WinQueryWindowDC: Difference between revisions
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This function returns the device context for a given window. | |||
==Syntax== | ==Syntax== | ||
WinQueryWindowDC(hwnd) | WinQueryWindowDC(hwnd) | ||
==Parameters== | ==Parameters== | ||
;hwnd (HWND) - input | ;hwnd (HWND) - input:Window handle. | ||
:Window handle. | |||
==Returns== | ==Returns== | ||
;hdc (HDC) - returns | ;hdc (HDC) - returns:Device-context handle. | ||
:Device-context handle. | ::NULLHANDLE - Either WinOpenWindowDC has not been called for this window, or an error has occurred. | ||
: | ::Other - Device context handle. | ||
: | |||
==Errors== | ==Errors== | ||
Possible returns from WinGetLastError | Possible returns from WinGetLastError | ||
;PMERR_INVALID_HWND (0x1001) | ;PMERR_INVALID_HWND (0x1001):An invalid window handle was specified. | ||
:An invalid window handle was specified. | |||
==Remarks== | ==Remarks== | ||
A handle is returned only if a device context has been opened for the window with WinOpenWindowDC. | A handle is returned only if a device context has been opened for the window with WinOpenWindowDC. | ||
==Example Code== | ==Example Code== | ||
This example shows how to check if WinOpenWindowDC has been called for this window. | This example shows how to check if WinOpenWindowDC has been called for this window. | ||
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/* ... */ | /* ... */ | ||
} | } | ||
</pre> | </pre> | ||
Revision as of 03:09, 4 October 2023
This function returns the device context for a given window.
Syntax
WinQueryWindowDC(hwnd)
Parameters
- hwnd (HWND) - input
- Window handle.
Returns
- hdc (HDC) - returns
- Device-context handle.
- NULLHANDLE - Either WinOpenWindowDC has not been called for this window, or an error has occurred.
- Other - Device context handle.
Errors
Possible returns from WinGetLastError
- PMERR_INVALID_HWND (0x1001)
- An invalid window handle was specified.
Remarks
A handle is returned only if a device context has been opened for the window with WinOpenWindowDC.
Example Code
This example shows how to check if WinOpenWindowDC has been called for this window.
#define INCL_WINWINDOWMGR
#include <OS2.H>
HWND hwndClient; /* window handle. */
if(WinQueryWindowDC(hwndClient))
{
/* ... */
}
Definition
#define INCL_WINWINDOWMGR /* Or use INCL_WIN, INCL_PM, */ #include <os2.h> HWND hwnd; /* Window handle. */ HDC hdc; /* Device-context handle. */ hdc = WinQueryWindowDC(hwnd);
Related Functions
- WinEnableWindow
- WinIsThreadActive
- WinIsWindow
- WinIsWindowEnabled
- WinQueryDesktopWindow
- WinQueryObjectWindow
- WinQueryWindowProcess
- WinQueryWindowRect
- WinWindowFromDC
- WinWindowFromID
- WinWindowFromPoint