
4. VGA window display library
Outline of VGA window display
"VGA window" is an overlapping window provided by VGA display device. This
VGA window has the following features.
* Overlapping on any arbitrary screen such as CNC, PMC and C-EXE screen.
* Both graphics and character overlapping.
* Simultaneous updating of the base screen and VGA window screen.
* Two independent windows.
* Arbitrary size window on arbitrary position. (with a little limitation)
* Coexistence with character windows (which displayed by "win_xxx()"
functions). Character window is a part of the base screen for VGA
window.
+---------------------------------------------------+
│ Full screen │
│ │
│ +--------------------------+ │
│ │VGA window #0 │ │
│ │ │ │
│ │ +--------------------+ │
│ │Also VGA win- │VGA window #1 │ │
│ │dow is over- │ │ │
│ │lapped on the │ │ │
│ │other window. │Both character and │ │
│ │ │graphics are over- │ │
│ +--------------│lapped. │ │
│ │ │ │
│ │ │ │
│ +--------------------+ │
│ │
│ Displaying on the base screen is │
│ not affected by any VGA window. │
+---------------------------------------------------+
Each two VGA windows have their own screen buffers of character and graphics
display It is possible to output to the base screen during displaying
VGA windows. Output operation to hidden area of the base screen displays
nothing to the real screen but writes to the screen buffer memory. When the
VGA window closed, all contents of the base screen, including on the hidden
area, are output automatically.