How to animate variable fonts using Python and Drawbot

One of the most common uses of variable fonts is to make animations. You probably have already seen it: fonts that gain and lose weight, get wider and narrower, or even morph between a normal font and a stencil version, always incredibly smoothly.

You don’t need to buy expensive software to do that. In fact, a lot of these images are made in Drawbot, a free application for MacOS. Although Drawbot was initially developed as a tool for learning to code in Python, the fact that it can export in PDF, SVG, PNG, MP4, GIF and other formats made it an excellent tool for automating tasks in graphic design. You can even typeset a whole book in it and then export it as a print-ready PDF with CMYK colors!

In this post I share the code I used to create the animation of Malva Variable. Although my goal is not to make this a Python class, I took the care to annotate what every line of the code does. This way you’ll be able to read the code and have an idea of what’s happening at any given point.

To recreate the animation, copy and paste (or even better, type) the code below into Drawbot and save the file with a .py extension. If you want to, you can customize the variables at the beginning.

# -------------------------------
# EDIT THESE VARIABLES
# -------------------------------
# The size of the page
w, h = 980, 490
# The text to be drawn
text_string = 'Animating in Drawbot!'
# The number of lines
lines = 5
# The font name
font_name = 'MalvaVariable-Italic'
# The background and foreground colors
bg_r, bg_g, bg_b = 25, 29, 59
fg_r, fg_g, fg_b = 235, 0, 89
# The number of frames and the total duration
total_frames = 30
total_duration = 2 # in seconds
# -------------------------------

# Count the number of characters
chars = len(text_string)
# Calculate the font size
font_size = w / 12
# Get and store the minimum and maximum wght values
min_var = listFontVariations(font_name)['wght']['minValue']
max_var = listFontVariations(font_name)['wght']['maxValue']
# Calculate the duration of each frame
frame_duration = total_duration / total_frames

# For each frame...
for frame in range(total_frames):

    # Create a new page and set its duration
    newPage(w, h)
    frameDuration(frame_duration)

    # Draw the background rectangle
    fill(bg_r/255, bg_g/255, bg_b/255)
    rect(0,0,w,h)
    
    # Calculate the vertical position of the first line
    y = (h - (lines * font_size)) / 2
    y = y + w/50

    # Start each frame in a different wght value
    frame_start = (2 * pi) * frame / total_frames

    # For each line...
    for line in range(lines):
        
        # Start each LINE in a different wght value
        step_start = frame_start - (pi * (line / (lines - 1)))
        
        # Create a new empty text object and set its properties
        txt = FormattedString()
        txt.fill(fg_r/255, fg_g/255, fg_b/255)
        txt.font(font_name)
        txt.fontSize(font_size)
        txt.openTypeFeatures(ss01=True)

        # For each character
        for char_index in range(chars):
            
            # Calculate the wght value
            inst_step = pi * (char_index / (chars -1))
            curr_step = (cos(step_start - inst_step) + 1) / 2
            wght_value = min_var + curr_step * (max_var - min_var)
            
            # Add the character to the text object
            txt.append(
                text_string[char_index], 
                fontVariations=dict(wght=wght_value)
                )
        
        # After all characters were added 
        # to the text object, get its dimensions
        text_width, text_height = textSize(txt)

        # Calculate the horizontal position required 
        # to center this line on the page
        x = (w - text_width) / 2
        
        # Finally draw this line of text
        text(txt, (x, y))

        # Move the y coordinate up for the next line
        y = y + font_size
    
# Save the animation as a gif
saveImage("Animating in Drawbot.gif")

After copying the code into Drawbot, run the script either by clicking the Run button on the toolbar or by pressing ⌘R. After a few seconds, you’ll see a series of pages (or frames) on the left side of the window and a GIF file in the same folder you’ve saved the script.

Using other variable fonts

In case you don’t have Malva Variable in your system, you can use any other variable font instead. To find out which variable fonts are installed, type the code below in a new file and then run it. This tiny script loops through all installed fonts and checks each one of them for variable properties, the variation axes.

# For each font installed in the OS...
for f in installedFonts():
    # If the current font has variation axes...
    if listFontVariations(f):
        # Write the name of the current font to the output panel.
        print(f)

After you run the code above, you will get a list of all the variable fonts installed on your system. Use this information to choose a font to use in the main script.