astile.html

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## libAfterImage/tutorials/ASTile

SYNOPSIS

     Simple program based on libAfterImage to tile and tint image.

DESCRIPTION

     All we want to do here is to get image filename, tint color and
     desired geometry from the command line. We then load this image, and
     proceed on to tiling it based on parameters. Tiling geometry
     specifies rectangular shape on limitless plane on which original
     image is tiled. While we are at tiling the image we also tint it to
     specified color, or to some random value derived from the current
     time in seconds elapsed since 1971.
     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 :
     ASTile.1. Parsing ARGB32 tinting color.
     ASTile.2. Parsing geometry spec.
     ASTile.3. Tiling and tinting ASImage.

SEE ALSO

     ASView - explanation of basic steps needed to use libAfterImage and
              some other simple things.

SOURCE

        #include <libAfterImage/afterbase.h>
        #include <libAfterImage/afterimage.h>
        #include "common.h"

        void usage()
        {
            printf( "Usage: astile [-h]|[[-g geometry][-t tint_color] image]\n");
            printf( "Where: image    - source image filename.\n");
            printf( "       geometry - width and height of the resulting image,\n");
            printf( "                  and x, y of the origin of the tiling on source image.\n");
            printf( "       tint_color - color to tint image with.( defaults to current time :)\n");
        }

        int main(int argc, char* argv[])
        {
            Window w ;
            ASVisual *asv ;
            int screen = 0, depth = 0;
            char *image_file = "rose512.jpg" ;
            ARGB32 tint_color = time(NULL);
            int tile_x, tile_y, geom_flags = 0;
            unsigned int tile_width, tile_height ;
            ASImage *im ;

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

        #ifndef X_DISPLAY_MISSING
                /* parse_argb_color can only be used after display is open,
                   otherwise we are limited to colors defined as ARGB values : */
                dpy = XOpenDisplay(NULL);
                _XA_WM_DELETE_WINDOW = XInternAtom( dpy, "WM_DELETE_WINDOW", False);
                screen = DefaultScreen(dpy);
                depth = DefaultDepth( dpy, screen );
        #endif

            if( argc > 1 )
            {
                int i ;

                if( strncmp( argv[1], "-h", 2 ) == 0 )
                {
                    usage();
                    return 0;
                }

                for( i = 1 ; i < argc ; i++ )
                {
                    if( argv[i][0] == '-' && i < argc-1 )
                    {
                        switch(argv[i][1])
                        {
                            case 't' :          /* see ASTile.1 : */
                                if( parse_argb_color( argv[i+1], &tint_color ) ==
                                    argv[i+1] )
                                    show_warning( "unable to parse tint color - default used: #%8.8X",
                                                  tint_color );
                                break ;
                            case 'g' :          /* see ASTile.2 : */
                                geom_flags = XParseGeometry( argv[i+1],
                                                             &tile_x, &tile_y,
                                                             &tile_width,
                                                             &tile_height );
                                break ;
                        }
                        ++i ;
                    }else
                        image_file = argv[i] ;
                }
            }else
            {
                show_warning( "no image file or tint color specified - defaults used: \"%s\" #%8.8lX",
                              image_file, tint_color );
                usage();
            }

            /* see ASView.2 : */
            im = file2ASImage( image_file, 0xFFFFFFFF, SCREEN_GAMMA, 0, NULL );

            /* Making sure tiling geometry is sane : */
            if( !get_flags(geom_flags, XValue ) )
                tile_x = im->width/2 ;
            if( !get_flags(geom_flags, YValue ) )
                tile_y = im->height/2 ;
            if( !get_flags(geom_flags, WidthValue ) )
                tile_width = im->width*2 ;
            if( !get_flags(geom_flags, HeightValue ) )
                tile_height = im->height*2;
            printf( "%s: tiling image \"%s\" to %dx%d%+d%+d tinting with #%8.8lX\n",
                    get_application_name(), image_file, tile_width, tile_height,
                    tile_x, tile_y, tint_color );

            if( im != NULL )
            {
                /* see ASView.3 : */
                asv = create_asvisual( dpy, screen, depth, NULL );
                w = None ;
        #ifndef X_DISPLAY_MISSING
                /* see ASView.4 : */
                w = create_top_level_window( asv, DefaultRootWindow(dpy), 32, 32,
                                             tile_width, tile_height, 1, 0, NULL,
                                             "ASTile" );
                if( w != None )
                {
                    Pixmap p ;
                    ASImage *tinted_im ;

