asview(1)

NAME
asview - demonstrates loading and displaying of images libAfterImage/tutorials/ASView

NAMEASView

SYNOPSIS
Simple image viewer based on libAfterImage.

DESCRIPTION
All we want to do here is to get image filename from the command line,
then load this image, and display it in simple window.
After that we would want to wait, until user closes our window.

SOURCE
Source :
#define DO_CLOCKING
#include "../afterbase.h"
#include "../afterimage.h"
#include "common.h"
#ifdef DO_CLOCKING
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
#endif
void usage()
{
    printf( "Usage: asview [-h]|[image]);
    printf( "Where: image - filename of the image to display.);
}
int main(int argc, char* argv[])
{
    char *image_file = "rose512.jpg" ;
    ASImage *im ;
    ASVisual *asv ;
    int screen, depth ;
    /* see ASView.1 : */
    set_application_name( argv[0] );
#if (HAVE_AFTERBASE_FLAG==1)
    set_output_threshold(OUTPUT_LEVEL_DEBUG);
#ifdef DEBUG_ALLOCS
    fprintf( stderr, "have DEBUG_ALLOCS);
#endif
#ifdef AFTERBASE_DEBUG_ALLOCS
    fprintf( stderr, "have AFTERBASE_DEBUG_ALLOCS);
#endif
#endif
    if( argc > 1 )
    {
        if( strcmp( argv[1], "-h" ) == 0 )
        {
            usage();
            return 0;
        }
        image_file = argv[1] ;
    }else
    {
        show_warning(   "Image filename was not specified. "
                        "Using default:
        usage();
    }
#ifndef X_DISPLAY_MISSING
    dpy = XOpenDisplay(NULL);
    XSynchronize (dpy, True);
    _XA_WM_DELETE_WINDOW = XInternAtom( dpy, "WM_DELETE_WINDOW",
                                        False);
    screen = DefaultScreen(dpy);
    depth = DefaultDepth( dpy, screen );
    /* see ASView.3 : */
    asv = create_asvisual( dpy, screen, depth, NULL );
    /* asv = create_asvisual_for_id( dpy, screen, depth, 0x28, None, NULL ); */
#endif
    /* see ASView.2 : */
    im = file2ASImage( image_file, 0xFFFFFFFF, SCREEN_GAMMA, 0, getenv("IMAGE_PATH"), NULL );
    /* The following could be used to dump JPEG version of the image into
     * stdout : */
    /* ASImage2file( im, NULL, NULL, ASIT_Jpeg, NULL ); */
    ASImage2file( im, NULL, "asview.png", ASIT_Png, NULL );
    if( im != NULL )
    {
#ifndef X_DISPLAY_MISSING
        Window w ;
#if 0
        /* test example for get_asimage_channel_rects() : */
        XRectangle *rects ; unsigned int rects_count =0; int i ;
        rects = get_asimage_channel_rects( im, IC_ALPHA, 10,
                                            &rects_count );
        fprintf( stderr, " %d rectangles generated : , rects_count );
        for( i = 0 ; i < rects_count ; ++i )
            fprintf( stderr, "	rect[%d]=%dx%d%+d%+d;,
                     i, rects[i].width, rects[i].height,
                     rects[i].x, rects[i].y );
#endif
#if 0
        /* test example for fill_asimage : */
        fill_asimage(asv, im, 0, 0, 50, 50, 0xFFFF0000);
        fill_asimage(asv, im, 50, 50, 100, 50, 0xFFFF0000);
        fill_asimage(asv, im, 0, 100, 200, 50, 0xFFFF0000);
        fill_asimage(asv, im, 150, 0, 50, 50, 0xFFFF0000);
#endif
#if 0
        /* test example for conversion to argb32 :*/
        {
            ASImage *tmp = tile_asimage( asv, im, 0, 0, im->width, im->height, TINT_NONE, ASA_ARGB32,
                                          0, ASIMAGE_QUALITY_DEFAULT );
            destroy_asimage( &im );
            set_flags( tmp->flags, ASIM_DATA_NOT_USEFUL|ASIM_XIMAGE_NOT_USEFUL );
            im = tmp ;
        }
#endif
        /* see ASView.4 : */
        w = create_top_level_window( asv, DefaultRootWindow(dpy), 32, 32,
                                     im->width, im->height, 1, 0, NULL,
                                     "ASView", image_file );
        if( w != None )
        {
            Pixmap p ;

            XMapRaised   (dpy, w);
            XSync(dpy,False);
            /* see ASView.5 : */
            p = create_visual_pixmap( asv, DefaultRootWindow(dpy), im->width, im->height, 0 );

