Added old abandoned KDE3 version of gwenview

git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/applications/gwenview@1088034 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 2405 insertions, 0 deletions

diff --git a/src/gvcore/qxcfi.cpp b/src/gvcore/qxcfi.cpp
new file mode 100644
index 0000000..2a771bc
--- /dev/null
+++ b/src/gvcore/qxcfi.cpp
@@ -0,0 +1,2405 @@
+/*
+ * qxcfi.cpp: A Qt 3 plug-in for reading GIMP XCF image files
+ * Copyright (C) 2001 lignum Computing, Inc. <allen@lignumcomputing.com>
+ * $Id: qxcfi.cpp 531593 2006-04-19 15:46:52Z gateau $
+ *
+ * This plug-in is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <qiodevice.h>
+#include <kdeversion.h>
+#include <stdlib.h>
+#include "qxcfi.h"
+
+
+// Change a QRgb value's alpha only. (an optimization)
+inline QRgb qRgba ( QRgb rgb, int a )
+{
+  return ( ( a & 0xff ) << 24 | ( rgb & RGB_MASK ) );
+}
+
+
+namespace Gwenview {
+
+int SafeDataStream::at() const {
+  return mDevice->at();
+}
+
+const float INCHESPERMETER = (100. / 2.54);
+
+// Static global values
+
+int XCFImageFormat::random_table[RANDOM_TABLE_SIZE];
+
+int XCFImageFormat::add_lut[256][256];
+
+XCFImageFormat::LayerModes XCFImageFormat::layer_modes[] = {
+  { true },			// NORMAL_MODE
+  { true },			// DISSOLVE_MODE
+  { true },			// BEHIND_MODE
+  { false },			// MULTIPLY_MODE
+  { false },			// SCREEN_MODE
+  { false },			// OVERLAY_MODE
+  { false },			// DIFFERENCE_MODE
+  { false },			// ADDITION_MODE
+  { false },			// SUBTRACT_MODE
+  { false },			// DARKEN_ONLY_MODE
+  { false },			// LIGHTEN_ONLY_MODE
+  { false },			// HUE_MODE
+  { false },			// SATURATION_MODE
+  { false },			// COLOR_MODE
+  { false },			// VALUE_MODE
+  { false },			// DIVIDE_MODE
+  { true },			// ERASE_MODE
+  { true },			// REPLACE_MODE
+  { true },			// ANTI_ERASE_MODE
+};
+
+//////////////////////////////////////////////////////////////////////////////////
+// From GIMP "paint_funcs.c" v1.2
+
+/*!
+ * Multiply two color components. Really expects the arguments to be
+ * 8-bit quantities.
+ * \param a first minuend.
+ * \param b second minuend.
+ * \return product of arguments.
+ */
+inline int INT_MULT ( int a, int b )
+{
+  int c = a * b + 0x80;
+  return ( ( c >> 8 ) + c ) >> 8;
+}
+
+/*!
+ * Blend the two color components in the proportion alpha:
+ *
+ * result = alpha a + ( 1 - alpha b)
+ *
+ * \param a first component.
+ * \param b second component.
+ * \param alpha blend proportion.
+ * \return blended color components.
+ */
+
+inline int INT_BLEND ( int a, int b, int alpha )
+{
+  return INT_MULT( a - b, alpha ) + b;
+}
+
+// Actually from GLIB
+
+inline int MIN ( int a, int b )
+{
+  return ( a < b ? a : b );
+}
+
+inline int MAX ( int a, int b )
+{
+  return ( a > b ? a : b );
+}
+
+// From GIMP "gimpcolorspace.c" v1.2
+
+/*!
+ * Convert a color in RGB space to HSV space (Hue, Saturation, Value).
+ * \param red the red component (modified in place).
+ * \param green the green component (modified in place).
+ * \param blue the blue component (modified in place).
+ */
+void RGBTOHSV ( uchar& red, uchar& green, uchar& blue )
+{
+  int r, g, b;
+  double h, s, v;
+  int min, max;
+
+  h = 0.;
+
+  r = red;
+  g = green;
+  b = blue;
+
+  if ( r > g ) {
+    max = MAX( r, b );
+    min = MIN( g, b );
+  }
+  else {
+    max = MAX( g, b );
+    min = MIN( r, b );
+  }
+
+  v = max;
+
+  if ( max != 0 )
+    s = ( ( max - min ) * 255 ) / (double)max;
+  else
+    s = 0;
+
+  if ( s == 0 )
+    h = 0;
+  else {
+    int delta = max - min;
+    if ( r == max )
+      h = ( g - b ) / (double)delta;
+    else if ( g == max )
+      h = 2 + ( b - r ) / (double)delta;
+    else if ( b == max )
+      h = 4 + ( r - g ) / (double)delta;
+    h *= 42.5;
+
+    if ( h < 0 )
+      h += 255;
+    if ( h > 255 )
+      h -= 255;
+  }
+
+  red   = (uchar)h;
+  green = (uchar)s;
+  blue  = (uchar)v;
+}
+
+/*!
+ * Convert a color in HSV space to RGB space.
+ * \param hue the hue component (modified in place).
+ * \param saturation the saturation component (modified in place).
+ * \param value the value component (modified in place).
+ */
+void HSVTORGB ( uchar& hue, uchar& saturation, uchar& value )
+{
+  if ( saturation == 0 ) {
+    hue        = value;
+    saturation = value;
+    value      = value;
+  }
+  else {
+    double h = hue * 6. / 255.;
+    double s = saturation / 255.;
+    double v = value / 255.;
+
+    double f = h - (int)h;
+    double p = v * ( 1. - s );
+    double q = v * ( 1. - ( s * f ) );
+    double t = v * ( 1. - ( s * ( 1. - f ) ) );
+
+    // Worth a note here that gcc 2.96 will generate different results
+    // depending on optimization mode on i386.
+
+    switch ((int)h) {
+    case 0:
+      hue        = (uchar)( v * 255 );
+      saturation = (uchar)( t * 255 );
+      value      = (uchar)( p * 255 );
+      break;
+    case 1:
+      hue        = (uchar)( q * 255 );
+      saturation = (uchar)( v * 255 );
+      value      = (uchar)( p * 255 );
+      break;
+    case 2:
+      hue        = (uchar)( p * 255 );
+      saturation = (uchar)( v * 255 );
+      value      = (uchar)( t * 255 );
+      break;
+    case 3:
+      hue        = (uchar)( p * 255 );
+      saturation = (uchar)( q * 255 );
+      value      = (uchar)( v * 255 );
+      break;
+    case 4:
+      hue        = (uchar)( t * 255 );
+      saturation = (uchar)( p * 255 );
+      value      = (uchar)( v * 255 );
+      break;
+    case 5:
+      hue        = (uchar)( v * 255 );
+      saturation = (uchar)( p * 255 );
+      value      = (uchar)( q * 255 );
+    }
+  }
+}
+
+/*!
+ * Convert a color in RGB space to HLS space (Hue, Lightness, Saturation).
+ * \param red the red component (modified in place).
+ * \param green the green component (modified in place).
+ * \param blue the blue component (modified in place).
+ */
+void RGBTOHLS ( uchar& red, uchar& green, uchar& blue )
+{
+  int r = red;
+  int g = green;
+  int b = blue;
+
+  int min, max;
+
+  if ( r > g ) {
+    max = MAX( r, b );
+    min = MIN( g, b );
+  }
+  else {
+    max = MAX( g, b );
+    min = MIN( r, b );
+  }
+
+  double h;
+  double l = ( max + min ) / 2.;
+  double s;
+
+  if ( max == min ) {
+    s = 0.;
+    h = 0.;
+  }
+  else {
+    int delta = max - min;
+
+    if ( l < 128 )
+      s = 255 * (double)delta / (double)( max + min );
+    else
+      s = 255 * (double)delta / (double)( 511 - max - min );
+
+    if ( r == max )
+      h = ( g - b ) / (double)delta;
+    else if ( g == max )
+      h = 2 + ( b - r ) / (double)delta;
+    else
+      h = 4 + ( r - g ) / (double)delta;
+
+    h *= 42.5;
+
+    if ( h < 0 )
+      h += 255;
+    else if ( h > 255 )
+      h -= 255;
+  }
+
+  red   = (uchar)h;
+  green = (uchar)l;
+  blue  = (uchar)s;
+}
+
+/*!
