+
+sudo apt install python3-pil
+
+""")
+
+width = DisplayHATMini.WIDTH
+height = DisplayHATMini.HEIGHT
+buffer = Image.new("RGB", (width, height))
+draw = ImageDraw.Draw(buffer)
+font = ImageFont.load_default()
+
+displayhatmini = DisplayHATMini(buffer, backlight_pwm=True)
+displayhatmini.set_led(0.05, 0.05, 0.05)
+
+brightness = 1.0
+
+
+# Plumbing to convert Display HAT Mini button presses into pygame events
+def button_callback(pin):
+    global brightness
+
+    # Only handle presses
+    if not displayhatmini.read_button(pin):
+        return
+
+    if pin == displayhatmini.BUTTON_A:
+        brightness += 0.1
+        brightness = min(1, brightness)
+
+    if pin == displayhatmini.BUTTON_B:
+        brightness -= 0.1
+        brightness = max(0, brightness)
+
+
+displayhatmini.on_button_pressed(button_callback)
+
+draw.rectangle((0, 0, width, height), (255, 255, 255))
+draw.text((10, 70), "Backlight Up", font=font, fill=(0, 0, 0))
+draw.text((10, 160), "Backlight Down", font=font, fill=(0, 0, 0))
+
+while True:
+    displayhatmini.display()
+    displayhatmini.set_backlight(brightness)
+    time.sleep(1.0 / 30)

examples/pygame-basic.py

@@ -10,6 +10,10 @@
 
 print("""Display HAT Mini: Basic Pygame Demo""")
 
+if pygame.vernum < (2, 0, 0):
+    print("Need PyGame >= 2.0.0:\n    python3 -m pip install pygame --upgrade")
+    sys.exit(1)
+
 
 def _exit(sig, frame):
     global running

examples/pygame-button-interrupt.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+import os
+import sys
+import signal
+import pygame
+import time
+import math
+from threading import Lock
+
+from displayhatmini import DisplayHATMini
+
+
+print("""Display HAT Mini: Basic Pygame Demo""")
+
+if pygame.vernum < (2, 0, 0):
+    print("Need PyGame >= 2.0.0:\n    python3 -m pip install pygame --upgrade")
+    sys.exit(1)
+
+
+def _exit(sig, frame):
+    global running
+    running = False
+    print("\nExiting!...\n")
+
+
+def update_display():
+    display_hat.st7789.set_window()
+    # Grab the pygame screen as a bytes object
+    pixelbytes = pygame.transform.rotate(screen, 180).convert(16, 0).get_buffer()
+    # Lazy (slow) byteswap:
+    pixelbytes = bytearray(pixelbytes)
+    pixelbytes[0::2], pixelbytes[1::2] = pixelbytes[1::2], pixelbytes[0::2]
+    # Bypass the ST7789 PIL image RGB888->RGB565 conversion
+    for i in range(0, len(pixelbytes), 4096):
+        display_hat.st7789.data(pixelbytes[i:i + 4096])
+
+
+display_hat = DisplayHATMini(None)
+event_lock = Lock()
+
+os.putenv('SDL_VIDEODRIVER', 'dummy')
+pygame.display.init()  # Need to init for .convert() to work
+screen = pygame.Surface((display_hat.WIDTH, display_hat.HEIGHT))
+
+signal.signal(signal.SIGINT, _exit)
+
+
+# Plumbing to convert Display HAT Mini button presses into pygame events
+def button_callback(pin):
+    key = {
+        display_hat.BUTTON_A: 'a',
+        display_hat.BUTTON_B: 'b',
+        display_hat.BUTTON_X: 'x',
+        display_hat.BUTTON_Y: 'y'
+    }[pin]
+    event = pygame.KEYDOWN if display_hat.read_button(pin) else pygame.KEYUP
+    pygame.event.post(pygame.event.Event(event, unicode=key, key=pygame.key.key_code(key)))
+
+
+display_hat.on_button_pressed(button_callback)
+
+running = True
+
+while running:
+    for event in pygame.event.get():
+        if event.type == pygame.QUIT:
+            running = False
+            break
+        if event.type == pygame.KEYDOWN:
+            if event.key in (pygame.K_a, pygame.K_ESCAPE):
+                running = False
+                break
+
+    # Clear the screen
+    screen.fill((0, 0, 0))
+
+    box_w = display_hat.WIDTH // 3
+    box_h = display_hat.HEIGHT // 2
+
+    pygame.draw.rect(screen, (255, 0, 0), (0, 0, box_w, box_h))
+    pygame.draw.rect(screen, (0, 255, 0), (box_w, 0, box_w, box_h))
+    pygame.draw.rect(screen, (0, 0, 255), (box_w * 2, 0, box_w, box_h))
+
+    pygame.draw.rect(screen, (255, 255, 0), (0, box_h, box_w, box_h))
+    pygame.draw.rect(screen, (255, 0, 255), (box_w, box_h, box_w, box_h))
+    pygame.draw.rect(screen, (0, 255, 255), (box_w * 2, box_h, box_w, box_h))
+
+    r = 50
+    x = math.sin(time.time() * 2) * (display_hat.WIDTH - r) / 2
+    y = math.cos(time.time()) * (display_hat.HEIGHT - r) / 2
+    x += display_hat.WIDTH // 2
+    y += display_hat.HEIGHT // 2
+    pygame.draw.circle(screen, (0, 0, 0), (int(x), int(y)), r)
+
+    update_display()
+
+
+screen.fill((0, 0, 0))
+update_display()
+
+pygame.quit()
+sys.exit(0)

