Animation Example

Full script here: draw_dots.py

This tutorial covers making a simple Animated GIF, as well as using color in a vectorized fashion with the draw_dots method.

Import the Libraries

For this, the :class:Image and :class:ANimation are required. numpy is also used for moving the dots around randomly.:

import numpy as np
from py_gd import Image, Animation

Set up the Parameters and Create an Image

A few parameters for the animation – feel free to play with those.

After creating the Image, it’s cleared to set a white background (the default is transparent, which does not work with GIF):

N = 50 # number of dots
w, h = 400, 400  # Size of image

img = Image(width=w, height=h)
img.clear('white')

Set Colors

Assign random colors to the dots. get_colors() will return a list of all the colors set up on the image. The first few colors are transparent, white, black – so random colors are chosen exclusing the first four, up the total number of colors. The deafult colorscheme is the 14 “standard html” colors. See Working with Color for more info. Initial position of the dots is set randomly:

# random colors: excluding first three: transparent, white, black
num_colors = len(img.get_colors())
colors = np.random.randint(3, num_colors - 1, N)

# initial position of the points
points = (np.random.random((N, 2)) * w).astype(np.int32)

Draw the Initial Image

The dots are drawn in their itiial position for the first image of teh animation, and the image is saved as a PNG:

# draw the initial image
img.draw_dots(points, diameter=10, color=colors)

#  Save the first frame as a PNG
img.save('dots.png', 'png')

Create the Animation

The :class:Animation is created, with some basic parameters: the filename, and the delay between frames, in 1/100 of a second. After creating, the animation is begun with the initial image.

# create the animation
anim = Animation('dots.gif',
                 delay=10,  # in 1/100s
                 )

anim.begin(img)

Add Additional Frames

A loop is run, making a new frame for each iteration. Each time, the dots are moved a random amount. The same image can be re-used – clearing it each time, and then drawing the dots in their new position. Once the Image is created, it is added to the Animation.

Once complete, the Animation should be closed.

# Run a loop to move the dots, and make a new frame each time
for i in range(100):
    move = (np.random.random((N, 2)) * 20 - 10).astype(np.int32)
    points = points + move
    img.clear('white')
    img.draw_dots(points, diameter=10, color=colors)
    anim.add_frame(img)
anim.close()
_images/dots.gif