CTk Interactive Canvas

Interactive canvas widget for CustomTkinter with draggable, resizable rectangles featuring multi-selection, alignment, distribution, and professional-grade interaction controls.

Table of Contents

• Features
• Installation
• Quick Start
• Usage Examples
• Keyboard Modifiers
• API Reference
• Requirements
• Development
• License
• Contributing
• Changelog
• Credits

Features

Core Capabilities

• Draggable Rectangles: Click and drag to move objects
• Resizable Objects: Bottom-right handle for intuitive resizing
• Multi-Selection: Shift-click or drag-select multiple objects
• Alignment Tools: Align multiple rectangles (top, middle, bottom, start, center, end)
• Distribution Tools: Evenly distribute rectangles horizontally or vertically
• Panning: Middle-mouse or Space+drag to pan the canvas

Professional Controls

• Editor-style Constraints:
  • Shift during move: Lock to 45-degree angles (0°, 45°, 90°, 135°, etc.)
  • Shift during resize: Maintain aspect ratio
  • Ctrl during resize: Resize from center
  • Alt during resize: Constrain to one dimension
  • Shift+Ctrl during resize: Aspect ratio + center resize

Advanced Features

• 26 Magic Methods: NumPy-like interface for geometric operations
• Unit Conversion: Built-in mm ↔ px conversion with DPI support
• Intersection & Union: Geometric operations via & and | operators
• Point Containment: Test if coordinates are inside rectangles
• Sorting & Comparison: Area-based ordering and equality testing
• Coordinate Access: Index-based access and iteration

Installation

pip install ctk-interactive-canvas

Quick Start

import customtkinter as ctk
from ctk_interactive_canvas import InteractiveCanvas

root = ctk.CTk()
root.title("Interactive Canvas Demo")

canvas = InteractiveCanvas(root, width=800, height=600, bg='white')
canvas.pack()

rect1 = canvas.create_draggable_rectangle(50, 50, 150, 150, outline='blue', width=5)
rect2 = canvas.create_draggable_rectangle(200, 200, 300, 300, outline='red', width=5)

root.mainloop()

Usage Examples

Basic Rectangle Creation

canvas = InteractiveCanvas(root, width=800, height=600, bg='white')
canvas.pack()

rect = canvas.create_draggable_rectangle(
    x1=100, y1=100,
    x2=200, y2=200,
    outline='blue',
    width=5,
    fill=''
)

Selection Callbacks

def on_select():
    selected = canvas.get_selected()
    print(f"Selected: {len(selected)} objects")

def on_deselect():
    print("Selection cleared")

canvas = InteractiveCanvas(
    root,
    width=800,
    height=600,
    select_callback=on_select,
    deselect_callback=on_deselect
)

Alignment and Distribution

from ctk_interactive_canvas import DraggableRectangle

rectangles = [rect1, rect2, rect3]

DraggableRectangle.align(rectangles, mode='center')
DraggableRectangle.distribute(rectangles, mode='horizontal')

Mathematical Operations

translated = rect + [50, 30]

doubled = rect * 2

halved = rect / 2

rect += [10, 10]

intersection = rect1 & rect2
bounding = rect1 | rect2

if [x, y] in rect:
    print("Point inside rectangle!")

sorted_rects = sorted([rect1, rect2, rect3])

Unit Conversion

rect = canvas.create_draggable_rectangle(0, 0, 100, 100)

pos_mm = rect.get_topleft_pos(in_mm=True, dpi=300)
print(f"Position in mm: {pos_mm}")

rect.set_size([50, 50], in_mm=True, dpi=300)

Coordinate Access

x0, y0, x1, y1 = rect

rect[2] = 300

coords = rect[:]

for coord in rect:
    print(coord)

Keyboard Modifiers

API Reference

InteractiveCanvas

InteractiveCanvas(
    master=None,
    select_callback=None,
    deselect_callback=None,
    delete_callback=None,
    select_outline_color='#16fff6',
    dpi=300,
    create_bindings=True,
    **kwargs
)

Methods:

• create_draggable_rectangle(x1, y1, x2, y2, **kwargs) → DraggableRectangle
• copy_draggable_rectangle(rect, offset=[21, 21], **kwargs) → DraggableRectangle
• delete_draggable_rectangle(item_id) → None
• get_selected() → List[DraggableRectangle]
• get_draggable_rectangle(item_id) → DraggableRectangle
• select_all() → None
• deselect_all() → None

DraggableRectangle

Position & Size:

• get_topleft_pos(relative_pos=None, in_mm=False, dpi=None) → [x, y]
• set_topleft_pos(new_pos, relative_pos=None, in_mm=False, dpi=None)
• get_size(in_mm=False, dpi=None) → [width, height]
• set_size(new_size, in_mm=False, dpi=None)

Transformations:

• safe_rotate(angle, anchor='topleft') - Rotate 90°/180°/-90°/-180°
• copy_(offset=[50, 50], **kwargs) → DraggableRectangle

Class Methods:

• align(rectangles, mode, relative_pos=None) - Align multiple rectangles
• distribute(rectangles, mode, relative_pos=None) - Distribute evenly
• compare(rect1, rect2) → (bool, dict) - Compare two rectangles
• get_instances() → List[DraggableRectangle] - Get all alive instances

Magic Methods:

• Arithmetic: +, -, *, /, +=, -=, *=, /=
• Comparison: ==, !=, <, <=, >, >=
• Bitwise: & (intersection), | (union)
• Unary: -, +, abs()
• Container: len(), [], in, iter()
• Representation: str(), repr(), format(), bool(), hash()

Requirements

• Python ≥ 3.9
• CustomTkinter ≥ 5.1.0

Development

Install Development Dependencies

pip install -e ".[dev]"

Run Tests

pytest

Code Quality

black .
ruff check .
mypy src/ctk_interactive_canvas

License

See LICENSE file for details.

Contributing

See CONTRIBUTING.md for guidelines.

Changelog

See CHANGELOG.md for version history.

Credits

Author

T. K. Joram Smith (DeltaGa)

• Email: dev.github.tkjoramsmith@outlook.com
• GitHub: @DeltaGa

Acknowledgments

• CustomTkinter - Modern UI framework

Note: This package is in active development. APIs may change between minor versions until 1.0.0 release.