VGL(3) BSD Library Functions Manual VGL(3)
VGLBitmapAllocateBits, VGLBitmapCopy, VGLBitmapCreate, VGLBitmapDestroy, VGLBitmapPutChar, VGLBitmapString, VGLBlankDisplay, VGLBox,
VGLCheckSwitch, VGLClear, VGLEllipse, VGLEnd, VGLFilledBox, VGLFilledEllipse, VGLGetXY, VGLInit, VGLLine, VGLKeyboardInit, VGLKeyboardEnd,
VGLKeyboardGetCh, VGLMouseInit, VGLMouseMode, VGLMouseSetImage, VGLMouseSetStdImage, VGLMouseStatus, VGLPanScreen, VGLSetBorder,
VGLSetPalette, VGLSetPaletteIndex, VGLSetVScreenSize, VGLSetXY, VGLTextSetFontFile -- Video Graphics Library functions
Video Graphics Library (libvgl, -lvgl)
VGLMouseStatus(int *x, int *y, char *buttons);
VGLMouseSetImage(VGLBitmap *AndMask, VGLBitmap *OrMask);
VGLGetXY(VGLBitmap *object, int x, int y);
VGLSetXY(VGLBitmap *object, int x, int y, u_long color);
VGLLine(VGLBitmap *object, int x1, int y1, int x2, int y2, u_long color);
VGLBox(VGLBitmap *object, int x1, int y1, int x2, int y2, u_long color);
VGLFilledBox(VGLBitmap *object, int x1, int y1, int x2, int y2, u_long color);
VGLEllipse(VGLBitmap *object, int xc, int yc, int a, int b, u_long color);
VGLFilledEllipse(VGLBitmap *object, int xc, int yc, int a, int b, u_long color);
VGLBitmapCreate(int type, int xsize, int ysize, byte *bits);
VGLBitmapCopy(VGLBitmap *src, int srcx, int srcy, VGLBitmap *dst, int dstx, int dsty, int width, int hight);
VGLBitmapPutChar(VGLBitmap *Object, int x, int y, byte ch, byte fgcol, byte bgcol, int fill, int dir);
VGLBitmapString(VGLBitmap *Object, int x, int y, char *str, byte fgcol, byte bgcol, int fill, int dir);
VGLClear(VGLBitmap *object, u_long color);
VGLSetPalette(byte *red, byte *green, byte *blue);
VGLSetPaletteIndex(byte color, byte red, byte green, byte blue);
VGLSetVScreenSize(VGLBitmap *object, int vxsize, int vysize);
VGLPanScreen(VGLBitmap *object, int x, int y);
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 FreeBSD, see 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 mem-
ory 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:
VGLInit() initialize the library and set up the graphic mode mode.
VGLEnd() terminate graphic mode, and restore the screenmode that was active before VGLInit() was called.
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.
VGLTextSetFontFile() instruct the char/string functions to use the font in file filename instead of the builtin font.
VGLKeyboardInit() set up the keyboard in the ``raw'' I/O mode and specify the key code to be used. code must be VGL_XLATEKEYS, VGL_CODEKEYS,
or VGL_RAWKEYS. When VGL_XLATEKEYS is specified, the keyboard translates the raw keyboard scan code into a character code. If VGL_RAWKEYS
is used, the raw keyboard scan code is read as is. VGL_CODEKEYS is the intermediate key code; each key is assigned a unique code whereas
more than one raw scan code may be generated when a key is pressed.
VGLKeyboardEnd() when you have finished using the keyboard, call this function.
VGLKeyboardGetCh() read one byte from the keyboard. As the keyboard I/O is in the ``raw'' input mode, the function will not block even if
there is no input data, and returns 0.
VGLMouseInit() initialize the mouse. The optional on-screen mouse pointer is shown if the argument is VGL_MOUSESHOW.
VGLMouseMode() either shows the mouse pointer if the argument is VGL_MOUSESHOW, or hides the mouse pointer if the argument is VGL_MOUSEHIDE.
VGLMouseStatus() returns the current mouse pointer coordinates and button state in x, y, buttons. The return value reflects if the mouse
pointer is currently shown on screen or not.
