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fix(wm): implement window ownership and thread-safe glyph caching

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boreddevnl
2026-05-10 21:56:11 +02:00
parent f5a79e451a
commit 2d40ca30af
4 changed files with 107 additions and 53 deletions
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56
src/wm/font_manager.c
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@@ -3,6 +3,7 @@
#include "font_manager.h"
#include "stb_truetype.h"
#include "fat32.h"
#include "spinlock.h"
#include <stddef.h>
// Simple math implementations for stb_truetype
@@ -78,6 +79,9 @@ typedef struct {
unsigned char *bitmap;
} font_cache_entry_t;
static font_cache_entry_t font_cache[FONT_CACHE_SIZE] = {0};
// Global lock for the glyph cache. Prevents multi-core race conditions where
// bitmaps were being freed while in use by other cores.
static spinlock_t font_cache_lock = SPINLOCK_INIT;
bool font_manager_init(void) {
return true;
@@ -202,6 +206,8 @@ void font_manager_render_char_scaled(ttf_font_t *font, int x, int y, uint32_t co
if (!font) return;
uint32_t hash = (codepoint * 31 + (uint32_t)scale * 73) % FONT_CACHE_SIZE;
uint64_t fflags = spinlock_acquire_irqsave(&font_cache_lock);
font_cache_entry_t *entry = &font_cache[hash];
unsigned char *bitmap = NULL;
@@ -219,16 +225,27 @@ void font_manager_render_char_scaled(ttf_font_t *font, int x, int y, uint32_t co
real_scale = stbtt_ScaleForPixelHeight(info, scale);
}
// Drop lock during slow decompression to avoid contention
spinlock_release_irqrestore(&font_cache_lock, fflags);
bitmap = stbtt_GetCodepointBitmap(info, 0, real_scale, codepoint, &w, &h, &xoff, &yoff);
fflags = spinlock_acquire_irqsave(&font_cache_lock);
if (entry->bitmap) stbtt_FreeBitmap(entry->bitmap, NULL);
entry->codepoint = codepoint;
entry->scale = scale;
entry->font = font;
entry->w = w; entry->h = h; entry->xoff = xoff; entry->yoff = yoff;
entry->bitmap = bitmap;
// Check if someone else filled it while we were away
if (entry->bitmap && entry->codepoint == codepoint && entry->scale == scale && entry->font == font) {
if (bitmap) stbtt_FreeBitmap(bitmap, NULL);
bitmap = entry->bitmap;
w = entry->w; h = entry->h; xoff = entry->xoff; yoff = entry->yoff;
} else {
if (entry->bitmap) stbtt_FreeBitmap(entry->bitmap, NULL);
entry->codepoint = codepoint;
entry->scale = scale;
entry->font = font;
entry->w = w; entry->h = h; entry->xoff = xoff; entry->yoff = yoff;
entry->bitmap = bitmap;
}
}
// Hold lock while using the bitmap to prevent eviction
if (bitmap) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
@@ -242,6 +259,7 @@ void font_manager_render_char_scaled(ttf_font_t *font, int x, int y, uint32_t co
}
}
}
spinlock_release_irqrestore(&font_cache_lock, fflags);
}
void font_manager_render_char_sloped(ttf_font_t *font, int x, int y, uint32_t codepoint, uint32_t color, float scale, float slope, void (*put_pixel_fn)(int, int, uint32_t)) {
@@ -249,6 +267,7 @@ void font_manager_render_char_sloped(ttf_font_t *font, int x, int y, uint32_t co
if (!font) return;
uint32_t hash = (codepoint * 31 + (uint32_t)scale * 73) % FONT_CACHE_SIZE;
uint64_t fflags = spinlock_acquire_irqsave(&font_cache_lock);
font_cache_entry_t *entry = &font_cache[hash];
unsigned char *bitmap = NULL;
@@ -266,14 +285,22 @@ void font_manager_render_char_sloped(ttf_font_t *font, int x, int y, uint32_t co
real_scale = stbtt_ScaleForPixelHeight(info, scale);
}
spinlock_release_irqrestore(&font_cache_lock, fflags);
bitmap = stbtt_GetCodepointBitmap(info, 0, real_scale, codepoint, &w, &h, &xoff, &yoff);
if (entry->bitmap) stbtt_FreeBitmap(entry->bitmap, NULL);
entry->codepoint = codepoint;
entry->scale = scale;
entry->font = font;
entry->w = w; entry->h = h; entry->xoff = xoff; entry->yoff = yoff;
entry->bitmap = bitmap;
fflags = spinlock_acquire_irqsave(&font_cache_lock);
if (entry->bitmap && entry->codepoint == codepoint && entry->scale == scale && entry->font == font) {
if (bitmap) stbtt_FreeBitmap(bitmap, NULL);
bitmap = entry->bitmap;
w = entry->w; h = entry->h; xoff = entry->xoff; yoff = entry->yoff;
} else {
if (entry->bitmap) stbtt_FreeBitmap(entry->bitmap, NULL);
entry->codepoint = codepoint;
entry->scale = scale;
entry->font = font;
entry->w = w; entry->h = h; entry->xoff = xoff; entry->yoff = yoff;
entry->bitmap = bitmap;
}
}
if (bitmap) {
@@ -291,6 +318,7 @@ void font_manager_render_char_sloped(ttf_font_t *font, int x, int y, uint32_t co
}
}
}
spinlock_release_irqrestore(&font_cache_lock, fflags);
}
int font_manager_get_string_width(ttf_font_t *font, const char *s) {