tgaimage.cpp

#include <iostream>
#include <fstream>
#include <cstring>
#include "tgaimage.h"

TGAImage::TGAImage() : data(), width(0), height(0), bytespp(0) {}
TGAImage::TGAImage(const int w, const int h, const int bpp) : data(w*h*bpp, 0), width(w), height(h), bytespp(bpp) {}

bool TGAImage::read_tga_file(const std::string filename) {
    std::ifstream in;
    in.open (filename, std::ios::binary);
    if (!in.is_open()) {
        std::cerr << "can't open file " << filename << "\n";
        in.close();
        return false;
    }
    TGA_Header header;
    in.read(reinterpret_cast<char *>(&header), sizeof(header));
    if (!in.good()) {
        in.close();
        std::cerr << "an error occured while reading the header\n";
        return false;
    }
    width   = header.width;
    height  = header.height;
    bytespp = header.bitsperpixel>>3;
    if (width<=0 || height<=0 || (bytespp!=GRAYSCALE && bytespp!=RGB && bytespp!=RGBA)) {
        in.close();
        std::cerr << "bad bpp (or width/height) value\n";
        return false;
    }
    size_t nbytes = bytespp*width*height;
    data = std::vector<std::uint8_t>(nbytes, 0);
    if (3==header.datatypecode || 2==header.datatypecode) {
        in.read(reinterpret_cast<char *>(data.data()), nbytes);
        if (!in.good()) {
            in.close();
            std::cerr << "an error occured while reading the data\n";
            return false;
        }
    } else if (10==header.datatypecode||11==header.datatypecode) {
        if (!load_rle_data(in)) {
            in.close();
            std::cerr << "an error occured while reading the data\n";
            return false;
        }
    } else {
        in.close();
        std::cerr << "unknown file format " << (int)header.datatypecode << "\n";
        return false;
    }
    if (!(header.imagedescriptor & 0x20))
        flip_vertically();
    if (header.imagedescriptor & 0x10)
        flip_horizontally();
    std::cerr << width << "x" << height << "/" << bytespp*8 << "\n";
    in.close();
    return true;
}

bool TGAImage::load_rle_data(std::ifstream &in) {
    size_t pixelcount = width*height;
    size_t currentpixel = 0;
    size_t currentbyte  = 0;
    TGAColor colorbuffer;
    do {
        std::uint8_t chunkheader = 0;
        chunkheader = in.get();
        if (!in.good()) {
            std::cerr << "an error occured while reading the data\n";
            return false;
        }
        if (chunkheader<128) {
            chunkheader++;
            for (int i=0; i<chunkheader; i++) {
                in.read(reinterpret_cast<char *>(colorbuffer.bgra), bytespp);
                if (!in.good()) {
                    std::cerr << "an error occured while reading the header\n";
                    return false;
                }
                for (int t=0; t<bytespp; t++)
                    data[currentbyte++] = colorbuffer.bgra[t];
                currentpixel++;
                if (currentpixel>pixelcount) {
                    std::cerr << "Too many pixels read\n";
                    return false;
                }
            }
        } else {
            chunkheader -= 127;
            in.read(reinterpret_cast<char *>(colorbuffer.bgra), bytespp);
            if (!in.good()) {
                std::cerr << "an error occured while reading the header\n";
                return false;
            }
            for (int i=0; i<chunkheader; i++) {
                for (int t=0; t<bytespp; t++)
                    data[currentbyte++] = colorbuffer.bgra[t];
                currentpixel++;
                if (currentpixel>pixelcount) {
                    std::cerr << "Too many pixels read\n";
                    return false;
                }
            }
        }
    } while (currentpixel < pixelcount);
    return true;
}

bool TGAImage::write_tga_file(const std::string filename, const bool vflip, const bool rle) const {
    std::uint8_t developer_area_ref[4] = {0, 0, 0, 0};
    std::uint8_t extension_area_ref[4] = {0, 0, 0, 0};
    std::uint8_t footer[18] = {'T','R','U','E','V','I','S','I','O','N','-','X','F','I','L','E','.','\0'};
    std::ofstream out;
    out.open (filename, std::ios::binary);
    if (!out.is_open()) {
        std::cerr << "can't open file " << filename << "\n";
        out.close();
        return false;
    }
    TGA_Header header;
    header.bitsperpixel = bytespp<<3;
    header.width  = width;
    header.height = height;
    header.datatypecode = (bytespp==GRAYSCALE?(rle?11:3):(rle?10:2));
    header.imagedescriptor = vflip ? 0x00 : 0x20; // top-left or bottom-left origin
    out.write(reinterpret_cast<const char *>(&header), sizeof(header));
    if (!out.good()) {
        out.close();
        std::cerr << "can't dump the tga file\n";
        return false;
    }
    if (!rle) {
        out.write(reinterpret_cast<const char *>(data.data()), width*height*bytespp);
        if (!out.good()) {
            std::cerr << "can't unload raw data\n";
            out.close();
            return false;
        }
    } else {
        if (!unload_rle_data(out)) {
            out.close();
            std::cerr << "can't unload rle data\n";
            return false;
        }
    }
    out.write(reinterpret_cast<const char *>(developer_area_ref), sizeof(developer_area_ref));
    if (!out.good()) {
        std::cerr << "can't dump the tga file\n";
        out.close();
        return false;
    }
    out.write(reinterpret_cast<const char *>(extension_area_ref), sizeof(extension_area_ref));
    if (!out.good()) {
        std::cerr << "can't dump the tga file\n";
        out.close();
        return false;
    }
    out.write(reinterpret_cast<const char *>(footer), sizeof(footer));
    if (!out.good()) {
        std::cerr << "can't dump the tga file\n";
        out.close();
        return false;
    }
    out.close();
    return true;
}

