Screen (Graphics)

-lang fb|fblite dialects:

Screen mode [, [ depth ] [, [ num_pages ] [, [ flags ] [, [ refresh_rate ]]]]]
Screen , [ active_page ] [, [ visible_page ]]

-lang qb dialect:

Screen [ mode ] [, [ colormode ] [, [ active_page ] [, [ visible_page ]]]]

mode
depth
num_pages
flags
refresh_rate
active_page
visible_page
colormode

Screen tells the compiler to link the GfxLib and initializes a QB-only, QB-on-GUI or OpenGL graphics mode, depending on the flags setting.

In QB-only modes a dumb window or fullscreen resolution is set, one or more buffers in standard memory are created, console commands are redirected to their graphic versions, a default palette is set and an automatic screen refresh thread is started. QB-like graphics and console statements can be used.

In QB-on-GUI modes one or more buffers in standard memory are created, console commands are redirected to their graphic versions and a default palette is set. QB-like graphics and console statements can be used. It is up to the user to create a window and to refresh it with the contents of the graphics buffers.

In OpenGL modes a dumb window or fullscreen resolution is set, one or more buffers in standard memory are created, and the OS's OpenGL library is initialized. From here only OpenGL commands can be used; QB-like and console commands are forbidden. This allows to initialize OpenGL in a portable way; you can then also use ScreenControl to properly customize the GL pixel format to be used before Screen is called or to retrieve the list of supported OpenGL extensions after a mode has been set, and ScreenGLProc to obtain extension function pointers.

Any buffer that is created in standard memory uses one of three supported internal pixel formats, depending on the desired color depth; see Internal pixel formats for details.

If Screen fails to set the required mode, an "Illegal function call" error is issued and the screen pointer is set to 0. Thus Screen failures can be detected using standard On Error processing or retrieving the screen pointer with ScreenPtr.

Before setting a fullscreen mode the program should check if that mode is available in the graphics card using ScreenList.

mode details
Available modes list:
QB compatibility modes:

New FreeBASIC modes:


depth details
For modes 14 and up, the depth parameter changes the color depth to the specified new one; if depth is not specified, these modes run in 8bpp. For modes 13 and below, depth has no effect.

num_pages details
You can request any number of pages for any video mode; if you omit the parameter, only the visible page (number 0) will be available. A page is either the visible screen or an offscreen buffer, you can show a page while working on another one; see the ScreenSet statement for details. All pages are created in standard memory, the video card memory is never used for video buffering.

flags details:
(documented at the page ScreenRes)

Other details
While in windowed mode, clicking on the window close button will add a keypress of (Chr(255) & "k") to the Inkey buffer. Clicking on the Maximize window button will switch to fullscreen mode if possible. A successful Screen call sets currently visible and working pages both to page number 0, resets the palette to the specified mode one (see Default palettes), resets the clipping region to the size of the screen, disables custom coordinates mappings, moves the graphics cursor to the center of the screen, moves the text cursor to the top-left corner of the screen and sets foreground and background colors to bright white and black respectively.

' Sets screen mode 13 (320*200, 8bpp)
Screen 13
Print "Screen mode 13 set"

Sleep

#include "fbgfx.bi"
#if __FB_LANG__ = "fb"
Using FB '' Screen mode flags are in the FB namespace in lang FB
#endif

' Sets screen mode 18 (640*480) with 32bpp color depth and 4 pages, in windowed mode; switching disabled
Screen 18, 32, 4, (GFX_WINDOWED Or GFX_NO_SWITCH)

' Check to make sure Screen was opened successfully
If ScreenPtr = 0 Then
    Print "Error setting video mode!"
    End
End If

Print "Successfully set video mode"
Sleep

• In DOS, Windowing and OpenGL related switches are not available, and other issues, see GfxLib overview
  
  

• In the -lang fb and -lang fblite dialects, the usage is:
  

or:

• In the -lang qb dialect, the usage is:
  

• None in the -lang qb dialect.
  
• In QB the syntax was Screen mode,colormode,active_page,visible_page. Of those parameters FreeBASIC supports only mode and redefines the rest. The use of Screen , , apage,vpage to swap screen pages is only available in the -lang qb dialect.
  
• ScreenSet should be used in the -lang fb and -lang fblite dialects.
  
  

• Screen (Console)
  
• ScreenRes More flexible alternative to Screen
  
• ScreenList Check display modes available for FB GfxLib to use
  
• ScreenControl Select driver and more
  
• ScreenLock
  
• ScreenUnlock
  
• ScreenPtr Semi-low level access
  
• ScreenSet
  
• ScreenCopy
  
• ScreenInfo
  
• ScreenGLProc
  
• Internal pixel formats