.\" Copyright (c) 1997 Søren Schmidt
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.\" $FreeBSD$
.Dd October 28, 1999
.Dt VGL 3
.Os FreeBSD 3.0
.Sh NAME
.Nm VGLBitmapCopy ,
.Nm VGLBitmapPutChar ,
.Nm VGLBitmapString ,
.Nm VGLBlankDisplay ,
.Nm VGLBox ,
.Nm VGLCheckSwitch ,
.Nm VGLClear ,
.Nm VGLEllipse ,
.Nm VGLEnd ,
.Nm VGLFilledBox ,
.Nm VGLFilledEllipse ,
.Nm VGLInit ,
.Nm VGLLine ,
.Nm VGLMouseInit ,
.Nm VGLMouseMode ,
.Nm VGLMouseSetImage ,
.Nm VGLMouseSetStdImage ,
.Nm VGLMouseStatus ,
.Nm VGLSetBorder ,
.Nm VGLSetPalette ,
.Nm VGLSetPaletteIndex ,
.Nm VGLTextSetFontFile
.Nd Video Graphics Library functions (libvgl)
.Sh SYNOPSIS
.Fd #include <vgl.h>
.Ft int
.Fn VGLInit "int mode"
.Ft void 
.Fn VGLEnd "void"
.Ft void 
.Fn VGLCheckSwitch "void"
.Ft int 
.Fn VGLTextSetFontFile "char *filename"
.Ft int 
.Fn VGLMouseInit "int mode"
.Ft void 
.Fn VGLMouseMode "int mode"
.Ft int 
.Fn VGLMouseStatus "int *x" "int *y" "char *buttons"
.Ft void 
.Fn VGLMouseSetImage "VGLBitmap *AndMask" "VGLBitmap *OrMask"
.Ft void 
.Fn VGLMouseSetStdImage "void"
.Ft void 
.Fn VGLLine "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "byte color"
.Ft void 
.Fn VGLBox "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "byte color"
.Ft void 
.Fn VGLFilledBox "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "byte color"
.Ft void 
.Fn VGLEllipse "VGLBitmap *object" "int xc" "int yc" "int a" "int b" "byte color"
.Ft void 
.Fn VGLFilledEllipse "VGLBitmap *object" "int xc" "int yc" "int a" "int b" "byte color"
.Ft int 
.Fn VGLBitmapCopy "VGLBitmap *src" "int srcx" "int srcy" "VGLBitmap *dst" "int dstx" "int dsty" "int width" "int hight"
.Ft void 
.Fn VGLBitmapPutChar "VGLBitmap *Object" "int x" "int y" "byte ch" "byte fgcol" "byte bgcol" "int fill" "int dir"
.Ft void 
.Fn VGLBitmapString "VGLBitmap *Object" "int x" "int y" "char *str" "byte fgcol" "byte bgcol" "int fill" "int dir"
.Ft void 
.Fn VGLClear "VGLBitmap *object" "byte color"
.Ft void
.Fn VGLSetPalette "byte *red" "byte *green" "byte *blue"
.Ft void 
.Fn VGLSetPaletteIndex "byte color" "byte red" "byte green" "byte blue"
.Ft void 
.Fn VGLSetBorder "byte color"
.Ft void 
.Fn VGLBlankDisplay "int blank"
.Sh DESCRIPTION
.Nm Libvgl
is a library that enables the programmer access to the graphics
modes supported by the console driver (syscons). The library takes care of
programming the actual video hardware, and provides a number of simple
functions to do various graphic operations. There is also support for a
mouse via the standard mouse system in
.Fx ,
see
.Xr mouse 4 ,
including the ability to transparently have a mouse pointer superimposed on
the graphic image currently being worked on. 
The library takes care of screen switching by storing the current image in
memory before switching to another virtual console, and restoring when the
user switches back. This allows several graphic applications at once, but
on different virtual consoles.

