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# AFTERImage example 1: Image viewer

demonstrates loading and displaying of images

libAfterImage/tutorials/ASView

- NAME

  ASView

- 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

      #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]\n");
          printf( "Where: image - filename of the image to display.\n");
      }

      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\n");
      #endif
      #ifdef AFTERBASE_DEBUG_ALLOCS
          fprintf( stderr, "have AFTERBASE_DEBUG_ALLOCS\n");
      #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: \"%s\"", image_file );
              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 ); */

          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 : \n", rects_count );
              for( i = 0 ; i < rects_count ; ++i )
                  fprintf( stderr, "\trect[%d]=%dx%d%+d%+d;\n",
                           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 ;
      }

libAfterImage/tutorials/ASView.1 [1.1]

- 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,

libAfterImage/tutorials/ASView.2 [1.2]

- 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
      .XPM images.

- 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()

libAfterImage/tutorials/ASView.3 [1.3]

- 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.

libAfterImage/tutorials/ASView.4 [1.4]

- 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()

libAfterImage/tutorials/ASView.5 [1.5]

- 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()

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