GetDeviceCaps function (Windows)

GetDeviceCaps function

GetDeviceCaps function

Applies to: desktop apps only

The GetDeviceCaps function retrieves device-specific information for the specified device.

Syntax

int GetDeviceCaps(
  __in  HDC hdc,
  __in  int nIndex
);

Parameters

hdc [in]

A handle to the DC.

nIndex [in]

The item to be returned. This parameter can be one of the following values.

Index	Meaning
DRIVERVERSION	The device driver version.
TECHNOLOGY	Device technology. It can be any one of the following values. DT_PLOTTERVector plotter DT_RASDISPLAYRaster display DT_RASPRINTERRaster printer DT_RASCAMERARaster camera DT_CHARSTREAMCharacter stream DT_METAFILEMetafile DT_DISPFILEDisplay file If the hdc parameter is a handle to the DC of an enhanced metafile, the device technology is that of the referenced device as specified to the CreateEnhMetaFile function. To determine whether it is an enhanced metafile DC, use the GetObjectType function.
HORZSIZE	Width, in millimeters, of the physical screen.
VERTSIZE	Height, in millimeters, of the physical screen.
HORZRES	Width, in pixels, of the screen; or for printers, the width, in pixels, of the printable area of the page.
VERTRES	Height, in raster lines, of the screen; or for printers, the height, in pixels, of the printable area of the page.
LOGPIXELSX	Number of pixels per logical inch along the screen width. In a system with multiple display monitors, this value is the same for all monitors.
LOGPIXELSY	Number of pixels per logical inch along the screen height. In a system with multiple display monitors, this value is the same for all monitors.
BITSPIXEL	Number of adjacent color bits for each pixel.
PLANES	Number of color planes.
NUMBRUSHES	Number of device-specific brushes.
NUMPENS	Number of device-specific pens.
NUMFONTS	Number of device-specific fonts.
NUMCOLORS	Number of entries in the device's color table, if the device has a color depth of no more than 8 bits per pixel. For devices with greater color depths, 1 is returned.
ASPECTX	Relative width of a device pixel used for line drawing.
ASPECTY	Relative height of a device pixel used for line drawing.
ASPECTXY	Diagonal width of the device pixel used for line drawing.
PDEVICESIZE	Reserved.
CLIPCAPS	Flag that indicates the clipping capabilities of the device. If the device can clip to a rectangle, it is 1. Otherwise, it is 0.
SIZEPALETTE	Number of entries in the system palette. This index is valid only if the device driver sets the RC_PALETTE bit in the RASTERCAPS index and is available only if the driver is compatible with 16-bit Windows.
NUMRESERVED	Number of reserved entries in the system palette. This index is valid only if the device driver sets the RC_PALETTE bit in the RASTERCAPS index and is available only if the driver is compatible with 16-bit Windows.
COLORRES	Actual color resolution of the device, in bits per pixel. This index is valid only if the device driver sets the RC_PALETTE bit in the RASTERCAPS index and is available only if the driver is compatible with 16-bit Windows.
PHYSICALWIDTH	For printing devices: the width of the physical page, in device units. For example, a printer set to print at 600 dpi on 8.5-x11-inch paper has a physical width value of 5100 device units. Note that the physical page is almost always greater than the printable area of the page, and never smaller.
PHYSICALHEIGHT	For printing devices: the height of the physical page, in device units. For example, a printer set to print at 600 dpi on 8.5-by-11-inch paper has a physical height value of 6600 device units. Note that the physical page is almost always greater than the printable area of the page, and never smaller.
PHYSICALOFFSETX	For printing devices: the distance from the left edge of the physical page to the left edge of the printable area, in device units. For example, a printer set to print at 600 dpi on 8.5-by-11-inch paper, that cannot print on the leftmost 0.25-inch of paper, has a horizontal physical offset of 150 device units.
PHYSICALOFFSETY	For printing devices: the distance from the top edge of the physical page to the top edge of the printable area, in device units. For example, a printer set to print at 600 dpi on 8.5-by-11-inch paper, that cannot print on the topmost 0.5-inch of paper, has a vertical physical offset of 300 device units.
VREFRESH	For display devices: the current vertical refresh rate of the device, in cycles per second (Hz). A vertical refresh rate value of 0 or 1 represents the display hardware's default refresh rate. This default rate is typically set by switches on a display card or computer motherboard, or by a configuration program that does not use display functions such as ChangeDisplaySettings.
SCALINGFACTORX	Scaling factor for the x-axis of the printer.
SCALINGFACTORY	Scaling factor for the y-axis of the printer.
BLTALIGNMENT	Preferred horizontal drawing alignment, expressed as a multiple of pixels. For best drawing performance, windows should be horizontally aligned to a multiple of this value. A value of zero indicates that the device is accelerated, and any alignment may be used.
SHADEBLENDCAPS	Value that indicates the shading and blending capabilities of the device. See Remarks for further comments. SB_CONST_ALPHAHandles the SourceConstantAlpha member of the BLENDFUNCTION structure, which is referenced by the blendFunction parameter of the AlphaBlend function. SB_GRAD_RECTCapable of doing GradientFill rectangles. SB_GRAD_TRICapable of doing GradientFill triangles. SB_NONEDevice does not support any of these capabilities. SB_PIXEL_ALPHACapable of handling per-pixel alpha in AlphaBlend. SB_PREMULT_ALPHACapable of handling premultiplied alpha in AlphaBlend.
RASTERCAPS	Value that indicates the raster capabilities of the device, as shown in the following table. RC_BANDINGRequires banding support. RC_BITBLTCapable of transferring bitmaps. RC_BITMAP64Capable of supporting bitmaps larger than 64 KB. RC_DI_BITMAPCapable of supporting the SetDIBits and GetDIBits functions. RC_DIBTODEVCapable of supporting the SetDIBitsToDevice function. RC_FLOODFILLCapable of performing flood fills. RC_PALETTESpecifies a palette-based device. RC_SCALINGCapable of scaling. RC_STRETCHBLTCapable of performing the StretchBlt function. RC_STRETCHDIBCapable of performing the StretchDIBits function.
CURVECAPS	Value that indicates the curve capabilities of the device, as shown in the following table. CC_NONEDevice does not support curves. CC_CHORDDevice can draw chord arcs. CC_CIRCLESDevice can draw circles. CC_ELLIPSESDevice can draw ellipses. CC_INTERIORSDevice can draw interiors. CC_PIEDevice can draw pie wedges. CC_ROUNDRECTDevice can draw rounded rectangles. CC_STYLEDDevice can draw styled borders. CC_WIDEDevice can draw wide borders. CC_WIDESTYLEDDevice can draw borders that are wide and styled.
LINECAPS	Value that indicates the line capabilities of the device, as shown in the following table: LC_NONEDevice does not support lines. LC_INTERIORSDevice can draw interiors. LC_MARKERDevice can draw a marker. LC_POLYLINEDevice can draw a polyline. LC_POLYMARKERDevice can draw multiple markers. LC_STYLEDDevice can draw styled lines. LC_WIDEDevice can draw wide lines. LC_WIDESTYLEDDevice can draw lines that are wide and styled.
POLYGONALCAPS	Value that indicates the polygon capabilities of the device, as shown in the following table. PC_NONEDevice does not support polygons. PC_INTERIORSDevice can draw interiors. PC_POLYGONDevice can draw alternate-fill polygons. PC_RECTANGLEDevice can draw rectangles. PC_SCANLINEDevice can draw a single scanline. PC_STYLEDDevice can draw styled borders. PC_WIDEDevice can draw wide borders. PC_WIDESTYLEDDevice can draw borders that are wide and styled. PC_WINDPOLYGONDevice can draw winding-fill polygons.
TEXTCAPS	Value that indicates the text capabilities of the device, as shown in the following table. TC_OP_CHARACTERDevice is capable of character output precision. TC_OP_STROKEDevice is capable of stroke output precision. TC_CP_STROKEDevice is capable of stroke clip precision. TC_CR_90Device is capable of 90-degree character rotation. TC_CR_ANYDevice is capable of any character rotation. TC_SF_X_YINDEPDevice can scale independently in the x- and y-directions. TC_SA_DOUBLEDevice is capable of doubled character for scaling. TC_SA_INTEGERDevice uses integer multiples only for character scaling. TC_SA_CONTINDevice uses any multiples for exact character scaling. TC_EA_DOUBLEDevice can draw double-weight characters. TC_IA_ABLEDevice can italicize. TC_UA_ABLEDevice can underline. TC_SO_ABLEDevice can draw strikeouts. TC_RA_ABLEDevice can draw raster fonts. TC_VA_ABLEDevice can draw vector fonts. TC_RESERVEDReserved; must be zero. TC_SCROLLBLTDevice cannot scroll using a bit-block transfer. Note that this meaning may be the opposite of what you expect.
COLORMGMTCAPS	Value that indicates the color management capabilities of the device. CM_CMYK_COLORDevice can accept CMYK color space ICC color profile. CM_DEVICE_ICMDevice can perform ICM on either the device driver or the device itself. CM_GAMMA_RAMPDevice supports GetDeviceGammaRamp and SetDeviceGammaRamp CM_NONEDevice does not support ICM.