            {
                START_TIME(started);
                /* for( int i = 0 ; i < 100 ; ++i )  To test performance! */
                asimage2drawable( asv, p, im, NULL, 0, 0, 0, 0, im->width, im->height, False);
                SHOW_TIME("", started);
            }
            /* print_storage(NULL); */
            destroy_asimage( &im );
            /* see common.c:set_window_background_and_free(): */
            p = set_window_background_and_free( w, p );
        }
        /* no longer need this - lets clean it up :*/
        destroy_asvisual( asv, False );
        asv = NULL ;
        /* see common.c: wait_closedown() : */
        wait_closedown(w);
#else
        /* writing result into the file */
        ASImage2file( im, NULL, "asview.png", ASIT_Png, NULL );
#endif
    }
#ifdef DEBUG_ALLOCS
    /* different cleanups of static memory pools : */
    flush_ashash_memory_pool();
    asxml_var_cleanup();
    custom_color_cleanup();
    build_xpm_colormap( NULL );
    flush_default_asstorage();
    /* requires libAfterBase */
    print_unfreed_mem();
#endif
    return 0 ;
}

SYNOPSIS
Step 1. Initialization.

DESCRIPTION
libAfterImage requires only 2 global things to be setup, and both of
those are inherited from libAfterBase: dpy - pointer to open X display-
naturally that is something we cannot live without; application name -
used in all the text output, such as error and warning messages and
also debugging messages if such are enabled.
The following two line are about all that is required to setup both
of this global variables :

EXAMPLE
    set_application_name( argv[0] );
    dpy = XOpenDisplay(NULL);

NOTES
First line is setting up application name from command line's
program name. Second opens up X display specified in DISPLAY env.
variable. Naturally based on application purpose different parameters
can be passed to these functions, such as some custom display string.

SEE ALSO
libAfterBase, set_application_name(), XOpenDisplay(), Display,

SYNOPSIS
Step 2. Loading image file.

DESCRIPTION
At this point we are ready to load image from file into memory. Since
libAfterImage does not use any X facilities to store image - we don't
have to create any window or anything else yet. Even dpy is optional
here - it will only be used to try and parse names of colors from

EXAMPLE
    im = file2ASImage( image_file, 0xFFFFFFFF, SCREEN_GAMMA, 0, NULL);

NOTES
We used compression set to 0, as we do not intend to store
image in memory for any considerable amount of time, and we want to
avoid additional processing overhead related to image compression.
If image was loaded successfully, which is indicated by returned
pointer being not NULL, we can proceed to creation of the window and
displaying of the image.

SEE ALSO
file2ASImage()

SYNOPSIS
Step 3. Preparation of the visual.

DESCRIPTION
At this point we have to obtain Visual information, as window
creation is highly dependant on Visual being used. In fact when X
creates a window it ties it to a particular Visual, and all its
attributes, such as colormap, pixel values, pixmaps, etc. must be
associated with the same Visual. Accordingly we need to acquire
ASVisual structure, which is our abstraction layer from them naughty
X Visuals. :

EXAMPLE
    asv = create_asvisual( dpy, screen, depth, NULL );

NOTES
If any Window or Pixmap is created based on particular ASVisual, then
this ASVisual structure must not be destroyed untill all such
Windows and Pixmaps are destroyed.

SEE ALSO
See create_asvisual() for details.

SYNOPSIS
Step 4. Preparation of the window.

DESCRIPTION
Creation of top level window consists of several steps of its own:
a) create the window of desired size and placement
b) set ICCCM hints on the window
c) select appropriate events on the window
c) map the window.
First two steps has been moved out into create_top_level_window()
function.

EXAMPLE
    w = create_top_level_window( asv, DefaultRootWindow(dpy), 32, 32,
                                 im->width, im->height, 1, 0, NULL,
                                 "ASView" );
    if( w != None )
    {
        XSelectInput (dpy, w, (StructureNotifyMask | ButtonPress));
        XMapRaised   (dpy, w);
    }

NOTES
Map request should be made only for window that has all its hints set
up already, so that Window Manager can read them right away.
We want to map window as soon as possible so that User could see that
something really is going on, even before image is displayed.

SEE ALSO
ASImage, create_top_level_window()

SYNOPSIS
Step 5. Displaying the image.

DESCRIPTION
The simplest way to display image in the window is to convert it
into Pixmap, then set Window's background to this Pixmap, and,
at last, clear the window, so that background shows up.

EXAMPLE
 p = asimage2pixmap( asv, DefaultRootWindow(dpy), im, NULL, False );
 destroy_asimage( &im );

NOTES
We no longer need ASImage after we transfered it onto the Pixmap, so
we better destroy it to conserve resources.

SEE ALSO
asimage2pixmap(), destroy_asimage(), set_window_background_and_free()