GetDeviceCaps

Syntax

int GetDeviceCaps(hDC,nIndex)

This function retrieves device-specific information about a given display device. The
nIndex parameter specifies the type of information desired.

Parameter Type/Description  

hDC HDC Identifies the device context.  
nIndex int Specifies the item to return. It can be any one of the values given in Table R.9, “GDI Information Indexes.”  

Return Value

The return value specifies the value of the desired item.

Comments

Table R.9 lists the values for the nIndex parameter:

Table R.9 GDI Information Indexes

Index Meaning  

DRIVERVERSION Version number; for example, 0x100 for 1.0.  
TECHNOLOGY Device technology. It can be any one of the following values:  
  Value Meaning
  DT_PLOTTER Vector plotter
  DT_RASDISPLAY Raster display
  DT_RASPRINTER Raster printer
  DT_RASCAMERA Raster camera
  DT_CHARSTREAM Character stream
  DT_METAFILE Metafile
  DT_DISPFILE Display file
HORZSIZE Width of the physical display (in millimeters).  
VERTSIZE Height of the physical display (in millimeters).  
HORZRES Width of the display (in pixels).  
VERTRES Height of the display (in raster lines).  
LOGPIXELSX Number of pixels per logical inch along the display width.  
LOGPIXELSY Number of pixels per logical inch along the display height.  
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.  
ASPECTX Relative width of a device pixel as used for line drawing.  
ASPECTY Relative height of a device pixel as used for line drawing.  
ASPECTXY Diagonal width of the device pixel as used for line drawing.  
PDEVICESIZE Size of the PDEVICE internal data structure.  
CLIPCAPS Flag that indicates the clipping capabilities of the device. It is 1 if the device can clip to a rectangle, 0 if it cannot.  
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 version is 3.0 or higher.  

Table R.9 GDI Information Indexes (continued)

Index Meaning  

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 version is 3.0 or higher.  
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 version is 3.0 or higher.  
RASTERCAPS Value that indicates the raster capabilities of the device, as shown in the following list:  
  Capability Meaning
  RC_BANDING Requires banding support.
  RC_BITBLT Capable of transferring bitmaps.
  RC_BITMAP64 Capable of supporting bitmaps larger than 64K.
  RC_DI_BITMAP Capable of supporting SetDIBits and GetDIBits.
  RC_DIBTODEV Capable of supporting the SetDIBitsToDevice function.
  RC_FLOODFILL Capable of performing flood fills.
  RC_GDI20_OUTPUT Capable of supporting Windows version 2.0 features.
  RC_PALETTE Palette-based device.
  RC_SCALING Capable of scaling.
  RC_STRETCHBLT Capable of performing the StretchBlt function.
  RC_STRETCHDIB Capable of performing the StretchDIBits function.
CURVECAPS A bitmask that indicates the curve capabilities of the device. The bits have the following meanings:  
  Bit Meaning
  0 Device can do circles.
  1 Device can do pie wedges.
  2 Device can do chord arcs.
  3 Device can do ellipses.
  4 Device can do wide borders.
  5 Device can do styled borders.
  6 Device can do borders that are wide and styled.
  7 Device can do interiors.
  The high byte is 0.  
LINECAPS A bitmask that indicates the line capabilities of the device. The bits have the following meanings:  
  Bit Meaning
  0 Reserved.
  1 Device can do polyline.
  2 Reserved.
  3 Reserved.
  4 Device can do wide lines.
  5 Device can do styled lines.
  6 Device can do lines that are wide and styled.
  7 Device can do interiors.
  The high byte is 0.  
POLYGONALCAPS A bitmask that indicates the polygonal capabilities of the device. The bits have the following meanings:  
  Bit Meaning
  0 Device can do alternate fill polygon.
  1 Device can do rectangle.
  2 Device can do winding number fill polygon.
  3 Device can do scanline.
  4 Device can do wide borders.
  5 Device can do styled borders.
  6 Device can do borders that are wide and styled.
  7 Device can do interiors.
  The high byte is 0.  
TEXTCAPS A bitmask that indicates the text capabilities of the device. The bits have the following meanings:  
  Bit Meaning
  0 Device can do character output precision.
  1 Device can do stroke output precision.
  2 Device can do stroke clip precision.
  3 Device can do 90-degree character rotation.
  4 Device can do any character rotation.
  5 Device can do scaling independent of X and Y.
  6 Device can do doubled character for scaling.
  7 Device can do integer multiples for scaling.
  8 Device can do any multiples for exact scaling.
  9 Device can do double-weight characters.
  10 Device can do italicizing.
  11 Device can do underlining.
  12 Device can do strikeouts.
  13 Device can do raster fonts.
  14 Device can do vector fonts.
  15 Reserved. Must be returned zero.

For a list of all the available abilities, see the LOGFONT data structure in Chapter 7, “Data Types and Structures.”