PNGTextureWriter.cpp

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#include <tdme/engine/fileio/textures/PNGTextureWriter.h>
 
#include <stdio.h>
#include <stdlib.h>
 
#include <string>
#include <vector>
 
#include <tdme/tdme.h>
#include <tdme/engine/fileio/textures/Texture.h>
#include <tdme/os/filesystem/FileSystem.h>
#include <tdme/os/filesystem/FileSystemInterface.h>
#include <tdme/utilities/ByteBuffer.h>
#include <tdme/utilities/Console.h>
 
#include <ext/libpng/png.h>
 
using std::string;
using std::to_string;
using std::vector;
 
using tdme::engine::fileio::textures::PNGTextureWriter;
 
using tdme::engine::fileio::textures::Texture;
using tdme::os::filesystem::FileSystem;
using tdme::os::filesystem::FileSystemInterface;
using tdme::utilities::ByteBuffer;
using tdme::utilities::Console;
 
 
void PNGTextureWriter::writePNGDataToMemory(png_structp png_ptr, png_bytep inBytes, png_size_t inBytesToWrite) {
    png_voidp io_ptr = png_get_io_ptr(png_ptr);
    if (io_ptr == nullptr) return;
 
    PNGOutputStream* pngOutputStream = static_cast<PNGOutputStream*>(io_ptr);
    pngOutputStream->writeBytes((int8_t*)inBytes, inBytesToWrite);
}
 
void PNGTextureWriter::flushPNGDataToMemory(png_structp png_ptr) {
    // no op
}
 
bool PNGTextureWriter::write(Texture* texture, const string& pathName, const string& fileName, bool removeAlphaChannel, bool flipY) {
    vector<uint8_t> data;
    if (write(texture, data, removeAlphaChannel, flipY) == false) return false;
 
    FileSystem::getInstance()->setContent(pathName, fileName, data);
 
    return true;
}
 
bool PNGTextureWriter::write(Texture* texture, vector<uint8_t>& pngData, bool removeAlphaChannel, bool flipY) {
    // see: https://gist.github.com/niw/5963798
    png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png) {
        return false;
    }
 
    png_infop info = png_create_info_struct(png);
    if (!info) {
        return false;
    }
 
    if (setjmp(png_jmpbuf(png))) {
        return false;
    }
 
    // create PNG input stream
    PNGOutputStream pngOutputStream(&pngData);
 
    // set up custom read function
    png_set_write_fn(png, &pngOutputStream, PNGTextureWriter::writePNGDataToMemory, PNGTextureWriter::flushPNGDataToMemory);
 
    //
    auto bytesPerPixel = texture->getDepth() / 8;
    auto width = texture->getTextureWidth();
    auto height = texture->getTextureHeight();
    auto pixels = texture->getTextureData();
 
    // output is 8bit depth, RGBA format.
    png_set_IHDR(
        png,
        info,
        width,
        height,
        8,
        removeAlphaChannel == false && bytesPerPixel == 4?PNG_COLOR_TYPE_RGBA:PNG_COLOR_TYPE_RGB,
        PNG_INTERLACE_NONE,
        PNG_COMPRESSION_TYPE_DEFAULT,
        PNG_FILTER_TYPE_DEFAULT
    );
    png_write_info(png, info);
 
    // remove the alpha channel for PNG_COLOR_TYPE_RGB format
    if (removeAlphaChannel == true) {
        png_set_filler(png, 0, PNG_FILLER_AFTER);
    }
 
    //
    png_bytep* row_pointers = new png_bytep[height];
    if (flipY == true) {
        for (auto y = 0; y < height; y++) row_pointers[y] = pixels->getBuffer() + width * bytesPerPixel * (height - 1 - y);
    } else {
        for (auto y = 0; y < height; y++) row_pointers[y] = pixels->getBuffer() + width * bytesPerPixel * y;
    }
 
    png_write_image(png, row_pointers);
    png_write_end(png, NULL);
 
    free (row_pointers);
 
    png_destroy_write_struct(&png, &info);
 
    return true;
}