9. EXT: Using built-in images

9.1. All Images

The code below displays all the built-in images.

from microbit import *

built_in_images = [Image.ANGRY, Image.ARROW_E, Image.ARROW_N, Image.ARROW_NE,
    Image.ARROW_NW, Image.ARROW_S, Image.ARROW_SE, Image.ARROW_SW,
    Image.ARROW_W, Image.ASLEEP, Image.BUTTERFLY, Image.CHESSBOARD,
    Image.CLOCK1, Image.CLOCK10, Image.CLOCK11, Image.CLOCK12,
    Image.CLOCK2, Image.CLOCK3, Image.CLOCK4, Image.CLOCK5, Image
    .CLOCK6, Image.CLOCK7, Image.CLOCK8, Image.CLOCK9, Image.CONFUSED,
    Image.COW, Image.DIAMOND, Image.DIAMOND_SMALL, Image.DUCK,
    Image.FABULOUS, Image.GHOST, Image.GIRAFFE, Image.HAPPY,
    Image.HEART, Image.HEART_SMALL, Image.HOUSE, Image.MEH,
    Image.MUSIC_CROTCHET, Image.MUSIC_QUAVER, Image.MUSIC_QUAVERS,
    Image.NO, Image.PACMAN, Image.PITCHFORK, Image.RABBIT, Image.ROLLERSKATE,
    Image.SAD, Image.SCISSORS, Image.SILLY, Image.SKULL, Image.SMILE,
    Image.SNAKE, Image.SQUARE, Image.SQUARE_SMALL, Image.STICKFIGURE,
    Image.SURPRISED, Image.SWORD, Image.TARGET, Image.TORTOISE,
    Image.TRIANGLE, Image.TRIANGLE_LEFT, Image.TSHIRT, Image.UMBRELLA,
    Image.XMAS, Image.YES,
]

while True:
    display.show(built_in_images, delay=100)

---

Tasks

1. Edit the built-in images list from above to just include animals.

2. Edit the built-in images list from above to just include faces.

3. Edit the built-in images list from above to just include objects.

4. Edit the built-in images list from above to just include shapes.

Q1

Edit the built-in images list from above to just include animals.

from microbit import *

animal_images = [
                    Image.RABBIT,
                    Image.COW,
                    Image.DUCK,
                    Image.TORTOISE,
                    Image.BUTTERFLY,
                    Image.GIRAFFE,
                    Image.SNAKE,
                ]
while True:
    display.show(animal_images, delay=250)

Q2

Edit the built-in images list from above to just include animals.

from microbit import *

face_images = [
                Image.HAPPY,
                Image.SMILE,
                Image.SAD,
                Image.CONFUSED,
                Image.ANGRY,
                Image.ASLEEP,
                Image.SURPRISED,
                Image.SILLY,
                Image.FABULOUS,
                Image.MEH,
            ]

while True:
    display.show(face_images, delay=250)

Q3

Edit the built-in images list from above to just include objects.

from microbit import *

object_images = [
                Image.CHESSBOARD,
                Image.PITCHFORK,
                Image.TARGET,
                Image.TSHIRT,
                Image.ROLLERSKATE,
                Image.HOUSE,
                Image.STICKFIGURE,
                Image.GHOST,
                Image.SWORD,
                Image.SKULL,
                Image.UMBRELLA,
            ]

while True:
    display.show(object_images, delay=250)

Q4

Edit the built-in images list from above to just include shapes.

from microbit import *

shape_images = [
                Image.TRIANGLE,
                Image.TRIANGLE_LEFT,
                Image.DIAMOND,
                Image.DIAMOND_SMALL,
                Image.SQUARE,
                Image.SQUARE_SMALL,
            ]

while True:
    display.show(shape_images, delay=250)

Tip

Advanced code to collect the list of all images is below.

from microbit import *

dir_images = dir(Image)
built_in_images = ["Image." + img for img in dir_images if type(getattr(Image, img)) == Image]
built_in_images_string = ", ".join(built_in_images)
built_in_images_string.replace('"', '')
print(built_in_images_string)

---

9.2. Random times for flashing an image

Import the random library. Then use randint to get a random times for flashing an image.

random.randint(a, b)

Return a random integer from a to b, including both.

The code below gets a random integer from 600 to 900 and uses that for the sleep time during which the image is shown.

