The value of the return code from this subfunction, if it is not -1, is saved by the system and passed back to the presentation driver on all future calls to this DC instance. This value is expected to be a pointer or handle to the instance data.
The handling routine initializes relevant fields in the instance data to their default values. For example, it calls WinQueryProcessCP to get the initial Code Page ID.
STARTDOC/ABORTDOC/ENDDOC (Hardcopy drivers only)
The hardcopy driver allows the following sequences to GreEscapes within the subfunctions EnableDeviceContext and BeginCloseDC brackets:
GreEscape DEVESC_STARTDOC
Instance data refers to information (such as the name of a spool file and whether a bit map has been created) that applies to a specific instance of a device context. Global data, which applies to all instances of a device context that is using the same presentation driver, is held in the Physical Device Block (PDB). A pointer to this block is passed in the DENPARAMS structure to the EnableDeviceContext routine to be included in the instance data. See Instance Data. A typical example of instance data follows:
typedef struct _DC {
USHORT DCIIdentifier; /* Contains DC_IDENTIFIER */
ULONG DCIDCType; /* DC type 0-8 *
HDC DCIhdc; /* DC handle */
struct _DC * DCINextEntry; /* Next instance */
LONG DCISaveCount; /* Number of saved DC states */
pBitmapHeader DCISelListEntry; /* Selected bit-map list entry */
USHORT DCIBitmapType; /* Current bit-map type */
POINTL DCICurrPos; /* Current position */
DCHARBUNDLE DCICurTxtAts; /* Current Text attributes bundle */
DLINEBUNDLE DCICurLinAts; /* Current Line attributes bundle */
DAREABUNDLE DCICurPtnAts; /* Current Pattern attributes bundle */
DIMAGEBUNDLE DCICurImgAts; /* Current Image attributes bundle */
DMARKERBUNDLE DCICurMrkAts; /* Current Marker attributes bundle */
USHORT DCILinePatCnt; /* Current line pattern count */
USHORT DCILineTypMask; /* Mask used for line types */
POINTL DCIPatternOrigin; /* Pattern origin */
pBitmapHeader DCIMarker; /* Pointer to marker definition */
BOOL DCIMarkerSimReq; /* On, if simulation required */
USHORT DCIFontType; /* Type of current font */
pRealizedFontType DCIRealizedFonts; /* Font table array */
USHORT DCIFontTabNum; /* Number of Font table entries */
BOOL DCIPairKerning; /* Enabled\disabled state */
ULONG DCICodePage; /* Currently selected code page */
BOOL DCITextSim; /* Set if text simulation required */
POINTL DCIOrigin; /* Current DC origin */
PCOLORTABLE DCIColorTable; /* Pointer to color table */
BOOL DCIBackgndDefined; /* Status of CLR_BACKGROUND */
BOOL DCINeutralDefined; /* Status of CLR_NEUTRAL */
USHORT DCIColTabSize; /* Color table size */
USHORT DCIColFormat; /* Format of color table */
USHORT DCIColStatus; /* Status of color table */
USHORT DCILowIndex; /* Lowest index in table */
USHORT DCIHighIndex; /* Highest index in table */
USHORT DCISysColState; /* Latest state of system colors */
COLORPAIR DCILineColatts; /* Line color indexes */
COLORPAIR DCIPattColatts; /* Pattern colors indexes */
COLORPAIR DCICharColatts; /* Character colors indexes */
COLORPAIR DCIImagColatts; /* Image colors indexes */
COLORPAIR DCIMarkColatts; /* Marker colors indexes */
ClipRectangle DCIClipRects[CACHED_CLIPS];
/* Clip rectangles */
BOOL ClipChanged; /* */
USHORT DCIClipOrder; /* Order of clip rectangles */
USHORT DCIClipNum; /* Number of clip rectangles */
RECTL DCIBoundingClip; /* Current screen/bit-map area */
USHORT DCIEngineClips; /* Clip regions in engine */
BOOL DCIIsDirty; /* Indicates when clip regions */
/* are invalid
RECTL DCIGPIBounds; /* Current GPI bounds */
BOOL DCIDefGPIBounds; /* On, if GPI bounds are default */
RECTL DCIUserBounds; /* Current user bounds */
BOOL DCIDefUserBounds; /* On, if user bounds are default */
SHORT DCIConvFactor; /* For device, conversion */
BOOL DCICorrInvalid; /* Correlation rectangles invalid */
RECTL DCIPickWindowPage; /* Pick window in page coordinates */
DevRect DCIPickWindowDevice;
/* Pick window in device coordinates */
PRECTL DCICorrRects; /* Current correlation rectangles */
USHORT DCICorrNum; /* Number of correlation rectangles */
USHORT DCICorrSize; /* Number of correlation rectangles for */
/* which storage has been allocated */
XFORM DCITransform; /* Transformation data */
FONTDETAILS DCIAvioFonts[CNT_LOADABLE_LCIDS + 1];
/* AVIO loadable font definitions */
USHORT DCIChanged; /* Shows non-default bundles */
USHORT DCISpacingType; /* Spacing type of current font */
BOOL DCIXFrmSimple; /* Transform type */
ULONG StyleNumber; /* Line style state and mask */
USHORT DCICommandMask; /* Used to mask command bits */
POINTL DCICurrPosWorld; /* Current world position */
pBitmapHeader Pattern; /* Pattern for direct DC */
AVIOINFO DCIAvioInfo; /* Avioparms material */
FONTDETAILS CurrentFont; /* Presentation Mgr. format current font */
PDEVPAL Palette; /* Handle/pointer of palette */
PRGB2 DCIDeviceDefaultPalette;
/* Device default palette that was */
/* current the last time color table */
/* indexes were calculated */
} DC;