"""
Copyright (c) 2020-2023 Russ Hughes
This file incorporates work covered by the following copyright and
permission notice and is licensed under the same terms:
The MIT License (MIT)
Copyright (c) 2019 Ivan Belokobylskiy
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
The driver is based on devbis' st7789py_mpy module from
https://github.com/devbis/st7789py_mpy.
This driver adds support for:
- LilyGo T-HMI 320x240 TFT LCD display
- Display rotation
- Hardware based scrolling
- Drawing text using 8 and 16 bit wide bitmap fonts with heights that are
multiples of 8. Included are 12 bitmap fonts derived from classic pc
BIOS text mode fonts.
- Drawing text using converted TrueType fonts.
- Drawing converted bitmaps
"""
from esp32 import RMT
import time
from micropython import const
from machine import mem32, Pin
import ustruct as struct
# memory mapped registers of ESP32S3 for setting and clearing GPIO pins
# see the ESP32S3 datasheet for more information.
GPIO_OUT_W1TS_REG = const(0x60004008)
GPIO_OUT_W1TC_REG = const(0x6000400C)
GPIO_OUT1_W1TS_REG = const(0x60004014)
GPIO_OUT1_W1TC_REG = const(0x60004018)
# see the make_gpio_table script in the utils directory
# of the repository for more information on these tables.
GPIO_OUT1_W1TC_MASK = const(0x0001E780)
# fmt: off
GPIO_OUT1_W1TS_MASKS = (
0x0, 0x10000, 0x8000, 0x18000,
0x80, 0x10080, 0x8080, 0x18080,
0x100, 0x10100, 0x8100, 0x18100,
0x180, 0x10180, 0x8180, 0x18180,
0x200, 0x10200, 0x8200, 0x18200,
0x280, 0x10280, 0x8280, 0x18280,
0x300, 0x10300, 0x8300, 0x18300,
0x380, 0x10380, 0x8380, 0x18380,
0x400, 0x10400, 0x8400, 0x18400,
0x480, 0x10480, 0x8480, 0x18480,
0x500, 0x10500, 0x8500, 0x18500,
0x580, 0x10580, 0x8580, 0x18580,
0x600, 0x10600, 0x8600, 0x18600,
0x680, 0x10680, 0x8680, 0x18680,
0x700, 0x10700, 0x8700, 0x18700,
0x780, 0x10780, 0x8780, 0x18780,
0x2000, 0x12000, 0xa000, 0x1a000,
0x2080, 0x12080, 0xa080, 0x1a080,
0x2100, 0x12100, 0xa100, 0x1a100,
0x2180, 0x12180, 0xa180, 0x1a180,
0x2200, 0x12200, 0xa200, 0x1a200,
0x2280, 0x12280, 0xa280, 0x1a280,
0x2300, 0x12300, 0xa300, 0x1a300,
0x2380, 0x12380, 0xa380, 0x1a380,
0x2400, 0x12400, 0xa400, 0x1a400,
0x2480, 0x12480, 0xa480, 0x1a480,
0x2500, 0x12500, 0xa500, 0x1a500,
0x2580, 0x12580, 0xa580, 0x1a580,
0x2600, 0x12600, 0xa600, 0x1a600,
0x2680, 0x12680, 0xa680, 0x1a680,
0x2700, 0x12700, 0xa700, 0x1a700,
0x2780, 0x12780, 0xa780, 0x1a780,
0x4000, 0x14000, 0xc000, 0x1c000,
0x4080, 0x14080, 0xc080, 0x1c080,
0x4100, 0x14100, 0xc100, 0x1c100,
0x4180, 0x14180, 0xc180, 0x1c180,
0x4200, 0x14200, 0xc200, 0x1c200,
0x4280, 0x14280, 0xc280, 0x1c280,
0x4300, 0x14300, 0xc300, 0x1c300,
0x4380, 0x14380, 0xc380, 0x1c380,
0x4400, 0x14400, 0xc400, 0x1c400,
0x4480, 0x14480, 0xc480, 0x1c480,
0x4500, 0x14500, 0xc500, 0x1c500,
0x4580, 0x14580, 0xc580, 0x1c580,
0x4600, 0x14600, 0xc600, 0x1c600,
