pods::SDL::Video(3) User Contributed Perl Documentation pods::SDL::Video(3)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
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, $key );
"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 returns 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 returns 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.
"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 returns 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 returns 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 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 returns 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
perl v5.18.1 2013-09-28 pods::SDL::Video(3)
