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Seamless Windows Palette Management Disclosure Number: IPCOM000116156D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 6 page(s) / 266K

Publishing Venue


Related People

King, PR: AUTHOR [+1]


Disclosed is a method allowing the manipulation of the graphics hardware palette by a seamless Windows* application.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 23% of the total text.

Seamless Windows Palette Management

      Disclosed is a method allowing the manipulation of the graphics
hardware palette by a seamless Windows* application.

      The Figure is a block diagram showing system operation
according to this method.  To enable Seamless operation, the OS/2**
Presentation Manager** (PM) display driver 1 calls a special virtual
device driver (VWIN) 2, using the DOSRequestVDD call.  The PM driver
passes initialization data to enable the access of Windows Seamless
driver 3 to necessary PM data and shared data/code.  After
initialization, the PM driver 1 again calls VWIN to define the
current video mode and cursor size.   The PM display driver 1
initializes a FSRamSemaphore for synchronizing access to the video
hardware.  Both the PM and Windows Seamless drivers must employ the
FSRamSemaphore to coordinate video access.  The PM driver may force
the release of this semaphore, when necessary.  The PM Shield
component 4, diagrammed above, communicates with the PM driver 1,
sending notifications whenever a Seamless Video Display Metafile

(VDM) is created or destroyed, so that the PM driver 1 can modify its
processing logic to be compatible with the Seamless environment.  At
PM death and resurrection (that is, on a switch to a DOS, Windows or
OS/2 full-screen session), PM driver 1 calls VWIN to broadcast
suspend/resume drawing messages to the Seamless VDMs, with messages
transmitted to the Windows drivers of the VDM through INT (Interrupt)

      The Windows Seamless driver 3 is usually derived from the
standard Windows driver by conditional compile, starting in the
disabled state to establish all necessary addressability and data.
The Windows Seamless driver hooks Int 2Fh to receive all notification
of foreground/background switching.  The Win Shield component 5
enables the Windows Seamless driver to use INT 2Fh when synchronized
with the PM Desktop.  When the first Enable() call is received, the
Windows display driver 3 calls VWIN with a pointer to a Windows
driver initialization structure.  VWIN 2 completes this structure for
the Windows driver 3.

      PM Shield 4 maintains Workplace Shell** windowing state
information, including information related to the Seamless VDMs (or
"BlackHoles").  Upon the creation of a Seamless VDM, PM Shield 4
notifies the virtual video driver, such as VVGA or VSVGA), to allow
direct hardware access.  While normally the virtual video drivers
control and intercept attempts to access the hardware, in a Seamless
VDM virtual video is modified to allow this hardware I/O.  As
windowing related events, such as create, destroy, move and resize,
occur in the Seamless VDMs, the PM shield 4 duplicates these events
within the Workplace Shell, tracking the "BlackHoles".  PM Shield 4
also registers with PMWIN to be posted whenever events altering the
state of the Desdtop occur.  These events are forwarded to VWIN,
which broadcasts them to the Win Shield 5 in each VD...