0x4680, 0x14680, 0xc680, 0x1c680,
0x4700, 0x14700, 0xc700, 0x1c700,
0x4780, 0x14780, 0xc780, 0x1c780,
0x6000, 0x16000, 0xe000, 0x1e000,
0x6080, 0x16080, 0xe080, 0x1e080,
0x6100, 0x16100, 0xe100, 0x1e100,
0x6180, 0x16180, 0xe180, 0x1e180,
0x6200, 0x16200, 0xe200, 0x1e200,
0x6280, 0x16280, 0xe280, 0x1e280,
0x6300, 0x16300, 0xe300, 0x1e300,
0x6380, 0x16380, 0xe380, 0x1e380,
0x6400, 0x16400, 0xe400, 0x1e400,
0x6480, 0x16480, 0xe480, 0x1e480,
0x6500, 0x16500, 0xe500, 0x1e500,
0x6580, 0x16580, 0xe580, 0x1e580,
0x6600, 0x16600, 0xe600, 0x1e600,
0x6680, 0x16680, 0xe680, 0x1e680,
0x6700, 0x16700, 0xe700, 0x1e700,
0x6780, 0x16780, 0xe780, 0x1e780,
)
# fmt: on
# RMT pulse duration
# increase if you see display glitches
# decrease to speed up updates
PULSE = const(16)
# GPIO Pin Masks for setting and clearing pins
PIN_WR = const(8)
MASK_DC = const(1 << 7) # OUT
MASK_CS = const(1 << 6) # OUT
MASK_BACKLIGHT = const(1 << 38 - 32) # OUT1
# ST7796 contoller commands
ST7796_NOP = const(0x00)
ST7796_SWRESET = const(0x01)
ST7796_RDDID = const(0x04)
ST7796_RDDST = const(0x09)
ST7796_SLPIN = const(0x10)
ST7796_SLPOUT = const(0x11)
ST7796_PTLON = const(0x12)
ST7796_NORON = const(0x13)
ST7796_INVOFF = const(0x20)
ST7796_INVON = const(0x21)
ST7796_DISPOFF = const(0x28)
ST7796_DISPON = const(0x29)
ST7796_CASET = const(0x2A)
ST7796_RASET = const(0x2B)
ST7796_RAMWR = const(0x2C)
ST7796_RAMRD = const(0x2E)
ST7796_PTLAR = const(0x30)
ST7796_VSCRDEF = const(0x33)
ST7796_COLMOD = const(0x3A)
ST7796_MADCTL = const(0x36)
ST7796_VSCSAD = const(0x37)
ST7796_MADCTL_MY = const(0x80)
ST7796_MADCTL_MX = const(0x40)
ST7796_MADCTL_MV = const(0x20)
ST7796_MADCTL_ML = const(0x10)
ST7796_MADCTL_BGR = const(0x08)
ST7796_MADCTL_MH = const(0x04)
ST7796_MADCTL_RGB = const(0x00)
ST7796_RDID1 = const(0xDA)
ST7796_RDID2 = const(0xDB)
ST7796_RDID3 = const(0xDC)
ST7796_RDID4 = const(0xDD)
COLOR_MODE_65K = const(0x50)
COLOR_MODE_262K = const(0x60)
COLOR_MODE_12BIT = const(0x03)
COLOR_MODE_16BIT = const(0x05)
COLOR_MODE_18BIT = const(0x06)
COLOR_MODE_16M = const(0x07)
# Color definitions
BLACK = const(0x0000)
BLUE = const(0x001F)
RED = const(0xF800)
GREEN = const(0x07E0)
CYAN = const(0x07FF)
MAGENTA = const(0xF81F)
YELLOW = const(0xFFE0)
WHITE = const(0xFFFF)
_ENCODE_PIXEL = const(">H")
_ENCODE_POS = const(">HH")
_DECODE_PIXEL = const(">BBB")
_BUFFER_PIXELS = const(256)
_BIT7 = const(0x80)
_BIT6 = const(0x40)
_BIT5 = const(0x20)
_BIT4 = const(0x10)
_BIT3 = const(0x08)
_BIT2 = const(0x04)
_BIT1 = const(0x02)
_BIT0 = const(0x01)
# Rotation tables (width, height)[rotation % 4]
ROTATIONS = ((240, 320), (320, 240), (240, 320), (320, 240))
# MADCTL ROTATIONS[rotation % 4]
MADCTLS = (0x00, 0x60, 0xC0, 0xA0)
[docs]def color565(red, green=0, blue=0):
"""
Convert red, green and blue values (0-255) into a 16-bit 565 encoding.