VGLMouseSetImage() with this function it is possible to change the image of the mouse pointer on screen.
VGLMouseSetStdImage() this function restores the mouse pointer to the standard arrow.
VGLGetXY() retrieves the color of the pixel located at x, y, coordinates of the object argument, and returns it as a byte value.
VGLSetXY() sets the color of the pixel located at x, y, coordinates of the object argument to color byte value.
VGLLine() draw a line from x1, y1 to x2, y2 in color color.
VGLBox() draw a box with upper left hand corner at x1, y1 and lower right hand corner at x2, y2 in color color.
VGLFilledBox() draw a filled (solid) box with upper left hand corner at x1, y1 and lower right hand corner at x2, y2 in color color.
VGLEllipse() draw an ellipse centered at xc, yc make it a pixels wide, and b pixels high in color color.
VGLFilledEllipse() draw a filled (solid) ellipse centered at xc, yc make it a pixels wide, and b pixels high in color color.
VGLBitmapCreate() create a bitmap object and initialize it with the specified values and bit data. type must be MEMBUF for the in-memory
bitmap. bits may be NULL so that bitmap data may be associated later.
There also is a macro, VGLBITMAP_INITIALIZER(type, xsize, ysize, bits) to initialize a statically declared bitmap object.
VGLBitmapDestroy() free the bitmap data and the bitmap object.
VGLBitmapAllocateBits() allocate a bit data buffer for the specified object.
VGLBitmapCopy() copy a rectangle of pixels from bitmap src upper left hand corner at srcx, srcy to bitmap dst at dstx, dsty of the size
VGLBitmapPutChar() write the character ch at position x, y in foreground color fgcol. If fill is != 0, use the color bgcol as background
otherwise the background is transparent. The character is drawn in the direction specified by the argument dir.
VGLBitmapString() write the string str at position x, y in foreground color fgcol. If fill is != 0, use the color bgcol as background other-
wise the background is transparent. The string is drawn in the direction specified by the argument dir.
VGLClear() clears the entire bitmap to color color.
VGLSetPalette() this function sets the palette used, the arguments red, green, blue should point to byte arrays of 256 positions each.
VGLSetPaletteIndex() set the palette index color to the specified RGB value.
VGLSetBorder() set the border color to color color.
VGLSetVScreenSize() change the virtual screen size of the display. Note that this function must be called when our vty is in the foreground.
And object must be VGLDisplay. Passing an in-memory bitmap to this function results in error.
The desired virtual screen width may not be achievable because of the video card hardware. In such case the video driver (and underlying
video BIOS) may choose the next largest values. Always examine object->VXsize and VYsize after calling this function, in order to see how
the virtual screen is actually set up.
In order to set up the largest possible virtual screen, you may call this function with arbitrary large values.
VGLPanScreen() change the origin of the displayed screen in the virtual screen. Note that this function must be called when our vty is in
the foreground. object must be VGLDisplay. Passing an in-memory bitmap to this function results in error.
VGLBlankDisplay() blank the display if the argument blank != 0. This can be done to shut off the screen during display updates that the user
should first see when it is done.
Program termination and signal processing
It is important to call VGLEnd() before terminating the program. Care must be taken if you install signal handlers and try to call VGLEnd()
and exit(3) to end the program. If a signal is caught while the program is inside libvgl functions, VGLEnd() may not be able to properly
restore the graphics hardware.
The recommended way to handle signals and program termination is to have a flag to indicate signal's delivery. Your signal handlers set this
flag but do not terminate the program immediately. The main part of the program checks the flag to see if it is supposed to terminate, and
calls VGLEnd() and exit(3) if the flag is set.
Note that VGLInit() installs its internal signal handlers for SIGINT, SIGTERM, SIGSEGV, and SIGBUS, and terminates the program at appropriate
time, after one of these signals is caught. If you want to have your own signal handlers for these signals, install handlers after
SIGUSR1 and SIGUSR2 are internally used by libvgl to control screen switching and the mouse pointer, and are not available to libvgl client
The vgl library appeared in FreeBSD 3.0.
Soren Schmidt <sos@FreeBSD.org>
February 25, 2012 BSD