examples/pygame-demo.py

@@ -12,6 +12,10 @@
 
 print("""Display HAT Mini: Pygame Demo""")
 
+if pygame.vernum < (2, 0, 0):
+    print("Need PyGame >= 2.0.0:\n    python3 -m pip install pygame --upgrade")
+    sys.exit(1)
+
 
 hue_to_rgb = []
 

library/displayhatmini/__init__.py

@@ -27,7 +27,7 @@ class DisplayHATMini():
     WIDTH = 320
     HEIGHT = 240
 
-    def __init__(self, buffer):
+    def __init__(self, buffer, backlight_pwm=False):
         """Initialise displayhatmini
         """
 
@@ -55,11 +55,18 @@ def __init__(self, buffer):
         self.led_b_pwm = GPIO.PWM(self.LED_B, 2000)
         self.led_b_pwm.start(100)
 
+        if backlight_pwm:
+            GPIO.setup(self.BACKLIGHT, GPIO.OUT)
+            self.backlight_pwm = GPIO.PWM(self.BACKLIGHT, 500)
+            self.backlight_pwm.start(100)
+        else:
+            self.backlight_pwm = None
+
         self.st7789 = ST7789(
             port=self.SPI_PORT,
             cs=self.SPI_CS,
             dc=self.SPI_DC,
-            backlight=self.BACKLIGHT,
+            backlight=None if backlight_pwm else self.BACKLIGHT,
             width=self.WIDTH,
             height=self.HEIGHT,
             rotation=180,
@@ -81,6 +88,16 @@ def set_led(self, r=0, g=0, b=0):
             self.led_g_pwm.ChangeDutyCycle((1.0 - g) * 100)
             self.led_b_pwm.ChangeDutyCycle((1.0 - b) * 100)
 
+    def set_backlight(self, value):
+        if self.backlight_pwm is not None:
+            self.backlight_pwm.ChangeDutyCycle(value * 100)
+        else:
+            self.st7789.set_backlight(int(value))
+
+    def on_button_pressed(self, callback):
+        for pin in (self.BUTTON_A, self.BUTTON_B, self.BUTTON_X, self.BUTTON_Y):
+            GPIO.add_event_detect(pin, GPIO.BOTH, callback=callback)
+
     def read_button(self, pin):
         return not GPIO.input(pin)