GpiQueryDevice: Difference between revisions
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Created page with "This function returns the handle of the currently associated device context. ==Syntax== hdc = GpiQueryDevice(HPS ''hps'') ==Parameters== ; ''hps'' (HPS) - input : Presenta..." |
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This function returns the handle of the currently associated device context. | This function returns the handle of the currently associated device context. | ||
==Syntax== | ==Syntax== | ||
hdc = GpiQueryDevice(HPS ''hps'') | hdc = GpiQueryDevice(HPS ''hps'') | ||
==Parameters== | ==Parameters== | ||
; ''hps'' (HPS) - input | ;''hps'' (HPS) - input: Presentation-space handle. | ||
: Presentation-space handle. | |||
==Returns== | ==Returns== | ||
; ''hdc'' (HDC) - returns | ; ''hdc'' (HDC) - returns:Device-context handle. | ||
:Device-context handle. | ::HDC_ERROR - Error | ||
: | ::NULLHANDLE - No device context is currently associated | ||
:: | ::Otherwise - Device context handle. | ||
: | |||
==Errors== | ==Errors== | ||
Possible returns from WinGetLastError | Possible returns from WinGetLastError | ||
:PMERR_INV_HPS (0x207F) :An invalid presentation-space handle was specified. | |||
:An invalid presentation-space handle was specified. | :PMERR_INV_HDC (0x207C) :An invalid device-context handle or (micro presentation space) presentation-space handle was specified. | ||
:An invalid device-context handle or (micro presentation space) presentation-space handle was specified. | |||
==Example Code== | ==Example Code== | ||
This example uses the GpiQueryDevice function to retrieve a device-context handle for the presentation space of the desktop window. The handle is used in the [[DevQueryCaps]] function to determine the width and height of the Presentation Manager screen. | |||
This example uses the GpiQueryDevice function to retrieve a device-context handle for the presentation space of the desktop window. The handle is used in the DevQueryCaps function to determine the width and height of the Presentation Manager screen. | |||
<pre> | <pre> | ||
#define INCL_GPICONTROL /* GPI control Functions */ | #define INCL_GPICONTROL /* GPI control Functions */ | ||
Line 51: | Line 35: | ||
DevQueryCaps(hdc, CAPS_HEIGHT, 1L, &lHeight); | DevQueryCaps(hdc, CAPS_HEIGHT, 1L, &lHeight); | ||
</pre> | </pre> | ||
[[Category:Gpi]] | [[Category:Gpi]] |
Latest revision as of 04:09, 26 November 2023
This function returns the handle of the currently associated device context.
Syntax
hdc = GpiQueryDevice(HPS hps)
Parameters
- hps (HPS) - input
- Presentation-space handle.
Returns
- hdc (HDC) - returns
- Device-context handle.
- HDC_ERROR - Error
- NULLHANDLE - No device context is currently associated
- Otherwise - Device context handle.
Errors
Possible returns from WinGetLastError
- PMERR_INV_HPS (0x207F) :An invalid presentation-space handle was specified.
- PMERR_INV_HDC (0x207C) :An invalid device-context handle or (micro presentation space) presentation-space handle was specified.
Example Code
This example uses the GpiQueryDevice function to retrieve a device-context handle for the presentation space of the desktop window. The handle is used in the DevQueryCaps function to determine the width and height of the Presentation Manager screen.
#define INCL_GPICONTROL /* GPI control Functions */ #define INCL_WINWINDOWMGR /* Window Manager Functions */ #define INCL_DEV /* Device Function definitions */ #include <os2.h> HPS hps; /* presentation space handle */ HDC hdc; /* device context handle */ LONG lWidth, lHeight; hps = WinGetScreenPS(HWND_DESKTOP); hdc = GpiQueryDevice(hps); DevQueryCaps(hdc, CAPS_WIDTH, 1L, &lWidth); DevQueryCaps(hdc, CAPS_HEIGHT, 1L, &lHeight);