Add display.py

display.py

@@ -0,0 +1,121 @@
+import enum
+
+class Font(enum.Enum):
+    
+    F61 = (0x61, 5)
+    F62 = (0x62, 5)
+    F63 = (0x63, 5)
+    F64 = (0x64, 5)
+    F65 = (0x65, 5)
+    F66 = (0x66, 5)
+    F67 = (0x67, 5)
+    F68 = (0x68, 5)
+    F69 = (0x69, 5)
+    F70 = (0x70, 5)
+    F71 = (0x71, 5)
+    F72 = (0x72, 5)
+    F73 = (0x73, 5)
+    F74 = (0x74, 5)
+    F75 = (0x75, 5)
+    F76 = (0x76, 5)
+    SMALL_F = (0x64, 5)
+    BITMAP = (0x77, 5)
+
+    # F<HEIGHT>_<Fat>/<Thin>
+
+    F13_F = (0x61, 13) # on 0x70 too
+    F9_F = (0x62, 9)
+    F19_F = (0x63, 19)
+    F7_F = (0x64, 7)
+    F7 = (0x65, 7)
+    F6 = (0x66, 7)
+    SYMBOL = (0x67, 16)
+    F16_T = (0x68, 16)
+    F13_T = (0x69, 13)
+    #F13_F = (0x70, 13)
+    F15_T = (0x71, 15)
+    F5 =(0x72, 5)
+    F13_TT = (0x73, 13)
+
+    # 74: Only one character... and only A seems to work
+    F13 = (0x75, 13) # same as F13_T but wider...
+
+
+    def __init__(self, cmd, height):
+        self.cmd = cmd
+        self.height = height
+
+class DisplayBuffer:
+    """ Acts as a buffer for creating commands to send to the display """
+
+    def __init__(self, address: int, width: int, height:int):
+        self.address = address
+        self.width = width
+        self.height = height
+
+        # create initial frame buffer
+        self.reset_buffer()       
+    
+    def reset_buffer(self):
+        self.buffer = bytearray()
+
+        # add display header: 0xff (start), address, 0xA2 (always 0xA2)
+        self.buffer.extend([0xff, self.address, 0xA2])
+
+        # set display size
+        self.buffer.extend([0xd0, self.width])  # width 
+        self.buffer.extend([0xd1, self.height]) # height 
+
+    def put_text(self, text:str,  x: int = 0, y: int = 0, font: Font = Font.SMALL_F):
+        # set position (TODO: make the position aware of the font size, y-coordinate seems a bit fishy xD )
+        self.buffer.extend([0xd2, x]) # x coordinate
+        self.buffer.extend([0xd3, y]) # y coordinate
+
+        # select font
+        self.buffer.extend([0xd4, font.cmd])
+
+        # write characters 
+#        self.buffer.extend([ord(c) for c in text])
+        self.buffer.extend([c for c in text])
+
+
+    def put_bitmap(self, bitmap: bytearray, x: int = 0, y: int = 0):
+        # set position
+        self.buffer.extend([0xd2, x]) # x coordinate
+        self.buffer.extend([0xd3, y]) # y coordinate
+
+        # select bitmap font
+        self.buffer.extend([0xd4, Font.BITMAP.cmd])
+
+        # TODO: write real bitmap data here (somehow xD)
+        self.buffer.extend(bitmap)
+        
+    def finalize_buffer(self) -> bytearray:
+        """ completes the this frame and returns the bytes to be written to the display """
+        
+        # add checksum
+        self._add_checksum(self.buffer)
+
+        # add stop command
+        self.buffer.append(0xff)
+
+        # reset the buffer and return the old one
+        buffer = self.buffer
+        self.reset_buffer()
+
+        return buffer
+
+    @staticmethod
+    def _add_checksum(data: bytearray):
+        """ appends a checksum to the specified data """
+        # sum all bytes except the first and take the lower 8 bits
+        csum = sum(data[1:]) & 0xff
+
+        # append checksum to data
+        if csum == 0xfe:
+            data.extend([0xfe, 0x00])
+        elif csum == 0xff:
+            data.extend([0xfe, 0x01])
+        else:
+            data.append(csum)
+