/ 
SDL-2.541_08
River stage two • 23 direct dependents • 25 total dependents
/ SDL::Video

NAME

SDL::Video - Bindings to the video category in SDL API

CATEGORY

Core, Video

SYNOPSIS

use SDL;
use SDL::Video;
use SDL::Surface;
use SDL::Rect;

# the size of the window box or the screen resolution if fullscreen
my $screen_width   = 800;
my $screen_height  = 600;

SDL::init(SDL_INIT_VIDEO);

# setting video mode
my $screen_surface = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_ANYFORMAT);

# drawing something somewhere
my $mapped_color   = SDL::Video::map_RGB($screen_surface->format(), 0, 0, 255); # blue
SDL::Video::fill_rect($screen_surface, 
                      SDL::Rect->new($screen_width / 4, $screen_height / 4, 
                                     $screen_width / 2, $screen_height / 2), $mapped_color);

# update an area on the screen so its visible
SDL::Video::update_rect($screen_surface, 0, 0, $screen_width, $screen_height);

sleep(5); # just to have time to see it

CONSTANTS

The constants are exported by default. You can avoid this by doing:

use SDL::Video ();

and access them directly:

SDL::Video::SDL_SWSURFACE;

or by choosing the export tags below:

Export tag: ':surface'

SDL_ASYNCBLIT       Use asynchronous blit if possible
SDL_SWSURFACE       Stored in the system memory.
SDL_HWSURFACE       Stored in video memory

Export tag: ':video'

SDL_ANYFORMAT       Allow any pixel-format
SDL_HWPALETTE       Have an exclusive palette
SDL_DOUBLEBUF       Double buffered
SDL_FULLSCREEN      Full screen surface
SDL_OPENGL          Have an OpenGL context
SDL_OPENGLBLIT      Support OpenGL blitting. 
                    NOTE: This option is kept for compatibility only, and is not recommended for new code.
SDL_RESIZABLE       Resizable surface
SDL_NOFRAME         No window caption or edge frame
SDL_HWACCEL         Use hardware acceleration blit
SDL_SRCCOLORKEY     Use colorkey blitting
SDL_RLEACCELOK      Private flag
SDL_RLEACCEL        Accelerated colorkey blitting with RLE
SDL_SRCALPHA        Use alpha blending blit (per-surface alpha)
SDL_PREALLOC        Use preallocated memory

Export tag ':overlay'

SDL_YV12_OVERLAY    Planar mode: Y + V + U  (3 planes)
SDL_IYUV_OVERLAY    Planar mode: Y + U + V  (3 planes)
SDL_YUY2_OVERLAY    Packed mode: Y0+U0+Y1+V0 (1 plane)
SDL_UYVY_OVERLAY    Packed mode: U0+Y0+V0+Y1 (1 plane)
SDL_YVYU_OVERLAY    Packed mode: Y0+V0+Y1+U0 (1 plane)

Export tag ':palette'

SDL_LOGPAL          Logical palette, which controls how blits are mapped to/from the surface
SDL_PHYSPAL         Physical palette, which controls how pixels look on the screen

Export tag ':grab'

SDL_GRAB_QUERY
SDL_GRAB_OFF
SDL_GRAB_ON
SDL_GRAB_FULLSCREEN Used internally

Export tag ':gl'

SDL_GL_RED_SIZE
SDL_GL_GREEN_SIZE
SDL_GL_BLUE_SIZE
SDL_GL_ALPHA_SIZE
SDL_GL_BUFFER_SIZE
SDL_GL_DOUBLEBUFFER
SDL_GL_DEPTH_SIZE
SDL_GL_STENCIL_SIZE
SDL_GL_ACCUM_RED_SIZE
SDL_GL_ACCUM_GREEN_SIZE
SDL_GL_ACCUM_BLUE_SIZE
SDL_GL_ACCUM_ALPHA_SIZE
SDL_GL_STEREO
SDL_GL_MULTISAMPLEBUFFERS
SDL_GL_MULTISAMPLESAMPLES
SDL_GL_ACCELERATED_VISUAL
SDL_GL_SWAP_CONTROL

Core Functions

get_video_surface

my $surface = SDL::Video::get_video_surface();

This function returns the current display SDL::Surface. If SDL is doing format conversion on the display surface, this function returns the publicly visible surface, not the real video surface.

Example:

# somewhere after you set the video mode
my $surface = SDL::Video::get_video_surface();

printf( "our screen is %d pixels wide and %d pixels high\n", $surface->w, $surface->h );

get_video_info

my $video_info = SDL::Video::get_video_info();

This function returns a read-only structure containing information about the video hardware. If it is called before SDL::Video::set_video_mode, the vfmt member of the returned structure will contain the pixel format of the best video mode.

Example:

use SDL;
use SDL::Video;
use SDL::VideoInfo;
use SDL::PixelFormat;

SDL::init(SDL_INIT_VIDEO);

my $video_info = SDL::Video::get_video_info();

printf( "we can have %dbits per pixel\n", $video_info->vfmt->BitsPerPixel );

video_driver_name

my $driver_name = SDL::Video::video_driver_name();

This function will return the name of the initialized video driver up to a maximum of 1024 characters. The driver name is a simple one word identifier like "x11", "windib" or "directx".

Note: Some platforms allow selection of the video driver through the SDL_VIDEODRIVER environment variable.

Example:

use SDL;
use SDL::Video;

SDL::init(SDL_INIT_VIDEO);

print SDL::Video::video_driver_name() . "\n";

list_modes

my @modes = @{ SDL::Video::list_modes( $pixel_format, $flags ) };

Returns a reference to an array:

  • of available screen dimensions (as SDL::Rect's) for the given format and video flags.

  • with first array element 'all'. In this case you can set all modes.

  • with first array element 'none' if no mode is available.

Note: <list_modes> should be called before the video_mode ist set. Otherwise you will always get 'all'.

