IImageReadFormat Class Reference

#include <IImageReadFormat.h>

Inheritance diagram for IImageReadFormat:

Public Types
enum	{ kOptionSetImage = 1, kOptionSetLayer = 2 }
enum	{ kOptionUseFullRes = kMaxInt32, kOptionUseSmallestRes = 0 }

Public Member Functions
virtual bool16	Open (IPMStream *iPMStream)=0
virtual bool16	GetImageAttributes (IImageAttributes *iImageAttributes)=0
virtual bool16	GetGraphicLayerInfo (IGraphicLayerInfo *iLayerInfo)=0
virtual bool16	Close ()=0
virtual bool16	CanRead (IPMStream *iPMStream)=0
virtual bool16	SetFormatOption (uint32 formatOption, uint32 &formatData)=0
virtual bool16	ReadData (ImageStreamRecord &outRecord)=0
Public Member Functions inherited from IPMUnknown
virtual IPMUnknown *	QueryInterface (PMIID interfaceID) const =0
virtual void	AddRef () const =0
virtual void	Release () const =0

Detailed Description

Interface defining the mechanism for reading an image from a stream.

Image format reading sequence:

First, the app calls CanRead with the data stream. If the filter returns kTrue, the app calls Open with the data stream. The app then may or may not call SetFormatOption and GetImageAttributes. In general the app will only query for that information once and then cache it for later use. The app then calls GetImageAttributes, which returns the attributes of the currently selected image within the file (high res or low res in this revision). At this point, the app calls ReadData repeatedly, possibly in random order. The data returned should come from the currently set image, layer, and plane as specified via SetFormatOption. Note that calls to SetFormatOption and GetImageAttributes can happen any time and multiple times between Open and Close. Finally, the app calls close and terminates the connection.

See Also

IImageWriteFormat

Member Function Documentation

virtual bool16 IImageReadFormat::CanRead ( IPMStream *  iPMStream )

pure virtual

Called to determine if this reader can process the data in the given stream.

This can be the first call to the image format reader. It does not take place after the Open call. CanRead is the filter's oppurtunity to determine if it in fact can read the stream of data.

Parameters

iPMStream

IN The stream of data

Returns

kTrue if the reader can process the data in the stream, else kFalse

See Also

IPMStream

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::Close ( )

pure virtual

Closes this reader.

Returns

kTrue if the method succeeds, else kFalse

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::GetGraphicLayerInfo ( IGraphicLayerInfo *  iLayerInfo )

pure virtual

Retrieves the graphic layer information for the current image.

GetGraphicLayerInfo will return kFalse if Open has not been called.

Note: May return kTrue even if layers do not exist.

Parameters

iLayerInfo

OUT The IGraphicLayerInfo object to which the layer information is written

Returns

kTrue if the method succeeds, else kFalse

See Also

IGraphicLayerInfo

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::GetImageAttributes ( IImageAttributes *  iImageAttributes )

pure virtual

Retrieves the image attributes for the current image (there may be only one; see note below about multiple images).

GetImageAttributes will return kFalse if Open has not been called.

GetAttributes is a separate method so that IImageReadFormat users can cache the information.

IMPORTANT: If the format supports more than one image per file and there is another image, then the attributes returned are those for the currently set image (via the SetFormatOption call).

Parameters

iImageAttributes

OUT The IImageAttributes object to which the attributes are written

Returns

kTrue if the method succeeds, else kFalse

See Also

IImageAttributes

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::Open ( IPMStream *  iPMStream )

pure virtual

Open is the initial call made to the image format reader (after the optional CanRead call, however). The image format reader should do any initialization and check the stream to make sure it really understands the data.

Parameters

iPMStream

IN The stream to read

Returns

kTrue if the reader can process the data in the given stream, else kFalse

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::ReadData ( ImageStreamRecord &  outRecord )

pure virtual

Reads data from the image. The data copied into outRecord.buffer is expected to be in the format described by the image attributes.

Note: For 1-bit data each row is bit-padded to a byte boundary.

Parameters

outRecord

IN/OUT Describes the data to be read and holds pointer to the caller-provided buffer to which data is copied

See Also

IImageStream

Implemented in CImageReadFormat.

virtual bool16 IImageReadFormat::SetFormatOption ( uint32  formatOption, uint32 &  formatData  )

pure virtual

Sets an additional format option. It allows the caller to request a particular resolution of image or a specific layer in a multi-layer image, if the IImageReadFormat instance supports the options. Returns kTrue if the reader supports the option and the image contains sufficient data to satisify the request, otherwise kFalse.

Inputs are as follows:

formatOption = kOptionSetImage, formatData = kOptionUseFullRes. The resolution of the main image will be returned in formatData.

formatOption = kOptionSetImage, formatData = kOptionUseSmallestRes. If there are multiple images then the resolution of the smallest subsampled version of the main image will be returned in formatData.

formatOption = kOptionSetImage, formatData = desired resolution. If there are multiple images then the closest resolution which is greater than or equal to the desired resolution will be returned in formatData.

formatOption = kOptionSetLayer, formatData = zero based index of desired layer. Sets the index of the layer to use. No return value will be placed in formatData.

Note: This call must be made after the call to Open().

Parameters

formatOption	IN The selector for the format to use
formatData	IN/OUT The data to use with the specified selector on input; various on output

Returns

kTrue if the method succeeds, else kFalse

Implemented in CImageReadFormat.