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// SPDX-License-Identifier: GPL-3.0-only
// SPDX-FileCopyrightText: 2026 Project Tick
// SPDX-FileContributor: Project Tick Team
/*
* ProjT Launcher - Minecraft Launcher
* Copyright (C) 2026 Project Tick
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 3.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "PngReader.h"
#include <QFile>
#include <QDebug>
#include <png.h>
#include <csetjmp>
#include <cstring>
QString PngReader::s_lastError;
namespace
{
struct PngReadContext
{
const unsigned char* data;
size_t size;
size_t offset;
};
void pngReadCallback(png_structp png_ptr, png_bytep data, png_size_t length)
{
PngReadContext* ctx = static_cast<PngReadContext*>(png_get_io_ptr(png_ptr));
if (ctx->offset + length > ctx->size)
{
png_error(png_ptr, "Read past end of data");
return;
}
std::memcpy(data, ctx->data + ctx->offset, length);
ctx->offset += length;
}
void pngErrorCallback(png_structp png_ptr, png_const_charp error_msg)
{
PngReader::setLastError(QString::fromUtf8(error_msg));
longjmp(png_jmpbuf(png_ptr), 1);
}
void pngWarningCallback(png_structp, png_const_charp warning_msg)
{
qWarning() << "PNG warning:" << warning_msg;
}
} // namespace
QImage PngReader::readFromData(const QByteArray& data)
{
if (data.size() < 8)
{
s_lastError = "Data too small to be a PNG";
return QImage();
}
// Check PNG signature
if (!isPngData(data))
{
s_lastError = "Invalid PNG signature";
return QImage();
}
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, pngErrorCallback, pngWarningCallback);
if (!png_ptr)
{
s_lastError = "Failed to create PNG read struct";
return QImage();
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr, nullptr, nullptr);
s_lastError = "Failed to create PNG info struct";
return QImage();
}
QImage result;
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
return QImage();
}
PngReadContext ctx;
ctx.data = reinterpret_cast<const unsigned char*>(data.constData());
ctx.size = data.size();
ctx.offset = 0;
png_set_read_fn(png_ptr, &ctx, pngReadCallback);
png_read_info(png_ptr, info_ptr);
png_uint_32 width = png_get_image_width(png_ptr, info_ptr);
png_uint_32 height = png_get_image_height(png_ptr, info_ptr);
png_byte color_type = png_get_color_type(png_ptr, info_ptr);
png_byte bit_depth = png_get_bit_depth(png_ptr, info_ptr);
// Convert to 8-bit RGBA
if (bit_depth == 16)
{
png_set_strip_16(png_ptr);
}
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
png_set_palette_to_rgb(png_ptr);
}
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
{
png_set_expand_gray_1_2_4_to_8(png_ptr);
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
{
png_set_tRNS_to_alpha(png_ptr);
}
if (color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_PALETTE)
{
png_set_filler(png_ptr, 0xFF, PNG_FILLER_AFTER);
}
if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
png_set_gray_to_rgb(png_ptr);
}
png_read_update_info(png_ptr, info_ptr);
// Allocate row pointers
std::vector<png_bytep> row_pointers(height);
result = QImage(width, height, QImage::Format_RGBA8888);
if (result.isNull())
{
png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
s_lastError = "Failed to allocate QImage";
return QImage();
}
for (png_uint_32 y = 0; y < height; y++)
{
row_pointers[y] = result.scanLine(y);
}
png_read_image(png_ptr, row_pointers.data());
png_read_end(png_ptr, nullptr);
png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
s_lastError.clear();
return result;
}
QImage PngReader::readFromFile(const QString& filePath)
{
QFile file(filePath);
if (!file.open(QIODevice::ReadOnly))
{
s_lastError = QString("Failed to open file: %1").arg(file.errorString());
return QImage();
}
QByteArray data = file.readAll();
return readFromData(data);
}
bool PngReader::isPngFile(const QString& filePath)
{
QFile file(filePath);
if (!file.open(QIODevice::ReadOnly))
{
return false;
}
QByteArray header = file.read(8);
return isPngData(header);
}
bool PngReader::isPngData(const QByteArray& data)
{
if (data.size() < 8)
{
return false;
}
static const unsigned char png_signature[8] = { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
return std::memcmp(data.constData(), png_signature, 8) == 0;
}
QString PngReader::lastError()
{
return s_lastError;
}
void PngReader::setLastError(const QString& error)
{
s_lastError = error;
}
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