Example:

use SDL;
use SDL::Video;
use SDL::VideoInfo;
use SDL::PixelFormat;
use SDL::Rect;

SDL::init(SDL_INIT_VIDEO);

my $video_info = SDL::Video::get_video_info();

my @modes = @{ SDL::Video::list_modes($video_info->vfmt, SDL_NOFRAME) };

if($#modes > 0)
{
    print("available modes:\n");
    foreach my $mode ( @modes )
    {
        printf("%d x %d\n", $mode->w, $mode->h );
    }
}
elsif($#modes == 0)
{
    printf("%s video modes available\n", $modes[0]);
}

video_mode_ok

my $bpp_ok = SDL::Video::video_mode_ok( $width, $height, $bpp, $flags );

This function is used to check whether the requested mode is supported by the current video device. The arguments passed to this function are the same as those you would pass to SDL::Video::set_video_mode. It returns 0 if the mode is not supported at all, otherwise the suggested bpp.

Example:

use SDL;
use SDL::Video;

SDL::init(SDL_INIT_VIDEO);

my $video_mode_ok = SDL::Video::video_mode_ok( 800, 600, 32, SDL_SWSURFACE );

unless($video_mode_ok)
{
    printf( "this video mode is not supported\n" );
}

set_video_mode

my $surface = SDL::Video::set_video_mode( 800, 600, 32, SDL_SWSURFACE|SDL_DOUBLEBUF|SDL_FULLSCREEN);

Sets up a video mode with the specified width, height, bits-per-pixel and flags. set_video_mode returns a SDL::Surface on success otherwise it returns undef on error, the error message is retrieved using SDL::get_error.

List of available flags

SDL_SWSURFACE

Create the video surface in system memory

SDL_HWSURFACE

Create the video surface in video memory

SDL_ASYNCBLIT

Enables the use of asynchronous updates of the display surface. This will usually slow down blitting on single CPU machines, but may provide a speed increase on SMP systems.

SDL_ANYFORMAT

Normally, if a video surface of the requested bits-per-pixel (bpp) is not available, SDL will emulate one with a shadow surface. Passing SDL_ANYFORMAT prevents this and causes SDL to use the video surface, regardless of its pixel depth.

SDL_HWPALETTE

Give SDL exclusive palette access. Without this flag you may not always get the colors you request with SDL::set_colors or SDL::set_palette.

SDL_DOUBLEBUF

Enable hardware double buffering; only valid with SDL_HWSURFACE. Calling SDL::Video::flip will flip the buffers and update the screen. All drawing will take place on the surface that is not displayed at the moment. If double buffering could not be enabled then SDL::Video::flip will just perform a SDL::Video::update_rect on the entire screen.

SDL_FULLSCREEN

SDL will attempt to use a fullscreen mode. If a hardware resolution change is not possible (for whatever reason), the next higher resolution will be used and the display window centered on a black background.

SDL_OPENGL

Create an OpenGL rendering context. You should have previously set OpenGL video attributes with SDL::Video::GL_set_attribute.

SDL_OPENGLBLIT

Create an OpenGL rendering context, like above, but allow normal blitting operations. The screen (2D) surface may have an alpha channel, and SDL::update_rects must be used for updating changes to the screen surface. NOTE: This option is kept for compatibility only, and will be removed in next versions. Is not recommended for new code.

SDL_RESIZABLE

Create a resizable window. When the window is resized by the user a SDL_VIDEORESIZE event is generated and SDL::Video::set_video_mode can be called again with the new size.

SDL_NOFRAME

If possible, SDL_NOFRAME causes SDL to create a window with no title bar or frame decoration. Fullscreen modes automatically have this flag set.

Note 1: Use SDL_SWSURFACE if you plan on doing per-pixel manipulations, or blit surfaces with alpha channels, and require a high framerate. When you use hardware surfaces (by passing the flag SDL_HWSURFACE as parameter), SDL copies the surfaces from video memory to system memory when you lock them, and back when you unlock them. This can cause a major performance hit. Be aware that you may request a hardware surface, but receive a software surface because the video driver doesn't support hardware surface. Many platforms can only provide a hardware surface when using SDL_FULLSCREEN. The SDL_HWSURFACE flag is best used when the surfaces you'll be blitting can also be stored in video memory.

Note 2: If you want to control the position on the screen when creating a windowed surface, you may do so by setting the environment variables SDL_VIDEO_CENTERED=center or SDL_VIDEO_WINDOW_POS=x,y. You can also set them via SDL::putenv.

Note 3: This function should be called in the main thread of your application.

User note 1: Some have found that enabling OpenGL attributes like SDL_GL_STENCIL_SIZE (the stencil buffer size) before the video mode has been set causes the application to simply ignore those attributes, while enabling attributes after the video mode has been set works fine.

User note 2: Also note that, in Windows, setting the video mode resets the current OpenGL context. You must execute again the OpenGL initialization code (set the clear color or the shade model, or reload textures, for example) after calling SDL::set_video_mode. In Linux, however, it works fine, and the initialization code only needs to be executed after the first call to SDL::Video::set_video_mode (although there is no harm in executing the initialization code after each call to SDL::Video::set_video_mode, for example for a multiplatform application).

convert_surface

$converted_surface = SDL::Video::convert_surface( $surface, $format, $flags );

Creates a new SDL::surface of the specified SDL::PixelFormat, and then copies and maps the given surface to it. It is also useful for making a copy of a surface.

The flags parameter is passed to SDL::Surface->new and has those semantics. This function is used internally by SDL::Video::display_format. This function can only be called after SDL::init.

it returns a SDL::Surface on success or undef on error.

display_format

$new_surface = SDL::Video::display_format( $surface );

This function takes a surface and copies it to a new surface of the pixel format and colors of the video framebuffer, suitable for fast blitting onto the display surface. It calls SDL::Video::convert_surface.

If you want to take advantage of hardware colorkey or alpha blit acceleration, you should set the colorkey and alpha value before calling this function.