"""
try:
red, green, blue = red # see if the first var is a tuple/list
except TypeError:
pass
return (red & 0xF8) << 8 | (green & 0xFC) << 3 | blue >> 3
def _encode_pos(x, y):
"""Encode a postion into bytes."""
return struct.pack(_ENCODE_POS, x, y)
def _encode_pixel(color):
"""Encode a pixel color into bytes."""
return struct.pack(_ENCODE_PIXEL, color)
[docs]class THMI:
"""
T_HMI driver class
Args:
rotation (int): display rotation
- 0-Portrait
- 1-Landscape
- 2-Inverted Portrait
- 3-Inverted Landscape
rotations (list): list of rotation values
"""
def __init__(
self,
rotation=0,
rotations=MADCTLS,
):
"""
Initialize T_HMI's st7789 display.
"""
# turn on display
Pin(10, Pin.OUT, value=1)
time.sleep_ms(100)
# configure pins
Pin(48, Pin.OUT)
Pin(47, Pin.OUT)
Pin(39, Pin.OUT)
Pin(40, Pin.OUT)
Pin(41, Pin.OUT)
Pin(42, Pin.OUT)
Pin(45, Pin.OUT)
Pin(46, Pin.OUT)
Pin(7, Pin.OUT) # dc
Pin(6, Pin.OUT) # cs
self.wr = Pin(PIN_WR, Pin.OUT, value=1) # wr
self.rmt = RMT(0, pin=self.wr, clock_div=1)
self.pulse = [0, 1]
self.bl = Pin(38, Pin.OUT) # backlight0
self.last = None
self._rotation = rotation % 4
self._rotations = rotations
mem32[GPIO_OUT_W1TS_REG] = MASK_CS
mem32[GPIO_OUT_W1TS_REG] = MASK_DC
self.soft_reset()
self.sleep_mode(False)
self._set_color_mode(COLOR_MODE_65K | COLOR_MODE_16BIT)
time.sleep_ms(50)
self.rotation(self._rotation)
self.inversion_mode(False)
time.sleep_ms(10)
self._write(ST7796_NORON)
time.sleep_ms(10)
self.backlight_on()
self._write(ST7796_DISPON)
time.sleep_ms(125)
def backlight_on(self):
self.bl.value(1)
def backlight_off(self):
self.bl.value(0)
# @micropython.native
def _write_byte(self, b):
"""Write to the display using 8 bit parallel mode. Note: this is not fast."""
if b != self.last:
out1 = GPIO_OUT1_W1TS_MASKS[b]
mem32[GPIO_OUT1_W1TS_REG] = out1
mem32[GPIO_OUT1_W1TC_REG] = out1 ^ GPIO_OUT1_W1TC_MASK
self.last = b
self.rmt.write_pulses(PULSE, self.pulse)
# @micropython.native
def _write(self, command=None, data=None):
"""Write to the display: command and/or data."""
mem32[GPIO_OUT_W1TC_REG] = MASK_CS
if command is not None:
mem32[GPIO_OUT_W1TC_REG] = MASK_DC
for b in bytes([command]):
self._write_byte(b)
if data is not None:
mem32[GPIO_OUT_W1TS_REG] = MASK_DC
for b in data:
self._write_byte(b)
mem32[GPIO_OUT_W1TS_REG] = MASK_CS
[docs] def soft_reset(self):
"""
Soft reset display.
"""
self._write(ST7796_SWRESET)
time.sleep_ms(150)
[docs] def sleep_mode(self, value):
"""
Enable or disable display sleep mode.
