SDL Image Slideshow

Xenther has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to write a simple image slideshow using SDL. I can load images, move them around the screen, but I can't seem to scale the images. I'm trying to use the SDL::GFX::Rotozoom module but the surface I get back doesn't seem to have the "w" or "h" methods. Maybe I'm just missing something really simple. Any help would be greatly appreciated! Thanks!!

#!/usr/bin/perl
use strict;
use warnings;
use SDL;
use SDL::Video;
use SDL::Rect;
use SDL::Surface;
use SDLx::Sprite;
use SDL::GFX::Rotozoom;
use SDLx::App;

my $disp = SDLx::App->new( 
            title          => 'Ken Burns',
            width          => 1024,
        height         => 800,
        depth          => 32,
        flags        => SDL_ANYFORMAT,
        resizeable    => 1,
        exit_on_quit    => 1 
        
    );

#$disp->fullscreen();

my $x = 0;
my $y = 0;

# This photo is larger than the 1024x800 app size
my $big_image = SDLx::Sprite->new( image => '/path/to/photo.jpg' );

my $lil_image = SDL::GFX::Rotozoom::surface( $big_image, 0, 0.7, SMOOT
+HING_ON );

for $x ( 0 .. ($lil_image->w-$disp->w) ) {
        $lil_image->draw_xy(
        $disp,
        -$x,0
    );

    SDL::Video::update_rect( $disp, 0, 0, $disp->w, $disp->h );
#    SDL::delay(2);
}


for $y ( 0 .. ($lil_image->h-$disp->h) ) {
        $lil_image->draw_xy(
        $disp,
        -($lil_image->w-$disp->w),-$y
    );

    SDL::Video::update_rect( $disp, 0, 0, $disp->w, $disp->h );
#    SDL::delay(2);
}


for $x ( 0 .. ($lil_image->w-$disp->w) ) {
        $lil_image->draw_xy(
        $disp,
        -($lil_image->w-$disp->w)+$x,-($lil_image->h-$disp->h)
    );

    SDL::Video::update_rect( $disp, 0, 0, $disp->w, $disp->h );
#    SDL::delay(2);
}

 
for $y ( 0 .. ($lil_image->h-$disp->h) ) {
    $lil_image->draw_xy(
        $disp,
        0,-($lil_image->h-$disp->h)+$y
    );

    SDL::Video::update_rect( $disp, 0, 0, $disp->w, $disp->h );
#    SDL::delay(1);
}

#SDL::delay(200);
[download]

Comment on SDL Image Slideshow Download Code

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Re: SDL Image Slideshow by zentara (Cardinal) on Jun 12, 2012 at 12:33 UTC
Hi, I'm not sure what you are trying to do in your code, but there is 1 glaring error right from the start. `# This photo is larger than the 1024x800 app size my $big_image = SDLx::Sprite->new( image => '/path/to/photo.jpg' ); my $lil_image = SDL::GFX::Rotozoom::surface( $big_image, 0, 0.7, SMOOTHING_ON );` [download] If you read perldoc SDL::GFX::Rotozoom you will see that SDL::GFX::Rotozoom::surface requires a surface as input, NOT a SDLx::Sprite as you do in your code. From the perldoc: `my $picture = SDL::Video::load_BMP('test.bmp'); my $rotated = SDL::GFX::Rotozoom::surface( $picture, 45, .8, SMOOTHING_ON +);` [download] Furthermore, from looking thru the SDL perldocs, it seems you can only load BMP files at this time. Have a look at the example script at /examples/GFX/script_roto.pl in the SDL module distribution. Upon further investigation, it looks like you can load a jpg into an SDL::Surface with SDL::Image `use SDL::Image; SDL::Image::init(IMG_INIT_JPG); #loads JPG support SDL::Image::load("file.png"); #loads PNG support SDL::Image::quit(); #unloads everything` [download] I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply] [d/l] [select]
Re: SDL Image Slideshow by zentara (Cardinal) on Jun 12, 2012 at 13:11 UTC
Just in case you are still scratching your head, here is a script that will load a jpg and scale it down. I cobbled it together from the perldocs. #!/usr/bin/perl use strict; use warnings; use SDL; use SDL::Video; use SDL::Rect; use SDL::Surface; use SDLx::Sprite; use SDL::GFX::Rotozoom; use SDLx::App; use SDL::Image; SDL::Image::init(IMG_INIT_JPG); #loads JPG support my $display = SDL::Video::set_video_mode( 640, 480, 32, SDL_SWSURFACE +); my $pixel = SDL::Video::map_RGB( $display->format, 0, 0, 0 ); SDL::Video::fill_rect( $display, SDL::Rect->new( 0, 0, $display->w, $display->h ), $pixel ); Carp::confess SDL::get_error if !$display; my $disp = SDLx::App->new( title => 'Ken Burns', width => 1024, height => 800, depth => 32, flags => SDL_ANYFORMAT, resizeable => 1, exit_on_quit => 1 ); #$disp->fullscreen(); my $big_image = SDL::Image::load('1Zen16.jpg'); #loads jpg print "$big_image\n"; my $lil_image = SDL::GFX::Rotozoom::surface( $big_image, 0, 0.7, SMOOT +HING_ON ); print "$lil_image\n"; draw($lil_image); #my $temp_surf = SDL::GFX::Rotozoom::shrink_surface( $big_image, .7, . +7); # shrink dos'nt work for me... gives floatingpoint errors #Carp::confess SDL::get_error if !$temp_surf; #draw( $temp_surf ); sub draw { SDL::Video::fill_rect( $display, SDL::Rect->new( 0, 0, $display->w, $display->h ), $pixel ); my $surface = $_[0]; SDL::Video::blit_surface( $surface, SDL::Rect->new( 0, 0, $surface->w, $surface->h ), $display, SDL::Rect->new( 0, 0, $display->w, $display->w ) ); SDL::Video::update_rect( $display, 0, 0, 640, 480 ); } $disp->run(); [download] I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply] [d/l]
Re^2: SDL Image Slideshow by peter.l (Initiate) on Jul 09, 2013 at 08:09 UTC
`#my $temp_surf = SDL::GFX::Rotozoom::shrink_surface( $big_image, .7, . +7); # shrink dos'nt work for me... gives floatingpoint errors #Carp::confess SDL::get_error if !$temp_surf; #draw( $temp_surf );` [download] i think you get an floatingpoint error cause shrink needs a shrinkingfactor and 0.7 < 1. try something like `my $temp_surf = SDL::GFX::Rotozoom::shrink_surface( $big_image, 7, 7);` [download] or `my $temp_surf = SDL::GFX::Rotozoom::shrink_surface( $big_image, 1.3, 1 +.3);` [download] this should work	[reply] [d/l] [select]