If you want an alpha channel, see SDL::Video::display_format_alpha. Return Value

Note: Remember to use a different variable for the returned surface, otherwise you have a memory leak, since the original surface isn't freed.

display_format_alpha

$new_surface = SDL::Video::display_format_alpha( $surface );

This function takes a surface and copies it to a new surface of the pixel format and colors of the video framebuffer plus an alpha channel, suitable for fast blitting onto the display surface. It calls SDL::Video::convert_surface.

If you want to take advantage of hardware colorkey or alpha blit acceleration, you should set the colorkey and alpha value before calling this function.

This function can be used to convert a colorkey to an alpha channel, if the SDL_SRCCOLORKEY flag is set on the surface. The generated surface will then be transparent (alpha=0) where the pixels match the colorkey, and opaque (alpha=255) elsewhere.

Note: The video surface must be initialised using SDL::Video::set_video_mode before this function is called, or it will segfault.

load_BMP

$surface = SDL::Video::load_BMP( $filename );

Loads a SDL::Surface from a named Windows BMP file. SDL::Video::load_BMP returns a SDL::Surface on success or undef on error.

Note: When loading a 24-bit Windows BMP file, pixel data points are loaded as blue, green, red, and NOT red, green, blue (as one might expect).

use SDL;
use SDL::Video;
use SDL::Rect;
use SDL::Surface;

my $screen_width  = 640;
my $screen_height = 480;

SDL::init(SDL_INIT_VIDEO);

my $screen  = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_SWSURFACE);

my $picture = SDL::Video::load_BMP('test.bmp');

die(SDL::get_error) unless $picture;

my $rect    = SDL::Rect->new(0, 0, $screen_width, $screen_height);

SDL::Video::blit_surface( $picture, SDL::Rect->new(0, 0, $picture->w, $picture->h), 
                          $screen,  SDL::Rect->new(0, 0, $screen->w,  $screen->h) );

SDL::Video::update_rect( $screen, 0, 0, $screen_width, $screen_height );

sleep(2);

save_BMP

$saved_BMP = SDL::Video::save_BMP( $surface, $filename );

Saves the given SDL::Surface as a Windows BMP file named filename. it returns 0 on success or -1 on error.

set_color_key

$set_color_key = SDL::Video::set_color_key( $surface, $flag, $key );

Sets the color key (transparent pixel) in a blittable surface and enables or disables RLE blit acceleration. $key can be an integer or an SDL::Color object. If you pass an SDL::Color object SDL::Video::map_RGB will be called on it before setting the color key.

RLE acceleration can substantially speed up blitting of images with large horizontal runs of transparent pixels (i.e., pixels that match the key value). The key must be of the same pixel format as the surface, SDL::Video::map_RGB is often useful for obtaining an acceptable value. If flag is SDL_SRCCOLORKEY then key is the transparent pixel value in the source image of a blit.

If flag is OR'd with SDL_RLEACCEL then the surface will be drawn using RLE acceleration when drawn with SDL::Video::blit_surface. The surface will actually be encoded for RLE acceleration the first time SDL::Video::blit_surface or SDL::Video::display_format|/display_format is called on the surface. If flag is 0, this function clears any current color key.

SDL::Video::set_color_key returns 0 on success or -1 on error.

set_alpha

$set_alpha = SDL::Video::set_alpha( $surface, $flag, $alpha );

set_alpha is used for setting the per-surface alpha value and/or enabling and disabling alpha blending.

The surface parameter specifies which SDL::surface whose alpha attributes you wish to adjust. flags is used to specify whether alpha blending should be used ( SDL_SRCALPHA ) and whether the surface should use RLE acceleration for blitting ( SDL_RLEACCEL ). flags can be an OR'd combination of these two options, one of these options or 0. If SDL_SRCALPHA is not passed as a flag then all alpha information is ignored when blitting the surface. The alpha parameter is the per-surface alpha value; a surface need not have an alpha channel to use per-surface alpha and blitting can still be accelerated with SDL_RLEACCEL.

Note: The per-surface alpha value of 128 is considered a special case and is optimised, so it's much faster than other per-surface values.

Alpha affects surface blitting in the following ways:

RGBA->RGB with SDL_SRCALPHA

The source is alpha-blended with the destination, using the alpha channel. SDL_SRCCOLORKEY and the per-surface alpha are ignored.

RGBA->RGB without SDL_SRCALPHA

The RGB data is copied from the source. The source alpha channel and the per-surface alpha value are ignored. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied.

RGB->RGBA with SDL_SRCALPHA

The source is alpha-blended with the destination using the per-surface alpha value. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied. The alpha channel of the copied pixels is set to opaque.

RGB->RGBA without SDL_SRCALPHA

The RGB data is copied from the source and the alpha value of the copied pixels is set to opaque. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied.

RGBA->RGBA with SDL_SRCALPHA

The source is alpha-blended with the destination using the source alpha channel. The alpha channel in the destination surface is left untouched. SDL_SRCCOLORKEY is ignored.

RGBA->RGBA without SDL_SRCALPHA

The RGBA data is copied to the destination surface. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied.

RGB->RGB with SDL_SRCALPHA

The source is alpha-blended with the destination using the per-surface alpha value. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied.

RGB->RGB without SDL_SRCALPHA

The RGB data is copied from the source. If SDL_SRCCOLORKEY is set, only the pixels not matching the colorkey value are copied.

Note: When blitting, the presence or absence of SDL_SRCALPHA is relevant only on the source surface, not the destination. Note: Note that RGBA->RGBA blits (with SDL_SRCALPHA set) keep the alpha of the destination surface. This means that you cannot compose two arbitrary RGBA surfaces this way and get the result you would expect from "overlaying" them; the destination alpha will work as a mask.

Note: Also note that per-pixel and per-surface alpha cannot be combined; the per-pixel alpha is always used if available.

