path: root/src/render/tga.cc

/*
   render/tga.cc
   This file is part of the Osirion project and is distributed under
   the terms of the GNU General Public License version 2
*/

/*
   Documentation and examples on the TGA file format:

   http://www.dca.fee.unicamp.br/~martino/disciplinas/ea978/tgaffs.pdf
   http://www.fileformat.info/format/tga/egff.htm
   http://www.morrowland.com/apron/tut_gl.php

   Notes

   TGA image type                          Colormap  RLE
    0         No image data included in file No       No
    1         Colormapped image data         Yes      No
    2         Truecolor image data           No       No
    3         Monochrome image data          No       No
    9         Colormapped image data         Yes      Yes
    10        Truecolor image data           No       Yes
    11        Monochrome image data          No       Yes
	
   TGA multi-byte integer values have LSB first
*/



#include <fstream>
#include <sstream>
#include <string>

#include "filesystem/filesystem.h"
#include "render/tga.h"
#include "sys/sys.h"

const unsigned char		TGA_NONE = 0;
const unsigned char		TGA_TRUECOLOR = 2;
const unsigned char 		TGA_TRUECOLOR_RLE = 10;

namespace render
{

Image *TGA::load(const char *filename)
{
	Image *image = 0;

	if (!filename)
		return 0;

	filesystem::File *tga_file = filesystem::open(filename);
	if (!tga_file) {
		con_warn << "Could not open " << filename << std::endl;
		return 0;
	}

	// TGA header
	unsigned char header[18];
        memset(header, 0, sizeof(header));

	if (!tga_file->read(header, 18)) {
		con_warn << "Error reading " << filename << std::endl;
		filesystem::close(tga_file);
		return 0;
	}

        // byte 0       - image ID field length
	unsigned int tga_idlength = header[0];

        // byte 1       - color map type
	unsigned int tga_colormap = header[1];

        // byte 2       - image type
	unsigned int tga_type = header[2];

        // byte 3+4     - color map first entry index
	//unsigned int tga_colormap_first = header[3] + (header[4] << 8 );

	// byte 5+6	- color map length (in bits)
	unsigned int tga_color_map_length = header[5] +(header[6] << 8 );

	// byte 7 	- color map entry length
	unsigned int tga_colormap_entry = header[7];

	// byte 8+9	- image x origin
	// byte 10+11	- image y origin
        // byte 12+13   - image width (LSB first)
	unsigned int tga_width = header[12] + (header[13] << 8);

        // byte 14+15   - image height (LSB first)
	unsigned int tga_height = header[14] + (header[15] << 8);

        // byte 16      - image color depth (in bits)
	unsigned int tga_depth = header[16];

        // byte 17      - image descriptor byte
	unsigned int tga_descriptor = header[17];
	
	con_debug << "  " << filename << " "
		<< tga_width << "x" << tga_height << "x" << tga_depth << "bpp" << std::endl;
	
	// read the image id if there is one
	if (tga_idlength)
		tga_file->skip(tga_idlength);

	// read color map data (even for non-color mapped images)
	if (tga_colormap) {
		if (tga_colormap > 1)
			con_warn << filename << ": invalid color map type!" << std::endl;
		
		tga_file->skip(tga_color_map_length*tga_colormap_entry);
	}

	unsigned int index = 0;
	unsigned int channels = tga_depth / 8;

	switch(tga_type) {

	case TGA_NONE:
		con_warn << "Error reading " << filename 
			<< ": no image data!" << std::endl;
		filesystem::close(tga_file);
		return 0;
		break;

	case TGA_TRUECOLOR:
		if ((tga_depth == 24) || (tga_depth == 32)) {

			image = new Image(tga_width, tga_height, channels);

			for (size_t i = 0; i < tga_width * tga_height; i++) {
				tga_file->read((void *)(*image)[i*(size_t)channels], channels);
			}

			image->swap_channels();

		} else if (tga_depth == 16) {
			
			channels = 3;
			image = new Image(tga_width, tga_height,channels);

			for (size_t i =0; i < tga_width * tga_height; i++) {
				// unpack one pixel
				unsigned char pixel_data[2];
				tga_file->read((void *)pixel_data, 2);
				unsigned int unpacked = pixel_data[0] + pixel_data[1]* 0xff;

				unsigned int b = (unpacked & 0x1f) << 3;
                                unsigned int g = ((unpacked >> 5) & 0x1f) << 3;
                                unsigned int r = ((unpacked >> 10) & 0x1f) << 3;
				
				// store it
				image->data()[i * channels] = (unsigned char) b;
				image->data()[i * channels+1] = (unsigned char) g;
				image->data()[i * channels+2] = (unsigned char) r;
			}
		} else {
			con_warn << "Error reading " << filename 
				<< ": unsupported image depth '" << tga_depth << "'!" << std::endl;
			filesystem::close(tga_file);
			return 0;	
		}
		
		break;

	case TGA_TRUECOLOR_RLE:

		image = new Image(tga_width, tga_height, channels);

		while (index < tga_width * tga_height) {
			unsigned char rle = 0;
			unsigned char pixel_data[channels];

			// read RLE packet byte
			tga_file->read(&rle, 1);
			
			if (rle < 128) {
				rle++; // rle contains the number of pixels-1
				tga_file->read((void *)(*image)[index*channels], rle*channels);
				index += rle;

