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KImgIO

tga.cpp

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00001 /* This file is part of the KDE project
00002    Copyright (C) 2003 Dominik Seichter <domseichter@web.de>
00003    Copyright (C) 2004 Ignacio CastaƱo <castano@ludicon.com>
00004 
00005    This program is free software; you can redistribute it and/or
00006    modify it under the terms of the Lesser GNU General Public
00007    License as published by the Free Software Foundation; either
00008    version 2 of the License, or (at your option) any later version.
00009 */
00010 
00011 /* this code supports:
00012  * reading:
00013  *     uncompressed and run length encoded indexed, grey and color tga files.
00014  *     image types 1, 2, 3, 9, 10 and 11.
00015  *     only RGB color maps with no more than 256 colors.
00016  *     pixel formats 8, 15, 24 and 32.
00017  * writing:
00018  *     uncompressed true color tga files
00019  */
00020 
00021 #include "tga.h"
00022 
00023 #include <assert.h>
00024 
00025 #include <QtGui/QImage>
00026 #include <QtCore/QDataStream>
00027 
00028 #include <kdebug.h>
00029 
00030 typedef quint32 uint;
00031 typedef quint16 ushort;
00032 typedef quint8 uchar;
00033 
00034 namespace { // Private.
00035 
00036     // Header format of saved files.
00037     uchar targaMagic[12] = { 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
00038 
00039     enum TGAType {
00040         TGA_TYPE_INDEXED        = 1,
00041         TGA_TYPE_RGB            = 2,
00042         TGA_TYPE_GREY           = 3,
00043         TGA_TYPE_RLE_INDEXED    = 9,
00044         TGA_TYPE_RLE_RGB        = 10,
00045         TGA_TYPE_RLE_GREY       = 11
00046     };
00047 
00048 #define TGA_INTERLEAVE_MASK 0xc0
00049 #define TGA_INTERLEAVE_NONE 0x00
00050 #define TGA_INTERLEAVE_2WAY 0x40
00051 #define TGA_INTERLEAVE_4WAY 0x80
00052 
00053 #define TGA_ORIGIN_MASK     0x30
00054 #define TGA_ORIGIN_LEFT     0x00
00055 #define TGA_ORIGIN_RIGHT    0x10
00056 #define TGA_ORIGIN_LOWER    0x00
00057 #define TGA_ORIGIN_UPPER    0x20
00058 
00060     struct TgaHeader {
00061         uchar id_length;
00062         uchar colormap_type;
00063         uchar image_type;
00064         ushort colormap_index;
00065         ushort colormap_length;
00066         uchar colormap_size;
00067         ushort x_origin;
00068         ushort y_origin;
00069         ushort width;
00070         ushort height;
00071         uchar pixel_size;
00072         uchar flags;
00073 
00074         enum { SIZE = 18 }; // const static int SIZE = 18;
00075     };
00076 
00077     static QDataStream & operator>> ( QDataStream & s, TgaHeader & head )
00078     {
00079         s >> head.id_length;
00080         s >> head.colormap_type;
00081         s >> head.image_type;
00082         s >> head.colormap_index;
00083         s >> head.colormap_length;
00084         s >> head.colormap_size;
00085         s >> head.x_origin;
00086         s >> head.y_origin;
00087         s >> head.width;
00088         s >> head.height;
00089         s >> head.pixel_size;
00090         s >> head.flags;
00091         return s;
00092     }
00093 
00094     static bool IsSupported( const TgaHeader & head )
00095     {
00096         if( head.image_type != TGA_TYPE_INDEXED &&
00097             head.image_type != TGA_TYPE_RGB &&
00098             head.image_type != TGA_TYPE_GREY &&
00099             head.image_type != TGA_TYPE_RLE_INDEXED &&
00100             head.image_type != TGA_TYPE_RLE_RGB &&
00101             head.image_type != TGA_TYPE_RLE_GREY )
00102         {
00103             return false;
00104         }
00105         if( head.image_type == TGA_TYPE_INDEXED ||
00106             head.image_type == TGA_TYPE_RLE_INDEXED )
00107         {
00108             if( head.colormap_length > 256 || head.colormap_size != 24 )
00109             {
00110                 return false;
00111             }
00112         }
00113         if( head.width == 0 || head.height == 0 )
00114         {
00115             return false;
00116         }
00117         if( head.pixel_size != 8 && head.pixel_size != 16 &&
00118             head.pixel_size != 24 && head.pixel_size != 32 )
00119         {
00120             return false;
00121         }
00122         return true;
00123     }
00124 
00125     struct Color555 {
00126         ushort b : 5;
00127         ushort g : 5;
00128         ushort r : 5;
00129     };
00130 
00131     struct TgaHeaderInfo {
00132         bool rle;
00133         bool pal;
00134         bool rgb;
00135         bool grey;
00136         bool supported;
00137 
00138         TgaHeaderInfo( const TgaHeader & tga ) : rle(false), pal(false), rgb(false), grey(false), supported(true)
00139         {
00140             switch( tga.image_type ) {
00141                 case TGA_TYPE_RLE_INDEXED:
00142                     rle = true;
00143                     // no break is intended!
