Merge pull request #12 from KohaAloha/master

add a palette cycling example

Author: FROGGS

code_listings/froggs.png

@@ -0,0 +1,57 @@
+use Modern::Perl;
+use SDL;
+use SDL::Video;
+use SDL::Color;
+use SDL::Image;
+use SDL::Event;
+use SDL ':init';
+use SDL::Event;
+use SDL::Events ':all';
+my $screen_width  = 300;
+my $screen_height = 340;
+my $x             = 0;
+my $quit          = 0;
+SDL::init(SDL_INIT_VIDEO);
+
+# make a screen surface
+my $screen_surface
+    = SDL::Video::set_video_mode( $screen_width, $screen_height, 8,
+    SDL_SWSURFACE | SDL_HWPALETTE );
+
+# load and blit an image
+my $img = SDL::Image::load('froggs.png');
+
+# this image blit only needs to be done *once* :)
+SDL::Video::blit_surface( $img, undef, $screen_surface, undef );
+
+
+while ( !$quit ) {
+
+    # check for a quit?
+    get_events();
+    #
+    set_palette();
+}
+
+sub get_events {
+    my $event = SDL::Event->new();
+
+    #Pump the event queue
+    SDL::Events::pump_events;
+    while ( SDL::Events::poll_event($event) ) {
+        $quit = 1 if $event->type == SDL_QUIT;
+    }
+}
+
+sub set_palette {
+    my @clrs;
+
+    #push 256 color objects into an array
+    foreach my $i ( 0 .. 255 ) { $clrs[$i] = SDL::Color->new( $x, 0, $i ); }
+
+    # update surfaces' palette with 256 new colors
+    my $rc
+        = SDL::Video::set_palette( $screen_surface, SDL_PHYSPAL, 0, @clrs );
+    $x++;
+    $x = 0 if $x == 255;
+}