Add `pygame.draw.aarect()` for anti-aliased rectangles

[Fantastair]

Description

pygame.draw.rect() provides functionality to draw both regular rectangles and rounded rectangles, but it does not support anti-aliasing.

In contrast, other pygame.draw primitives already have dedicated anti-aliased counterparts:

• draw.circle() --- draw.aacircle()
• draw.line() --- draw.aaline()
• draw.lines() --- draw.aalines()

So I'm wondering if we should also add an anti-aliasing version for draw.rect() (e.g., pygame.draw.aarect()).

I am willing to take on the implementation of this interface and submit a corresponding pull request after getting positive feedback on this issue.

[BatteRaquette581]

By pygame.draw.aarect(), do you mean drawing a FRect? pygame.draw.rect() and pygame.draw.aarect() would be identical if the rectangle was made up of integers. Anti-aliasing is a technique for edges and lines that aren't in a (x,0) or (0,y) format in terms (e.g diagonals, lines that would be jagged without AA), but the rectangles draw here don't have those.

[Fantastair]

Thank you for your question. You are correct that integer rectangles do not benefit from anti-aliasing on straight edges.

However, draw.rect() supports drawing rounded rectangles directly, while draw.aarect() is specifically designed to enhance the quality of rounded edges.

Manually combining Surface.fill() with draw.aacircle() to construct smooth rounded rectangles is cumbersome and error-prone. Therefore, I propose implementing a native aarect() function that enables precise anti-aliasing of rounded corners with a single call.

[BatteRaquette581]

I see then, it seems to be using the draw_circle_quadrant function for corners, and that seems to be using the Bresenham algorithm instead of the smoother Xiaolin Wu's line algorithm for anti-aliasing. I can possibly take on this task!