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Documentation Index

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LWXGL maps all colors through a fixed 16-entry palette. Every color you specify is an index from 0 to 15 — there are no hex color codes, RGB structs, or named color strings in the API. On startup, GCreateWindow allocates all 16 palette entries in the X11 colormap, and they remain valid for the lifetime of the window.

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Palette Reference

IndexNameApprox RGB
0Black#000000
1Dark Blue#0303AD
2Dark Green#00AA00
3Dark Cyan#00A8A8
4Dark Red#BA0606
5Dark Magenta#A800A8
6Orange#E67E22
7Light Gray#A8A8A8
8Dark Gray#555753
9Light Blue#5757FF
10Light Green#55FF55
11Light Cyan#60F0F0
12Light Red#FF5555
13Light Magenta#F054F0
14Yellow#F4F236
15White#FFFFFF

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Direct Color Indices

Most of the API accepts a plain int palette index:

Text & Rectangles

GCreateText color, GCreateRect fg/bg

Drawing Primitives

GPrimitiveLine, GPrimitiveRect, GPrimitiveCircle fg/bg, GPrimitiveSprite color

Image Pixel Data

Each byte in the GGetImageData buffer is a direct palette index

Window Background

GCreateWindow bgcol parameter
Pass the index as a plain integer literal or a #define constant: 
/* Fill 10 pixels with Orange (index 6) */
unsigned char *pixels = GGetImageData(0);
for (int i = 0; i < 10; i++) pixels[i] = 6;

/* White text on a dark background */
GCreateText(1, 20, 20, 15, "Score: 0");

/* Dark-red border, dark-blue fill */
GCreateRect(2, 50, 50, 100, 60, 4, 1);

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Packed Color Bytes

Two widget creation functions — GCreateButton and GCreateInput — accept packed color bytes instead of separate fg/bg parameters. A packed color is a single int where:
  • High nibble (bits 7–4): foreground palette index (text color and border color)
  • Low nibble (bits 3–0): background palette index (fill color)
Packed value 0x7F:
  High nibble = 0x7 = 7  → Light Gray  (foreground)
  Low nibble  = 0xF = 15 → White       (background)

Packed value 0x0A:
  High nibble = 0x0 = 0  → Black       (foreground)
  Low nibble  = 0xA = 10 → Light Green (background)
Internally LWXGL extracts the two components with the macros: 
#define H(b)  (((b) >> 4) & 0x0F)   /* high nibble → foreground */
#define L(b)  ((b) & 0x0F)           /* low nibble  → background */
You can define your own helper macro to assemble packed values from named indices: 
#define PACK_COLOR(fg, bg) (((fg) << 4) | (bg))

/* Button: normal = gray text on white, hover = light-blue on white, pressed = green on white */
GCreateButton(0, 10, 10, 80, 28,
    PACK_COLOR(7, 15),   /* normal  */
    PACK_COLOR(9, 15),   /* hover   */
    PACK_COLOR(10, 15),  /* pressed */
    "OK", my_callback);

/* Input: black text on white; hover: dark-gray text on light-cyan */
GCreateInput(1, 10, 50, -1, 24,
    PACK_COLOR(0, 15),   /* normal */
    PACK_COLOR(8, 11),   /* hover  */
    20);

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Background Color

The bgcol parameter of GCreateWindow is a direct palette index. It determines the color used to clear the entire window at the start of every GRenderWindow call — effectively the “canvas background” behind all elements. 
GCreateWindow(800, 600, "My App", 8); /* Dark Gray background */
GCreateRect also accepts direct fg/bg indices with -1 as an opt-out: 
/* Fill only — no border */
GCreateRect(3, 0, 0, 800, 600, -1, 1);  /* Dark Blue panel, no border */

/* Border only — no fill */
GCreateRect(4, 10, 10, 200, 150, 15, -1); /* White border, transparent interior */
Define named constants for the palette indices you use most often. This makes your code far easier to read and update later — especially if you want to retheme your UI by changing a single #define.
#define COL_BG        8   /* Dark Gray */
#define COL_TEXT      15  /* White */
#define COL_ACCENT    9   /* Light Blue */
#define COL_DANGER    4   /* Dark Red */
#define COL_SUCCESS   10  /* Light Green */

GCreateText(0, 20, 20, COL_TEXT, "Status: OK");
GCreateRect(1, 0, 0, 800, 4, -1, COL_ACCENT); /* accent bar */

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