DeviceCapabilitiesA function (wingdi.h)

Article
02/09/2023

The DeviceCapabilities function retrieves the capabilities of a printer driver.

Syntax

int DeviceCapabilitiesA(
  [in]  LPCSTR         pDevice,
  [in]  LPCSTR         pPort,
  [in]  WORD           fwCapability,
  [out] LPSTR          pOutput,
  [in]  const DEVMODEA *pDevMode
);

Parameters

[in] pDevice

A pointer to a null-terminated string that contains the name of the printer. Note that this is the name of the printer, not of the printer driver.

[in] pPort

A pointer to a null-terminated string that contains the name of the port to which the device is connected, such as LPT1.

[in] fwCapability

The capabilities to be queried. This parameter can be one of the following values.

Value	Meaning
DC_BINNAMES	Retrieves the names of the printer's paper bins. The pOutput buffer receives an array of string buffers. Each string buffer is 24 characters long and contains the name of a paper bin. The return value indicates the number of entries in the array. The name strings are null-terminated unless the name is 24 characters long. If pOutput is NULL, the return value is the number of bin entries required.
DC_BINS	Retrieves a list of available paper bins. The pOutput buffer receives an array of WORD values that indicate the available paper sources for the printer. The return value indicates the number of entries in the array. For a list of the possible array values, see the description of the dmDefaultSource member of the DEVMODE structure. If pOutput is NULL, the return value indicates the required number of entries in the array.
DC_COLLATE	If the printer supports collating, the return value is 1; otherwise, the return value is zero. The pOutput parameter is not used.
DC_COLORDEVICE	If the printer supports color printing, the return value is 1; otherwise, the return value is zero. The pOutput parameter is not used.
DC_COPIES	Returns the number of copies the device can print.
DC_DRIVER	Returns the version number of the printer driver.
DC_DUPLEX	If the printer supports duplex printing, the return value is 1; otherwise, the return value is zero. The pOutput parameter is not used.
DC_ENUMRESOLUTIONS	Retrieves a list of the resolutions supported by the printer. The pOutput buffer receives an array of LONG values. For each supported resolution, the array contains a pair of LONG values that specify the x and y dimensions of the resolution, in dots per inch. The return value indicates the number of supported resolutions. If pOutput is NULL, the return value indicates the number of supported resolutions.
DC_EXTRA	Returns the number of bytes required for the device-specific portion of the DEVMODE structure for the printer driver.
DC_FIELDS	Returns the dmFields member of the printer driver's DEVMODE structure. The dmFields member indicates which members in the device-independent portion of the structure are supported by the printer driver.
DC_FILEDEPENDENCIES	Retrieves the names of any additional files that need to be loaded when a driver is installed. The pOutput buffer receives an array of string buffers. Each string buffer is 64 characters long and contains the name of a file. The return value indicates the number of entries in the array. The name strings are null-terminated unless the name is 64 characters long. If pOutput is NULL, the return value is the number of files.
DC_MAXEXTENT	Returns the maximum paper size that the dmPaperLength and dmPaperWidth members of the printer driver's DEVMODE structure can specify. The LOWORD of the return value contains the maximum dmPaperWidth value, and the HIWORD contains the maximum dmPaperLength value.
DC_MEDIAREADY	Retrieves the names of the paper forms that are currently available for use. The pOutput buffer receives an array of string buffers. Each string buffer is 64 characters long and contains the name of a paper form. The return value indicates the number of entries in the array. The name strings are null-terminated unless the name is 64 characters long. If pOutput is NULL, the return value is the number of paper forms.
DC_MEDIATYPENAMES	Retrieves the names of the supported media types. The pOutput buffer receives an array of string buffers. Each string buffer is 64 characters long and contains the name of a supported media type. The return value indicates the number of entries in the array. The strings are null-terminated unless the name is 64 characters long. If pOutput is NULL, the return value is the number of media type names required.
DC_MEDIATYPES	Retrieves a list of supported media types. The pOutput buffer receives an array of DWORD values that indicate the supported media types. The return value indicates the number of entries in the array. For a list of possible array values, see the description of the dmMediaType member of the DEVMODE structure. If pOutput is NULL, the return value indicates the required number of entries in the array.
DC_MINEXTENT	Returns the minimum paper size that the dmPaperLength and dmPaperWidth members of the printer driver's DEVMODE structure can specify. The LOWORD of the return value contains the minimum dmPaperWidth value, and the HIWORD contains the minimum dmPaperLength value.
DC_ORIENTATION	Returns the relationship between portrait and landscape orientations for a device, in terms of the number of degrees that portrait orientation is rotated counterclockwise to produce landscape orientation. The return value can be one of the following: 0 No landscape orientation. 90 Portrait is rotated 90 degrees to produce landscape. 270 Portrait is rotated 270 degrees to produce landscape.
DC_NUP	Retrieves an array of integers that indicate that printer's ability to print multiple document pages per printed page. The pOutput buffer receives an array of DWORD values. Each value represents a supported number of document pages per printed page. The return value indicates the number of entries in the array. If pOutput is NULL, the return value indicates the required number of entries in the array.
DC_PAPERNAMES	Retrieves a list of supported paper names (for example, Letter or Legal). The pOutput buffer receives an array of string buffers. Each string buffer is 64 characters long and contains the name of a paper form. The return value indicates the number of entries in the array. The name strings are null-terminated unless the name is 64 characters long. If pOutput is NULL, the return value is the number of paper forms.
DC_PAPERS	Retrieves a list of supported paper sizes. The pOutput buffer receives an array of WORD values that indicate the available paper sizes for the printer. The return value indicates the number of entries in the array. For a list of the possible array values, see the description of the dmPaperSize member of the DEVMODE structure. If pOutput is NULL, the return value indicates the required number of entries in the array.
DC_PAPERSIZE	Retrieves the dimensions, in tenths of a millimeter, of each supported paper size. The pOutput buffer receives an array of POINT structures. Each structure contains the width (x-dimension) and length (y-dimension) of a paper size as if the paper were in the DMORIENT_PORTRAIT orientation. The return value indicates the number of entries in the array.
DC_PERSONALITY	Retrieves a list of printer description languages supported by the printer. The pOutput buffer receives an array of string buffers. Each buffer is 32 characters long and contains the name of a printer description language. The return value indicates the number of entries in the array. The name strings are null-terminated unless the name is 32 characters long. If pOutput is NULL, the return value indicates the required number of array entries.
DC_PRINTERMEM	The return value is the amount of available printer memory, in kilobytes. The pOutput parameter is not used.
DC_PRINTRATE	The return value indicates the printer's print rate. The value returned for DC_PRINTRATEUNIT indicates the units of the DC_PRINTRATE value. The pOutput parameter is not used.
DC_PRINTRATEPPM	The return value indicates the printer's print rate, in pages per minute. The pOutput parameter is not used.
DC_PRINTRATEUNIT	The return value is one of the following values that indicate the print rate units for the value returned for the DC_PRINTRATE flag. The pOutput parameter is not used. PRINTRATEUNIT_CPS Characters per second. PRINTRATEUNIT_IPM Inches per minute. PRINTRATEUNIT_LPM Lines per minute. PRINTRATEUNIT_PPM Pages per minute.
DC_SIZE	Returns the dmSize member of the printer driver's DEVMODE structure.
DC_STAPLE	If the printer supports stapling, the return value is a nonzero value; otherwise, the return value is zero. The pOutput parameter is not used.
DC_TRUETYPE	Retrieves the abilities of the driver to use TrueType fonts. For DC_TRUETYPE, the pOutput parameter should be NULL. The return value can be one or more of the following: DCTT_BITMAP Device can print TrueType fonts as graphics. DCTT_DOWNLOAD Device can download TrueType fonts. DCTT_SUBDEV Device can substitute device fonts for TrueType fonts.
DC_VERSION	Returns the specification version to which the printer driver conforms.

