GreUnlockDevice: Difference between revisions

Latest revision as of 23:21, 17 January 2020

GreUnlockDevice allows all pending screen input or output operations blocked by GreLockDevice to continue.

This function must be supported by all presentation drivers. For hardcopy devices, the hardcopy driver need do nothing except return TRUE (Successful). GreUnlockDevice is used to enable another process to access a resource (device context) that had been previously locked to prevent simultaneous update.

Simulation support: None. This function is mandatory for all drivers.

Syntax

GreUnlockDevice(hdc, pInstance, lFunction)

Parameters

hdc (HDC) - input: Device context handle.
pInstance (PVOID) - input: Pointer to instance data.
lFunction (ULONG) - input: High-order WORD=flags; low-order WORD=NGreUnlockDevice.

Return Code

rc (BOOL) - returns

Return codes.

On completion, the handling routine must return a BOOLEAN value to indicate success or an error.

TRUE Successful
FALSE Error

Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. An error code for conditions that the handling routine is expected to check is:

PMERR_DEV_FUNC_NOT_INSTALLED

Refer to the "Error Explanations" section in the Presentation Manager Programming Reference for further explanation.

Remarks

This function is used to synchronize the use and update of the visible region.

@@ Line 1: / Line 1: @@
 GreUnlockDevice allows all pending screen input or output operations blocked by GreLockDevice to continue.
 This function must be supported by all presentation drivers. For hardcopy devices, the hardcopy driver need do nothing except return TRUE (Successful). GreUnlockDevice is used to enable another process to access a resource (device context) that had been previously locked to prevent simultaneous update.
 ;Simulation support: None. This function is mandatory for all drivers.
 ==Syntax==
-  GreUnlockDevice(hdc, pInstance, lFunction);
+ GreUnlockDevice(hdc, pInstance, lFunction)
 ==Parameters==
-;hdc (HDC) - input
+;hdc (HDC) - input:Device context handle.
-:Device context handle.
+;pInstance (PVOID) - input:Pointer to instance data.
+;lFunction (ULONG) - input:High-order WORD=flags; low-order WORD=NGreUnlockDevice.
-;pInstance (PVOID) - input
-:Pointer to instance data.
-;lFunction (ULONG) - input
-:High-order WORD=flags; low-order WORD=NGreUnlockDevice.
 ==Return Code==
-;rc (BOOL) - returns
+;rc (BOOL) - returns:Return codes.
-:Return codes.
+:On completion, the handling routine must return a BOOLEAN value to indicate success or an error.
+:*TRUE Successful
-:On completion, the handling routine must return a BOOLEAN value to indicate success or an error.
+:*FALSE Error
+:Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. An error code for conditions that the handling routine is expected to check is:
-:*TRUE Successful
+:*PMERR_DEV_FUNC_NOT_INSTALLED
-:*FALSE Error
+:Refer to the "Error Explanations" section in the ''Presentation Manager Programming Reference'' for further explanation.
-:Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. An error code for conditions that the handling routine is expected to check is:
-:*PMERR_DEV_FUNC_NOT_INSTALLED
-:Refer to the "Error Explanations" section in the Presentation Manager Programming Reference for further explanation.
 ==Remarks==
 This function is used to synchronize the use and update of the visible region.
-==Sample Code==
-<PRE>
-#define INCL_GRE_DEVMISC3
-#include <os2.h>
-HDC      hdc;        /*  Device context handle. */
-PVOID    pInstance;  /*  Pointer to instance data. */
-ULONG    lFunction;  /*  High-order WORD=flags; low-order WORD=NGreUnlockDevice. */
-BOOL     rc;         /*  Return codes. */
-rc = GreUnlockDevice(hdc, pInstance, lFunction);
-</PRE>
 [[Category:Gre]]