asscale(1)               AfterStep X11 window manager               asscale(1)



NAME
       asscale - demonstrates image loading and scaling
       libAfterImage/tutorials/ASScale

NAMEASScale
SYNOPSIS
       Simple program based on libAfterImage to scale an image.

DESCRIPTION
       We will load image and scale it up to new size, specified as command
       line arguments
       We then display the result in simple window.
       After that we would want to wait, until user closes our window.

       In this tutorial we will only explain new steps, not described in
       previous tutorial. New steps described in this tutorial are :
       ASScale.1. Parsing geometry spec.
       ASScale.2. Scaling ASImage.

SEE ALSO
       Tutorial 1: ASView - explanation of basic steps needed to use
                            libAfterImage and some other simple things.

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

       void usage()
       {
           printf( "Usage: asscale [-h]|[image [WIDTH[xHEIGHT]]]0);
           printf( "Where: image - is image filename.0);
           printf( "       WIDTH - width to scale image to.( Naturally :)0);
           printf( "       HEIGHT- height to scale image to.0);
       }

       int main(int argc, char* argv[])
       {
           char *image_file = "rose512.jpg" ;
           int dummy, geom_flags = 0;
           unsigned int to_width, to_height ;
           ASImage *im ;
           int clip_x = 0, clip_y = 0, clip_width = 0, clip_height = 0 ;
           int slice_x_start = 0, slice_x_end = 0, slice_y_start = 0, slice_y_end = 0 ;
           Bool slice_scale = False ;
           Display *dpy = NULL;

           /* see ASView.1 : */
           set_application_name( argv[0] );

           if( argc > 1 )
           {
               int i = 2;
               if( strncmp( argv[1], "-h", 2 ) == 0 )
               {
                   usage();
                   return 0;
               }
               image_file = argv[1] ;
               if( argc > 2 )   /* see ASScale.1 : */
                   geom_flags = XParseGeometry( argv[2], &dummy, &dummy,
                                                &to_width, &to_height );

               while( ++i < argc )
               {
                   if( strncmp( argv[i], "-sx1", 4 ) == 0 && i+1 < argc )
                       slice_x_start = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-sx2", 4 ) == 0 && i+1 < argc )
                       slice_x_end = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-sy1", 4 ) == 0 && i+1 < argc )
                       slice_y_start = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-sy2", 4 ) == 0 && i+1 < argc )
                       slice_y_end = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-cx", 4 ) == 0 && i+1 < argc )
                       clip_x = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-cy", 4 ) == 0 && i+1 < argc )
                       clip_y = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-cwidth", 7 ) == 0 && i+1 < argc )
                       clip_width = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-cheight", 8 ) == 0 && i+1 < argc )
                       clip_height = atoi(argv[++i]) ;
                   else if( strncmp( argv[i], "-ss", 3 ) == 0 )
                       slice_scale = True ;
               }


           }else
           {
               show_warning( "no image file or scale geometry - defaults used:"
                             "
                             image_file );
               usage();
           }
           /* see ASView.2 : */
           im = file2ASImage( image_file, 0xFFFFFFFF, SCREEN_GAMMA, 0, getenv("IMAGE_PATH"), NULL );

           if( im != NULL )
           {
               ASVisual *asv ;
               ASImage *scaled_im ;
               /* Making sure tiling geometry is sane : */
               if( !get_flags(geom_flags, WidthValue ) )
                   to_width = im->width*2 ;
               if( !get_flags(geom_flags, HeightValue ) )
                   to_height = im->height*2;
               printf( "%s: scaling image
                       get_application_name(), image_file, to_width, to_height,
                       (double)to_width/(double)(im->width),
                       (double)to_height/(double)(im->height) );

       #ifndef X_DISPLAY_MISSING
               {
                   Window w ;
                   int screen, depth ;

                   dpy = XOpenDisplay(NULL);
                   _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 );
                   /* see ASView.4 : */
                   w = create_top_level_window( asv, DefaultRootWindow(dpy),
                                                32, 32,
                                                to_width, to_height, 1, 0, NULL,
                                                "ASScale", image_file );
                   if( w != None )
                   {
                       Pixmap p ;