Args:
value (bool): if True enable sleep mode. if False disable sleep
mode
"""
if value:
self._write(ST7796_SLPIN)
else:
self._write(ST7796_SLPOUT)
[docs] def inversion_mode(self, value):
"""
Enable or disable display inversion mode.
Args:
value (bool): if True enable inversion mode. if False disable
inversion mode
"""
if value:
self._write(ST7796_INVON)
else:
self._write(ST7796_INVOFF)
def _set_color_mode(self, mode):
"""
Set display color mode.
Args:
mode (int): color mode
COLOR_MODE_65K, COLOR_MODE_262K, COLOR_MODE_12BIT,
COLOR_MODE_16BIT, COLOR_MODE_18BIT, COLOR_MODE_16M
"""
self._write(ST7796_COLMOD, bytes([mode & 0x77]))
[docs] def rotation(self, rotation):
"""
Set display rotation.
Args:
rotation (int):
- 0-Portrait
- 1-Landscape
- 2-Inverted Portrait
- 3-Inverted Landscape
"""
rotation %= 4
self._rotation = rotation
madctl = self._rotations[rotation]
self.width, self.height = ROTATIONS[rotation]
self._write(ST7796_MADCTL, bytes([madctl]))
# @micropython.native
def _set_window(self, x0, y0, x1, y1):
"""
Set window to column and row address.
Args:
x0 (int): column start address
y0 (int): row start address
x1 (int): column end address
y1 (int): row end address
"""
if x0 <= x1 <= self.width and y0 <= y1 <= self.height:
self._write(ST7796_CASET, _encode_pos(x0, x1))
self._write(ST7796_RASET, _encode_pos(y0, y1))
self._write(ST7796_RAMWR)
[docs] def vline(self, x, y, length, color):
"""
Draw vertical line at the given location and color.
Args:
x (int): x coordinate
Y (int): y coordinate
length (int): length of line
color (int): 565 encoded color
"""
self.fill_rect(x, y, 1, length, color)
[docs] def hline(self, x, y, length, color):
"""
Draw horizontal line at the given location and color.
Args:
x (int): x coordinate
Y (int): y coordinate
length (int): length of line
color (int): 565 encoded color
"""
self.fill_rect(x, y, length, 1, color)
[docs] def pixel(self, x, y, color):
"""
Draw a pixel at the given location and color.
Args:
x (int): x coordinate
Y (int): y coordinate
color (int): 565 encoded color
"""
self._set_window(x, y, x, y)
self._write(None, _encode_pixel(color))
[docs] def blit_buffer(self, buffer, x, y, width, height):
"""
Copy buffer to display at the given location.
Args:
buffer (bytes): Data to copy to display
x (int): Top left corner x coordinate
Y (int): Top left corner y coordinate
width (int): Width
height (int): Height
"""
self._set_window(x, y, x + width - 1, y + height - 1)
self._write(None, buffer)
[docs] def rect(self, x, y, w, h, color):
"""
Draw a rectangle at the given location, size and color.
Args:
x (int): Top left corner x coordinate
y (int): Top left corner y coordinate
width (int): Width in pixels
height (int): Height in pixels
color (int): 565 encoded color
"""
self.hline(x, y, w, color)
self.vline(x, y, h, color)
self.vline(x + w - 1, y, h, color)
self.hline(x, y + h - 1, w, color)
# @micropython.native
[docs] def fill_rect(self, x, y, width, height, color):
"""
Draw a rectangle at the given location, size and filled with color.
Args:
x (int): Top left corner x coordinate
y (int): Top left corner y coordinate
width (int): Width in pixels
height (int): Height in pixels
color (int): 565 encoded color
"""
high_byte = color >> 8
low_byte = color & 0xFF
self._set_window(x, y, x + width - 1, y + height - 1)
mem32[GPIO_OUT_W1TC_REG] = MASK_CS
mem32[GPIO_OUT_W1TS_REG] = MASK_DC
for _ in range(width * height):
self._write_byte(high_byte)
self._write_byte(low_byte)
mem32[GPIO_OUT_W1TS_REG] = MASK_CS
[docs] def fill(self, color):
"""
Fill the entire FrameBuffer with the specified color.