+ * Implement the HLS "double hex-cone".
+ * \param n1 lightness fraction (?)
+ * \param n2 saturation fraction (?)
+ * \param hue hue "angle".
+ * \return HLS value.
+ */
+int HLSVALUE ( double n1, double n2, double hue )
+{
+  double value;
+
+  if ( hue > 255 )
+    hue -= 255;
+  else if ( hue < 0 )
+    hue += 255;
+
+  if ( hue < 42.5 )
+    value = n1 + ( n2 - n1 ) * ( hue / 42.5 );
+  else if ( hue < 127.5 )
+    value = n2;
+  else if ( hue < 170 )
+    value = n1 + ( n2 - n1 ) * ( ( 170 - hue ) / 42.5 );
+  else
+    value = n1;
+
+  return (int)( value * 255 );
+}
+
+/*!
+ * Convert a color in HLS space to RGB space.
+ * \param hue the hue component (modified in place).
+ * \param lightness the lightness component (modified in place).
+ * \param saturation the saturation component (modified in place).
+ */
+void HLSTORGB ( uchar& hue, uchar& lightness, uchar& saturation )
+{
+  double h = hue;
+  double l = lightness;
+  double s = saturation;
+
+  if ( s == 0 ) {
+    hue        = (uchar)l;
+    lightness  = (uchar)l;
+    saturation = (uchar)l;
+  }
+  else {
+    double m1, m2;
+
+    if ( l < 128 )
+      m2 = ( l * ( 255 + s ) ) / 65025.;
+    else
+      m2 = ( l + s - ( l * s ) / 255. ) / 255.;
+
+    m1 = ( l / 127.5 ) - m2;
+
+    hue        = HLSVALUE( m1, m2, h + 85 );
+    lightness  = HLSVALUE( m1, m2, h );
+    saturation = HLSVALUE( m1, m2, h - 85 );
+  }
+}
+//////////////////////////////////////////////////////////////////////////////////
+
+
+XCFImageFormat::XCFImageFormat() {
+    // From GIMP "paint_funcs.c" v1.2
+    srand( RANDOM_SEED );
+
+    for ( int i = 0; i < RANDOM_TABLE_SIZE; i++ )
+      random_table[i] = rand();
+
+    for ( int i = 0; i < RANDOM_TABLE_SIZE; i++ ) {
+      int tmp;
+      int swap = i + rand() % ( RANDOM_TABLE_SIZE - i );
+      tmp = random_table[i];
+      random_table[i] = random_table[swap];
+      random_table[swap] = tmp;
+    }
+
+    for ( int j = 0; j < 256; j++ ) {
+      for ( int k = 0; k < 256; k++ ) {
+	int tmp_sum = j + k;
+	if ( tmp_sum > 255 )
+	  tmp_sum = 255;
+	add_lut[j][k] = tmp_sum;
+      }
+    }
+  }
+
+
+bool XCFImageFormat::installIOHandler ( const QString& ) {
+    QImageIO::defineIOHandler( "XCF", "gimp xcf", 0,
+			       &XCFImageFormat::readXCF,
+#ifdef TMP_WRITE
+			       &XCFImageFormat::writeXCF );
+#else
+			       0 );
+#endif
+    return true;
+}
+
+
+void XCFImageFormat::registerFormat() {
+	QImageIO::defineIOHandler( "XCF","^gimp xcf",
+		0,XCFImageFormat::readXCF,0L);
+}
+
+
+/*!
+ * The Qt QImageIO architecture invokes this routine to read the image.
+ * The file (or other data stream) is already open and the
+ * initial string indicating a XCF file has been matched (but the stream
+ * is positioned at its beginning).
+ *
+ * The XCF file is binary and is stored in big endian format. The
+ * SafeDataStream class is used to read the file. Even though the XCF file
+ * was not written with SafeDataStream, there is still a good match. At least
+ * in version 001 of XCF and version 4 of SafeDataStream. Any other combination
+ * is suspect.
+ *
+ * Any failures while reading the XCF image are reported by the
+ * QImage::status() method.
+ *
+ * \param image_io the QImageIO object connected to the XCF image.
+ */
+void XCFImageFormat::readXCF ( QImageIO* image_io )
+{
+  XCFImage xcf_image;
+
+  // The XCF data is stored in big endian format, which SafeDataStream handles
+  // very well.
+
+  SafeDataStream xcf_io( image_io->ioDevice() );
+
+  char tag[14];
+  xcf_io.readRawBytes( tag, sizeof(tag) );
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on header tag" );
+    return;
+  }
+
+  xcf_io >> xcf_image.width >> xcf_image.height >> xcf_image.type;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on image info" );
+    return;
+  }
+
+  if ( !loadImageProperties( xcf_io, xcf_image ) ) return;
+
+  // The layers appear to be stored in top-to-bottom order. This is
+  // the reverse of how a merged image must be computed. So, the layer
+  // offsets are pushed onto a LIFO stack (thus, we don't have to load
+  // all the data of all layers before beginning to construct the
+  // merged image).
+
+  QValueStack< Q_INT32 > layer_offsets;
+
+  while ( true ) {
+    Q_INT32 layer_offset;
+
+    xcf_io >> layer_offset;
+
+    if ( xcf_io.failed() ) {
+      qDebug( "XCF: read failure on layer offsets" );
+      return;
+    }
+
+    if ( layer_offset == 0 ) break;
+
+    layer_offsets.push( layer_offset );
+  }
+
+  xcf_image.num_layers = layer_offsets.size();
+
+  if ( layer_offsets.size() == 0 ) {
+    qDebug( "XCF: no layers!" );
+    return;
+  }
+
+  // Load each layer and add it to the image
+
+  while ( !layer_offsets.isEmpty() ) {
+    Q_INT32 layer_offset = layer_offsets.pop();
+
+    xcf_io.device()->at( layer_offset );
+
+    if ( !loadLayer( xcf_io, xcf_image ) ) return;
+  }
+
+  if ( !xcf_image.initialized ) {
+    qDebug( "XCF: no visible layers!" );
+    return;
+  }
+
+  image_io->setImage( xcf_image.image );
+  image_io->setStatus( 0 );
+}
+
+/*!
+ * Construct the QImage which will eventually be returned to the QImage
+ * loader.
+ *
+ * There are a couple of situations which require that the QImage is not
+ * exactly the same as The GIMP's representation. The full table is:
+ * \verbatim
+ *  Grayscale  opaque      :  8 bpp indexed
+ *  Grayscale  translucent : 32 bpp + alpha
+ *  Indexed    opaque      :  1 bpp if num_colors <= 2
+ *                         :  8 bpp indexed otherwise
+ *  Indexed    translucent :  8 bpp indexed + alpha if num_colors < 256
+ *                         : 32 bpp + alpha otherwise
+ *  RGB        opaque      : 32 bpp
+ *  RGBA       translucent : 32 bpp + alpha
+ * \endverbatim
+ * Whether the image is translucent or not is determined by the bottom layer's
+ * alpha channel. However, even if the bottom layer lacks an alpha channel,
+ * it can still have an opacity < 1. In this case, the QImage is promoted
+ * to 32-bit. (Note this is different from the output from the GIMP image
+ * exporter, which seems to ignore this attribute.)
+ *
+ * Independently, higher layers can be translucent, but the background of
+ * the image will not show through if the bottom layer is opaque.
+ *
+ * For indexed images, translucency is an all or nothing effect.
+ * \param xcf_image contains image info and bottom-most layer.
+ */
+void XCFImageFormat::initializeImage ( XCFImage& xcf_image )
+{
+  // (Aliases to make the code look a little better.)
+  Layer& layer( xcf_image.layer );
+  QImage& image( xcf_image.image );
+
+  switch ( layer.type ) {
+  case RGB_GIMAGE:
+    if ( layer.opacity == OPAQUE_OPACITY ) {
+      image.create( xcf_image.width, xcf_image.height, 32 );
+      image.fill( qRgb( 255, 255, 255 ) );
+      break;
+    } // else, fall through to 32-bit representation
+
+  case RGBA_GIMAGE:
+    image.create( xcf_image.width, xcf_image.height, 32 );
+    image.fill( qRgba( 255, 255, 255, 0 ) );
+    // Turning this on prevents fill() from affecting the alpha channel,
+    // by the way.
