Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/DRESsedAlarm184/LWXGL/llms.txt

Use this file to discover all available pages before exploring further.

LWXGL uses a fixed 16-entry indexed color palette rather than arbitrary RGB values. Every color in the library is expressed as a small integer index between 0 and 15, or the special sentinel CLR_NONE (-1) for transparency. The palette is allocated from the X colormap during CreateWindow and shared across all rendering operations, which means a single palette change instantly affects every widget and image that uses the modified index.

​
The 16 Palette Entries

The default palette is defined in main.cc as the color_palette array. Named constants for each entry are declared in libLWXGL.h.
ConstantValueRGB
CLR_NONE-1Transparent / no-draw
CLR_BLACK0x00, 0, 0
CLR_BLUE0x13, 3, 173
CLR_GREEN0x20, 170, 0
CLR_CYAN0x30, 168, 168
CLR_RED0x4186, 6, 6
CLR_MAGENTA0x5168, 0, 168
CLR_ORANGE0x6230, 126, 34
CLR_LGRAY0x7168, 168, 168
CLR_GRAY0x885, 87, 83
CLR_LBLUE0x987, 87, 255
CLR_LGREEN0xA85, 255, 85
CLR_LCYAN0xB96, 240, 240
CLR_LRED0xC255, 85, 85
CLR_LMAGENTA0xD240, 84, 240
CLR_YELLOW0xE244, 242, 54
CLR_WHITE0xF255, 255, 255
CLR_NONE is never stored in the palette array — it is a sentinel value recognized by drawing functions to mean “skip this draw.” The 16 real palette entries occupy indices 0x0 through 0xF.

​
Packing Two Colors into One int

Many element-creation functions accept a single int that encodes both a fill color and a border/outline color. The packing uses the low nibble for the fill and the high nibble for the border:
NibbleMeaning
Low nibble (value & 0x0F)Fill / interior color
High nibble ((value >> 4) & 0x0F)Border / outline color
This is expressed in source code with the L(b) and H(b) macros defined in main.cc: 
#define L(b)  ((b) & 0x0F)
#define H(b)  (((b) >> 4) & 0x0F)

​
Building a Packed Color

// Fill = CLR_LGRAY (0x7), border = CLR_WHITE (0xF)
int style = CLR_LGRAY | (CLR_WHITE << 4);   // 0xF7

// Fill = CLR_BLACK (0x0), border = CLR_CYAN (0x3)
int dark_box = CLR_BLACK | (CLR_CYAN << 4); // 0x30

​
Where Packed Colors Are Used

CreateButton accepts three packed-color arguments — one for each interactive state: 
void CreateButton(int id, int x, int y, int w, int h,
                  int u,    // unpressed state: fill | (border << 4)
                  int hvr,  // hover state:     fill | (border << 4)
                  int p,    // pressed state:   fill | (border << 4)
                  const char* label, void (*onclick)(void));

int normal  = CLR_LGRAY   | (CLR_GRAY  << 4);  // 0x87
int hovered = CLR_WHITE   | (CLR_LBLUE << 4);  // 0x9F
int pressed = CLR_LBLUE   | (CLR_BLUE  << 4);  // 0x19

CreateButton(1, 20, 20, 100, 28, normal, hovered, pressed, "Click me", on_click);
CreateInput, CreateCheckbox, and CreateConsole use the same packing scheme for their color parameters.

​
Runtime Palette Modification

The palette can be changed at any time after CreateWindow using the three palette functions.

​
PaletteModify

void PaletteModify(int idx, unsigned char r, unsigned char g, unsigned char b, int redraw);
Replaces palette entry idx with the new RGB values. Internally, XFreeColors releases the old pixel value and XAllocColor claims a new one. If redraw is non-zero, RedrawAllImages is called immediately to re-blit every ImageElement using the new color. 
// Swap CLR_RED to a softer coral tone
PaletteModify(CLR_RED, 220, 80, 60, 1);
Changing a palette entry affects every element that uses that color index — buttons, rects, text, images, and the window background. There is no per-element override. Use PaletteReset to restore the defaults when needed.

​
PaletteQuery

void PaletteQuery(int idx, unsigned char* r, unsigned char* g, unsigned char* b);
Reads the current RGB values of palette entry idx from the X colormap into the provided pointers. Useful for saving palette state before making temporary modifications. 
unsigned char r, g, b;
PaletteQuery(CLR_GREEN, &r, &g, &b);
// r=0, g=170, b=0 (default)

​
PaletteReset

void PaletteReset();
Frees all 16 current color allocations and re-allocates them from the original color_palette array in main.cc. Also calls RedrawAllImages to refresh pixel data. 
// Restore all colors to their defaults
PaletteReset();

​
Palette Changes and TGA Images

TGA images can be loaded with an option to replace the image’s black (RGB 0, 0, 0) pixels with the current palette color for a given index. The change_palette parameter in AllocateTGA, AllocateMemoryTGA, and CreateTGAImage enables this behavior: 
// Load a TGA; black pixels → current CLR_WHITE color
int ok = AllocateTGA("icon", "/path/to/icon.tga", CLR_WHITE, 0);
When PaletteModify is subsequently called with redraw = 1, RedrawAllImages re-applies this substitution using the updated color, so icons automatically recolor when the palette changes.
To create a recolorable monochrome icon, draw it in pure black on a transparent (or distinct background) color, then load it with a non-negative change_palette index. Cycling the palette entry effectively re-tints all instances of that image.

Build docs developers (and LLMs) love

Get started for freeTalk to us