Args:
color (int): 565 encoded color
"""
self.fill_rect(0, 0, self.width, self.height, color)
# # @micropython.native
[docs] def clear(self, color=None):
"""
Very fast clear screen.
Args:
color (bool): True to clear to white, False to clear to black
or
color (int): 565 encoded color, with the upper and lower bytes
being set the same value as color.
"""
if isinstance(color, bool):
color = 0xFF if color else 0
elif color is None:
color = 0
else:
color &= 0xFF
self._set_window(0, 0, self.width, self.height)
out1 = GPIO_OUT1_W1TS_MASKS[color]
mem32[GPIO_OUT1_W1TS_REG] = out1
mem32[GPIO_OUT1_W1TC_REG] = out1 ^ GPIO_OUT1_W1TC_MASK
mem32[GPIO_OUT_W1TC_REG] = MASK_CS
mem32[GPIO_OUT_W1TS_REG] = MASK_DC
pulses = [0, 1] * self.width
count = self.height + 1
for _ in range(count * 2):
self.rmt.write_pulses(PULSE, pulses)
self.rmt.wait_done()
mem32[GPIO_OUT_W1TS_REG] = MASK_CS
# @micropython.native
[docs] def line(self, x0, y0, x1, y1, color):
"""
Draw a single pixel wide line starting at x0, y0 and ending at x1, y1.
Args:
x0 (int): Start point x coordinate
y0 (int): Start point y coordinate
x1 (int): End point x coordinate
y1 (int): End point y coordinate
color (int): 565 encoded color
"""
steep = abs(y1 - y0) > abs(x1 - x0)
if steep:
x0, y0 = y0, x0
x1, y1 = y1, x1
if x0 > x1:
x0, x1 = x1, x0
y0, y1 = y1, y0
dx = x1 - x0
dy = abs(y1 - y0)
err = dx // 2
ystep = 1 if y0 < y1 else -1
while x0 <= x1:
if steep:
self.pixel(y0, x0, color)
else:
self.pixel(x0, y0, color)
err -= dy
if err < 0:
y0 += ystep
err += dx
x0 += 1
[docs] def vscrdef(self, tfa, vsa, bfa):
"""
Set Vertical Scrolling Definition.
To scroll a 135x240 display these values should be 40, 240, 40.
There are 40 lines above the display that are not shown followed by
240 lines that are shown followed by 40 more lines that are not shown.
You could write to these areas off display and scroll them into view by
changing the TFA, VSA and BFA values.
Args:
tfa (int): Top Fixed Area
vsa (int): Vertical Scrolling Area
bfa (int): Bottom Fixed Area
"""
struct.pack(">HHH", tfa, vsa, bfa)
self._write(ST7796_VSCRDEF, struct.pack(">HHH", tfa, vsa, bfa))
[docs] def vscsad(self, vssa):
"""
Set Vertical Scroll Start Address of RAM.
Defines which line in the Frame Memory will be written as the first
line after the last line of the Top Fixed Area on the display
Example:
for line in range(40, 280, 1):
tft.vscsad(line)
utime.sleep(0.01)
Args:
vssa (int): Vertical Scrolling Start Address
"""
self._write(ST7796_VSCSAD, struct.pack(">H", vssa))
# @micropython.native
[docs] def text(self, font, text, x0, y0, color=WHITE, background=BLACK):
"""
Draw text on display in specified font and colors. 8 and 16 bit wide
fonts are supported.
Args:
font (module): font module to use.