+    image.setAlphaBuffer( true );
+    break;
+
+  case GRAY_GIMAGE:
+    if ( layer.opacity == OPAQUE_OPACITY ) {
+      image.create( xcf_image.width, xcf_image.height, 8, 256 );
+      setGrayPalette( image );
+      image.fill( 255 );
+      break;
+    } // else, fall through to 32-bit representation
+
+  case GRAYA_GIMAGE:
+    image.create( xcf_image.width, xcf_image.height, 32 );
+    image.fill( qRgba( 255, 255, 255, 0 ) );
+    image.setAlphaBuffer( true );
+    break;
+
+  case INDEXED_GIMAGE:
+    // As noted in the table above, there are quite a few combinations
+    // which are possible with indexed images, depending on the
+    // presence of transparency (note: not translucency, which is not
+    // supported by The GIMP for indexed images) and the number of
+    // individual colors.
+
+    // Note: Qt treats a bitmap with a Black and White color palette
+    // as a mask, so only the "on" bits are drawn, regardless of the
+    // order color table entries. Otherwise (i.e., at least one of the
+    // color table entries is not black or white), it obeys the one-
+    // or two-color palette. Have to ask about this...
+
+    if ( xcf_image.num_colors <= 2 ) {
+      image.create( xcf_image.width, xcf_image.height,
+		    1, xcf_image.num_colors,
+		    QImage::LittleEndian );
+      image.fill( 0 );
+      setPalette( xcf_image, image );
+    }
+
+    else if ( xcf_image.num_colors <= 256 ) {
+      image.create( xcf_image.width, xcf_image.height,
+		    8, xcf_image.num_colors,
+		    QImage::LittleEndian );
+      image.fill( 0 );
+      setPalette( xcf_image, image );
+    }
+
+    break;
+
+  case INDEXEDA_GIMAGE:
+
+    if ( xcf_image.num_colors == 1 ) {
+
+      // Plenty(!) of room to add a transparent color
+
+      xcf_image.num_colors++;
+      xcf_image.palette.resize( xcf_image.num_colors );
+      xcf_image.palette[1] = xcf_image.palette[0];
+      xcf_image.palette[0] = qRgba( 255, 255, 255, 0 );
+
+      image.create( xcf_image.width, xcf_image.height,
+		    1, xcf_image.num_colors,
+		    QImage::LittleEndian );
+      image.fill( 0 );
+      setPalette( xcf_image, image );
+      image.setAlphaBuffer( true );
+    }
+
+    else if ( xcf_image.num_colors < 256 ) {
+
+      // Plenty of room to add a transparent color
+
+      xcf_image.num_colors++;
+      xcf_image.palette.resize( xcf_image.num_colors );
+      for ( int c = xcf_image.num_colors-1; c >= 1; c-- )
+	xcf_image.palette[c] = xcf_image.palette[c-1];
+      xcf_image.palette[0] = qRgba( 255, 255, 255, 0 );
+
+      image.create( xcf_image.width, xcf_image.height,
+		    8, xcf_image.num_colors );
+      image.fill( 0 );
+      setPalette( xcf_image, image );
+      image.setAlphaBuffer( true );
+    }
+
+    else {
+      // No room for a transparent color, so this has to be promoted to
+      // true color. (There is no equivalent PNG representation output
+      // from The GIMP as of v1.2.)
+      image.create( xcf_image.width, xcf_image.height, 32 );
+      image.fill( qRgba( 255, 255, 255, 0 ) );
+      image.setAlphaBuffer( true );
+    }
+
+    break;
+  }
+
+  image.setDotsPerMeterX( (int)( xcf_image.x_resolution * INCHESPERMETER ) );
+  image.setDotsPerMeterY( (int)( xcf_image.y_resolution * INCHESPERMETER ) );
+}
+
+/*!
+ * Compute the number of tiles in the current layer and allocate
+ * QImage structures for each of them.
+ * \param xcf_image contains the current layer.
+ */
+void XCFImageFormat::composeTiles ( XCFImage& xcf_image )
+{
+  Layer& layer( xcf_image.layer );
+
+  layer.nrows = ( layer.height + TILE_HEIGHT - 1 ) / TILE_HEIGHT;
+  layer.ncols = ( layer.width + TILE_WIDTH - 1 ) / TILE_WIDTH;
+
+  layer.image_tiles.resize( layer.nrows );
+
+  if ( layer.type == GRAYA_GIMAGE || layer.type == INDEXEDA_GIMAGE )
+    layer.alpha_tiles.resize( layer.nrows );
+
+  if ( layer.mask_offset != 0 )
+    layer.mask_tiles.resize( layer.nrows );
+
+  for ( uint j = 0; j < layer.nrows; j++ ) {
+    layer.image_tiles[j].resize( layer.ncols );
+
+    if ( layer.type == GRAYA_GIMAGE || layer.type == INDEXEDA_GIMAGE )
+      layer.alpha_tiles[j].resize( layer.ncols );
+
+    if ( layer.mask_offset != 0 )
+      layer.mask_tiles[j].resize( layer.ncols );
+  }
+
+  for ( uint j = 0; j < layer.nrows; j++ ) {
+    for ( uint i = 0; i < layer.ncols; i++ ) {
+
+      uint tile_width = (i+1) * TILE_WIDTH <= layer.width ?
+	TILE_WIDTH : layer.width - i*TILE_WIDTH;
+
+      uint tile_height = (j+1) * TILE_HEIGHT <= layer.height ?
+	TILE_HEIGHT : layer.height - j*TILE_HEIGHT;
+
+      // Try to create the most appropriate QImage (each GIMP layer
+      // type is treated slightly differently)
+
+      switch ( layer.type ) {
+      case RGB_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 32, 0 );
+	layer.image_tiles[j][i].setAlphaBuffer( false );
+	break;
+
+      case RGBA_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 32, 0 );
+	layer.image_tiles[j][i].setAlphaBuffer( true );
+	break;
+
+      case GRAY_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 8, 256 );
+	setGrayPalette( layer.image_tiles[j][i] );
+	break;
+
+      case GRAYA_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 8, 256 );
+	setGrayPalette( layer.image_tiles[j][i] );
+
+	layer.alpha_tiles[j][i] = QImage( tile_width, tile_height, 8, 256 );
+	setGrayPalette( layer.alpha_tiles[j][i] );
+	break;
+
+      case INDEXED_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 8,
+					  xcf_image.num_colors );
+	setPalette( xcf_image, layer.image_tiles[j][i] );
+	break;
+
+      case INDEXEDA_GIMAGE:
+	layer.image_tiles[j][i] = QImage( tile_width, tile_height, 8,
+					  xcf_image.num_colors );
+	setPalette( xcf_image, layer.image_tiles[j][i] );
+
+	layer.alpha_tiles[j][i] = QImage( tile_width, tile_height, 8, 256 );
+	setGrayPalette( layer.alpha_tiles[j][i] );
+      }
+
+      if ( layer.mask_offset != 0 ) {
+	layer.mask_tiles[j][i] = QImage( tile_width, tile_height, 8, 256 );
+	setGrayPalette( layer.mask_tiles[j][i] );
+      }
+    }
+  }
+}
+
+/*!
+ * Apply a grayscale palette to the QImage. Note that Qt does not distinguish
+ * between grayscale and indexed images. A grayscale image is just
+ * an indexed image with a 256-color, grayscale palette.
+ * \param image image to set to a grayscale palette.
+ */
+void XCFImageFormat::setGrayPalette ( QImage& image )
+{
+  for ( int i = 0; i < 256; i++ )
+    image.setColor( i, qRgb(i,i,i) );
+}
+
+/*!
+ * Copy the indexed palette from the XCF image into the QImage.
+ * \param xcf_image XCF image containing the palette read from the data stream.
+ * \param image image to apply the palette to.
+ */
+void XCFImageFormat::setPalette ( XCFImage& xcf_image, QImage& image )
+{
+  for ( int i = 0; i < xcf_image.num_colors; i++ )
+    image.setColor( i, xcf_image.palette[i] );
+}
+
+/*!
+ * An XCF file can contain an arbitrary number of properties associated
+ * with the image (and layer and mask).
+ * \param xcf_io the data stream connected to the XCF image
+ * \param xcf_image XCF image data.
