Raylib

Quick Guide

Parameter	Type	Description
(none)	—	RaylibBackend() takes no parameters

Introduction

RaylibBackend is CoshUI's backend for raylibpy. Unlike PygameBackend, it doesn't draw onto an explicit surface object — raylib always draws to the currently active window — so RaylibBackend() takes no constructor parameters at all.

Setup

import raylibpy
import coshui as cui

raylibpy.init_window(800, 600, "My App")

while not raylibpy.window_should_close():
    raylibpy.begin_drawing()
    raylibpy.clear_background(raylibpy.RAYWHITE)

    with cui.CoshUIRenderer(cui.RaylibBackend()):
        cui.Label(id="hello", text="Hello, raylib!")

    raylibpy.end_drawing()

This makes RaylibBackend the most drop-in friendly backend if you're migrating an existing raylib project — there's no context or surface plumbing required beyond making sure the window is already initialized.

---

How Rendering Works

Like every other backend, RaylibBackend.flush() walks the render stack produced by CoshUI's render pass and dispatches each RenderContext to _draw_rect, _draw_text, or _draw_image based on which visual properties are set.

---

Rects and Borders

For rects with a uniform border_radius (all four corners equal), CoshUI uses raylib's native draw_rectangle_rounded() and draw_rectangle_rounded_lines_ex() for the fill and border respectively, since raylib only supports a single uniform roundness value out of the box. If border_radius is asymmetric (different per corner), CoshUI falls back to a custom implementation (_draw_asymmetric_rect) that manually draws each rounded corner as a circle sector alongside straight rectangle segments, since raylib has no native support for independently-radiused corners.

Rotation is handled using raylib's matrix stack — rl_push_matrix(), rl_translatef(), and rl_rotatef() are used to rotate around the rect's center before drawing, then popped back afterward.

---

Text

Fonts are loaded with load_font_ex() at a fixed internal resolution of 128px and then scaled at draw time, which keeps text looking sharp across different font_size values without needing to reload separate font assets. Fonts are cached by path so they're only loaded once. Word-wrapping is handled the same way as the other backends — manually measuring with measure_text_ex() word-by-word. Rotated text uses draw_text_pro() with an origin set to the text's own center so it rotates in place.

---

Images

Images are loaded with load_texture() and cached by path. They're drawn using draw_texture_pro(), which lets CoshUI scale, position, and rotate the texture in a single call without needing a separate transform step like the other backends require.

---

Clipping

Clipping uses raylib's scissor mode via begin_scissor_mode() / end_scissor_mode(), which is raylib's native equivalent to a clip rect.

---

Input Polling

RaylibBackend.poll_input() reads get_mouse_position() and get_mouse_delta() for position and delta, and is_mouse_button_down(MOUSE_BUTTON_LEFT) for the left mouse button. Like the other backends, this is called automatically each frame and doesn't need to be invoked manually.