asview(1)                AfterStep X11 window manager                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]0);
           printf( "Where: image - filename of the image to display.0);
       }


       int main(int argc, char* argv[])
       {
           char *image_file = "rose512.jpg" ;
           ASImage *im ;
           ASVisual *asv ;
           int screen = 0, depth = 24;
           Display *dpy = NULL;

           /* 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_ALLOCS0);
       #endif
       #ifdef AFTERBASE_DEBUG_ALLOCS
           fprintf( stderr, "have AFTERBASE_DEBUG_ALLOCS0);
       #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 );
       #endif
           /* see ASView.3 : */
           asv = create_asvisual( dpy, screen, depth, NULL );
           /* asv = create_asvisual_for_id( dpy, screen, depth, 0x28, None, NULL ); */

           /* 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 );
               ASImage2file( im, NULL, "asview.gif", ASIT_Gif, 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 : 0, rects_count );
               for( i = 0 ; i < rects_count ; ++i )
                   fprintf( stderr, "rect[%d]=%dx%d%+d%+d;0,
                            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 );
               }
               /* see common.c: wait_closedown() : */
               wait_closedown(w);
               dpy = NULL;

               /* no longer need this - lets clean it up :*/
               destroy_asvisual( asv, False );
               asv = NULL ;

       #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()



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