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadImageProperties ( SafeDataStream& xcf_io,
+					   XCFImage& xcf_image )
+{
+  while ( true ) {
+    PropType type;
+    QByteArray bytes;
+
+    if ( !loadProperty( xcf_io, type, bytes ) ) {
+      qDebug( "XCF: error loading global image properties" );
+      return false;
+    }
+
+    QDataStream property( bytes, IO_ReadOnly );
+
+    switch ( type ) {
+    case PROP_END:
+      return true;
+
+    case PROP_COMPRESSION:
+      property >> xcf_image.compression;
+      break;
+
+    case PROP_GUIDES:
+      // This property is ignored.
+      break;
+	  
+    case PROP_RESOLUTION:
+      property >> xcf_image.x_resolution >> xcf_image.y_resolution;
+      break;
+      
+    case PROP_TATTOO:
+      property >> xcf_image.tattoo;
+      break;
+
+    case PROP_PARASITES:
+      while ( !property.atEnd() ) {
+ char* tag;
+ Q_UINT32 size;
+
+ property.readBytes( tag, size );
+
+ Q_UINT32 flags;
+ char* data;
+ property >> flags >> data;
+
+ if ( strcmp( tag, "gimp-comment" ) == 0 )
+   xcf_image.image.setText( "Comment", 0, data );
+
+ delete[] tag;
+ delete[] data;
+      }
+      break;
+
+    case PROP_UNIT:
+      property >> xcf_image.unit;
+      break;
+
+    case PROP_PATHS:
+      // This property is ignored.
+      break;
+
+    case PROP_USER_UNIT:
+      // This property is ignored.
+      break;
+
+    case PROP_COLORMAP:
+      property >> xcf_image.num_colors;
+
+      xcf_image.palette.reserve( xcf_image.num_colors );
+
+      for ( int i = 0; i < xcf_image.num_colors; i++ ) {
+	uchar r, g, b;
+	property >> r >> g >> b;
+	xcf_image.palette.push_back( qRgb(r,g,b) );
+      }
+      break;
+
+    default:
+      qDebug( "XCF: unimplemented image property %d, size %d", type, bytes.size() );
+    }
+  }
+}
+
+/*!
+ * Load a layer from the XCF file. The data stream must be positioned at
+ * the beginning of the layer data.
+ * \param xcf_io the image file data stream.
+ * \param xcf_image contains the layer and the color table
+ * (if the image is indexed).
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadLayer ( SafeDataStream& xcf_io, XCFImage& xcf_image )
+{
+  Layer& layer( xcf_image.layer );
+
+  if ( layer.name != 0 ) delete[] layer.name;
+
+  xcf_io >> layer.width >> layer.height >> layer.type >> layer.name;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on layer" );
+    return false;
+  }
+
+  if ( !loadLayerProperties( xcf_io, layer ) ) return false;
+#if 0
+  cout << "layer: \"" << layer.name << "\", size: " << layer.width << " x "
+       << layer.height << ", type: " << layer.type << ", mode: " << layer.mode
+       << ", opacity: " << layer.opacity << ", visible: " << layer.visible
+       << ", offset: " << layer.x_offset << ", " << layer.y_offset << endl;
+#endif
+  // Skip reading the rest of it if it is not visible. Typically, when
+  // you export an image from the The GIMP it flattens (or merges) only
+  // the visible layers into the output image.
+
+  if ( layer.visible == 0 ) return true;
+
+  // If there are any more layers, merge them into the final QImage.
+
+  xcf_io >> layer.hierarchy_offset >> layer.mask_offset;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on layer image offsets" );
+    return false;
+  }
+
+  // Allocate the individual tile QImages based on the size and type
+  // of this layer.
+
+  composeTiles( xcf_image );
+
+  xcf_io.device()->at( layer.hierarchy_offset );
+
+  // As tiles are loaded, they are copied into the layers tiles by
+  // this routine. (loadMask(), below, uses a slightly different
+  // version of assignBytes().)
+
+  layer.assignBytes = assignImageBytes;
+
+  if ( !loadHierarchy( xcf_io, layer ) ) return false;
+
+  if ( layer.mask_offset != 0 ) {
+    xcf_io.device()->at( layer.mask_offset );
+
+    if ( !loadMask( xcf_io, layer ) ) return false;
+  }
+
+  // Now we should have enough information to initialize the final
+  // QImage. The first visible layer determines the attributes
+  // of the QImage.
+
+  if ( !xcf_image.initialized ) {
+    initializeImage( xcf_image );
+
+    copyLayerToImage( xcf_image );
+
+    xcf_image.initialized = true;
+  }
+  else
+    mergeLayerIntoImage( xcf_image );
+
+  return true;
+}
+
+/*!
+ * An XCF file can contain an arbitrary number of properties associated
+ * with a layer.
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param layer layer to collect the properties.
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadLayerProperties ( SafeDataStream& xcf_io, Layer& layer )
+{
+  while ( true ) {
+    PropType type;
+    QByteArray bytes;
+
+    if ( !loadProperty( xcf_io, type, bytes ) ) {
+      qDebug( "XCF: error loading layer properties" );
+      return false;
+    }
+
+    QDataStream property( bytes, IO_ReadOnly );
+
+    switch ( type ) {
+    case PROP_END:
+      return true;
+
+    case PROP_ACTIVE_LAYER:
+      layer.active = true;
+      break;
+
+    case PROP_OPACITY:
+      property >> layer.opacity;
+      break;
+
+    case PROP_VISIBLE:
+      property >> layer.visible;
+      break;
+
+    case PROP_LINKED:
+      property >> layer.linked;
+      break;
+
+    case PROP_PRESERVE_TRANSPARENCY:
+      property >> layer.preserve_transparency;
+      break;
+
+    case PROP_APPLY_MASK:
+      property >> layer.apply_mask;
+      break;
+
+    case PROP_EDIT_MASK:
+      property >> layer.edit_mask;
+      break;
+
+    case PROP_SHOW_MASK:
+      property >> layer.show_mask;
+      break;
+
+    case PROP_OFFSETS:
+      property >> layer.x_offset >> layer.y_offset;
+      break;
+
+    case PROP_MODE:
+      property >> layer.mode;
+      break;
+
+    case PROP_TATTOO:
+      property >> layer.tattoo;
+      break;
+
+    default:
+      qDebug( "XCF: unimplemented layer property %d, size %d", type, bytes.size() );
+    }
+  }
+}
+
+/*!
+ * An XCF file can contain an arbitrary number of properties associated
+ * with a channel. Note that this routine only reads mask channel properties.
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param layer layer containing the mask channel to collect the properties.
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadChannelProperties ( SafeDataStream& xcf_io, Layer& layer )
+{
+  while ( true ) {
+    PropType type;
+    QByteArray bytes;
+
+    if ( !loadProperty( xcf_io, type, bytes ) ) {
+      qDebug( "XCF: error loading channel properties" );
+      return false;
+    }
+
+    QDataStream property( bytes, IO_ReadOnly );
+
+    switch ( type ) {
+    case PROP_END:
+      return true;
+
+    case PROP_OPACITY:
+      property >> layer.mask_channel.opacity;
+      break;
+
+    case PROP_VISIBLE:
+      property >> layer.mask_channel.visible;
+      break;
+
+    case PROP_SHOW_MASKED:
+      property >> layer.mask_channel.show_masked;
+      break;
+
+    case PROP_COLOR:
+      property >> layer.mask_channel.red >> layer.mask_channel.green
+	       >> layer.mask_channel.blue;
+      break;
+      
+    case PROP_TATTOO:
+      property >> layer.mask_channel.tattoo;
+      break;
+
+    default:
+      qDebug( "XCF: unimplemented channel property %d, size %d", type, bytes.size() );
+    }
+  }
+}
+
+/*!
+ * The GIMP stores images in a "mipmap"-like hierarchy. As far as the QImage
+ * is concerned, however, only the top level (i.e., the full resolution image)
+ * is used.
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param layer the layer to collect the image.
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadHierarchy ( SafeDataStream& xcf_io, Layer& layer )
+{
+  Q_INT32 width;
+  Q_INT32 height;
+  Q_INT32 bpp;
+  Q_UINT32 offset;
+
+  xcf_io >> width >> height >> bpp >> offset;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on layer %s image header", layer.name );
+    return false;
+  }
+
+  // GIMP stores images in a "mipmap"-like format (multiple levels of
+  // increasingly lower resolution). Only the top level is used here,
+  // however.