00144                 case TGA_TYPE_INDEXED:
00145                     if( tga.colormap_type!=1 || tga.colormap_size!=24 || tga.colormap_length>256 ) {
00146                         supported = false;
00147                     }
00148                     pal = true;
00149                     break;
00150 
00151                 case TGA_TYPE_RLE_RGB:
00152                     rle = true;
00153                     // no break is intended!
00154                 case TGA_TYPE_RGB:
00155                     rgb = true;
00156                     break;
00157 
00158                 case TGA_TYPE_RLE_GREY:
00159                     rle = true;
00160                     // no break is intended!
00161                 case TGA_TYPE_GREY:
00162                     grey = true;
00163                     break;
00164 
00165                 default:
00166                     // Error, unknown image type.
00167                     supported = false;
00168             }
00169         }
00170     };
00171 
00172 
00173 
00174     static bool LoadTGA( QDataStream & s, const TgaHeader & tga, QImage &img )
00175     {
00176         // Create image.
00177         img = QImage( tga.width, tga.height, QImage::Format_RGB32 );
00178 
00179         TgaHeaderInfo info(tga);
00180         if( !info.supported ) {
00181             // File not supported.
00182             kDebug(399) << "This TGA file is not supported.";
00183             return false;
00184         }
00185 
00186                 // Bits 0-3 are the numbers of alpha bits (can be zero!)
00187                 const int numAlphaBits = tga.flags & 0xf;
00188                 // However alpha exists only in the 32 bit format.
00189         if( ( tga.pixel_size == 32 ) && ( tga.flags & 0xf ) ) {
00190             img = QImage( tga.width, tga.height, QImage::Format_ARGB32 );
00191         }
00192 
00193         uint pixel_size = (tga.pixel_size/8);
00194         uint size = tga.width * tga.height * pixel_size;
00195 
00196         if (size < 1)
00197         {
00198             kDebug(399) << "This TGA file is broken with size " << size;
00199             return false;
00200         }
00201 
00202         // Read palette.
00203         char palette[768];
00204         if( info.pal ) {
00205             // @todo Support palettes in other formats!
00206             s.readRawData( palette, 3 * tga.colormap_length );
00207         }
00208 
00209         // Allocate image.
00210         uchar * const image = new uchar[size];
00211 
00212         if( info.rle ) {
00213             // Decode image.
00214             char * dst = (char *)image;
00215             int num = size;
00216 
00217             while (num > 0) {
00218                 // Get packet header.
00219                 uchar c;
00220                 s >> c;
00221 
00222                 uint count = (c & 0x7f) + 1;
00223                 num -= count * pixel_size;
00224 
00225                 if (c & 0x80) {
00226                     // RLE pixels.
