Function ImHashData

imgui/imgui.cpp:1906–1914

Known size hash It is ok to call ImHashData on a string with known length but the ### operator won't be supported. FIXME-OPT: Replace with e.g. FNV1a hash? CRC32 pretty much randomly access 1KB. Need to do proper measurements.

// It is ok to call ImHashData on a string with known length but the ### operator won't be supported.
// FIXME-OPT: Replace with e.g. FNV1a hash? CRC32 pretty much randomly access 1KB. Need to do proper measurements.
ImGuiID ImHashData(const void* data_p, size_t data_size, ImU32 seed)
{
    ImU32 crc = ~seed;
    const unsigned char* data = (const unsigned char*)data_p;
    const ImU32* crc32_lut = GCrc32LookupTable;
    while (data_size-- != 0)
        crc = (crc >> 8) ^ crc32_lut[(crc & 0xFF) ^ *data++];
    return ~crc;
}

// Zero-terminated string hash, with support for ### to reset back to seed value
// We support a syntax of "label###id" where only "###id" is included in the hash, and only "label" gets displayed.