Escape API 函数
The Escape function allows applications to access capabilities of a particular device not directly available through GDI. Escape calls made by an application are translated and sent to the driver.
int Escape(
HDC hdc, // handle to device context
int nEscape, // escape function
int cbInput, // number of bytes in input structure
LPCSTR lpvInData, // pointer to input structure
LPVOID lpvOutData // pointer to output structure
);
Parameters
hdc
Identifies the device context.
nEscape
Specifies the escape function to be performed. This parameter must be one of the predefined escape values. Use the ExtEscape function if your application defines a private escape value.
cbInput
Specifies the number of bytes of data pointed to by the lpvInData parameter.
lpvInData
Points to the input structure required for the specified escape.
lpvOutData
Points to the structure that receives output from this escape. This parameter should be NULL if no data is returned.
Return Values
If the function succeeds, the return value is greater than zero, except with the QUERYESCSUPPORT printer escape, which checks for implementation only. If the escape is not implemented, the return value is zero.
If the function fails, the return value is an error. To get extended error information, call GetLastError.
Errors
If the function fails, the return value is one of the following values.
Value Meaning
SP_ERROR General error. If SP_ERROR is returned, Escape may set the last error code to:ERROR_INVALID_PARAMETER
ERROR_DISK_FULL
ERROR_NOT_ENOUGH_MEMORY
ERROR_PRINT_CANCELLED
SP_OUTOFDISK Not enough disk space is currently available for spooling, and no more space will become available.
SP_OUTOFMEMORY Not enough memory is available for spooling.
SP_USERABORT The user terminated the job through Windows Print Manager.
Remarks
The Win32 API provides six new functions that supersede some printer escapes:
Function Description
AbortDoc Terminates a print job. Supersedes the ABORTDOC escape.
EndDoc Ends a print job. Supersedes the ENDDOC escape.
EndPage Ends a page. Supersedes the NEWFRAME escape. Unlike NEWFRAME, this function is always called after printing a page.
SetAbortProc Sets the abort function for a print job. Supersedes the SETABORTPROC escape.
StartDoc Starts a print job. Supersedes the STARTDOC escape.
StartPage Prepares printer driver to receive data.
The Win32 API provides six new indexes for the GetDeviceCaps function that supersede some printer escapes:
Index Description
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" 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"x11" 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"x11" paper, that cannot print on the leftmost 0.25" 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"x11" paper, that cannot print on the topmost 0.5" of paper, has a vertical physical offset of 300 device units.
Of the original printer escapes, only the following can be used by Win32-based application:
Escape Description
QUERYYESCSUPPORT Determines whether a particular escape is implemented by the device driver.
Following is a list of the obsolete printer escapes that are supported only for compatibility with 16-bit versions of Windows:
Escape Description
ABORTDOC Stops the current print job and erases everything the application has written to the device since the last ENDDOC escape.
ENDDOC Ends a print job started by the STARTDOC escape.
GETPHYSPAGESIZE Retrieves the physical page size and copies it to the specified location.
GETPRINTINGOFFSET Retrieves the offset from the upper-left corner of the physical page where the actual printing or drawing begin
s.
GETSCALINGFACTOR Retrieves the scaling factors for the x-axis and the y-axis of a printer.
NEWFRAME Informs the printer that the application has finished writing to a page.
NEXTBAND Informs the printer that the application has finished writing to a band.
PASSTHROUGH Allows the application to send data directly to a printer.
SETABORTPROC Sets the Abort function for a print job.
STARTDOC Informs a printer driver that a new print job is starting.
See Also
AbortDoc, EndDoc, EndPage, ExtEscape, SetAbortProc, StartDoc, StartPage, ResetDC
