Using Functions in Multi-Monitor and Windows NT 4.0-Compatible Modes | 13
Using Functions in Multi-Monitor and Windows NT
4.0-Compatible Modes
Multi-monitor and the Windows NT 4.0-compatible modes
treat functions differently depending on the function’s
parameters. This section describes how functions work in
these modes.
Using functions that require HDC and
screen-number parameters
For functions that require both an HDC (handle to display-
device context) and screen number, the modes differ as follows:
• In Windows NT 4.0-compatible modes (full and partial),
the
HDC
is from any screen display, and the screen number
is the Windows NT 4.0 virtual screen number.
• Multi-monitor mode is signaled by combining the high bit
in the screen-number parameter with the Windows 2000
display number. The application can create the
hdc
for
the particular display and supply it as the first parameter to
the functions. If the application wants the DLL to create
the
hdc
, it uses
NULL
as the first parameter. Otherwise,
the DLL creates an
hdc
using the display number. For an
example of each method, see “DGetDriverVersionMM” on
page 19.
• The
hdc
is always used for unattached displays.
The Windows 2000 display number is the same as that passed
to the GDI (graphical device interface) function
EnumDisplay-
Devices
(the number shown via Identify minus one).
The Windows NT 4.0 virtual screen number is the screen
number assigned by the DLL; it is independent of the
operating system. The DLL counts only DOME screens.
The GDI call uses 32-bit screen numbers, while the DOME
DLL uses 16-bit screen numbers.
Summary of Contents for Dome DX/PCI
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