Then it is used to calculate sleep time during which the display is cleared.

This creates some variation in the flashing of the image.

from microbit import *
import random

while True:
    on_time = random.randint(600, 900)
    off_time = 1000 - on_time
    display.show(Image.HEART)
    sleep(on_time)
    display.clear()
    sleep(off_time)

---

Tasks

1. Write the code to have the heart appear for 500ms, but clear the screen for a random time ranging from 100 to 500ms.

2. Write the code to have the heart appear for a random time ranging from 100 to 500ms, but clear the screen for 500ms.

Q1

Write the code to have the heart appear for 500ms but clear the screen for a random time ranging from 100 to 500ms.

from microbit import *
import random

while True:
    on_time = 500
    off_time = random.randint(100, 500)
    display.show(Image.HEART)
    sleep(on_time)
    display.clear()
    sleep(off_time)

Q2

Write the code to have the heart appear for a random time ranging from 100 to 500ms, but clear the screen for 500ms.

from microbit import *
import random

while True:
    on_time = random.randint(100, 500)
    off_time = 500
    display.show(Image.HEART)
    sleep(on_time)
    display.clear()
    sleep(off_time)

---

9.3. Random images

Import the random library. Then use random.choice to show a random image from a list.

random.choice(image_list)

Return a random image from the list of images: image_list.

The code below shows a random image from a list every 500ms.

from microbit import *
import random

shape_list = [
    Image.TRIANGLE,
    Image.TRIANGLE_LEFT,
    Image.DIAMOND,
    Image.DIAMOND_SMALL,
    Image.SQUARE,
    Image.SQUARE_SMALL,
]
while True:
    img = random.choice(shape_list)
    display.show(img)
    sleep(500)

---

Tasks

1. Write the code to show a random face image every second.

2. Write the code to show a random animal image every 800ms.

Q1

Write the code to show a random face image every second.

from microbit import *
import random

face_images = [
                Image.HAPPY,
                Image.SMILE,
                Image.SAD,
                Image.CONFUSED,
                Image.ANGRY,
                Image.ASLEEP,
                Image.SURPRISED,
                Image.SILLY,
                Image.FABULOUS,
                Image.MEH,
            ]

while True:
    img = random.choice(face_images)
    display.show(img)
    sleep(1000)

Q2

Write the code to show a random animal image every 800ms.

from microbit import *
import random

animal_images = [
                    Image.RABBIT,
                    Image.COW,
                    Image.DUCK,
                    Image.TORTOISE,
                    Image.BUTTERFLY,
                    Image.GIRAFFE,
                    Image.SNAKE,
                ]

while True:
    img = random.choice(animal_images)
    display.show(img)
    sleep(800)

---

9.4. Image sentences using “mixed” lists

display.show can be used to show text images along with other images.

The text images must be one character in quotes.

Normally, a text image requires Image as in Image(“U”).

But the list input for display.show automatically treats “U” as Image(“U”).

Single quoted digits, e.g. “4”, work in a similar way.

Multiple digits in an image, as in Image(“12345”), set the pixel brightness for those pixels.

Strings, such as “1234” or “abcd”, will be ignored.

The image sentence below uses a built-in image and an image from a digit and an image from a letter.

from microbit import *

while True:
    # snake ate rabbit
    mixed_list = [Image.SNAKE, "8", Image.RABBIT]
    display.show(mixed_list, delay=300, clear=True)
    sleep(300)

---

Tasks

1. Write an image sentence using an image list that asks if you are sad.

2. Write an image sentence using an image list that encourages joy.

3. Write an image sentence using an image list that translates as “Are you surprised to be confused?”

Q1

Write an image sentence using an image list that asks if you are sad.

from microbit import *

while True:
    mixed_list = ["R", "U", Image.SAD]
    display.show(mixed_list, delay=700, clear=True)
    sleep(1000)

Q2

Write an image sentence using an image list that encourages joy.

from microbit import *

while True:
    mixed_list = ["B", Image.HAPPY]
    display.show(mixed_list, delay=700, clear=True)
    sleep(1000)

Q3

Write an image sentence using an image list that translates as “Are you surprised to be confused?”

from microbit import *

while True:
    mixed_list = ["R", "U", Image.SURPRISED, "2", "B", Image.CONFUSED, "?"]
    display.show(mixed_list, delay=700, clear=True)
    sleep(1000)