00227                                         assert(pixel_size <= 8);
00228                     char pixel[8];
00229                     s.readRawData( pixel, pixel_size );
00230                     do {
00231                         memcpy(dst, pixel, pixel_size);
00232                         dst += pixel_size;
00233                     } while (--count);
00234                 }
00235                 else {
00236                     // Raw pixels.
00237                     count *= pixel_size;
00238                     s.readRawData( dst, count );
00239                     dst += count;
00240                 }
00241             }
00242         }
00243         else {
00244             // Read raw image.
00245             s.readRawData( (char *)image, size );
00246         }
00247 
00248         // Convert image to internal format.
00249         int y_start, y_step, y_end;
00250         if( tga.flags & TGA_ORIGIN_UPPER ) {
00251             y_start = 0;
00252             y_step = 1;
00253             y_end = tga.height;
00254         }
00255         else {
00256             y_start = tga.height - 1;
00257             y_step = -1;
00258             y_end = -1;
00259         }
00260 
00261         uchar * src = image;
00262                
00263         for( int y = y_start; y != y_end; y += y_step ) {
00264             QRgb * scanline = (QRgb *) img.scanLine( y );
00265 
00266             if( info.pal ) {
00267                 // Paletted.
00268                 for( int x = 0; x < tga.width; x++ ) {
00269                     uchar idx = *src++;
00270                     scanline[x] = qRgb( palette[3*idx+2], palette[3*idx+1], palette[3*idx+0] );
00271                 }
00272             }
00273             else if( info.grey ) {
00274                 // Greyscale.
00275                 for( int x = 0; x < tga.width; x++ ) {
00276                     scanline[x] = qRgb( *src, *src, *src );
00277                     src++;
00278                 }
00279             }
00280             else {
00281                 // True Color.
00282                 if( tga.pixel_size == 16 ) {
00283                     for( int x = 0; x < tga.width; x++ ) {
00284                         Color555 c = *reinterpret_cast<Color555 *>(src);
00285                         scanline[x] = qRgb( (c.r << 3) | (c.r >> 2), (c.g << 3) | (c.g >> 2), (c.b << 3) | (c.b >> 2) );
00286                         src += 2;
00287                     }
00288                 }
00289                 else if( tga.pixel_size == 24 ) {
00290                     for( int x = 0; x < tga.width; x++ ) {
00291                         scanline[x] = qRgb( src[2], src[1], src[0] );
00292                         src += 3;
00293                     }
00294                 }
00295                 else if( tga.pixel_size == 32 ) {
00296                     for( int x = 0; x < tga.width; x++ ) {
00297                                                 // ### TODO: verify with images having really some alpha data
00298                                                 const uchar alpha = ( src[3] << ( 8 - numAlphaBits ) );
00299                         scanline[x] = qRgba( src[2], src[1], src[0], alpha );
00300                         src += 4;
00301                     }
00302                 }
00303             }
00304         }
00305 
00306         // Free image.
00307         delete [] image;
00308 
00309         return true;
00310     }
00311 
00312 } // namespace
00313 
00314 
00315 TGAHandler::TGAHandler()
00316 {
00317 }
00318 
00319 bool TGAHandler::canRead() const
00320 {
00321     if (canRead(device())) {
00322         setFormat("tga");
00323         return true;
00324     }
00325     return false;
00326 }
00327 
00328 bool TGAHandler::read(QImage *outImage)
00329 {
00330     //kDebug(399) << "Loading TGA file!";
00331 
00332     QDataStream s( device() );
00333     s.setByteOrder( QDataStream::LittleEndian );
00334 
00335 
00336     // Read image header.
00337     TgaHeader tga;
00338     s >> tga;
00339     s.device()->seek( TgaHeader::SIZE + tga.id_length );
00340 
00341     // Check image file format.
00342     if( s.atEnd() ) {
00343         kDebug(399) << "This TGA file is not valid.";
00344         return false;
00345     }
00346 
00347     // Check supported file types.