Below is a short description of the various functions:
.Pp
.Fn VGLInit
initialize the library and set up the graphic mode
.Em mode .
.Pp
.Fn VGLEnd
terminate graphic mode, and restore the screenmode that was active before
.Fn VGLInit
was called.
.Pp
.Fn VGLCheckSwitch
if the program goes into longer periods of processing without doing
any graphics output, calling this function occasionally will allow 
the system to switch screens.
.Pp
.Fn VGLTextSetFontFile 
instruct the char/string functions to use the font in file
.Em filename
instead of the builtin font.
.Pp
.Fn VGLMouseInit 
initialize the mouse. The optional on-screen mouse pointer is shown if the
argument is 
.Em VGL_MOUSESHOW .
.Pp
.Fn VGLMouseMode
either shows the mouse pointer if the argument is
.Em VGL_MOUSESHOW ,
or hides the mouse pointer if the argument is
.Em VGL_MOUSEHIDE .
.Pp
.Fn VGLMouseStatus
returns the current mouse pointer coordinates and button state in
.Em x , y ,
buttons. The return value reflects if the mouse pointer 
is currently shown on screen or not.
.Pp
.Fn VGLMouseSetImage
with this function it is possible to change the image of the mouse pointer
on screen.
.Pp
.Fn VGLMouseSetStdImage
this function restores the mouse pointer to the standard arrow.
.Pp
.Fn VGLLine 
draw a line from
.Em x1 , y1
to
.Em x2 , y2
in color
.Em color .
.Pp
.Fn VGLBox
draw a box with upper left hand corner at
.Em x1 , y1
and lower right hand corner at
.Em x2 , y2
in color
.Em color .
.Pp
.Fn VGLFilledBox
draw a filled (solid) box with upper left hand corner at
.Em x1 , y1
and lower right hand corner at
.Em x2 , y2
in color
.Em color .
.Pp
.Fn VGLEllipse 
draw an ellipse centered at 
.Em xc , yc
make it 
.Em a
pixels wide, and 
.Em b
pixels high in color
.Em color .
.Pp
.Fn VGLFilledEllipse
draw a filled (solid) ellipse centered at 
.Em xc , yc
make it 
.Em a
pixels wide, and 
.Em b
pixels high in color
.Em color .
.Pp
.Fn VGLBitmapCopy
copy a rectangle of pixels from bitmap
.Em src
upper left hand corner at 
.Em srcx , srcy
to bitmap
.Em dst
at 
.Em dstx , dsty
of the size
.Em width , height .
.Pp
.Fn VGLBitmapPutChar
write the character
.Em ch
at position
.Em x , y
in foreground color 
.Em fgcol .
If 
.Em fill
is != 0, use the color
.Em bgcol
as background otherwise the background is transparent.
The character is drawn in the direction specified by the argument
.Em dir .
.Pp
.Fn VGLBitmapString
write the string
.Em str
at position
.Em x , y
in foreground color 
.Em fgcol .
If 
.Em fill
is != 0, use the color
.Em bgcol
as background otherwise the background is transparent.
The string is drawn in the direction specified by the argument
.Em dir .
.Pp
.Fn VGLClear
clears the entire bitmap to color
.Em color .
.Pp
.Fn VGLSetPalette
this function sets the palette used, the arguments
.Em red , green , blue
should point to byte arrays of 256 positions each.
.Pp
.Fn VGLSetPaletteIndex
set the palette index 
.Em color
to the specified RGB value.
.Pp
.Fn VGLSetBorder
set the border color to color
.Em color .
.Pp
.Fn VGLBlankDisplay
blank the display if the argment
.Em blank
!= 0. This can be done to shut off the screen during display updates that
the user should first see when it's done.
.Sh AUTHORS
.An Søren Schmidt Aq sos@FreeBSD.org
.Sh HISTORY
The 
.Nm vgl
library appeared in
.Fx 3.0 .