			} else {
				rle -= 127; // rle contains 128 + the number of identical pixels-1
				tga_file->read(pixel_data, channels);
			
				while (rle) {
					memcpy((void *)(*image)[index*channels], (void *)pixel_data, channels);
					index++;
					rle--;
				}
			}
		}

		image->swap_channels();

		break;
	
	default:
		con_warn << "Error reading " << filename 
			<< ": unsupported TGA type '" << (int) tga_type << "'!" << std::endl;
		filesystem::close(tga_file);
		return 0;
	}

	filesystem::close(tga_file);

	if ((tga_descriptor & 0x20) == 0x0) {
		// origin at bottom left
		image->flip();
	}

	if ((tga_descriptor & 0x10) == 0x10) {
		con_warn << filename << ": descriptor bit 4 (left-right) set!" << std::endl;
	}

	return image;
}

void TGA::save(const char *filename, Image & image)
{
	if (!filename)
		return;

	std::ofstream ofs(filename);

        if (!ofs.is_open()) {
                con_warn << "Could not write " << filename << std::endl;
                return;
        }

	// write TGA header
	unsigned char header[18];
	memset(header, 0, sizeof(header));

	// byte 0       - image ID field length         = 0 (no image ID field present)
        // byte 1       - color map type                = 0 (no palette present)
        // byte 2       - image type                    = 10 (truecolor RLE encoded)
        header[2] = TGA_TRUECOLOR_RLE;
        // byte 3-11    - palette data (not used)
        // byte 12+13   - image width
        header[12] = (image.width() & 0xff);
        header[13] = ((image.width() >> 8) & 0xff);
        // byte 14+15   - image height
        header[14] = (image.height() & 0xff);
        header[15] = ((image.height() >> 8) & 0xff);
        // byte 16      - image color depth             = 24 (RGB) or 32 (RGBA)
        header[16] = image.channels() * 8;
        // byte 17      - image descriptor byte		= 0x20 (origin at bottom left)
        header[17] = 0x20;

	// write header
        ofs.write((char *)header, sizeof(header));

	// write image data
	// TGA has the R and B channels switched
	unsigned char pixel_data[image.channels()];
	unsigned char block_data[image.channels()*128];
	unsigned char rle_packet;
	bool compress = false;
	size_t block_length = 0;

	for (int y = image.height()-1; y >= 0; y--) {
		for (size_t x = 0; x < image.width(); x++) {
			size_t index = y*image.width()*image.channels() + x * image.channels();

			pixel_data[0] = *image[index+2];
			pixel_data[1] = *image[index+1];
			pixel_data[2] = *image[index];
			if (image.channels() == 4)
 				pixel_data[3] = *image[index+3];
			
			if (block_length == 0) {
				memcpy(block_data, pixel_data, image.channels());
				block_length++;
				compress = false;
			} else {
				if (!compress) {

					// uncompressed block and pixel_data differs from the last pixel
					if (memcmp(&block_data[(block_length-1)*image.channels()], pixel_data, image.channels()) != 0) {
						// append pixel
						memcpy(&block_data[block_length*image.channels()], pixel_data, image.channels());

						block_length++;
					} else {

					// uncompressed block and pixel data is identical
						if (block_length > 1 ) {
						// write the uncompressed block
							rle_packet = block_length - 2;
							ofs.write((char *)&rle_packet, 1);
							ofs.write((char *)block_data, (block_length-1) * image.channels());
							block_length = 1;
						}
						memcpy(block_data, pixel_data, image.channels());
						block_length++;
						compress = true;
					}

				} else {

					// compressed block and pixel data is identical
					if (memcmp(block_data, pixel_data, image.channels()) == 0) {
						block_length++;

					} else {

					// compressed block and pixel data differs
						if (block_length > 1) {
						// write the compressed block
							rle_packet = block_length + 127;
							ofs.write((char *)&rle_packet, 1);
							ofs.write((char *)block_data, image.channels());
							block_length = 0;
						}
						memcpy(&block_data[block_length * image.channels()], pixel_data, image.channels());
						block_length++;
						compress = false;
					}
				}
			}

			if (block_length == 128) {
				rle_packet = block_length - 1;
				if (!compress) {
					ofs.write((char *)&rle_packet, 1);
					ofs.write((char *)block_data, 128 * image.channels());
				} else {
					rle_packet += 128;
					ofs.write((char *)&rle_packet, 1);
					ofs.write((char *)block_data, image.channels());
				}

				block_length = 0;
				compress = false;
			}
		}
	}

	// write remaining bytes
	if (block_length) {
		rle_packet = block_length - 1;
		if (!compress) {
			ofs.write((char *)&rle_packet, 1);
			ofs.write((char *)block_data, block_length * image.channels());
		} else {
			rle_packet += 128;
			ofs.write((char *)&rle_packet, 1);
			ofs.write((char *)block_data, image.channels());
		}
	}


	// write footer (optional, but the specification recommends it)
	char footer[26];
	memset(footer, 0, sizeof(footer));
	strncpy(&footer[8] , "TRUEVISION-XFILE", 16);
	footer[24] = '.';
	footer[25] = 0;
	ofs.write(footer, sizeof(footer));

	// close file
	ofs.close();

	con_print << "Wrote " << filename << std::endl;
}

}