SDL::Video::set_alpha returns 0 on success or -1 on error.

fill_rect

$fill_rect = SDL::Video::fill_rect( $dest, $dest_rect, $pixel );

This function performs a fast fill of the given SDL::Rect with the given SDL::PixelFormat. If dest_rect is NULL, the whole surface will be filled with color.

The color should be a pixel of the format used by the surface, and can be generated by the SDL::Video::map_RGB or SDL::Video::map_RGBA|/map_RGBA functions. If the color value contains an alpha value then the destination is simply "filled" with that alpha information, no blending takes place.

If there is a clip rectangle set on the destination (set via SDL::Video::set_clip_rect), then this function will clip based on the intersection of the clip rectangle and the dstrect rectangle, and the dstrect rectangle will be modified to represent the area actually filled.

If you call this on the video surface (ie: the value of SDL::Video::get_video_surface) you may have to update the video surface to see the result. This can happen if you are using a shadowed surface that is not double buffered in Windows XP using build 1.2.9.

SDL::Video::fill_rect returns 0 on success or -1 on error.

for an example see "SYNOPSIS".

Surface Locking and Unlocking

lock_surface

int SDL::Video::lock_surface( $surface );

SDL::Video::lock_surface sets up the given SDL::Surface for directly accessing the pixels. Between calls to SDL::lock_surface and SDL::unlock_surface, you can write to ( surface-set_pixels>) and read from ( surface-get_pixels> ), using the pixel format stored in surface-format>. Once you are done accessing the surface, you should use SDL::Video::unlock_surface to release the lock.

Not all surfaces require locking. If SDL::Video::MUSTLOCK evaluates to 0, then reading and writing pixels to the surface can be performed at any time, and the pixel format of the surface will not change. No operating system or library calls should be made between the lock/unlock pairs, as critical system locks may be held during this time. SDL::Video::lock_surface returns 0 on success or -1 on error.

Note: Since SDL 1.1.8, the surface locks are recursive. This means that you can lock a surface multiple times, but each lock must have a matching unlock.

use strict;
use warnings;
use Carp;

use SDL v2.3;
use SDL::Video;
use SDL::Event;
use SDL::Events;
use SDL::Surface;

my $screen;

sub putpixel
{
    my($x, $y, $color) = @_;
    my $lineoffset     = $y * ($screen->pitch / 4);
    $screen->set_pixels( $lineoffset+ $x, $color);
}

sub render
{
    if( SDL::Video::MUSTLOCK( $screen) )
    {
        return if (SDL::Video::lock_surface( $screen ) < 0)
    }
    
    my $ticks                = SDL::get_ticks();
    my ($i, $y, $yofs, $ofs) = (0,0,0,0);
    for ($i = 0; $i < 480; $i++)
    {
        for (my $j = 0, $ofs = $yofs; $j < 640; $j++, $ofs++)
        {
            $screen->set_pixels( $ofs, (  $i * $i + $j * $j + $ticks ) );
        }
        $yofs += $screen->pitch / 4;
    }
    
    putpixel(10, 10, 0xff0000);
    putpixel(11, 10, 0xff0000);
    putpixel(10, 11, 0xff0000);
    putpixel(11, 11, 0xff0000);
    
    SDL::Video::unlock_surface($screen) if (SDL::Video::MUSTLOCK($screen));
    
    SDL::Video::update_rect($screen, 0, 0, 640, 480);    
    
    return 0;
}

sub main
{
    Carp::cluck 'Unable to init SDL: '.SDL::get_error() if( SDL::init(SDL_INIT_VIDEO) < 0);
    
    $screen = SDL::Video::set_video_mode( 640, 480, 32, SDL_SWSURFACE);
    
    Carp::cluck 'Unable to set 640x480x32 video' . SDL::get_error() if(!$screen);
    
    while(1)
    {
        render();
        
        my $event = SDL::Event->new();
        
        while( SDL::Events::poll_event($event) )
        {
            my $type = $event->type;
            return 0 if( $type == SDL_KEYDOWN || $type == SDL_QUIT);
        }
        SDL::Events::pump_events();
    }
}

main();

unlock_surface

SDL::Video::unlock_surface( $surface );

Surfaces that were previously locked using SDL::Video::lock_surface must be unlocked with SDL::Video::unlock_surface. Surfaces should be unlocked as soon as possible. SDL::Video::unlock_surface doesn't return anything.

Note: Since 1.1.8, the surface locks are recursive. See SDL::Video::lock_surface for more information.

MUSTLOCK

int SDL::Video::MUSTLOCK( $surface );

MUSTLOCK returns 0 if the surface does not have to be locked during pixel operations, otherwise 1.

Screen Updating Functions

set_clip_rect

SDL::Video::set_clip_rect( $surface, $rect );

Sets the clipping rectangle for the given SDL::Surface. When this surface is the destination of a blit, only the area within the clip rectangle will be drawn into. The rectangle pointed to by rect will be clipped to the edges of the surface so that the clip rectangle for a surface can never fall outside the edges of the surface. If rect is NULL the clipping rectangle will be set to the full size of the surface. SDL::Video::set_clip_rect doesn't return anything.

get_clip_rect

SDL::Video::get_clip_rect( $surface, $rect );

Gets the clipping rectangle for the given SDL::Surface. When this surface is the destination of a blit, only the area within the clip rectangle is drawn into. The rectangle pointed to by rect will be filled with the clipping rectangle of the surface. SDL::Video::get_clip_rect doesn't return anything;

use SDL;
use SDL::Video;
use SDL::Rect;
use SDL::Surface;

my $screen_width  = 640;
my $screen_height = 480;

SDL::init(SDL_INIT_VIDEO);

my $screen  = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_SWSURFACE);

my $rect = SDL::Rect->new(0, 0, 0, 0);

SDL::Video::get_clip_rect($screen, $rect);

printf( "rect is %d, %d, %d, %d\n", $rect->x, $rect->y, $rect->w, $rect->h);

blit_surface

SDL::Video::blit_surface( $src_surface, $src_rect, $dest_surface, $dest_rect );

This performs a fast blit from the given source SDL::Surface to the given destination SDL::Surface. The width and height in $src_rect determine the size of the copied rectangle. Only the position is used in the $dest_rect (the width and height are ignored). Blits with negative dest_rect coordinates will be clipped properly. If $src_rect is undef, the entire surface is copied. If $dest_rect is undef, then the destination position (upper left corner) is (0, 0). The final blit rectangle is saved in $dest_rect after all clipping is performed ($src_rect is not modified). The blit function should not be called on a locked surface. I.e. when you use your own drawing functions you may need to lock a surface, but this is not the case with SDL::Video::blit_surface. Like most surface manipulation functions in SDL, it should not be used together with OpenGL.

