# Render Overlapping Rectangles on an ASCII Canvas Implement `render_canvas(width, height, rectangles)`. The canvas initially contains spaces and is returned as a list of `height` strings, each of length `width`. Each rectangle is `(x, y, w, h, border_char, fill_char)`, where `(x, y)` is its upper-left corner, `w` is its width, and `h` is its height. Draw the outermost cells with `border_char` and interior cells with `fill_char`. Coordinates may place part or all of a rectangle outside the canvas; clip safely. Rectangles are drawn in input order, so later rectangles overwrite earlier pixels wherever they overlap. ## Constraints - `0 <= width, height <= 1000` - `1 <= w, h <= 1000` - `x` and `y` may be negative. - `border_char` and `fill_char` are single printable characters. - The total canvas area is at most `10^6` cells. ## Example For a `5` by `4` canvas and rectangle `(1, 1, 3, 2, '#', '.')`, return: ```text ### ### ``` A one-cell-wide or one-cell-high rectangle consists entirely of border cells. ## Clarifications Canvas coordinates use zero-based columns and rows. Preserve trailing spaces in every returned row. Explain how clipping prevents invalid indexing without changing whether a visible cell is a border or interior cell of the original rectangle. ## Hints Intersect each rectangle's coordinate range with the canvas before visiting pixels, but compute border status in the rectangle's original coordinates. ## Extensions - Return only changed regions for a very large sparse canvas. - Support transparency or z-indexes. - Add tests for total clipping, corner clipping, thin rectangles, and overwrite order.