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quicktex/src/BlockDecoder.h

82 lines
3.0 KiB
C++

/* Python-rgbcx Texture Compression Library
Copyright (C) 2021 Andrew Cassidy <drewcassidy@me.com>
Partially derived from rgbcx.h written by Richard Geldreich 2020 <richgel99@gmail.com>
and licenced under the public domain
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <cmath>
#include <cstdint>
#include <span>
#include <vector>
#include "ColorBlock.h"
#include "util.h"
#include "ndebug.h"
namespace rgbcx {
template <class B, size_t M, size_t N> class BlockDecoder {
public:
using DecodedBlock = ColorBlock<M, N>;
using EncodedBlock = B;
BlockDecoder() noexcept = default;
virtual ~BlockDecoder() noexcept = default;
virtual void DecodeBlock(DecodedBlock dest, EncodedBlock *const block) const noexcept(ndebug) = 0;
void DecodeRow(std::span<DecodedBlock> dests, std::span<const EncodedBlock> blocks) {
assert(dests.size() == blocks.size());
for (int i = 0; i < dests.size; i++) { DecodeBlock(&dests[i], &blocks[i]); }
}
std::vector<Color> DecodeImage(uint8_t *bytes, unsigned image_width, unsigned image_height, unsigned chunk_size = 0, bool threaded = false) {
assert(threaded == chunk_size > 0);
unsigned block_width = maximum(1U, ((image_width + 3) / 4));
unsigned block_height = maximum(1U, ((image_height + 3) / 4));
using Row = typename DecodedBlock::Row;
auto image = std::vector<Color>(block_width * block_height * N * M);
auto blocks = reinterpret_cast<B *>(bytes);
if (!threaded) {
for (unsigned x = 0; x < block_width; x++) {
for (unsigned y = 0; y < block_height; y++) {
unsigned pixel_x = x * N;
unsigned pixel_y = y * M;
assert(pixel_x >= 0);
assert(pixel_y >= 0);
assert(pixel_y + M <= image_height);
assert(pixel_x + N <= image_width);
unsigned top_left = pixel_x + (pixel_y * image_width);
auto rows = std::array<Row *, M>();
for (unsigned i = 0; i < M; i++) { rows[i] = reinterpret_cast<Row *>(&image[top_left + i * image_width]); }
// auto dest = DecodedBlock(image, image_width, image_height, x, y);
DecodeBlock(DecodedBlock(rows), &blocks[x + block_width * y]);
}
}
}
return image;
}
};
} // namespace rgbcx