+
+  Q_UINT32 junk;
+  do {
+    xcf_io >> junk;
+
+    if ( xcf_io.failed() ) {
+      qDebug( "XCF: read failure on layer %s level offsets", layer.name );
+      return false;
+    }
+  } while ( junk != 0 );
+
+  QIODevice::Offset saved_pos = xcf_io.device()->at();
+
+  xcf_io.device()->at( offset );
+
+  if ( !loadLevel( xcf_io, layer, bpp ) ) return false;
+
+  xcf_io.device()->at( saved_pos );
+
+  return true;
+}
+
+/*!
+ * Load one level of the image hierarchy (but only the top level is ever used).
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param layer the layer to collect the image.
+ * \param bpp the number of bytes in a pixel.
+ * \return true if there were no I/O errors.
+ * \sa loadTileRLE().
+ */
+bool XCFImageFormat::loadLevel ( SafeDataStream& xcf_io, Layer& layer, Q_INT32 bpp )
+{
+  Q_INT32 width;
+  Q_INT32 height;
+  Q_UINT32 offset;
+
+  xcf_io >> width >> height >> offset;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on layer %s level info", layer.name );
+    return false;
+  }
+
+  if ( offset == 0 ) return true;
+
+  for ( uint j = 0; j < layer.nrows; j++ ) {
+    for ( uint i = 0; i < layer.ncols; i++ ) {
+
+      if ( offset == 0 ) {
+	qDebug( "XCF: incorrect number of tiles in layer %s", layer.name );
+	return false;
+      }
+
+      QIODevice::Offset saved_pos = xcf_io.device()->at();
+
+      Q_UINT32 offset2;
+
+      xcf_io >> offset2;
+
+      if ( xcf_io.failed() ) {
+	qDebug( "XCF: read failure on layer %s level offset look-ahead",
+		layer.name );
+	return false;
+      }
+
+      // Evidently, RLE can occasionally expand a tile instead of compressing it!
+
+      if ( offset2 == 0 )
+	offset2 = offset + (uint)( TILE_WIDTH * TILE_HEIGHT * 4 * 1.5 );
+
+      xcf_io.device()->at( offset );
+
+      int size = layer.image_tiles[j][i].width() * layer.image_tiles[j][i].height();
+
+      if ( !loadTileRLE( xcf_io, layer.tile, size, offset2 - offset, bpp ) )
+	return false;
+
+      // The bytes in the layer tile are juggled differently depending on
+      // the target QImage. The caller has set layer.assignBytes to the
+      // appropriate routine.
+
+      layer.assignBytes( layer, i, j );
+
+      xcf_io.device()->at( saved_pos );
+      
+      xcf_io >> offset;
+
+      if ( xcf_io.failed() ) {
+	qDebug( "XCF: read failure on layer %s level offset", layer.name );
+	return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+/*!
+ * A layer can have a one channel image which is used as a mask.
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param layer the layer to collect the mask image.
+ * \return true if there were no I/O errors.
+ */
+bool XCFImageFormat::loadMask ( SafeDataStream& xcf_io, Layer& layer )
+{
+  Q_INT32 width;
+  Q_INT32 height;
+  char* name;
+
+  xcf_io >> width >> height >> name;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on mask info" );
+    return false;
+  }
+
+  delete name;
+
+  if ( !loadChannelProperties( xcf_io, layer ) ) return false;
+
+  Q_UINT32 hierarchy_offset;
+
+  xcf_io >> hierarchy_offset;
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on mask image offset" );
+    return false;
+  }
+
+  xcf_io.device()->at( hierarchy_offset );
+
+  layer.assignBytes = assignMaskBytes;
+
+  if ( !loadHierarchy( xcf_io, layer ) ) return false;
+
+  return true;
+}
+
+/*!
+ * This is the routine for which all the other code is simply
+ * infrastructure. Read the image bytes out of the file and
+ * store them in the tile buffer. This is passed a full 32-bit deep
+ * buffer, even if bpp is smaller. The caller can figure out what to
+ * do with the bytes.
+ *
+ * The tile is stored in "channels", i.e. the red component of all
+ * pixels, then the green component of all pixels, then blue then
+ * alpha, or, for indexed images, the color indices of all pixels then
+ * the alpha of all pixels.
+ *
+ * The data is compressed with "run length encoding". Some simple data
+ * integrity checks are made.
+ *
+ * \param xcf_io the data stream connected to the XCF image.
+ * \param tile the buffer to expand the RLE into.
+ * \param image_size number of bytes expected to be in the image tile.
+ * \param data_length number of bytes expected in the RLE.
+ * \param bpp number of bytes per pixel.
+ * \return true if there were no I/O errors and no obvious corruption of
+ * the RLE data.
+ */
+bool XCFImageFormat::loadTileRLE ( SafeDataStream& xcf_io, uchar* tile, int image_size,
+				   int data_length, Q_INT32 bpp )
+{
+  uchar* data;
+
+  uchar* xcfdata;
+  uchar* xcfodata;
+  uchar* xcfdatalimit;
+
+  xcfdata = xcfodata = new uchar[data_length];
+
+  int read_length=xcf_io.device()->readBlock( (char*)xcfdata, data_length  );
+
+  if ( read_length<=0 ) {
+    delete[] xcfodata;
+    qDebug( "XCF: read failure on tile" );
+    return false;
+  }
+
+  xcfdatalimit = &xcfodata[read_length-1];
+
+  for ( int i = 0; i < bpp; ++i ) {
+
+    data = tile + i;
+
+    int count = 0;
+    int size = image_size;
+
+    while ( size > 0 ) {
+      if ( xcfdata > xcfdatalimit )
+	goto bogus_rle;
+
+      uchar val = *xcfdata++;
+
+      uint length = val;
+
+      if ( length >= 128 ) {
+	length = 255 - ( length - 1 );
+	if ( length == 128 ) {
+	  if ( xcfdata >= xcfdatalimit )
+	    goto bogus_rle;
+
+	  length = ( *xcfdata << 8 ) + xcfdata[1];
+
+	  xcfdata += 2;
+	}
+
+	count += length;
+	size -= length;
+
+	if ( size < 0 )
+	  goto bogus_rle;
+
+	if ( &xcfdata[length-1] > xcfdatalimit )
+	  goto bogus_rle;
+
+	while ( length-- > 0 ) {
+	  *data = *xcfdata++;
+	  data += sizeof(QRgb);
+	}
+      }
+      else {
+	length += 1;
+	if ( length == 128 ) {
+
+	  if ( xcfdata >= xcfdatalimit )
+	    goto bogus_rle;
+
+	  length = ( *xcfdata << 8 ) + xcfdata[1];
+	  xcfdata += 2;
+	}
+
+	count += length;
+	size -= length;
+
+	if ( size < 0 )
+	  goto bogus_rle;
+
+	if ( xcfdata > xcfdatalimit )
+	  goto bogus_rle;
+
+	val = *xcfdata++;
+
+	while ( length-- > 0 ) {
+	  *data = val;
+	  data += sizeof(QRgb);
+	}
+      }
+    }
+  }
+
+  delete[] xcfodata;
+  return true;
+
+ bogus_rle:
+
+  qDebug( "The run length encoding could not be decoded properly" );
+  delete[] xcfodata;
+  return false;
+}
+
+/*!
+ * Copy the bytes from the tile buffer into the image tile QImage, taking into
+ * account all the myriad different modes.
+ * \param layer layer containing the tile buffer and the image tile matrix.
+ * \param i column index of current tile.
+ * \param j row index of current tile.
+ */
+void XCFImageFormat::assignImageBytes ( Layer& layer, uint i, uint j )
+{
+  uchar* tile = layer.tile;
+
+  switch ( layer.type ) {
+  case RGB_GIMAGE:
+    for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+      for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+	layer.image_tiles[j][i].setPixel( k, l, qRgb( tile[0], tile[1], tile[2] ) );
+	tile += sizeof(QRgb);
+      }
+    }
+    break;
+
+  case RGBA_GIMAGE:
+    for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+      for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+	layer.image_tiles[j][i].setPixel( k, l,
+					  qRgba( tile[0], tile[1], tile[2], tile[3] ) );
+	tile += sizeof(QRgb);
+      }
+    }
+    break;
+
+  case GRAY_GIMAGE:
+  case INDEXED_GIMAGE:
+    for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+      for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+	layer.image_tiles[j][i].setPixel( k, l, tile[0] );
+	tile += sizeof(QRgb);
+      }
+    }
+    break;
+
+  case GRAYA_GIMAGE:
+  case INDEXEDA_GIMAGE:
+    for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+      for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+
+	// The "if" here should not be necessary, but apparently there
+	// are some cases where the image can contain larger indices
+	// than there are colors in the palette. (A bug in The GIMP?)
