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