tga.cpp

/* This file is part of the KDE project
   Copyright (C) 2003 Dominik Seichter <domseichter@web.de>
   Copyright (C) 2004 Ignacio Castaño <castano@ludicon.com>
 
   This program is free software; you can redistribute it and/or
   modify it under the terms of the Lesser GNU General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
*/
 
/* this code supports:
 * reading:
 *     uncompressed and run length encoded indexed, grey and color tga files.
 *     image types 1, 2, 3, 9, 10 and 11.
 *     only RGB color maps with no more than 256 colors.
 *     pixel formats 8, 15, 24 and 32.
 * writing:
 *     uncompressed true color tga files
 */
 
#include "tga.h"
 
#include <assert.h>
 
#include <tqimage.h>
#include <tqdatastream.h>
 
#include <kdebug.h>
 
typedef TQ_UINT32 uint;
typedef TQ_UINT16 ushort;
typedef TQ_UINT8 uchar;
 
namespace { // Private.
 
    // Header format of saved files.
    uchar targaMagic[12] = { 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 
    enum TGAType {
        TGA_TYPE_INDEXED        = 1,
        TGA_TYPE_RGB            = 2,
        TGA_TYPE_GREY           = 3,
        TGA_TYPE_RLE_INDEXED    = 9,
        TGA_TYPE_RLE_RGB        = 10,
        TGA_TYPE_RLE_GREY       = 11
    };
 
#define TGA_INTERLEAVE_MASK 0xc0
#define TGA_INTERLEAVE_NONE 0x00
#define TGA_INTERLEAVE_2WAY 0x40
#define TGA_INTERLEAVE_4WAY 0x80
 
#define TGA_ORIGIN_MASK     0x30
#define TGA_ORIGIN_LEFT     0x00
#define TGA_ORIGIN_RIGHT    0x10
#define TGA_ORIGIN_LOWER    0x00
#define TGA_ORIGIN_UPPER    0x20
 
    struct TgaHeader {
        uchar id_length;
        uchar colormap_type;
        uchar image_type;
        ushort colormap_index;
        ushort colormap_length;
        uchar colormap_size;
        ushort x_origin;
        ushort y_origin;
        ushort width;
        ushort height;
        uchar pixel_size;
        uchar flags;
    
        enum { SIZE = 18 }; // const static int SIZE = 18;
    };
 
    static TQDataStream & operator>> ( TQDataStream & s, TgaHeader & head )
    {
        s >> head.id_length;
        s >> head.colormap_type;
        s >> head.image_type;
        s >> head.colormap_index;
        s >> head.colormap_length;
        s >> head.colormap_size;
        s >> head.x_origin;
        s >> head.y_origin;
        s >> head.width;
        s >> head.height;
        s >> head.pixel_size;
        s >> head.flags;
        return s;
    }
 
    static bool IsSupported( const TgaHeader & head )
    {
        if( head.image_type != TGA_TYPE_INDEXED &&
            head.image_type != TGA_TYPE_RGB &&
            head.image_type != TGA_TYPE_GREY &&
            head.image_type != TGA_TYPE_RLE_INDEXED &&
            head.image_type != TGA_TYPE_RLE_RGB &&
            head.image_type != TGA_TYPE_RLE_GREY )
        {
            return false;
        }
        if( head.image_type == TGA_TYPE_INDEXED ||
            head.image_type == TGA_TYPE_RLE_INDEXED )
        {
            if( head.colormap_length > 256 || head.colormap_size != 24 )
            {
                return false;
            }
        }
        if( head.width == 0 || head.height == 0 )
        {
            return false;
        }
        if( head.pixel_size != 8 && head.pixel_size != 16 &&
            head.pixel_size != 24 && head.pixel_size != 32 )
        {
            return false;
        }
        return true;
    }
 
    struct Color555 {
        ushort b : 5;
        ushort g : 5;
        ushort r : 5;
    };
    
    struct TgaHeaderInfo {
        bool rle;
        bool pal;
        bool rgb;
        bool grey;
        bool supported;
    
        TgaHeaderInfo( const TgaHeader & tga ) : rle(false), pal(false), rgb(false), grey(false), supported(true)
        {
            switch( tga.image_type ) {
                case TGA_TYPE_RLE_INDEXED:
                    rle = true;
                    // no break is intended!
                case TGA_TYPE_INDEXED:
                    if( tga.colormap_type!=1 || tga.colormap_size!=24 || tga.colormap_length>256 ) {
                        supported = false;
                    }
                    pal = true;
                    break;
        
                case TGA_TYPE_RLE_RGB:
                    rle = true;
                    // no break is intended!
                case TGA_TYPE_RGB:
                    rgb = true;
                    break;
        
                case TGA_TYPE_RLE_GREY:
                    rle = true;
                    // no break is intended!
                case TGA_TYPE_GREY:
                    grey = true;
                    break;
        
                default:
                    // Error, unknown image type.
                    supported = false;
            }
        }
    };
 
    static bool LoadTGA( TQDataStream & s, const TgaHeader & tga, TQImage &img )
    {
        // Create image.
        if( !img.create( tga.width, tga.height, 32 )) {
            return false;
        }
 
        TgaHeaderInfo info(tga);
        if( !info.supported ) {
            // File not supported.
            kdDebug(399) << "This TGA file is not supported." << endl;
            return false;
        }
        
                // Bits 0-3 are the numbers of alpha bits (can be zero!)
                const int numAlphaBits = tga.flags & 0xf;
                // However alpha exists only in the 32 bit format.
        if( ( tga.pixel_size == 32 ) && ( tga.flags & 0xf ) ) {
            img.setAlphaBuffer( true );
        }
 
        uint pixel_size = (tga.pixel_size/8);
        uint size = tga.width * tga.height * pixel_size;
 
        if (size < 1)
        {
            kdDebug(399) << "This TGA file is broken with size " << size << endl;
            return false;
        }
 