+
+	if ( tile[0] < layer.image_tiles[j][i].numColors() )
+	  layer.image_tiles[j][i].setPixel( k, l, tile[0] );
+
+	layer.alpha_tiles[j][i].setPixel( k, l, tile[1] );
+	tile += sizeof(QRgb);
+      }
+    }
+    break;
+  }
+}
+
+/*!
+ * Copy the bytes from the tile buffer into the mask tile QImage.
+ * \param layer layer containing the tile buffer and the mask tile matrix.
+ * \param i column index of current tile.
+ * \param j row index of current tile.
+ */
+void XCFImageFormat::assignMaskBytes ( Layer& layer, uint i, uint j )
+{
+  uchar* tile = layer.tile;
+
+  for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+    for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+      layer.mask_tiles[j][i].setPixel( k, l, tile[0] );
+      tile += sizeof(QRgb);
+    }
+  }
+}
+
+/*!
+ * Read a single property from the image file. The property type is returned
+ * in type and the data is returned in bytes.
+ * \param xcf the image file data stream.
+ * \param type returns with the property type.
+ * \param bytes returns with the property data.
+ * \return true if there were no IO errors.  */
+bool XCFImageFormat::loadProperty ( SafeDataStream& xcf_io, PropType& type,
+				    QByteArray& bytes )
+{
+  Q_UINT32 tmp;
+  xcf_io >> tmp;
+  type=static_cast<PropType>(tmp);
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on property type" );
+    return false;
+  }
+
+  char* data;
+  Q_UINT32 size;
+
+  // The COLORMAP property is tricky: in version of GIMP older than 2.0.2, the
+  // property size was wrong (it was 4 + ncolors instead of 4 + 3*ncolors).
+  // This has been fixed in 2.0.2 (*), but the XCF format version has not been
+  // increased, so we can't rely on the property size. The UINT32 after the
+  // property size is the number of colors, which has always been correct, so
+  // we read it, compute the size from it and put it back in the stream.
+  //
+  // * See http://bugzilla.gnome.org/show_bug.cgi?id=142149 and
+  // gimp/app/xcf-save.c, revision 1.42
+  if ( type == PROP_COLORMAP ) {
+    Q_UINT32 ignoredSize, ncolors;
+    xcf_io >> ignoredSize;
+    if ( xcf_io.failed() ) {
+      qDebug( "XCF: read failure on property %d size", type );
+      return false;
+    }
+
+    xcf_io >> ncolors;
+    if ( xcf_io.failed() ) {
+      qDebug( "XCF: read failure on property %d size", type );
+      return false;
+    }
+    xcf_io.device()->ungetch( ncolors & 0xff);
+    xcf_io.device()->ungetch( (ncolors>> 8) & 0xff );
+    xcf_io.device()->ungetch( (ncolors>>16) & 0xff );
+    xcf_io.device()->ungetch( (ncolors>>24) & 0xff );
+    
+    size=4 + 3 * ncolors;
+    data = new char[size];
+
+    xcf_io.readRawBytes( data, size );
+  }
+
+  // The USER UNIT property size is not correct. I'm not sure why, though.
+
+  else if ( type == PROP_USER_UNIT ) {
+    float factor;
+    Q_INT32 digits;
+    char* unit_strings;
+
+    xcf_io >> size >> factor >> digits;
+
+    if ( xcf_io.failed() ) {
+      qDebug( "XCF: read failure on property %d", type );
+      return false;
+    }
+
+    for ( int i = 0; i < 5; i++ ) {
+      xcf_io >> unit_strings;
+
+      if ( xcf_io.failed() ) {
+	qDebug( "XCF: read failure on property %d", type );
+	return false;
+      }
+
+      delete[] unit_strings;
+    }
+
+    size = 0;
+  }
+
+  else
+    xcf_io.readBytes( data, size );
+
+  if ( xcf_io.failed() ) {
+    qDebug( "XCF: read failure on property %d data, size %d", type, size );
+    return false;
+  }
+
+  if ( size != 0 ) {
+    bytes.resize( size );
+
+    for ( uint i = 0; i < size; i++ ) bytes[i] = data[i];
+
+    delete[] data;
+  }
+
+  return true;
+}
+
+/*!
+ * Copy a layer into an image, taking account of the manifold modes. The
+ * contents of the image are replaced.
+ * \param xcf_image contains the layer and image to be replaced.
+ */
+void XCFImageFormat::copyLayerToImage ( XCFImage& xcf_image )
+{
+  Layer& layer( xcf_image.layer );
+  QImage& image( xcf_image.image );
+
+  PixelCopyOperation copy = 0;
+
+  switch ( layer.type ) {
+  case RGB_GIMAGE:
+  case RGBA_GIMAGE:
+    copy = copyRGBToRGB; break;
+  case GRAY_GIMAGE:
+    if ( layer.opacity == OPAQUE_OPACITY )
+      copy = copyGrayToGray;
+    else
+      copy = copyGrayToRGB;
+    break;
+  case GRAYA_GIMAGE:
+    copy = copyGrayAToRGB; break;
+  case INDEXED_GIMAGE:
+    copy = copyIndexedToIndexed; break;
+  case INDEXEDA_GIMAGE:
+    if ( xcf_image.image.depth() <= 8 )
+      copy = copyIndexedAToIndexed;
+    else
+      copy = copyIndexedAToRGB;
+  }
+
+  // For each tile...
+
+  for ( uint j = 0; j < layer.nrows; j++ ) {
+    uint y = j * TILE_HEIGHT;
+      
+    for ( uint i = 0; i < layer.ncols; i++ ) {
+      uint x = i * TILE_WIDTH;
+
+      // This seems the best place to apply the dissolve because it
+      // depends on the global position of each tile's
+      // pixels. Apparently it's the only mode which can apply to a
+      // single layer.
+
+      if ( layer.mode == DISSOLVE_MODE ) {
+	if ( layer.type == RGBA_GIMAGE )
+	  dissolveRGBPixels( layer.image_tiles[j][i], x, y );
+
+	else if ( layer.type == GRAYA_GIMAGE )
+	  dissolveAlphaPixels( layer.alpha_tiles[j][i], x, y );
+      }
+
+      for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+	for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+
+	  int m = x + k + layer.x_offset;
+	  int n = y + l + layer.y_offset;
+
+	  if ( m < 0 || m >= image.width() || n < 0 || n >= image.height() )
+	    continue;
+
+	  (*copy)( layer, i, j, k, l, image, m, n );
+	}
+      }
+    }
+  }
+}
+
+/*!
+ * Copy an RGB pixel from the layer to the RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyRGBToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				    QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.opacity;
+
+  if ( layer.type == RGBA_GIMAGE )
+    src_a = INT_MULT( src_a, qAlpha( src ) );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Copy a Gray pixel from the layer to the Gray image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyGrayToGray ( Layer& layer, uint i, uint j, int k, int l,
+				      QImage& image, int m, int n )
+{
+  int src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  image.setPixel( m, n, src );
+}
+
+/*!
+ * Copy a Gray pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyGrayToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				     QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.opacity;
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Copy a GrayA pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyGrayAToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				      QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Copy an Indexed pixel from the layer to the Indexed image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyIndexedToIndexed ( Layer& layer, uint i,uint j,int k,int l,
+					    QImage& image, int m, int n )
+{
+  int src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  image.setPixel( m, n, src );
+}
+
+/*!
+ * Copy an IndexedA pixel from the layer to the Indexed image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyIndexedAToIndexed ( Layer& layer,uint i,uint j,int k,int l,
+					     QImage& image, int m, int n )
+{
+  uchar src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  if ( layer.apply_mask == 1 &&
+       layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a,
+		      layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  if ( src_a > 127 )
+    src++;
+  else
+    src = 0;
+
+  image.setPixel( m, n, src );
+}
+
+/*!
+ * Copy an IndexedA pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::copyIndexedAToRGB ( Layer& layer, uint i, uint j, int k, int l,
+					 QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  // This is what appears in the GIMP window
+
+  if ( src_a <= 127 )
+    src_a = 0;
+  else
+    src_a = OPAQUE_OPACITY;
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Merge a layer into an image, taking account of the manifold modes.
