Adding shapes like circles rectangles to PDF file by using Python ReportLab

Interactive Google Colab Practice Notebook

Practice drawing concentric circles, alternating color fills, random RGB color generation, and nested rectangles with ReportLab shapes directly inside Google Colab.

View on GitHub

PDF pages in Python to add shapes like circles with random colour fills using ReportLab drawing.

Circles can be drawn by specifying center X, Y coordinates and giving a radius. We can also specify the color used to fill the circle using fillColor. Here two concentric circles are drawn with alternating background colors.

With Two Alternate Coloured Circles 🔝

from pathlib import Path
from reportlab.graphics.shapes import Drawing, Circle
from reportlab.graphics import renderPDF

output_dir = Path('output')
output_dir.mkdir(exist_ok=True)
my_path = output_dir / 'two_color_circles.pdf'

d = Drawing(600, 600)

for rd in range(0, 300, 10):
    if rd % 20 == 0:
        d.add(Circle(300, 300, 300 - rd, fillColor=[1, 0, 0]))
    else:
        d.add(Circle(300, 300, 300 - rd, fillColor=[0, 1, 0]))

renderPDF.drawToFile(d, str(my_path), '')
print(f"PDF created: {my_path}")

Random Multi Coloured Concentric Circles 🔝

We can generate floating-point numbers between 0 and less than 1 (exclusive) by using random.random().
random.uniform() returns floats between start and stop (inclusive).
More about Random numbers

Random coloured concentric circles in PDF

import random
from pathlib import Path
from reportlab.graphics.shapes import Drawing, Circle
from reportlab.graphics import renderPDF

output_dir = Path('output')
output_dir.mkdir(exist_ok=True)
my_path = output_dir / 'random_color_circles.pdf'

d = Drawing(1200, 1200)

for rd in range(0, 600, 20):
    r = random.random()
    g = random.random()
    b = random.random()
    d.add(Circle(600, 600, 600 - rd, fillColor=[r, g, b]))

renderPDF.drawToFile(d, str(my_path), '')
print(f"PDF created: {my_path}")

Drawing Random Colour Filled Rectangles 🔝

Here we have used random.uniform(0,1) to generate random floats between 0 and 1 (inclusive of 0 and 1). Check this link for the difference between random.uniform() and random.random().

More about Random numbers

Here width and height are assigned to variables so they can easily be adjusted at a single point.

w, h = 620, 620

Full code for nested random color rectangles:

import random
from pathlib import Path
from reportlab.graphics.shapes import Drawing, Rect
from reportlab.graphics import renderPDF

output_dir = Path('output')
output_dir.mkdir(exist_ok=True)
my_path = output_dir / 'random_color_rectangles.pdf'

w, h = 620, 620
d = Drawing(w, h)

for rd in range(0, int(w / 2), 20):
    r = random.uniform(0, 1)
    g = random.uniform(0, 1)
    b = random.uniform(0, 1)   
    d.add(Rect(rd, rd, w - (rd * 2), h - (rd * 2), fillColor=[r, g, b]))
        
renderPDF.drawToFile(d, str(my_path), '')
print(f"PDF created: {my_path}")

Practical Uses of Vector Shapes in ReportLab

Vector shapes are fundamental elements in modern PDF document generation and automated publishing workflows:

Custom Visual Backgrounds & Headers: Generate textured color banners, geometric borders, and dynamic watermarks for invoices and certificates.
Data Visualization Base Components: Build standalone infographics, custom gauges, process flow diagrams, and target concentric markers without heavy external image dependencies.
Dynamic Card Layouts: Draw nested rectangles with rounded corners (`rx`, `ry`) to structure product cards, badge backgrounds, and highlighted info boxes.

Common Errors & Troubleshooting

Shapes Overlapping in Wrong Z-Order: ReportLab renders shapes in the order they are added to the Drawing canvas. When drawing concentric shapes, always add larger outer shapes first, followed by smaller inner shapes.
Invalid Color RGB Format: fillColor accepts lists or tuples of RGB values between 0.0 and 1.0 (e.g., [1.0, 0.0, 0.0] for pure red) or ReportLab colors.HexColor / colors.Color objects. Passing values above `1` (like `255`) without converting will throw color rendering errors.
FileNotFoundError on Export: Always use pathlib.Path to ensure export directory structures exist before invoking renderPDF.drawToFile().

Frequently Asked Questions (FAQ)

Q: What is the difference between `random.random()` and `random.uniform()` when setting RGB colors?
A: `random.random()` returns floats in the half-open interval $[0.0, 1.0)$, while `random.uniform(a, b)` returns floats in $[a, b]$. In practice for RGB floats in $[0, 1]$, both methods work effectively, but `random.uniform(0, 1)` allows explicit bounds.

Q: How can I remove the black border stroke around drawn shapes?
A: Set strokeColor=None or strokeWidth=0 when creating the Circle or Rect object.

Using shapes like Circles & Rectangles in PDF