java-topology/defects/raylib/patch/raylib-0001-getglyphindex-hashmap.md

# UNDF: UNDF-2026-000000259
# raylib-0001: GetGlyphIndex — O(T×G) linear scan per character in all text hot paths

## CWE-407 — Algorithmic Complexity

| Field | Value |
|-------|-------|
| ID | raylib-0001 |
| Severity | HIGH |
| Ecosystem | raylib |
| Package | rtext |
| File | `src/rtext.c` |
| Lines | 1453–1479 (GetGlyphIndex), callers: 1292, 1363, 1420, 1488, 1499 |
| Complexity | O(T × G) per text render/measure call |
| Hot path | Every DrawText, DrawTextEx, MeasureText, MeasureTextEx, DrawTextCodepoints |

## Background

raylib exposes a `Font` struct that holds an array of `GlyphInfo[]` indexed by
position, not by codepoint value.  When text is drawn or measured, each
character must be converted from its Unicode codepoint to an array index via
`GetGlyphIndex`.

The function is called once per character in every text rendering and
measurement operation, making it the innermost operation in all text paths.

## Defect

`GetGlyphIndex` performs a linear scan over the entire glyph array to find the
matching codepoint:

```c
// src/rtext.c:1453
int GetGlyphIndex(Font font, int codepoint)
{
    int index = 0;
    if (!IsFontValid(font)) return index;

#define SUPPORT_UNORDERED_CHARSET
#if defined(SUPPORT_UNORDERED_CHARSET)
    int fallbackIndex = 0;      // Get index of fallback glyph '?'

    // Look for character index in the unordered charset
    for (int i = 0; i < font.glyphCount; i++)
    {
        if (font.glyphs[i].value == 63) fallbackIndex = i;

        if (font.glyphs[i].value == codepoint)
        {
            index = i;
            break;
        }
    }

    if ((index == 0) && (font.glyphs[0].value != codepoint)) index = fallbackIndex;
#else
    index = codepoint - 32;
#endif

    return index;
}
```

The `#define SUPPORT_UNORDERED_CHARSET` is defined right before the `#if` check,
so this branch **always executes** and the O(1) fast path is dead code.

Call sites that call `GetGlyphIndex` inside per-character loops:

| Function | File | Hot loop |
|----------|------|----------|
| `DrawTextCodepoints` | rtext.c:1290 | `for (int i = 0; i < codepointCount; i++)` |
| `MeasureTextEx` | rtext.c:1357 | `for (int i = 0; i < size;)` |
| `MeasureTextCodepoints` | rtext.c:1417 | `for (int i = 0; i < length; i++)` |
| `DrawTextCodepoint` (via DrawText) | rtext.c:1263 | called per character |

With a font containing G glyphs and a string of T characters, every draw or
measure call costs O(T × G) comparisons.  A full Unicode font (G ≈ 4000–10000
glyphs) rendering a paragraph (T ≈ 500 chars) performs 2–5 million comparisons
per frame just for text layout.

## Fix

Build a codepoint→index lookup table at font load time.  raylib already has
`rlHashTable` or can use a simple sorted array with binary search.  The
simplest approach is a hash table keyed by codepoint:

**Option A — hash map (O(1) lookup after O(G) build):**

```c
// In Font struct (raylib.h), add:
// int *glyphIndex;   // hash table: codepoint → glyph array index

// At font load time (LoadFontData / GenImageFontAtlas):
void BuildGlyphIndex(Font *font)
{
    // Allocate power-of-two hash table sized 2× glyph count
    int tableSize = 1;
    while (tableSize < font->glyphCount * 2) tableSize <<= 1;
    font->glyphIndex = (int *)RL_CALLOC(tableSize, sizeof(int));
    int mask = tableSize - 1;
    // sentinel: -1 = empty slot
    for (int i = 0; i < tableSize; i++) font->glyphIndex[i] = -1;
    for (int i = 0; i < font->glyphCount; i++)
    {
        int h = (font->glyphs[i].value * 2654435761u) & mask;
        while (font->glyphIndex[h] != -1) h = (h + 1) & mask;
        font->glyphIndex[h] = i;
    }
}

// GetGlyphIndex becomes O(1):
int GetGlyphIndex(Font font, int codepoint)
{
    if (!IsFontValid(font)) return 0;
    if (!font.glyphIndex) { /* fallback linear scan */ }
    int tableSize = /* stored in Font or inferred */ ...;
    int mask = tableSize - 1;
    int h = ((unsigned)codepoint * 2654435761u) & mask;
    while (font.glyphIndex[h] != -1)
    {
        int i = font.glyphIndex[h];
        if (font.glyphs[i].value == codepoint) return i;
        h = (h + 1) & mask;
    }
    return 0;  // fallback to '?'
}
```

**Option B — sort glyphs array by codepoint at load time and use binary search
(O(log G) lookup, zero additional memory):**

```c
// Sort once at load:
int CompareGlyphs(const void *a, const void *b) {
    return ((GlyphInfo *)a)->value - ((GlyphInfo *)b)->value;
}
qsort(font->glyphs, font->glyphCount, sizeof(GlyphInfo), CompareGlyphs);

// Binary search in GetGlyphIndex replaces the #else branch:
// Remove #define SUPPORT_UNORDERED_CHARSET and use binary search always.
```

Option B is the minimal-change fix and eliminates the `SUPPORT_UNORDERED_CHARSET`
dead-code hazard.

## Speedup

| G (font glyph count) | T (chars per frame) | Before (ops) | After (ops) | Speedup |
|----------------------|---------------------|--------------|-------------|---------|
| 95 (ASCII) | 500 | 47,500 | 500 | 95× |
| 1000 (extended) | 500 | 500,000 | 500 | 1000× |
| 4000 (CJK subset) | 500 | 2,000,000 | 500 | 4000× |
| 10,000 (full Unicode) | 500 | 5,000,000 | 500 | 10,000× |

For ASCII-only games the improvement is ~95× per draw call.  For
internationalized titles using large Unicode fonts the pathology reaches
millions of comparisons per frame, making text rendering a bottleneck even at
low scene complexity.

## Note

The `#define SUPPORT_UNORDERED_CHARSET` pragma immediately before the `#if`
check ensures the efficient `index = codepoint - 32` path (the `#else` branch)
**can never execute**.  The dead code comment appears to be an old optimization
path left behind when the unordered charset support was added.  Removing the
define and restoring the `#else` path would only work for fonts built in ASCII
order starting at codepoint 32, so the hash map or sorted binary search
approach is the correct general fix.