                    XMapRaised   (dpy, w);
                    /* see ASTile.3 : */
                    tinted_im = tile_asimage( asv, im, tile_x, tile_y,
                                              tile_width, tile_height,
                                              tint_color, ASA_XImage, 0,
                                              ASIMAGE_QUALITY_TOP );
                    destroy_asimage( &im );
                    /* see ASView.5 : */
                    p = asimage2pixmap( asv, DefaultRootWindow(dpy), tinted_im,
                                        NULL, True );
                    destroy_asimage( &tinted_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);
        #else
                {
                    ASImage *tinted_im ;
                    /* see ASTile.3 : */
                    tinted_im = tile_asimage( asv, im, tile_x, tile_y,
                                              tile_width, tile_height,
                                              tint_color, ASA_ASImage, 0,
                                              ASIMAGE_QUALITY_TOP );
                    destroy_asimage( &im );
                    /* writing result into the file */
                    ASImage2file( tinted_im, NULL, "astile.jpg", ASIT_Jpeg, NULL );
                    destroy_asimage( &tinted_im );
                }
        #endif
            }
            return 0 ;
        }

## libAfterImage/tutorials/ASTile.1

SYNOPSIS

     Step 1. Color parsing.

DESCRIPTION

     libAfterImage utilizes function provided by libAfterBase for color
     parsing. In case libAfterBase is unavailable - libAfterImage
     includes its own copy of that function. This function differs from
     standard XParseColor in a way that it allows for parsing of alpha
     channel in addition to red, green and blue. It autodetects if value
     include alpha channel or not, using the following logic:
     If number of hex digits in color spec is divisible by 4 and is not
     equal to 12 then first digits are treated as alpha channel.
     In case named color is specified or now apha channel is specified
     alpha value of 0xFF will be used, marking this color as solid.

EXAMPLE

         if( parse_argb_color( argv[i+1], &tint_color ) == argv[i+1] )
               show_warning( "unable to parse tint color - default used: #%8.8X",
                            tint_color );

NOTES

     On success parse_argb_color returns pointer to the character
     immidiately following color specification in original string.
     Therefore test for returned value to be equal to original string will
     can be used to detect error.

SEE ALSO

     libAfterBase, parse_argb_color(), ARGB32

## libAfterImage/tutorials/ASTile.2

SYNOPSIS

     Step 2. 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. We only have to fill the rest
     with some sensible defaults. Default x is width/2, y is height/2, and
     default size is same as image's width.

EXAMPLE

         geom_flags = XParseGeometry ( argv[i+1], &tile_x, &tile_y,
                                                &tile_width, &tile_height );

SEE ALSO

     ASScale.1

## libAfterImage/tutorials/ASTile.3

SYNOPSIS

     Step 3. Actuall tiling of the image.

DESCRIPTION

     Actuall tiling is quite simple - just call tile_asimage and it will
     generate new ASImage containing tiled and tinted image. For the sake
     of example we set quality to TOP, but normally GOOD quality is quite
     sufficient, and is a default. Again, 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 convinience, by setting use_cached to True
     in call to asimage2pixmap(). That ought to save us alot of processing.

     Tinting works in both directions - it can increase intensity of the
     color or decrease it. If any particular channel of the tint_color is
     greater then 127 then intensity is increased, otherwise its decreased.

EXAMPLE

         tinted_im = tile_asimage( asv, im, tile_x, tile_y,
                                   tile_width, tile_height,
                                   tint_color,
                                   ASA_XImage, 0, ASIMAGE_QUALITY_TOP );
         destroy_asimage( &im );

NOTES
SEE ALSO

     tile_asimage().