asmerge(1)               AfterStep X11 window manager               asmerge(1)



NAME
       asmerge - demonstrates blending of multiple image using different
       algorithms libAfterImage/tutorials/ASMerge

NAMEASMerge
SYNOPSIS
       Scaling and blending of arbitrary number of images
       using libAfterImage.

DESCRIPTION
       We will attempt to interpret command line arguments as sequence of
       image filenames, geometries and blending types. We'll then try and
       load all the images, scaling first one to requested size, and
       blending others at specifyed locations of the first image.
       We then display the result in simple window.
       After that we would want to wait, until user closes our window.

       New steps described in this tutorial are :
       Step 1. Layers.
       Step 2. Merging methods.
       Step 3. Layer parameters.
       Step 4. Actual blending of the set of images.

SEE ALSO
       Tutorial 1: ASView  - explanation of basic steps needed to use
                             libAfterImage and some other simple things.
       Tutorial 2: ASScale - image scaling basics.
       Tutorial 3: ASTile  - image tiling and tinting

SOURCE
       Source :
       #include "../afterbase.h"
       #include "../afterimage.h"
       #include "common.h"

       char *burning_rose[] =
       {
           "asmerge",
           "rose512.jpg",
           "add",
           "back.xpm:512x386",
           "hue",
           "fore.xpm:512x386"
       };

       void usage()
       {
           printf( "Usage: asmerge [-h]|[image op1 image1 [op2 image2 [...]]]0);
           printf( "Where: image  - is background image filename0);
           printf( "       image1 - is first overlay's filename0);
           printf( "       op1,op2,... - overlay operation."
                   " Supported operations are :0);
           list_scanline_merging( stdout,
                   "         %-15.15s- %s0);
       }

       int main(int argc, char* argv[])
       {
           Display *dpy = NULL;
           ASVisual *asv ;
           int screen = 0, depth = 0;
           int to_width = 1, to_height = 1;
           ASImageLayer *layers ;
           int layers_num = 0, i;
           ASImage *merged_im ;

           /* see ASView.1 : */
           set_application_name( argv[0] );
       #if (HAVE_AFTERBASE_FLAG==1)
           set_output_threshold(OUTPUT_LEVEL_DEBUG);
       #endif
           if( argc == 2 && strncmp(argv[1],"-h", 2) == 0 )
           {
               usage();
               return 0;
           }
           if( argc <= 3 )
           {
               show_error( "not enough arguments, please see usage:%s", " ");
               usage() ;
               printf( "Using the default,
               printf( "rose512.jpg add back.xpm:512x386 hue "
                       "fore.xpm:512x3860);
               argv = &(burning_rose[0]) ;
               argc = 6;
           }

       #ifndef X_DISPLAY_MISSING
           dpy = XOpenDisplay(NULL);
           _XA_WM_DELETE_WINDOW = XInternAtom( dpy, "WM_DELETE_WINDOW", False);
           screen = DefaultScreen(dpy);
           depth = DefaultDepth( dpy, screen );
       #endif
           /* see ASView.3 : */
           asv = create_asvisual( dpy, screen, depth, NULL );

           /* see ASMerge.1 : */
           layers = safecalloc( argc/2, sizeof(ASImageLayer) );

           for( i = 1 ; i < argc ; i++ )
           {
               int x = 0, y = 0;
               unsigned int width, height ;
               int geom_flags = 0 ;
               char *separator;
               char *filename ;
               /* see ASMerge.2 */
               if( i > 1 )
               {
                   /* see blend_scanlines_name2func() : */
                   if((layers[layers_num].merge_scanlines =
                        blend_scanlines_name2func( argv[i] )) == NULL )
                       continue ;
                   if( ++i >= argc )
                       break;
               }
               if( (separator = strchr( argv[i], ':' )) != NULL )
               {   /* see ASTile.1 : */
                   geom_flags = XParseGeometry( separator+1,
                                                &x, &y, &width, &height);
                   filename = mystrndup( argv[i], separator-argv[i] );
               }else
                   filename = argv[i] ;
               layers[layers_num].im = file2ASImage( filename, 0xFFFFFFFF,
                                                     SCREEN_GAMMA, 100, getenv("IMAGE_PATH"), NULL );
               if( filename != argv[i] )
                   free( filename );
               if( layers[layers_num].im != NULL )
               {
                   if( !get_flags(geom_flags, WidthValue) )
                       width = layers[layers_num].im->width  ;
                   if( !get_flags(geom_flags, HeightValue) )
                       height = layers[layers_num].im->height ;
                   /* see ASMerge.3 : */
                   if( layers[layers_num].merge_scanlines == NULL )
                       layers[layers_num].merge_scanlines =
                           alphablend_scanlines ;
                   layers[layers_num].clip_width = width ;
                   layers[layers_num].clip_height = height ;
                   if( layers_num > 0 )
                   {
                       layers[layers_num].dst_x = x ;
                       layers[layers_num].dst_y = y ;
                   }else
                   {
                       to_width = width ;
                       to_height = height ;
                       if( width != layers[layers_num].im->width ||
                           height != layers[layers_num].im->height )
                       {
                           ASImage *scaled_bottom ;
                           /* see ASScale.2 : */
                           scaled_bottom = scale_asimage( asv,
                                                          layers[layers_num].im,
                                                          width, height,
                                                          False, 100,
                                                       ASIMAGE_QUALITY_DEFAULT );
                           destroy_asimage( &(layers[layers_num].im) );
                           layers[layers_num].im = scaled_bottom ;
                       }
                   }
                   ++layers_num ;
               }
           }

           if( layers_num <= 0 )
           {
               show_error( "there is no images to merge. Aborting");
               return 2;
           }