The results of blitting operations vary greatly depending on whether SDL_SRCALPHA is set or not. See SDL::Video::set_alpha for an explanation of how this affects your results. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully explain.

if (source surface has SDL_SRCALPHA set) {
   if (source surface has alpha channel (that is, surface->format->Amask != 0))
       blit using per-pixel alpha, ignoring any colour key
   else {
       if (source surface has SDL_SRCCOLORKEY set)
           blit using the colour key AND the per-surface alpha value
       else
           blit using the per-surface alpha value
   }
} else {
   if (source surface has SDL_SRCCOLORKEY set)
       blit using the colour key
   else
       ordinary opaque rectangular blit
}

See "[RGBA]mask" in SDL::PixelFormat for details on surface->format->Amask.

SDL::Video::blit_surface doesn't returns anything.

For an example see SDL::Video::load_BMP.

update_rect

update_rect( $surface, $left, $top, $width, $height );

Makes sure the given area is updated on the given screen. The rectangle must be confined within the screen boundaries because there's no clipping. update_rect doesn't return any value.

Note: This function should not be called while screen is locked by SDL::Video::lock_surface

Note2: If x, y, width and height are all equal to 0, update_rect will update the entire screen.

For an example see SYNOPSIS

update_rects

update_rects( $surface, @rects );

Makes sure the given list of rectangles is updated on the given screen. The rectangle must be confined within the screen boundaries because there's no clipping. update_rects doesn't return any value.

Note: This function should not be called while screen is locked by SDL::Video::lock_surface.

Example:

use SDL;
use SDL::Video;
use SDL::Surface;
use SDL::Rect;

# the size of the window box or the screen resolution if fullscreen
my $screen_width   = 800;
my $screen_height  = 600;

SDL::init(SDL_INIT_VIDEO);

# setting video mode
my $screen_surface = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_SWSURFACE);

# drawing the whole screen blue
my $mapped_color   = SDL::Video::map_RGB($screen_surface->format(), 0, 0, 255); # blue
SDL::Video::fill_rect($screen_surface, 
                      SDL::Rect->new(0, 0, $screen_width, $screen_height),
                      $mapped_color);

my @rects = ();
push(@rects, SDL::Rect->new(200,   0, 400, 600));
push(@rects, SDL::Rect->new(  0, 150, 800, 300));
					   
# updating parts of the screen (should look like a cross)
SDL::Video::update_rects($screen_surface, @rects);

sleep(2);

flip

$flip = SDL::Video::flip( $screen_surface );

On hardware that supports double-buffering, this function sets up a flip and returns. The hardware will wait for vertical retrace, and then swap video buffers before the next video surface blit or lock will return. On hardware that doesn't support double-buffering or if SDL_SWSURFACE was set, this is equivalent to calling SDL::Video::update_rect( $screen, 0, 0, 0, 0 ).

A software screen surface is also updated automatically when parts of a SDL window are redrawn, caused by overlapping windows or by restoring from an iconified state. As a result there is no proper double buffer behavior in windowed mode for a software screen, in contrast to a full screen software mode.

The SDL_DOUBLEBUF flag must have been passed to SDL::Video::set_video_mode, when setting the video mode for this function to perform hardware flipping.

flip returns 0 on success or -1 on error.

Note: If you want to swap the buffers of an initialized OpenGL context, use the function SDL::Video::GL_swap_buffers instead.

Example:

use SDL;
use SDL::Video;
use SDL::Surface;

# the size of the window box or the screen resolution if fullscreen
my $screen_width   = 800;
my $screen_height  = 600;

SDL::init(SDL_INIT_VIDEO);

# setting video mode
my $screen_surface = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_DOUBLEBUF|SDL_FULLSCREEN);

# do some video operations here

# doing page flipping
unless( SDL::Video::flip($screen_surface) == 0 )
{
    printf( STDERR "failed to swap buffers: %s\n", SDL::get_error() );
}

Palette, Color and Pixel Functions

set_colors

$set_colors = SDL::Video::set_colors( $surface, $start, $color1, $color2, ... )

Sets a portion of the colormap for the given 8-bit surface.

When surface is the surface associated with the current display, the display colormap will be updated with the requested colors. If SDL_HWPALETTE was set in SDL::Video::set_video_mode flags, SDL::Video::set_colors will always return 1, and the palette is guaranteed to be set the way you desire, even if the window colormap has to be warped or run under emulation. The color components of a SDL::Color structure are 8-bits in size, giving you a total of 2563 = 16777216 colors. Palettized (8-bit) screen surfaces with the SDL_HWPALETTE flag have two palettes, a logical palette that is used for mapping blits to/from the surface and a physical palette (that determines how the hardware will map the colors to the display). SDL::Video::set_colors modifies both palettes (if present), and is equivalent to calling SDL::Video::set_palette with the flags set to ( SDL_LOGPAL | SDL_PHYSPAL ).

If surface is not a palettized surface, this function does nothing, returning 0. If all of the colors were set as passed to SDL::Video::set_colors, it will return 1. If not all the color entries were set exactly as given, it will return 0, and you should look at the surface palette to determine the actual color palette.

set_palette

$set_palette = set_palette( $surface, $flags, $start, $color1, $color2, ... );

Sets a portion of the palette for the given 8-bit surface.

