Method transcode_slice

engine/dlib/src/basis/transcoder/basisu_transcoder.cpp:7819–8643

	}

	bool basisu_lowlevel_etc1s_transcoder::transcode_slice(void* pDst_blocks, uint32_t num_blocks_x, uint32_t num_blocks_y, const uint8_t* pImage_data, uint32_t image_data_size, block_format fmt,
		uint32_t output_block_or_pixel_stride_in_bytes, bool bc1_allow_threecolor_blocks, const bool is_video, const bool is_alpha_slice, const uint32_t level_index, const uint32_t orig_width, const uint32_t orig_height, uint32_t output_row_pitch_in_blocks_or_pixels,
		basisu_transcoder_state* pState, bool transcode_alpha, void *pAlpha_blocks, uint32_t output_rows_in_pixels)
	{
		// 'pDst_blocks' unused when disabling *all* hardware transcode options
		// (and 'bc1_allow_threecolor_blocks' when disabling DXT)
		BASISU_NOTE_UNUSED(pDst_blocks);
		BASISU_NOTE_UNUSED(bc1_allow_threecolor_blocks);
		BASISU_NOTE_UNUSED(transcode_alpha);
		BASISU_NOTE_UNUSED(pAlpha_blocks);

		assert(g_transcoder_initialized);
		if (!g_transcoder_initialized)
		{
			BASISU_DEVEL_ERROR("basisu_lowlevel_etc1s_transcoder::transcode_slice: Transcoder not globally initialized.\n");
			return false;
		}

		if (!pState)
			pState = &m_def_state;

		const uint32_t total_blocks = num_blocks_x * num_blocks_y;

		if (!output_row_pitch_in_blocks_or_pixels)
		{
			if (basis_block_format_is_uncompressed(fmt))
				output_row_pitch_in_blocks_or_pixels = orig_width;
			else
			{
				if (fmt == block_format::cFXT1_RGB)
					output_row_pitch_in_blocks_or_pixels = (orig_width + 7) / 8;
				else
					output_row_pitch_in_blocks_or_pixels = num_blocks_x;
			}
		}

		if (basis_block_format_is_uncompressed(fmt))
		{
			if (!output_rows_in_pixels)
				output_rows_in_pixels = orig_height;
		}
		
		basisu::vector<uint32_t>* pPrev_frame_indices = nullptr;
		if (is_video)
		{
			// TODO: Add check to make sure the caller hasn't tried skipping past p-frames
			//const bool alpha_flag = (slice_desc.m_flags & cSliceDescFlagsHasAlpha) != 0;
			//const uint32_t level_index = slice_desc.m_level_index;

			if (level_index >= basisu_transcoder_state::cMaxPrevFrameLevels)
			{
				BASISU_DEVEL_ERROR("basisu_lowlevel_etc1s_transcoder::transcode_slice: unsupported level_index\n");
				return false;
			}

			pPrev_frame_indices = &pState->m_prev_frame_indices[is_alpha_slice][level_index];
			if (pPrev_frame_indices->size() < total_blocks)
				pPrev_frame_indices->resize(total_blocks);