           /* see ASMerge.4 */
           merged_im = merge_layers( asv, layers, layers_num,
                                     to_width, to_height,
       #ifndef X_DISPLAY_MISSING
                                     ASA_XImage,
       #else
                                     ASA_ASImage,
       #endif
                                     0, ASIMAGE_QUALITY_DEFAULT );
           while( --layers_num >= 0 )
               destroy_asimage( &(layers[layers_num].im) );
           free( layers );

           if( merged_im )
           {
       #ifndef X_DISPLAY_MISSING
           /* see ASView.4 : */
               Window w = create_top_level_window( asv, DefaultRootWindow(dpy),
                                                   32, 32,
                                                   to_width, to_height,
                                                   1, 0, NULL,
                                                   "ASMerge", NULL );
               if( w != None )
               {
                   Pixmap p ;

                   XMapRaised   (dpy, w);
                   /* see ASView.5 : */
                   p = asimage2pixmap( asv, DefaultRootWindow(dpy), merged_im,
                                   NULL, True );

                   destroy_asimage( &merged_im );
                   /* see common.c: set_window_background_and_free() : */
                   p = set_window_background_and_free( w, p );
                   /* see common.c: wait_closedown() : */
               }
               wait_closedown(w);
               dpy = NULL;
       #else
               /* writing result into the file */
               ASImage2file( merged_im, NULL, "asmerge.jpg", ASIT_Jpeg, NULL );
               destroy_asimage( &merged_im );
       #endif
           }
       #ifdef DEBUG_ALLOCS
           build_xpm_colormap(NULL);
           print_unfreed_mem();
       #endif
           return 0 ;
       }

SYNOPSIS
       Step 1. Layers.

DESCRIPTION
       libAfterImage performs blending/merging of different images, using
       arrays of ASImageLayer structures, with first element representing
       the bottommost image. Each structure specifies exact position on
       resulting image where overlay should be blended to, tint of the
       overlay, size, to which overlay should be tiled, overlay's origin,
       and overlay's background color. Arbitrary number of layers can be
       merged whithin single run.

       Accordingly all that is needed to merge bunch of images is to create
       array of ASImageLayer structures and fill it up appropriately.

EXAMPLE
           layers = safecalloc( argc/2, sizeof(ASImageLayer) );

SYNOPSIS
       Step 2. Merging methods.

DESCRIPTION
       Each layer can be merged in using its own method. There are about 15
       different methods implemented in libAfterImage, and user app can
       implement other methods of its own. To specify method all that is
       needed is to set merge_scanlines member of ASImageLayer to pointer
       to the function, implementing specific method.

       libAfterImage provides facility to parse method name strings into
       actuall function pointers. That could be used to simplifi scripting,
       etc.

EXAMPLE
              if((layers[layers_num].merge_scanlines =
                  blend_scanlines_name2func( argv[i] )) == NULL )
                  continue ;
       NOTE
       All layers MUST have valid merge_scanlines pointer, even the
       bottommost layer, despite the fact that it has nothing to be merged
       with. If merge_scanlines is set to NULL - this layer will be ignored.
       That could be used to turn on/off particular layers.

SYNOPSIS
       Step 3. Layer parameters.

DESCRIPTION
       Several ASImageLayer members are mandatory and cannot be set to 0.
       Such as : im - image to be merged; clip_width, clip_height - this will
       be used to tile the image; merge_scanlines - must be set to a pointer
       to the function implementing merging method. If any of this is set
       to 0  - then layer will be ignored. The rest of the parameters are
       optional. Note thou that tint parameter will tint overlay's RGB
       components and alpha component, as the result it could be used to
       make opaque images - semitransparent.

EXAMPLE
           if( layers[layers_num].merge_scanlines == NULL )
               layers[layers_num].merge_scanlines =
                   alphablend_scanlines ;
           layers[layers_num].clip_width = width ;
           layers[layers_num].clip_height = height ;
           if( layers_num > 0 )
           {
               layers[layers_num].dst_x = x ;
               layers[layers_num].dst_y = y ;
           }

SYNOPSIS
       Step 4. Actual blending of the set of images.

DESCRIPTION
       After set of layers has been prepared - it can be passed to
       merge_layers() function, that will create new ASImage of specifyed
       size, and then blend all the layers together to fill this image.

EXAMPLE
               merged_im = merge_layers( asv, layers, layers_num,
                                         to_width, to_height,
                                         ASA_ASImage, 0,
                                         ASIMAGE_QUALITY_DEFAULT );
               while( --layers_num >= 0 )
                   destroy_asimage( &(layers[layers_num].im) );
               free( layers );

NOTES
       After we've blended layers - we no longer need ASImageLayer array.
       So proceeding to clean it up, by destroying overlay AsImages first,
       and then freeing array itself.

SEE ALSO
       merge_asimage().



3rd Berkeley Distribution      AfterStep v.2.2.9                    asmerge(1)