// TODO: it is not necessary to break a raw chunk for two equal pixels (for the matter of the resulting size)
bool TGAImage::unload_rle_data(std::ofstream &out) const {
    const std::uint8_t max_chunk_length = 128;
    size_t npixels = width*height;
    size_t curpix = 0;
    while (curpix<npixels) {
        size_t chunkstart = curpix*bytespp;
        size_t curbyte = curpix*bytespp;
        std::uint8_t run_length = 1;
        bool raw = true;
        while (curpix+run_length<npixels && run_length<max_chunk_length) {
            bool succ_eq = true;
            for (int t=0; succ_eq && t<bytespp; t++)
                succ_eq = (data[curbyte+t]==data[curbyte+t+bytespp]);
            curbyte += bytespp;
            if (1==run_length)
                raw = !succ_eq;
            if (raw && succ_eq) {
                run_length--;
                break;
            }
            if (!raw && !succ_eq)
                break;
            run_length++;
        }
        curpix += run_length;
        out.put(raw?run_length-1:run_length+127);
        if (!out.good()) {
            std::cerr << "can't dump the tga file\n";
            return false;
        }
        out.write(reinterpret_cast<const char *>(data.data()+chunkstart), (raw?run_length*bytespp:bytespp));
        if (!out.good()) {
            std::cerr << "can't dump the tga file\n";
            return false;
        }
    }
    return true;
}

TGAColor TGAImage::get(const int x, const int y) const {
    if (!data.size() || x<0 || y<0 || x>=width || y>=height)
        return {};
    return TGAColor(data.data()+(x+y*width)*bytespp, bytespp);
}

void TGAImage::set(int x, int y, const TGAColor &c) {
    if (!data.size() || x<0 || y<0 || x>=width || y>=height) return;
    memcpy(data.data()+(x+y*width)*bytespp, c.bgra, bytespp);
}

int TGAImage::get_bytespp() {
    return bytespp;
}

int TGAImage::get_width() const {
    return width;
}

int TGAImage::get_height() const {
    return height;
}

void TGAImage::flip_horizontally() {
    if (!data.size()) return;
    int half = width>>1;
    for (int i=0; i<half; i++) {
        for (int j=0; j<height; j++) {
            TGAColor c1 = get(i, j);
            TGAColor c2 = get(width-1-i, j);
            set(i, j, c2);
            set(width-1-i, j, c1);
        }
    }
}

void TGAImage::flip_vertically() {
    if (!data.size()) return;
    size_t bytes_per_line = width*bytespp;
    std::vector<std::uint8_t> line(bytes_per_line, 0);
    int half = height>>1;
    for (int j=0; j<half; j++) {
        size_t l1 = j*bytes_per_line;
        size_t l2 = (height-1-j)*bytes_per_line;
        std::copy(data.begin()+l1, data.begin()+l1+bytes_per_line, line.begin());
        std::copy(data.begin()+l2, data.begin()+l2+bytes_per_line, data.begin()+l1);
        std::copy(line.begin(), line.end(), data.begin()+l2);
    }
}

std::uint8_t *TGAImage::buffer() {
    return data.data();
}

void TGAImage::clear() {
    data = std::vector<std::uint8_t>(width*height*bytespp, 0);
}

void TGAImage::scale(int w, int h) {
    if (w<=0 || h<=0 || !data.size()) return;
    std::vector<std::uint8_t> tdata(w*h*bytespp, 0);
    int nscanline = 0;
    int oscanline = 0;
    int erry = 0;
    size_t nlinebytes = w*bytespp;
    size_t olinebytes = width*bytespp;
    for (int j=0; j<height; j++) {
        int errx = width-w;
        int nx   = -bytespp;
        int ox   = -bytespp;
        for (int i=0; i<width; i++) {
            ox += bytespp;
            errx += w;
            while (errx>=(int)width) {
                errx -= width;
                nx += bytespp;
                memcpy(tdata.data()+nscanline+nx, data.data()+oscanline+ox, bytespp);
            }
        }
        erry += h;
        oscanline += olinebytes;
        while (erry>=(int)height) {
            if (erry>=(int)height<<1) // it means we jump over a scanline
                memcpy(tdata.data()+nscanline+nlinebytes, tdata.data()+nscanline, nlinebytes);
            erry -= height;
            nscanline += nlinebytes;
        }
    }
    data = tdata;
    width = w;
    height = h;
}