displayio example

Author: ladyada

examples/miniqr_displaytest.py

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+import board
+import pulseio
+import displayio
+import adafruit_miniqr
+
+DISPLAY_W = 128
+DISPLAY_H = 128
+
+backlight = pulseio.PWMOut(board.TFT_BACKLIGHT)
+backlight.duty_cycle = 0
+
+def draw_QR(matrix):
+    # how big each pixel is, add 2 blocks on either side
+    BLOCK_SIZE = DISPLAY_W // (qr.matrix.width+4)  
+    
+    # Center the QR code in the middle of the screen
+    X_OFFSET = (DISPLAY_W - BLOCK_SIZE * qr.matrix.width) // 2
+    Y_OFFSET = (DISPLAY_H - BLOCK_SIZE * qr.matrix.height) // 2
+    
+    # monochome (2 color) palette
+    palette = displayio.Palette(2)
+    palette[0] = 0xFFFFFF
+    palette[1] = 0x000000
+    
+    # bitmap the size of the screen, monochrome (2 colors)
+    bitmap = displayio.Bitmap(DISPLAY_H, DISPLAY_W, 2)
+    
+    # raster the QR code
+    line = bytearray(DISPLAY_W // 8)  # monochrome means 8 pixels per byte
+    for y in range(qr.matrix.height):    # each scanline in the height
+        for i in range(len(line)):    # initialize it to be empty
+            line[i] = 0
+        for x in range(qr.matrix.width):
+            if qr.matrix[x, y]:
+                for b in range(BLOCK_SIZE):
+                    _x = X_OFFSET + x * BLOCK_SIZE + b
+                    line[_x // 8] |= 1 << (7-(_x % 8))
+                
+        for b in range(BLOCK_SIZE):
+            # load this line of data in, as many time as block size
+            bitmap._load_row(Y_OFFSET + y*BLOCK_SIZE+b, line)
+
+    # display the bitmap using our palette
+    splash = displayio.Group()
+    face = displayio.Sprite(bitmap, pixel_shader=palette, position=(0,0))
+    splash.append(face)
+    board.DISPLAY.show(splash)
+    board.DISPLAY.wait_for_frame()
+
+qr = adafruit_miniqr.QRCode()
+qr.add_data(b'https://www.adafruit.com/circuitpython')
+qr.make()
+draw_QR(qr.matrix)
+
+# turn on backlight
+backlight.duty_cycle = 35000
+
+while True:
+    pass