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An application-defined callback function used with the GrayString function. It is used to draw a string. The GRAYSTRINGPROC type defines a pointer to this callback function. GrayStringProc (or OutputProc) is a placeholder for the application-defined or library-defined function name.
Syntax
GRAYSTRINGPROC Graystringproc;
BOOL Graystringproc(
HDC unnamedParam1,
LPARAM unnamedParam2,
int unnamedParam3
)
{...}
Parameters
unnamedParam1
Type: HDC
A handle to a device context with a bitmap of at least the width and height specified by the nWidth and nHeight parameters passed to GrayString. This parameter is typically named hDc.
unnamedParam2
Type: LPARAM
A pointer to the string to be drawn. This parameter is typically named lpData.
unnamedParam3
Type: int
The length, in characters, of the string. This parameter is typically named nCount.
Return value
Type: BOOL
If it succeeds, the callback function should return TRUE.
If the function fails, the return value is FALSE.
Remarks
Note
The parameters are defined in the header with no names: typedef BOOL (CALLBACK* GRAYSTRINGPROC)(HDC, LPARAM, int);. Therefore, the syntax block lists them as unnamedParam1 - unnamedParam3. You can name these parameters anything in your app. However, they are usually named as shown in the parameter descriptions.
The callback function must draw an image relative to the coordinates (0,0).
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | winuser.h (include Windows.h) |