00348     if( !IsSupported(tga) ) {
00349         kDebug(399) << "This TGA file is not supported.";
00350         return false;
00351     }
00352 
00353 
00354     QImage img;
00355     bool result = LoadTGA(s, tga, img);
00356 
00357     if( result == false ) {
00358         kDebug(399) << "Error loading TGA file.";
00359         return false;
00360     }
00361 
00362 
00363     *outImage = img;
00364     return true;
00365 }
00366 
00367 bool TGAHandler::write(const QImage &image)
00368 {
00369     QDataStream s( device() );
00370     s.setByteOrder( QDataStream::LittleEndian );
00371 
00372     const QImage& img = image;
00373     const bool hasAlpha = (img.format() == QImage::Format_ARGB32);
00374     for( int i = 0; i < 12; i++ )
00375         s << targaMagic[i];
00376 
00377     // write header
00378     s << quint16( img.width() ); // width
00379     s << quint16( img.height() ); // height
00380     s << quint8( hasAlpha ? 32 : 24 ); // depth (24 bit RGB + 8 bit alpha)
00381     s << quint8( hasAlpha ? 0x24 : 0x20 ); // top left image (0x20) + 8 bit alpha (0x4)
00382 
00383     for( int y = 0; y < img.height(); y++ )
00384         for( int x = 0; x < img.width(); x++ ) {
00385             const QRgb color = img.pixel( x, y );
00386             s << quint8( qBlue( color ) );
00387             s << quint8( qGreen( color ) );
00388             s << quint8( qRed( color ) );
00389             if( hasAlpha )
00390                 s << quint8( qAlpha( color ) );
00391         }
00392 
00393     return true;
00394 }
00395 
00396 QByteArray TGAHandler::name() const
00397 {
00398     return "tga";
00399 }
00400 
00401 bool TGAHandler::canRead(QIODevice *device)
00402 {
00403     if (!device) {
00404         qWarning("TGAHandler::canRead() called with no device");
00405         return false;
00406     }
00407 
00408     qint64 oldPos = device->pos();
00409     QByteArray head = device->readLine(64);
00410     int readBytes = head.size();
00411 
00412     if (device->isSequential()) {
00413         while (readBytes > 0)
00414             device->ungetChar(head[readBytes-- - 1]);
00415     } else {
00416         device->seek(oldPos);
00417     }
00418 
00419     const QRegExp regexp("^.\x01[\x01-\x03\x09-\x0b]\x01{3}.[\x01\x18]");
00420     QString data(head);
00421 
00422     return data.contains(regexp);
00423 }
00424 
00425 
00426 class TGAPlugin : public QImageIOPlugin
00427 {
00428 public:
00429     QStringList keys() const;
00430     Capabilities capabilities(QIODevice *device, const QByteArray &format) const;
00431     QImageIOHandler *create(QIODevice *device, const QByteArray &format = QByteArray()) const;
00432 };
00433 
00434 QStringList TGAPlugin::keys() const
00435 {
00436     return QStringList() << "tga" << "TGA";
00437 }
00438 
00439 QImageIOPlugin::Capabilities TGAPlugin::capabilities(QIODevice *device, const QByteArray &format) const
00440 {
00441     if (format == "tga" || format == "TGA")
00442         return Capabilities(CanRead | CanWrite);
00443     if (!format.isEmpty())
00444         return 0;
00445     if (!device->isOpen())
00446         return 0;
00447 
00448     Capabilities cap;
00449     if (device->isReadable() && TGAHandler::canRead(device))
00450         cap |= CanRead;
00451     if (device->isWritable())
00452         cap |= CanWrite;
00453     return cap;
00454 }
00455 
00456 QImageIOHandler *TGAPlugin::create(QIODevice *device, const QByteArray &format) const
00457 {
00458     QImageIOHandler *handler = new TGAHandler;
00459     handler->setDevice(device);
00460     handler->setFormat(format);
00461     return handler;
00462 }
00463 
00464 Q_EXPORT_STATIC_PLUGIN(TGAPlugin)
00465 Q_EXPORT_PLUGIN2(tga, TGAPlugin)

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