text (str): text to write
x0 (int): column to start drawing at
y0 (int): row to start drawing at
color (int): 565 encoded color to use for characters
background (int): 565 encoded color to use for background
"""
wide = font.WIDTH // 8
fg_hi = color >> 8
fg_lo = color & 0xFF
bg_hi = background >> 8
bg_lo = background & 0xFF
buffer = bytearray(font.WIDTH * font.HEIGHT * 2)
for char in text:
ch = ord(char)
if (
font.FIRST <= ch < font.LAST
and x0 + font.WIDTH <= self.width
and y0 + font.HEIGHT <= self.height
):
buf_idx = 0
chr_idx = (ch - font.FIRST) * (font.HEIGHT * wide)
for _ in range(font.HEIGHT):
for _ in range(wide):
chr_data = font.FONT[chr_idx]
for _ in range(8):
if chr_data & 0x80:
buffer[buf_idx] = fg_hi
buffer[buf_idx + 1] = fg_lo
else:
buffer[buf_idx] = bg_hi
buffer[buf_idx + 1] = bg_lo
buf_idx += 2
chr_data <<= 1
chr_idx += 1
to_col = x0 + font.WIDTH - 1
to_row = y0 + font.HEIGHT - 1
if self.width > to_col and self.height > to_row:
self._set_window(x0, y0, to_col, to_row)
self._write(None, buffer)
x0 += font.WIDTH
# @micropython.native
[docs] def bitmap(self, bitmap, x, y, index=0):
"""
Draw a bitmap on display at the specified column and row
Args:
bitmap (bitmap_module): The module containing the bitmap to draw
x (int): column to start drawing at
y (int): row to start drawing at
index (int): Optional index of bitmap to draw from multiple bitmap
module
"""
bitmap_size = bitmap.HEIGHT * bitmap.WIDTH
buffer_len = bitmap_size * 2
buffer = bytearray(buffer_len)
bs_bit = bitmap.BPP * bitmap_size * index if index > 0 else 0
for i in range(0, buffer_len, 2):
color_index = 0
for _ in range(bitmap.BPP):
color_index <<= 1
color_index |= (
bitmap.BITMAP[bs_bit // 8] & 1 << (7 - (bs_bit % 8))
) > 0
bs_bit += 1
color = bitmap.PALETTE[color_index]
buffer[i + 1] = (color & 0xFF00) >> 8
buffer[i] = color & 0xFF
to_col = x + bitmap.WIDTH - 1
to_row = y + bitmap.HEIGHT - 1
if self.width > to_col and self.height > to_row:
self._set_window(x, y, to_col, to_row)
self._write(None, buffer)
# @micropython.native
[docs] def write(self, font, string, x, y, fg=WHITE, bg=BLACK):
"""
Write a string using a converted true-type font on the display starting
at the specified column and row
Args:
font (font): The module containing the converted true-type font
s (string): The string to write
x (int): column to start writing
y (int): row to start writing
fg (int): foreground color, optional, defaults to WHITE
bg (int): background color, optional, defaults to BLACK
"""
buffer_len = font.HEIGHT * font.MAX_WIDTH * 2
buffer = bytearray(buffer_len)
fg_hi = (fg & 0xFF00) >> 8
fg_lo = fg & 0xFF
bg_hi = (bg & 0xFF00) >> 8
bg_lo = bg & 0xFF
for character in string:
try:
char_index = font.MAP.index(character)
offset = char_index * font.OFFSET_WIDTH
bs_bit = font.OFFSETS[offset]
if font.OFFSET_WIDTH > 1:
bs_bit = (bs_bit << 8) + font.OFFSETS[offset + 1]
if font.OFFSET_WIDTH > 2:
bs_bit = (bs_bit << 8) + font.OFFSETS[offset + 2]
char_width = font.WIDTHS[char_index]
buffer_needed = char_width * font.HEIGHT * 2
for i in range(0, buffer_needed, 2):
if font.BITMAPS[bs_bit // 8] & 1 << (7 - (bs_bit % 8)) > 0:
buffer[i] = fg_hi
buffer[i + 1] = fg_lo
else:
buffer[i] = bg_hi
buffer[i + 1] = bg_lo
bs_bit += 1
to_col = x + char_width - 1
to_row = y + font.HEIGHT - 1
if self.width > to_col and self.height > to_row:
self._set_window(x, y, to_col, to_row)
self._write(None, buffer[:buffer_needed])
x += char_width
except ValueError:
pass
[docs] def write_width(self, font, string):
"""
Returns the width in pixels of the string if it was written with the
specified font
Args:
font (font): The module containing the converted true-type font
string (string): The string to measure
"""
width = 0
for character in string:
try:
char_index = font.MAP.index(character)
width += font.WIDTHS[char_index]
except ValueError:
pass
return width