Add text-to-picture and LCD partial update

Author: mathoudebine

main.py

@@ -2,12 +2,14 @@
 import struct
 from time import sleep
 import serial  # Install pyserial : pip install pyserial
-from PIL import Image  # Install PIL or Pillow
+from PIL import Image, ImageDraw, ImageFont  # Install PIL or Pillow
 
 # Set your COM port e.g. COM3 for Windows, /dev/ttyACM0 for Linux...
 COM_PORT = "/dev/ttyACM1"
 # COM_PORT = "COM5"
 
+DISPLAY_WIDTH = 320
+DISPLAY_HEIGHT = 480
 
 class Command:
     RESET = 101
@@ -18,14 +20,14 @@ class Command:
     DISPLAY_BITMAP = 197
 
 
-def SendReg(ser, reg, x, y, ex, ey):
+def SendReg(ser, cmd, x, y, ex, ey):
     byteBuffer = bytearray(6)
     byteBuffer[0] = (x >> 2)
     byteBuffer[1] = (((x & 3) << 6) + (y >> 4))
     byteBuffer[2] = (((y & 15) << 4) + (ex >> 6))
     byteBuffer[3] = (((ex & 63) << 2) + (ey >> 8))
     byteBuffer[4] = (ey & 255)
-    byteBuffer[5] = reg
+    byteBuffer[5] = cmd
     ser.write(bytes(byteBuffer))
 
 
@@ -50,14 +52,13 @@ def SetBrightness(ser, level):
     SendReg(ser, Command.SET_BRIGHTNESS, level, 0, 0, 0)
 
 
-def PrintImage(ser, image):
-    im = Image.open(image)
-    image_height = im.size[1]
-    image_width = im.size[0]
+def DisplayPILImage(ser, image, x, y):
+    image_height = image.size[1]
+    image_width = image.size[0]
 
-    SendReg(ser, Command.DISPLAY_BITMAP, 0, 0, image_width - 1, image_height - 1)
+    SendReg(ser, Command.DISPLAY_BITMAP, x, y, image_width - 1, image_height - 1)
 
-    pix = im.load()
+    pix = image.load()
     for h in range(image_height):
         line = bytes()
         for w in range(image_width):
@@ -73,6 +74,34 @@ def PrintImage(ser, image):
     sleep(0.01)  # Wait 10 ms after picture display
 
 
+def DisplayBitmap(ser, bitmap_path, x=0, y=0):
+    image = Image.open(bitmap_path)
+    DisplayPILImage(ser, image, x, y)
+
+
+def DisplayText(ser, text, x=0, y=0,
+                font="roboto/Roboto-Regular.ttf",
+                font_size=20,
+                font_color=(0, 0, 0),
+                background_color=(255, 255, 255)):
+    # Convert text to bitmap using PIL and display it
+
+    # The text bitmap is created with max width/height by default
+    # Note : alpha component from RGBA is not supported by the display
+    text_image = Image.new('RGB', (DISPLAY_WIDTH, DISPLAY_HEIGHT), background_color)
+
+    # Draw text with specified color & font
+    font = ImageFont.truetype("./res/fonts/" + font, font_size)
+    d = ImageDraw.Draw(text_image)
+    d.text((0, 0), text, font=font, fill=font_color)
+
+    # Crop text bitmap to the size of the text
+    text_width, text_height = d.textsize(text, font=font)
+    text_image = text_image.crop((0, 0, text_width, text_height))
+
+    DisplayPILImage(ser, text_image, x, y)
+
+
 if __name__ == "__main__":
     # Do not change COM port settings unless you know what you are doing
     lcd_comm = serial.Serial(COM_PORT, 115200, timeout=1, rtscts=1)
@@ -84,6 +113,15 @@ def PrintImage(ser, image):
     SetBrightness(lcd_comm, 0)
 
     # Display sample picture
-    PrintImage(lcd_comm, "res/example.png")
+    DisplayBitmap(lcd_comm, "res/example.png")
+
+    # Display sample text
+    DisplayText(lcd_comm, "Basic text", 50, 100)
+    
+    DisplayText(lcd_comm, "Custom text", 5, 150,
+                font="roboto/Roboto-BoldItalic.ttf",
+                font_size=40,
+                font_color=(0, 0, 255),
+                background_color=(255, 255, 0))
 
     lcd_comm.close()