        
        // Read palette.
        char palette[768];
        if( info.pal ) {
            // @todo Support palettes in other formats!
            s.readRawBytes( palette, 3 * tga.colormap_length );
        }
 
        // Allocate image.
        uchar * const image = new uchar[size];
 
        if( info.rle ) {
            // Decode image.
            char * dst = (char *)image;
            int num = size;
    
            while (num > 0) {
                // Get packet header.
                uchar c; 
                s >> c;
    
                uint count = (c & 0x7f) + 1;
                num -= count * pixel_size;
    
                if (c & 0x80) {
                    // RLE pixels.
                                        assert(pixel_size <= 8);
                    char pixel[8];
                    s.readRawBytes( pixel, pixel_size );
                    do {
                        memcpy(dst, pixel, pixel_size);
                        dst += pixel_size;
                    } while (--count);
                }
                else {
                    // Raw pixels.
                    count *= pixel_size;
                    s.readRawBytes( dst, count );
                    dst += count;
                }
            }
        }
        else {
            // Read raw image.
            s.readRawBytes( (char *)image, size );
        }
 
        // Convert image to internal format.                
        int y_start, y_step, y_end;
        if( tga.flags & TGA_ORIGIN_UPPER ) {
            y_start = 0;
            y_step = 1;
            y_end = tga.height;
        }
        else {
            y_start = tga.height - 1;
            y_step = -1;
            y_end = -1;
        }
 
        uchar * src = image;
               
        for( int y = y_start; y != y_end; y += y_step ) {
            TQRgb * scanline = (TQRgb *) img.scanLine( y );
        
            if( info.pal ) {
                // Paletted.
                for( int x = 0; x < tga.width; x++ ) {
                    uchar idx = *src++;
                    scanline[x] = tqRgb( palette[3*idx+2], palette[3*idx+1], palette[3*idx+0] );
                }
            }
            else if( info.grey ) {
                // Greyscale.
                for( int x = 0; x < tga.width; x++ ) {
                    scanline[x] = tqRgb( *src, *src, *src );
                    src++;
                }
            }
            else {
                // True Color.
                if( tga.pixel_size == 16 ) {
                    for( int x = 0; x < tga.width; x++ ) {
                        Color555 c = *reinterpret_cast<Color555 *>(src);
                        scanline[x] = tqRgb( (c.r << 3) | (c.r >> 2), (c.g << 3) | (c.g >> 2), (c.b << 3) | (c.b >> 2) );
                        src += 2;
                    }
                }
                else if( tga.pixel_size == 24 ) {
                    for( int x = 0; x < tga.width; x++ ) {
                        scanline[x] = tqRgb( src[2], src[1], src[0] );
                        src += 3;
                    }
                }
                else if( tga.pixel_size == 32 ) {
                    for( int x = 0; x < tga.width; x++ ) {
                                                // ### TODO: verify with images having really some alpha data
                                                const uchar alpha = ( src[3] << ( 8 - numAlphaBits ) );
                        scanline[x] = tqRgba( src[2], src[1], src[0], alpha );
                        src += 4;
                    }
                }
            }
        }
 
        // Free image.
        delete [] image;
        
        return true;
    }
    
} // namespace
 
 
TDE_EXPORT void kimgio_tga_read( TQImageIO *io )
{
    //kdDebug(399) << "Loading TGA file!" << endl;
    
    TQDataStream s( io->ioDevice() );
    s.setByteOrder( TQDataStream::LittleEndian );
 
 
    // Read image header.
    TgaHeader tga;
    s >> tga;
    s.device()->at( TgaHeader::SIZE + tga.id_length );
 
    // Check image file format.
    if( s.atEnd() ) {
        kdDebug(399) << "This TGA file is not valid." << endl;
        io->setImage( TQImage() );
        io->setStatus( -1 );
        return;
    }
 
    // Check supported file types.
    if( !IsSupported(tga) ) {
        kdDebug(399) << "This TGA file is not supported." << endl;
        io->setImage( TQImage() );
        io->setStatus( -1 );
        return;
    }
                
 
    TQImage img;
    bool result = LoadTGA(s, tga, img);
        
    if( result == false ) {
        kdDebug(399) << "Error loading TGA file." << endl;
        io->setImage( TQImage() );
        io->setStatus( -1 );
        return;
    }
 
 
    io->setImage( img );
    io->setStatus( 0 );
}
 
 
TDE_EXPORT void kimgio_tga_write( TQImageIO *io )
{
    TQDataStream s( io->ioDevice() );
    s.setByteOrder( TQDataStream::LittleEndian );
 
    const TQImage img = io->image();
    const bool hasAlpha = img.hasAlphaBuffer();
    for( int i = 0; i < 12; i++ )
        s << targaMagic[i];
 
    // write header
    s << TQ_UINT16( img.width() ); // width
    s << TQ_UINT16( img.height() ); // height
    s << TQ_UINT8( hasAlpha ? 32 : 24 ); // depth (24 bit RGB + 8 bit alpha)
    s << TQ_UINT8( hasAlpha ? 0x24 : 0x20 ); // top left image (0x20) + 8 bit alpha (0x4)
 
    for( int y = 0; y < img.height(); y++ )
        for( int x = 0; x < img.width(); x++ ) {
            const TQRgb color = img.pixel( x, y );
            s << TQ_UINT8( tqBlue( color ) );
            s << TQ_UINT8( tqGreen( color ) );
            s << TQ_UINT8( tqRed( color ) );
            if( hasAlpha )
                s << TQ_UINT8( tqAlpha( color ) );
        }
 
    io->setStatus( 0 );
}