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 [...]]]);
    printf( "Where: image  - is background image filename);
    printf( "       image1 - is first overlay's filename);
    printf( "       op1,op2,... - overlay operation."
            " Supported operations are :);
    list_scanline_merging( stdout,
            "         %-15.15s- %s);
}
int main(int argc, char* argv[])
{
    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( "trose512.jpg add back.xpm:512x386 hue "
                "fore.xpm:512x386);
        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);
        }
        if( dpy )
            XCloseDisplay (dpy);
#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().