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void FastWatermark::Nv12AddDateWatermark(unsigned char* nv12Buf, int width, int height, const char *text){
    unsigned int picSize = width * height * 3 / 2;
    int x = m_x_pos;

    for (const char* p = text; *p; p++) {
        // if (FT_Load_Char(face, *p, FT_LOAD_RENDER)) {
        //     mylog(E, "Failed to load glyph %c", *p);
        //     continue;
        // }
        // FT_GlyphSlot slot = face->glyph;

        auto it = glyphCache.find(*p);
        if (it == glyphCache.end()) {
            mylog(E, "Glyph not found in cache: %c", *p);
            assert(false);
            continue;
        }

        const CachedGlyph& glyph = it->second;
        int y_pos = m_y_pos - glyph.bitmap_top;

        for (int i = 0; i < glyph.height; i++) {
            for (int j = 0; j < glyph.width; j++) {
                uint8_t alpha = glyph.bitmap[i * glyph.pitch + j];
                
                if (alpha > 0) {
                    uint32_t index = (y_pos + i) * width + x + j;
                    if (index >= picSize) continue;  // 边界检查
                    
                    float alpha_ratio = alpha / 255.0f;
                    nv12Buf[index] = static_cast<uint8_t>(
                        (1.0f - alpha_ratio) * nv12Buf[index] + alpha_ratio * 255
                    );
                }
            }
        }

        x += glyph.advance;
    }
}