Palettized (8-bit) screen surfaces with the SDL_HWPALETTE flag have two palettes, a logical palette that is used for mapping blits to/from the surface and a physical palette (that determines how the hardware will map the colors to the display). Non screen surfaces have a logical palette only. SDL::Video::blit_surface always uses the logical palette when blitting surfaces (if it has to convert between surface pixel formats). Because of this, it is often useful to modify only one or the other palette to achieve various special color effects (e.g., screen fading, color flashes, screen dimming).

This function can modify either the logical or physical palette by specifying SDL_LOGPAL or SDL_PHYSPAL the in the flags parameter.

When surface is the surface associated with the current display, the display colormap will be updated with the requested colors. If SDL_HWPALETTE was set in SDL::Video::set_video_mode flags, SDL::Video::set_palette will always return 1, and the palette is guaranteed to be set the way you desire, even if the window colormap has to be warped or run under emulation. The color components of a SDL::Color structure are 8-bits in size, giving you a total of 2563 = 16777216 colors.

If surface is not a palettized surface, this function does nothing, returning 0. If all of the colors were set as passed to set_palette, it will return 1. If not all the color entries were set exactly as given, it will return 0, and you should look at the surface palette to determine the actual color palette.

set_gamma

$set_gamma = SDL::Video::set_gamma( $red_gamma, $green_gamma, $blue_gamma );

Sets the "gamma function" for the display of each color component. Gamma controls the brightness/contrast of colors displayed on the screen. A gamma value of 1.0 is identity (i.e., no adjustment is made).

This function adjusts the gamma based on the "gamma function" parameter, you can directly specify lookup tables for gamma adjustment with SDL::set_gamma_ramp.

Note: Not all display hardware is able to change gamma.

SDL::Video::set_gamma returns -1 on error.

Warning: Under Linux (X.org Gnome and Xfce), gamma settings affects the entire display (including the desktop)!

Example:

 use SDL;
 use SDL::Video;
 use SDL::Surface;
 use SDL::Rect;
 use Time::HiRes qw( usleep );

 # the size of the window box or the screen resolution if fullscreen
 my $screen_width   = 800;
 my $screen_height  = 600;

 SDL::init(SDL_INIT_VIDEO);

 # setting video mode
 my $screen_surface = SDL::Video::set_video_mode($screen_width, $screen_height, 32, SDL_SWSURFACE);
 
 # drawing something somewhere
 my $mapped_color   = SDL::Video::map_RGB($screen_surface->format(), 128, 128, 128); # gray
 SDL::Video::fill_rect($screen_surface, 
                       SDL::Rect->new($screen_width / 4, $screen_height / 4, $screen_width / 2, $screen_height / 2), 
                       $mapped_color);
 
 # update the whole screen
 SDL::Video::update_rect($screen_surface, 0, 0, $screen_width, $screen_height);

 usleep(500000);
 
 for(1..20)
 {
    SDL::Video::set_gamma( 1 - $_ / 20, 1, 1 );
	usleep(40000);
 }
 
 for(1..20)
 {
    SDL::Video::set_gamma( $_ / 20, 1, 1 );
	usleep(40000);
 }

 SDL::Video::set_gamma( 1, 1, 1 );
 
 usleep(500000);

get_gamma_ramp

$get_gamma_ramp = SDL::Video::get_gamma_ramp( \@red_table, \@green_table, \@blue_table );

Gets the gamma translation lookup tables currently used by the display. Each table is an array of 256 Uint16 values. SDL::Video::get_gamma_ramp returns -1 on error.

use SDL;
use SDL::Video;

SDL::init(SDL_INIT_VIDEO);

my (@red, @green, @blue);

my $ret = SDL::Video::get_gamma_ramp( \@red, \@green, \@blue );

if( -1 == $ret )
{
    print( "an error occurred" );
}
else
{
    printf( "for gamma = 1.0: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[255], $green[255], $blue[255] );
    printf( "for gamma = 0.5: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[127], $green[127], $blue[127] );
    printf( "for gamma = 0.0: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[0],   $green[0],   $blue[0]   );
}

set_gamma_ramp

$set_gamma_ramp = SDL::Video::set_gamma_ramp( \@red_table, \@green_table, \@blue_table );

Sets the gamma lookup tables for the display for each color component. Each table is an array ref of 256 Uint16 values, representing a mapping between the input and output for that channel. The input is the index into the array, and the output is the 16-bit gamma value at that index, scaled to the output color precision. You may pass NULL to any of the channels to leave them unchanged.

This function adjusts the gamma based on lookup tables, you can also have the gamma calculated based on a "gamma function" parameter with SDL::Video::set_gamma.

Not all display hardware is able to change gamma. SDL::Video::set_gamma_ramp returns -1 on error (or if gamma adjustment is not supported).

Example:

use SDL;
use SDL::Video;

SDL::init(SDL_INIT_VIDEO);

my (@red, @green, @blue);

my $ret = SDL::Video::get_gamma_ramp( \@red, \@green, \@blue );

$red[127] = 0xFF00;

   $ret = SDL::Video::set_gamma_ramp( \@red, \@green, \@blue );

   $ret = SDL::Video::get_gamma_ramp( \@red, \@green, \@blue );

if( -1 == $ret )
{
    print( "an error occurred" );
}
else
{
    printf( "for gamma = 1.0: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[255], $green[255], $blue[255] );
    printf( "for gamma = 0.5: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[127], $green[127], $blue[127] );
    printf( "for gamma = 0.0: red=0x%04X, green=0x%04X, blue=0x%04X\n", $red[0],   $green[0],   $blue[0]   );
}

map_RGB

$pixel = SDL::Video::map_RGB( $pixel_format, $r, $g, $b );

Maps the RGB color value to the specified SDL::PixelFormat and returns the pixel value as a 32-bit int. If the format has a palette (8-bit) the index of the closest matching color in the palette will be returned. If the specified pixel format has an alpha component it will be returned as all 1 bits (fully opaque).

