/*************************************************************************/
/*  image_compress_pvrtc.cpp                                             */
/*************************************************************************/
/*                         This file is part of:                         */
/*                          PANDEMONIUM ENGINE                           */
/*             https://github.com/Relintai/pandemonium_engine            */
/*************************************************************************/
/* Copyright (c) 2022-present Péter Magyar.                              */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
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/*************************************************************************/

#include "image_compress_pvrtc.h"

#include "core/io/image.h"
#include "core/object/reference.h"

#include <PvrTcEncoder.h>
#include <RgbaBitmap.h>

static void _compress_pvrtc4(Image *p_img) {
	Ref<Image> img = p_img->duplicate();

	bool make_mipmaps = false;
	if (!img->is_size_po2() || img->get_width() != img->get_height()) {
		make_mipmaps = img->has_mipmaps();
		img->resize_to_po2(true);
		// Resizing can fail for some formats
		if (!img->is_size_po2() || img->get_width() != img->get_height()) {
			ERR_FAIL_MSG("Failed to resize the image for compression.");
		}
	}
	img->convert(Image::FORMAT_RGBA8);
	if (!img->has_mipmaps() && make_mipmaps) {
		img->generate_mipmaps();
	}

	bool use_alpha = img->detect_alpha();

	Ref<Image> new_img;
	new_img.instance();
	new_img->create(img->get_width(), img->get_height(), img->has_mipmaps(), use_alpha ? Image::FORMAT_PVRTC4A : Image::FORMAT_PVRTC4);

	PoolVector<uint8_t> data = new_img->get_data();
	{
		PoolVector<uint8_t>::Write wr = data.write();
		PoolVector<uint8_t>::Read r = img->get_data().read();

		for (int i = 0; i <= new_img->get_mipmap_count(); i++) {
			int ofs, size, w, h;
			img->get_mipmap_offset_size_and_dimensions(i, ofs, size, w, h);
			Javelin::RgbaBitmap bm(w, h);
			void *dst = (void *)bm.GetData();
			memcpy(dst, &r[ofs], size);
			Javelin::ColorRgba<unsigned char> *dp = bm.GetData();
			for (int j = 0; j < size / 4; j++) {
				// Red and blue colors are swapped.
				SWAP(dp[j].r, dp[j].b);
			}
			new_img->get_mipmap_offset_size_and_dimensions(i, ofs, size, w, h);
			Javelin::PvrTcEncoder::EncodeRgba4Bpp(&wr[ofs], bm);
		}
	}

	p_img->create(new_img->get_width(), new_img->get_height(), new_img->has_mipmaps(), new_img->get_format(), data);
}

void _register_pvrtc_compress_func() {
	// FIXME: We claim to support PVRTC2 but use the same method as for PVRTC4.
	Image::_image_compress_pvrtc2_func = _compress_pvrtc4;
	Image::_image_compress_pvrtc4_func = _compress_pvrtc4;
}