+ * \param xcf_image contains the layer and image to merge.
+ */
+void XCFImageFormat::mergeLayerIntoImage ( XCFImage& xcf_image )
+{
+  Layer& layer( xcf_image.layer );
+  QImage& image( xcf_image.image );
+
+  PixelMergeOperation merge = 0;
+
+  switch ( layer.type ) {
+  case RGB_GIMAGE:
+  case RGBA_GIMAGE:
+    merge = mergeRGBToRGB; break;
+  case GRAY_GIMAGE:
+    if ( layer.opacity == OPAQUE_OPACITY )
+      merge = mergeGrayToGray;
+    else
+      merge = mergeGrayToRGB;
+    break;
+  case GRAYA_GIMAGE:
+    if ( xcf_image.image.depth() <= 8 )
+      merge = mergeGrayAToGray;
+    else
+      merge = mergeGrayAToRGB;
+    break;
+  case INDEXED_GIMAGE:
+    merge = mergeIndexedToIndexed; break;
+  case INDEXEDA_GIMAGE:
+    if ( xcf_image.image.depth() <= 8 )
+      merge = mergeIndexedAToIndexed;
+    else
+      merge = mergeIndexedAToRGB;
+  }
+
+  for ( uint j = 0; j < layer.nrows; j++ ) {
+    uint y = j * TILE_HEIGHT;
+      
+    for ( uint i = 0; i < layer.ncols; i++ ) {
+      uint x = i * TILE_WIDTH;
+
+      // This seems the best place to apply the dissolve because it
+      // depends on the global position of each tile's
+      // pixels. Apparently it's the only mode which can apply to a
+      // single layer.
+
+      if ( layer.mode == DISSOLVE_MODE ) {
+	if ( layer.type == RGBA_GIMAGE )
+	  dissolveRGBPixels( layer.image_tiles[j][i], x, y );
+
+	else if ( layer.type == GRAYA_GIMAGE )
+	  dissolveAlphaPixels( layer.alpha_tiles[j][i], x, y );
+      }
+
+      for ( int l = 0; l < layer.image_tiles[j][i].height(); l++ ) {
+	for ( int k = 0; k < layer.image_tiles[j][i].width(); k++ ) {
+
+	  int m = x + k + layer.x_offset;
+	  int n = y + l + layer.y_offset;
+
+	  if ( m < 0 || m >= image.width() || n < 0 || n >= image.height() )
+	    continue;
+
+	  (*merge)( layer, i, j, k, l, image, m, n );
+	}
+      }
+    }
+  }
+}
+
+/*!
+ * Merge an RGB pixel from the layer to the RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeRGBToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				     QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+  QRgb dst = image.pixel( m, n );
+
+  uchar src_r = qRed( src );
+  uchar src_g = qGreen( src );
+  uchar src_b = qBlue( src );
+  uchar src_a = qAlpha( src );
+
+  uchar dst_r = qRed( dst );
+  uchar dst_g = qGreen( dst );
+  uchar dst_b = qBlue( dst );
+  uchar dst_a = qAlpha( dst );
+
+  switch ( layer.mode ) {
+  case MULTIPLY_MODE: {
+    src_r = INT_MULT( src_r, dst_r );
+    src_g = INT_MULT( src_g, dst_g );
+    src_b = INT_MULT( src_b, dst_b );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DIVIDE_MODE: {
+    src_r = MIN( ( dst_r * 256 ) / ( 1 + src_r ), 255 );
+    src_g = MIN( ( dst_g * 256 ) / ( 1 + src_g ), 255 );
+    src_b = MIN( ( dst_b * 256 ) / ( 1 + src_b ), 255 );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case SCREEN_MODE: {
+    src_r = 255 - INT_MULT( 255 - dst_r, 255 - src_r );
+    src_g = 255 - INT_MULT( 255 - dst_g, 255 - src_g );
+    src_b = 255 - INT_MULT( 255 - dst_b, 255 - src_b );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case OVERLAY_MODE: {
+    src_r = INT_MULT( dst_r, dst_r + INT_MULT( 2 * src_r, 255 - dst_r ) );
+    src_g = INT_MULT( dst_g, dst_g + INT_MULT( 2 * src_g, 255 - dst_g ) );
+    src_b = INT_MULT( dst_b, dst_b + INT_MULT( 2 * src_b, 255 - dst_b ) );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DIFFERENCE_MODE: {
+    src_r = dst_r > src_r ? dst_r - src_r : src_r - dst_r;
+    src_g = dst_g > src_g ? dst_g - src_g : src_g - dst_g;
+    src_b = dst_b > src_b ? dst_b - src_b : src_b - dst_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case ADDITION_MODE: {
+    src_r = add_lut[dst_r][src_r];
+    src_g = add_lut[dst_g][src_g];
+    src_b = add_lut[dst_b][src_b];
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case SUBTRACT_MODE: {
+    src_r = dst_r > src_r ? dst_r - src_r : 0;
+    src_g = dst_g > src_g ? dst_g - src_g : 0;
+    src_b = dst_b > src_b ? dst_b - src_b : 0;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DARKEN_ONLY_MODE: {
+    src_r = dst_r < src_r ? dst_r : src_r;
+    src_g = dst_g < src_g ? dst_g : src_g;
+    src_b = dst_b < src_b ? dst_b : src_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case LIGHTEN_ONLY_MODE: {
+    src_r = dst_r < src_r ? src_r : dst_r;
+    src_g = dst_g < src_g ? src_g : dst_g;
+    src_b = dst_b < src_b ? src_b : dst_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case HUE_MODE: {
+    uchar new_r = dst_r;
+    uchar new_g = dst_g;
+    uchar new_b = dst_b;
+
+    RGBTOHSV( src_r, src_g, src_b );
+    RGBTOHSV( new_r, new_g, new_b );
+
+    new_r = src_r;
+
+    HSVTORGB( new_r, new_g, new_b );
+
+    src_r = new_r;
+    src_g = new_g;
+    src_b = new_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case SATURATION_MODE: {
+    uchar new_r = dst_r;
+    uchar new_g = dst_g;
+    uchar new_b = dst_b;
+
+    RGBTOHSV( src_r, src_g, src_b );
+    RGBTOHSV( new_r, new_g, new_b );
+
+    new_g = src_g;
+
+    HSVTORGB( new_r, new_g, new_b );
+
+    src_r = new_r;
+    src_g = new_g;
+    src_b = new_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case VALUE_MODE: {
+    uchar new_r = dst_r;
+    uchar new_g = dst_g;
+    uchar new_b = dst_b;
+
+    RGBTOHSV( src_r, src_g, src_b );
+    RGBTOHSV( new_r, new_g, new_b );
+
+    new_b = src_b;
+
+    HSVTORGB( new_r, new_g, new_b );
+
+    src_r = new_r;
+    src_g = new_g;
+    src_b = new_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case COLOR_MODE: {
+    uchar new_r = dst_r;
+    uchar new_g = dst_g;
+    uchar new_b = dst_b;
+
+    RGBTOHLS( src_r, src_g, src_b );
+    RGBTOHLS( new_r, new_g, new_b );
+
+    new_r = src_r;
+    new_b = src_b;
+
+    HLSTORGB( new_r, new_g, new_b );
+
+    src_r = new_r;
+    src_g = new_g;
+    src_b = new_b;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  }
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  uchar new_r, new_g, new_b, new_a;
+
+  new_a = dst_a + INT_MULT( OPAQUE_OPACITY - dst_a, src_a );
+
+  float src_ratio = (float)src_a / new_a;
+  float dst_ratio = 1. - src_ratio;
+
+  new_r = (uchar)( src_ratio * src_r + dst_ratio * dst_r + EPSILON );
+  new_g = (uchar)( src_ratio * src_g + dst_ratio * dst_g + EPSILON );
+  new_b = (uchar)( src_ratio * src_b + dst_ratio * dst_b + EPSILON );
+
+  if ( !layer_modes[layer.mode].affect_alpha )
+    new_a = dst_a;
+
+  image.setPixel( m, n, qRgba( new_r, new_g, new_b, new_a ) );
+}
+
+/*!
+ * Merge a Gray pixel from the layer to the Gray image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeGrayToGray ( Layer& layer, uint i, uint j, int k, int l,
+				       QImage& image, int m, int n )
+{
+  int src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  image.setPixel( m, n, src );
+}
+
+/*!
