Reading Input Data17

These functions are used by format-specific graphics exporters when transcoding. Applications will not normally need to call these functions.

GraphicsExportMayExporterReadInputData

Asks whether the image source is in a form that can be read.



 
pascal ComponentResult GraphicsExportMayExporterReadInputData ( GraphicsExportComponent ci,

                                         Boolean *mayReadInputData);

ci: Specifies the component instance that identifies your connection to the graphics exporter component.
mayReadInputData: Points to a Boolean to receive the answer.

DISCUSSION

Some kinds of image source, such as files and handles, form a stream of bytes that can be read directly. Others, such as pictures and pixmaps, cannot. Format-specific graphics exporters usually cannot transcode if they cannot read the original data, so those exporters which implement CanTranscode will usually call GraphicsExportMayExporterReadInputData .

GraphicsExportGetInputDataSize

Returns the number of bytes of original image data that can be read.



 
pascal ComponentResult GraphicsExportGetInputDataSize (GraphicsExportComponent ci,

                                         unsigned long *size);

ci: Specifies the component instance that identifies your connection to the graphics exporter component.
size: Points to a variable to receive the size in bytes.

RESULT CODES

paramErr -50 Invalid parameter, or the source image doesn't permit this operation.

GraphicsExportReadInputData

Reads original image data.



 
pascal ComponentResult GraphicsExportReadInputData (GraphicsExportComponent ci,

                                         void *dataPtr,

                                         unsigned long dataOffset,

                                         unsigned long dataSize);

ci: Specifies the component instance that identifies your connection to the graphics exporter component.
dataPtr: A pointer to a memory block to receive the data.
dataOffset: The offset of the image data within the source image data. The function begins reading image data from this offset.
dataSize: The number of bytes of image data to read.

DISCUSSION

GraphicsExportReadInputData communicates with the appropriate data handler to retrieve image data.

RESULT CODES

`noErr`	0	No error
`paramErr`	-50	Invalid parameter specified
`memFullErr`	-108	Not enough memory available