SDL::Video::map_RGB returns a pixel value best approximating the given RGB color value for a given pixel format. If the SDL::PixelFormat's bpp (color depth) is less than 32-bpp then the unused upper bits of the return value can safely be ignored (e.g., with a 16-bpp format the return value can be assigned to a Uint16, and similarly a Uint8 for an 8-bpp format).

use SDL;
use SDL::Video;
use SDL::PixelFormat;
use SDL::Surface;

SDL::init(SDL_INIT_VIDEO);

my $screen_surface = SDL::Video::set_video_mode(640, 480, 16, SDL_SWSURFACE);
#                                                          ^-- 16 bits per pixel

$r = 0x9C;
$g = 0xDC;
$b = 0x67;

printf( "for 24bpp it is: 0x%02X 0x%02X 0x%02X\n", $r, $g, $b);

my $_16bit = SDL::Video::map_RGB( $screen_surface->format, $r, $g, $b );

# 16bpp is 5 bits red, 6 bits green and 5 bits blue
# we will obtain the values for each color and calculating them back to 24/32bit color system
($r, $g, $b) = @{ SDL::Video::get_RGB( $screen_surface->format, $_16bit ) };

printf( "for 16bpp it is: 0x%02X 0x%02X 0x%02X\n", $r, $g, $b );

# so color #9CDC67 becomes #9CDF63

map_RGBA

$pixel = SDL::Video::map_RGBA( $pixel_format, $r, $g, $b, $a );

Maps the RGBA color value to the specified SDL::PixelFormat and returns the pixel value as a 32-bit int. If the format has a palette (8-bit) the index of the closest matching color in the palette will be returned. If the specified pixel format has no alpha component the alpha value will be ignored (as it will be in formats with a palette).

A pixel value best approximating the given RGBA color value for a given pixel format. If the pixel format bpp (color depth) is less than 32-bpp then the unused upper bits of the return value can safely be ignored (e.g., with a 16-bpp format the return value can be assigned to a Uint16, and similarly a Uint8 for an 8-bpp format).

get_RGB

$rgb_array_ref = SDL::Video::get_RGB( $pixel_format, $pixel );

Returns RGB values from a pixel in the specified pixel format. The pixel is an integer (e.g. 16bit RGB565, 24/32bit RGB888). This function uses the entire 8-bit [0..255] range when converting color components from pixel formats with less than 8-bits per RGB component (e.g., a completely white pixel in 16-bit RGB565 format would return [0xff, 0xff, 0xff] not [0xf8, 0xfc, 0xf8]).

For an example see SDL::Video::map_RGB.

get_RGBA

$rgba_array_ref = SDL::Video::get_RGBA( $pixel_format, $pixel );

Gets RGBA values from a pixel in the specified pixel format. This function uses the entire 8-bit [0..255] range when converting color components from pixel formats with less than 8-bits per RGB component (e.g., a completely white pixel in 16-bit RGB565 format would return [0xff, 0xff, 0xff] not [0xf8, 0xfc, 0xf8]).

If the surface has no alpha component, the alpha will be returned as 0xff (100% opaque).

GL Methods

GL_load_library

$gl_load_lib = SDL::Video::GL_load_library( 'path/to/static/glfunctions.dll' );

If you wish, you may load the OpenGL library from the given path at runtime, this must be done before SDL::Video::set_video_mode is called. You must then use SDL::Video::GL_get_proc_address to retrieve function pointers to GL functions.

GL_load_library returns 0 on success or -1 or error.

GL_get_proc_address

$proc_address = SDL::Video::GL_get_proc_address( $proc );

Returns the address of the GL function proc, or NULL if the function is not found. If the GL library is loaded at runtime, with SDL::Video::GL_load_library, then all GL functions must be retrieved this way. Usually this is used to retrieve function pointers to OpenGL extensions. Note that this function needs an OpenGL context to function properly, so it should be called after SDL::Video::set_video_mode has been called (with the SDL_OPENGL flag).

It returns undef if the function is not found.

Example:

my $has_multitexture = 1;

# Get function pointer
$gl_active_texture_ARB_ptr = SDL::Video::GL_get_proc_address("glActiveTextureARB");

# Check for a valid function ptr
unless($gl_active_texture_ARB_ptr)
{
    printf( STDERR "Multitexture Extensions not present.\n" );
    $has_multitexture = 0;
}

$gl_active_texture_ARB_ptr(GL_TEXTURE0_ARB) if $has_multitexture;

GL_get_attribute

$value = SDL::Video::GL_get_attribute( $attr );

It returns SDL/OpenGL attribute attr. This is useful after a call to SDL::Video::set_video_mode to check whether your attributes have been set as you expected. SDL::Video::GL_get_attribute returns undef if the attribute is not found.

Example:

print( SDL::Video::GL_set_attribute(SDL_GL_RED_SIZE) );

GL_set_attribute

$set_attr = SDL::Video::GL_set_attribute( $attr, $value );

This function sets the given OpenGL attribute attr to value. The requested attributes will take effect after a call to SDL::Video::set_video_mode. You should use SDL::Video::GL_get_attribute|/GL_get_attribute to check the values after a SDL::Video::set_video_mode call, since the values obtained can differ from the requested ones.

Available attributes:

  • SDL_GL_RED_SIZE

  • SDL_GL_GREEN_SIZE

  • SDL_GL_BLUE_SIZE

  • SDL_GL_ALPHA_SIZE

  • SDL_GL_BUFFER_SIZE

  • SDL_GL_DOUBLEBUFFER

  • SDL_GL_DEPTH_SIZE

  • SDL_GL_STENCIL_SIZE

  • SDL_GL_ACCUM_RED_SIZE

  • SDL_GL_ACCUM_GREEN_SIZE

  • SDL_GL_ACCUM_BLUE_SIZE

  • SDL_GL_ACCUM_ALPHA_SIZE

  • SDL_GL_STEREO

  • SDL_GL_MULTISAMPLEBUFFERS

  • SDL_GL_MULTISAMPLESAMPLES

  • SDL_GL_ACCELERATED_VISUAL

  • SDL_GL_SWAP_CONTROL

GL_set_attribute returns 0 on success or -1 on error.

