Spatial Indexing for Render Culling

Implement a Quadtree data structure for efficiently storing and querying objects by their 2D bounding boxes.

Integrate the Quadtree to spatially partition all drawn strokes on the canvas.

Perform view frustum culling by querying the Quadtree to retrieve only visible strokes.

Modify the render loop to draw only the subset of strokes that are inside the current viewport.