+ * Merge a GrayA pixel from the layer to the Gray image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeGrayAToGray ( Layer& layer, uint i, uint j, int k, int l,
+					QImage& image, int m, int n )
+{
+  int src = qGray( layer.image_tiles[j][i].pixel( k, l ) );
+  int dst = image.pixelIndex( m, n );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  switch ( layer.mode ) {
+  case MULTIPLY_MODE: {
+    src = INT_MULT( src, dst );
+  }
+  break;
+  case DIVIDE_MODE: {
+    src = MIN( ( dst * 256 ) / ( 1 + src ), 255 );
+  }
+  break;
+  case SCREEN_MODE: {
+    src = 255 - INT_MULT( 255 - dst, 255 - src );
+  }
+  break;
+  case OVERLAY_MODE: {
+    src = INT_MULT( dst, dst + INT_MULT( 2 * src, 255 - dst ) );
+  }
+  break;
+  case DIFFERENCE_MODE: {
+    src = dst > src ? dst - src : src - dst;
+  }
+  break;
+  case ADDITION_MODE: {
+    src = add_lut[dst][src];
+  }
+  break;
+  case SUBTRACT_MODE: {
+    src = dst > src ? dst - src : 0;
+  }
+  break;
+  case DARKEN_ONLY_MODE: {
+    src = dst < src ? dst : src;
+  }
+  break;
+  case LIGHTEN_ONLY_MODE: {
+    src = dst < src ? src : dst;
+  }
+  break;
+  }
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  uchar new_a = OPAQUE_OPACITY;
+
+  float src_ratio = (float)src_a / new_a;
+  float dst_ratio = 1. - src_ratio;
+
+  uchar new_g = (uchar)( src_ratio * src + dst_ratio * dst + EPSILON );
+
+  image.setPixel( m, n, new_g );
+}
+
+/*!
+ * Merge a Gray pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeGrayToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				      QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.opacity;
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Merge a GrayA pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeGrayAToRGB ( Layer& layer, uint i, uint j, int k, int l,
+				       QImage& image, int m, int n )
+{
+  int src = qGray( layer.image_tiles[j][i].pixel( k, l ) );
+  int dst = qGray( image.pixel( m, n ) );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+  uchar dst_a = qAlpha( image.pixel( m, n ) );
+
+  switch ( layer.mode ) {
+  case MULTIPLY_MODE: {
+    src = INT_MULT( src, dst );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DIVIDE_MODE: {
+    src = MIN( ( dst * 256 ) / ( 1 + src ), 255 );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case SCREEN_MODE: {
+    src = 255 - INT_MULT( 255 - dst, 255 - src );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case OVERLAY_MODE: {
+    src = INT_MULT( dst, dst + INT_MULT( 2 * src, 255 - dst ) );
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DIFFERENCE_MODE: {
+    src = dst > src ? dst - src : src - dst;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case ADDITION_MODE: {
+    src = add_lut[dst][src];
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case SUBTRACT_MODE: {
+    src = dst > src ? dst - src : 0;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case DARKEN_ONLY_MODE: {
+    src = dst < src ? dst : src;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  case LIGHTEN_ONLY_MODE: {
+    src = dst < src ? src : dst;
+    src_a = MIN( src_a, dst_a );
+  }
+  break;
+  }
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  uchar new_a = dst_a + INT_MULT( OPAQUE_OPACITY - dst_a, src_a );
+
+  float src_ratio = (float)src_a / new_a;
+  float dst_ratio = 1. - src_ratio;
+
+  uchar new_g = (uchar)( src_ratio * src + dst_ratio * dst + EPSILON );
+
+  if ( !layer_modes[layer.mode].affect_alpha )
+    new_a = dst_a;
+
+  image.setPixel( m, n, qRgba( new_g, new_g, new_g, new_a ) );
+}
+
+/*!
+ * Merge an Indexed pixel from the layer to the Indexed image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeIndexedToIndexed ( Layer& layer, uint i,uint j,int k,int l,
+					     QImage& image, int m, int n )
+{
+  int src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  image.setPixel( m, n, src );
+}
+
+/*!
+ * Merge an IndexedA pixel from the layer to the Indexed image. Straight-forward.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeIndexedAToIndexed ( Layer& layer,uint i,uint j,int k,int l,
+					      QImage& image, int m, int n )
+{
+  uchar src = layer.image_tiles[j][i].pixelIndex( k, l );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  if ( layer.apply_mask == 1 &&
+       layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a,
+		      layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  if ( src_a > 127 ) {
+    src++;
+    image.setPixel( m, n, src );
+  }
+}
+
+/*!
+ * Merge an IndexedA pixel from the layer to an RGB image. Straight-forward.
+ * The only thing this has to take account of is the opacity of the
+ * layer. Evidently, the GIMP exporter itself does not actually do this.
+ * \param layer source layer.
+ * \param i x tile index.
+ * \param j y tile index.
+ * \param k x pixel index of tile i,j.
+ * \param l y pixel index of tile i,j.
+ * \param image destination image.
+ * \param m x pixel of destination image.
+ * \param n y pixel of destination image.
+ */
+void XCFImageFormat::mergeIndexedAToRGB ( Layer& layer, uint i, uint j, int k, int l,
+					  QImage& image, int m, int n )
+{
+  QRgb src = layer.image_tiles[j][i].pixel( k, l );
+
+  uchar src_a = layer.alpha_tiles[j][i].pixelIndex( k, l );
+
+  src_a = INT_MULT( src_a, layer.opacity );
+
+  // Apply the mask (if any)
+
+  if ( layer.apply_mask == 1 && layer.mask_tiles.size() > j &&
+       layer.mask_tiles[j].size() > i )
+    src_a = INT_MULT( src_a, layer.mask_tiles[j][i].pixelIndex( k, l ) );
+
+  // This is what appears in the GIMP window
+
+  if ( src_a <= 127 )
+    src_a = 0;
+  else
+    src_a = OPAQUE_OPACITY;
+
+  image.setPixel( m, n, qRgba( src, src_a ) );
+}
+
+/*!
+ * Dissolving pixels: pick a random number between 0 and 255. If the pixel's
+ * alpha is less than that, make it transparent.
+ * \param image the image tile to dissolve.
+ * \param x the global x position of the tile.
+ * \param y the global y position of the tile.
+ */
+void XCFImageFormat::dissolveRGBPixels ( QImage& image, int x, int y )
+{
+  // The apparently spurious rand() calls are to wind the random
+  // numbers up to the same point for each tile.
+
+  for ( int l = 0; l < image.height(); l++ ) {
+    srand( random_table[( l + y ) % RANDOM_TABLE_SIZE] );
+
+    for ( int k = 0; k < x; k++ )
+      rand();
+
+    for ( int k = 0; k < image.width(); k++ ) {
+      int rand_val = rand() & 0xff;
+      QRgb pixel = image.pixel( k, l );
+
+      if ( rand_val > qAlpha( pixel ) ) {
+	image.setPixel( k, l, qRgba( pixel, 0 ) );
+      }
+    }
+  }
+}
+
+/*!
+ * Dissolving pixels: pick a random number between 0 and 255. If the pixel's
+ * alpha is less than that, make it transparent. This routine works for
+ * the GRAYA and INDEXEDA image types where the pixel alpha's are stored
+ * separately from the pixel themselves.
+ * \param image the alpha tile to dissolve.
+ * \param x the global x position of the tile.
+ * \param y the global y position of the tile.
+ */
+void XCFImageFormat::dissolveAlphaPixels ( QImage& image, int x, int y )
+{
+  // The apparently spurious rand() calls are to wind the random
+  // numbers up to the same point for each tile.
+
+  for ( int l = 0; l < image.height(); l++ ) {
+    srand( random_table[( l + y ) % RANDOM_TABLE_SIZE] );
+
+    for ( int k = 0; k < x; k++ )
+      rand();
+
+    for ( int k = 0; k < image.width(); k++ ) {
+      int rand_val = rand() & 0xff;
+      uchar alpha = image.pixelIndex( k, l );
+
+      if ( rand_val > alpha ) {
+ image.setPixel( k, l, 0 );
+      }
+    }
+  }
+}
+
+KDE_Q_EXPORT_PLUGIN( XCFImageFormat )
+
+} // namespace