Return value

The return value specifies the value of the desired item.

When nIndex is BITSPIXEL and the device has 15bpp or 16bpp, the return value is 16.

Remarks

When nIndex is SHADEBLENDCAPS:

For a printer, GetDeviceCaps returns whatever the printer reports.
For a display device, all blending operations are available; besides SB_NONE, the only return values are SB_CONST_ALPHA and SB_PIXEL_ALPHA, which indicate whether these operations are accelerated.

On a multiple monitor system, if hdc is the desktop, GetDeviceCaps returns the capabilities of the primary monitor. If you want info for other monitors, you must use the multi-monitor APIs or CreateDC to get a HDC for the device context (DC) of a specific monitor.

Note Display1 is typically the primary monitor, but not always.

GetDeviceCaps provides the following six indexes in place of printer escapes.

Index	Printer escape replaced
PHYSICALWIDTH	GETPHYSPAGESIZE
PHYSICALHEIGHT	GETPHYSPAGESIZE
PHYSICALOFFSETX	GETPRINTINGOFFSET
PHYSICALOFFSETY	GETPHYSICALOFFSET
SCALINGFACTORX	GETSCALINGFACTOR
SCALINGFACTORY	GETSCALINGFACTOR

Note GetDeviceCaps reports info that the display driver provides. If the display driver declines to report any info, GetDeviceCaps calculates the info based on fixed calculations. If the display driver reports invalid info, GetDeviceCaps returns the invalid info. Also, if the display driver declines to report info, GetDeviceCaps might calculate incorrect info because it assumes either fixed DPI (96 DPI) or a fixed size (depending on the info that the display driver did and didn’t provide). Unfortunately, a display driver that is implemented to the Windows Display Driver Model (WDDM) (introduced in Windows Vista) causes GDI to not get the info, so GetDeviceCaps must always calculate the info.

Examples

For an example, see Preparing to Print.

Requirements