# SPDX-FileCopyrightText: 2019 John Edgar Park for Adafruit Industries
#
# SPDX-License-Identifier: MIT

# The following Turtle Gizmo Setup is copied from examples at
# https://learn.adafruit.com/turtle-graphics-gizmo/ by John Park.

#==| Turtle Gizmo Setup start |========================================
import board
import busio
import displayio
from adafruit_st7789 import ST7789
from adafruit_turtle import turtle
displayio.release_displays()
spi = busio.SPI(board.SCL, MOSI=board.SDA)
display_bus = displayio.FourWire(spi, command=board.TX, chip_select=board.RX)
display = ST7789(display_bus, width=240, height=240, rowstart=80,
                 backlight_pin=board.A3, rotation=180)
turtle = turtle(display)
#==| Turtle Gizmo Setup end |=========================================

from time import sleep

# The following values display a square. Moving the corners
# away from the origin by 1/50th of a pixel in the x and y
# directions eliminates the square. So these values show
# the valid plot range. The x range is ~240 (good) but the y
# range is ~241 (bad).  This is ISSUE #1.

xmin = -120.5    # left side
ymax =  120.5    # top
xmax =  119.49   # right side
ymin = -120.5    # bottom

print("xmax-xmin, ymax-ymin =", xmax-xmin, ymax-ymin)

# ISSUE #2 is that changing turtle heading changes where
# goto() draws a line. Instead of first plotting a square
# and then a blank screen, uncommenting this line first
# plots a square missing its bottom, then only the right
# side of a square.

#turtle.setheading(90)

while True:
    for i in range(2):
        xmn = xmin - i/50
        xmx = xmax + i/50
        ymn = ymin - i/50
        ymx = ymax + i/50
        turtle.penup()
        turtle.goto(xmn, ymn)
        turtle.pendown()

        turtle.goto(xmn, ymx)  # left side
        turtle.goto(xmx, ymx)  # top
        turtle.goto(xmx, ymn)  # right side
        turtle.goto(xmn, ymn)  # bottom

        sleep(1)
        turtle.clear()