pxl8/src/pxl8_font.c

#include <string.h>

#include <SDL3/SDL.h>

#include "pxl8_font.h"

pxl8_result pxl8_font_create_atlas(const pxl8_font* font, u8** atlas_data, i32* atlas_width, i32* atlas_height) {
    if (!font || !atlas_data || !atlas_width || !atlas_height) {
        return PXL8_ERROR_NULL_POINTER;
    }
    
    i32 glyphs_per_row = 16;
    i32 rows_needed = (font->glyph_count + glyphs_per_row - 1) / glyphs_per_row;
    
    *atlas_width = glyphs_per_row * font->default_width;
    *atlas_height = rows_needed * font->default_height;
    
    i32 atlas_size = (*atlas_width) * (*atlas_height);
    *atlas_data = (u8*)SDL_malloc(atlas_size);
    if (!*atlas_data) {
        return PXL8_ERROR_OUT_OF_MEMORY;
    }
    
    memset(*atlas_data, 0, atlas_size);
    
    for (u32 i = 0; i < font->glyph_count; i++) {
        const pxl8_glyph* glyph = &font->glyphs[i];
        
        i32 atlas_x = (i % glyphs_per_row) * font->default_width;
        i32 atlas_y = (i / glyphs_per_row) * font->default_height;
        
        for (i32 y = 0; y < glyph->height && y < font->default_height; y++) {
            for (i32 x = 0; x < glyph->width && x < font->default_width; x++) {
                i32 glyph_idx = y * 8 + x;
                i32 atlas_idx = (atlas_y + y) * (*atlas_width) + (atlas_x + x);
                
                if (glyph->format == PXL8_FONT_FORMAT_INDEXED) {
                    u8 pixel_byte = glyph->data.indexed[glyph_idx / 8];
                    u8 pixel_bit = (pixel_byte >> (7 - (glyph_idx % 8))) & 1;
                    (*atlas_data)[atlas_idx] = pixel_bit ? 255 : 0;
                } else {
                    u32 rgba_pixel = glyph->data.rgba[glyph_idx];
                    (*atlas_data)[atlas_idx] = (rgba_pixel >> 24) & 0xFF;
                }
            }
        }
    }
    
    return PXL8_OK;
}

const pxl8_glyph* pxl8_font_find_glyph(const pxl8_font* font, u32 codepoint) {
    if (!font || !font->glyphs) return NULL;
    
    for (u32 i = 0; i < font->glyph_count; i++) {
        if (font->glyphs[i].codepoint == codepoint) {
            return &font->glyphs[i];
        }
    }
    
    return NULL;
}