Note: The SDL_DOUBLEBUF flag is not required to enable double buffering when setting an OpenGL video mode. Double buffering is enabled or disabled using the SDL_GL_DOUBLEBUFFER attribute.

Example:

SDL::Video::GL_set_attribute(SDL_GL_RED_SIZE, 5);

GL_swap_buffers

SDL::Video::GL_swap_buffers();

Swap the OpenGL buffers, if double-buffering is supported. SDL::Video::GL_swap_buffers doesn't return any value.

Video Overlay Functions

see SDL::Overlay

lock_YUV_overlay

$lock_overlay = SDL::Video::lock_YUV_overlay( $overlay );

Much the same as SDL::Video::lock_surface, lock_YUV_overlay locks the overlay for direct access to pixel data. It returns 0 on success or -1 on error.

unlock_YUV_overlay

SDL::Video::unlock_YUV_overlay( $overlay );

The opposite to SDL::Video::lock_YUV_overlay. Unlocks a previously locked overlay. An overlay must be unlocked before it can be displayed. unlock_YUV_overlay does not return anything.

display_YUV_overlay

$display_overlay = SDL::Video::display_YUV_overlay( $overlay, $dstrect );

Blit the overlay to the display surface specified when the overlay was created. The SDL::Rect structure, dstrect, specifies a rectangle on the display where the overlay is drawn. The x and y fields of dstrect specify the upper left location in display coordinates. The overlay is scaled (independently in x and y dimensions) to the size specified by dstrect, and is optimized for 2x scaling

It returns 0 on success or -1 on error.

Window Management Functions

wm_set_caption

SDL::Video::wm_set_caption( $title, $icon );

Sets the title-bar and icon name of the display window.

title is a UTF-8 encoded null-terminated string which will serve as the window title (the text at the top of the window). The function does not change the string. You may free the string after the function returns.

icon is a UTF-8 encoded null-terminated string which will serve as the iconified window title (the text which is displayed in the menu bar or desktop when the window is minimized). As with title this string may be freed after the function returns.

Example:

use SDL;
use SDL::Video;
use SDL::Surface;

SDL::init(SDL_INIT_VIDEO);

my $screen  = SDL::Video::set_video_mode(640, 480, 32, SDL_SWSURFACE);

SDL::Video::wm_set_caption( 'maximized title', 'minimized title' );

sleep(2);

wm_get_caption

SDL::Video::wm_get_caption( $title, $icon );

Retrieves the title-bar and icon name of the display window.

Example:

use SDL;
use SDL::Video;
use SDL::Surface;

SDL::init(SDL_INIT_VIDEO);

my $screen  = SDL::Video::set_video_mode(640, 480, 32, SDL_SWSURFACE);

SDL::Video::wm_set_caption( 'maximized title', 'minimized title' );

my ($title, $icon) = @{ SDL::Video::wm_get_caption() };

printf( "title is '%s' and icon is '%s'\n", $title, $icon );

wm_set_icon

SDL::Video::wm_set_icon( $icon );

Sets the icon for the display window. Win32 icons must be 32x32.

This function must be called before the first call to SDL::Video::set_video_mode. Note that this means SDL::Image cannot be used.

The shape is determined by the colorkey or alpha channel of the icon, if any. If neither of those are present, the icon is made opaque (no transparency).

Example:

SDL::Video::wm_set_icon(SDL::Video::load_BMP("icon.bmp"));

Another option, if your icon image does not have a colorkey set, is to use the SDL::Video::set_color_key to set the transparency.

Example:

my $image = SDL::Video::load_BMP("icon.bmp");

my colorkey = SDL::Video::map_RGB($image->format, 255, 0, 255); # specify the color that will be transparent

SDL::Video::set_color_key($image, SDL_SRCCOLORKEY, $colorkey);              

SDL::Video::wm_set_icon($image);

wm_grab_input

$grab_mode = SDL::Video::wm_grab_input($mode);

Grabbing means that the mouse is confined to the application window, and nearly all keyboard input is passed directly to the application, and not interpreted by a window manager, if any.

When mode is SDL_GRAB_QUERY the grab mode is not changed, but the current grab mode is returned.

mode and the return value of wm_grab_input can be one of the following:

  • SDL_GRAB_QUERY

  • SDL_GRAB_OFF

  • SDL_GRAB_ON

wm_iconify_window

$iconify_window = SDL::Video::wm_iconify_window();

If the application is running in a window managed environment SDL attempts to iconify/minimise it. If wm_iconify_window is successful, the application will receive a SDL_APPACTIVE loss event (see Application visibility events at SDL::Event).

Returns non-zero on success or 0 if iconification is not supported or was refused by the window manager.

Example:

use SDL;
use SDL::Video;
use SDL::Surface;

SDL::init(SDL_INIT_VIDEO);

my $screen  = SDL::Video::set_video_mode(640, 480, 32, SDL_SWSURFACE);

sleep(2);

SDL::Video::wm_iconify_window();

sleep(2);

wm_toggle_fullscreen

$toggle = SDL::Video::wm_toggle_fullscreen( $surface );

Toggles the application between windowed and fullscreen mode, if supported. (X11 is the only target currently supported, BeOS support is experimental).

AUTHORS

See "AUTHORS" in SDL.

SEE ALSO

Category Objects

SDL::Surface, SDL::Overlay, SDL::Color, SDL::Rect, SDL::Palette, SDL::PixelFormat, SDL::VideoInfo