[out] pOutput

A pointer to an array. The format of the array depends on the setting of the fwCapability parameter. See each capability above to find out what is returned if pOutput is NULL.

[in] pDevMode

A pointer to a DEVMODE structure. If this parameter is NULL, DeviceCapabilities retrieves the current default initialization values for the specified printer driver. Otherwise, the function retrieves the values contained in the structure to which pDevMode points.

Return value

If the function succeeds, the return value depends on the setting of the fwCapability parameter. A return value of zero generally indicates that, while the function completed successfully, there was some type of failure, such as a capability that is not supported. For more details, see the descriptions for the fwCapability values.

If the function returns -1, this may mean either that the capability is not supported or there was a general function failure.

Remarks

Note This is a blocking or synchronous function and might not return immediately. How quickly this function returns depends on run-time factors such as network status, print server configuration, and printer driver implementation—factors that are difficult to predict when writing an application. Calling this function from a thread that manages interaction with the user interface could make the application appear to be unresponsive.

The DEVMODE structure pointed to by the pDevMode parameter may be obtained by calling the DocumentProperties function.

If a printer driver supports custom device capabilities, the driver must call the SetPrinterData function for each custom capability. The SetPrinterData function adds the appropriate printer data to the print system, which enables 32-bit applications to access the custom capabilities on 64-bit Windows installations.

For each custom capability, you must first add printer data that describes the type of the capability. To do this, when you call SetPrinterData, set the pValueName string to CustomDeviceCapabilityType_Xxx, where "Xxx" is the hexadecimal representation of the capability. For example, you might have "CustomDeviceCapabilityType_1234". The registry data that you set must be of the REG_DWORD type, and you must set its value to one of the following:

0, if the custom capability is a DWORD
1, if the custom capability is a buffer of bytes
2, if the custom capability is an array of items

If the custom capability is an array of items, you must call SetPinterData a second time to provide information about the size of an item in the array. To do this, when you call SetPinterData, the pValueName string that you provide must be "CustomDeviceCapabilitySize_Xxx" where Xxx is the hexadecimal representation of the capability. For example, you might have "CustomDeviceCapabilitySize_1234". The registry data that you set must be of the REG_DWORD type, and you must set its value to the size in bytes of an item in the array.

Note

The wingdi.h header defines DeviceCapabilities as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

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	wingdi.h (include Windows.h)
Library	WinSpool.lib
DLL	WinSpool.drv