                       XMapRaised   (dpy, w);
                       /* see ASScale.2 : */
                       if( slice_x_start == 0 && slice_x_end == 0 &&
                           slice_y_start == 0 && slice_y_end == 0 )
                       {
                           scaled_im = scale_asimage2( asv, im,
                                                       clip_x, clip_y, clip_width, clip_height,
                                                       to_width, to_height,
                                                   ASA_XImage, 0,
                                                   ASIMAGE_QUALITY_DEFAULT );
                       }else
                       {
                           scaled_im = slice_asimage2( asv, im, slice_x_start, slice_x_end,
                                                      slice_y_start, slice_y_end,
                                                   to_width, to_height, slice_scale,
                                                   ASA_XImage, 0,
                                                   ASIMAGE_QUALITY_DEFAULT );
                       }
                       destroy_asimage( &im );
                       /* see ASView.5 : */
                       p = asimage2pixmap(asv, DefaultRootWindow(dpy), scaled_im,
                                           NULL, True );
                       /* print_storage(NULL); */
                       destroy_asimage( &scaled_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
               asv = create_asvisual( NULL, 0, 0, NULL );
               scaled_im = scale_asimage(asv, im, to_width, to_height,
                                         ASA_ASImage, 0,
                                         ASIMAGE_QUALITY_DEFAULT );
               /* writing result into the file */
               ASImage2file( scaled_im, NULL, "asscale.jpg", ASIT_Jpeg, NULL );
               destroy_asimage( &scaled_im );
               destroy_asimage( &im );
       #endif
           }
           return 0 ;
       }

SYNOPSIS
       Step 1. Parsing the geometry.

DESCRIPTION
       Geometry can be specified in WIDTHxHEIGHT+X+Y format. Accordingly we
       use standard X function to parse it: XParseGeometry. Returned flags
       tell us what values has been specified. Since we only need size -
       we check if it is specified and if not - simply default it to twice
       as big as original image. Accordingly we use dummy variable to pass
       to XParseGeometry.

EXAMPLE
           geom_flags = XParseGeometry( argv[3], &dummy, &dummy,
                                        &to_width, &to_height );

SYNOPSIS
       Step 2. Actual scaling the image.

DESCRIPTION
       scale_asimage() scales image both up and down, and is very easy to
       use - just pass it new size. In this example we use default quality.
       Default is equivalent to GOOD which should be sufficient in
       most cases. Compression is set to 0 since we do not intend to store
       image for long time. Even better - we don't need to store it at all -
       all we need is XImage, so we can transfer it to the server easily.
       That is why to_xim argument is set to ASA_XImage. As the result obtained
       ASImage will not have any data in its buffers, but it will have
       ximage member set to point to valid XImage. Subsequently we enjoy
       that convenience, by setting use_cached to True in call to
       asimage2pixmap. That ought to save us alot of processing.

       Scaling algorithm is rather sophisticated and is implementing 4 point
       interpolation. Which basically means that we try to approximate each
       missing point as an extension of the trend of 4 neighboring points -
       two on each side. Closest neighbor's have more weight then outside
       ones. 2D scaling is performed by scaling each scanline first, and
       then interpolating missing scanlines.
       Scaling down is somewhat skimpier, as it amounts to simple averaging
       of the multiple pixels. All calculations are done in integer math on
       per channel basis, and with precision 24.8 bits per channel per pixel.

EXAMPLE
           scaled_im = scale_asimage( asv, im, to_width, to_height,
                                      ASA_XImage, 0, ASIMAGE_QUALITY_DEFAULT );
           destroy_asimage( &im );

NOTES
       Scaling image up to very large height is much slower then to same
       width due to algorithm specifics. Yet even on inferior hardware it
       yields decent speeds.
       When we successfully scaled image - we no longer need the original -
       getting rid of it so it does not clog memory.

SEE ALSO
       scale_asimage().



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