TJPEGImage class

In unit Graphics

TJPEGImage - a class for handling images stored in JPEG (compressed) format.

Declaration

pascal

TJPEGImage = class(TFPImageBitmap)

Inheritance

TJPEGImage
TFPImageBitmap
TCustomBitmap
TRasterImage
TGraphic
TPersistent

Description

TJPEGImage is a TFPImageBitmap descendant which implements support for the JPEG ( Joint Photographic Experts Group) image format. JPEG images are commonly used for storing digital photographs. They can represent detailed color photos using a high degree of compression, resulting in very efficient storage, though with some loss of quality.

JPEG image files normally have a file extension like: jpeg, jpg, jpe, or jfif.

The CompressionQuality and Performance properties can be used to set the balance between storage efficiency and picture quality. CompressionQuality is an Integer value between 1 and 100, with 100 representing the best quality. Performance is an enumerated variable with two states: BestQuality or BestSpeed (for compression).

Properties

`CompressionQuality`	public	Determine the compression quality for the image data.
`GrayScale`	public	Indicates if the image contains grayscale image data.
`MinHeight`	public	Minimum height allowed for the image when read using an FCL image reader.
`MinWidth`	public	Minimum width allowed for the image when read using an FCL image reader.
`ProgressiveEncoding`	public	Indicates if progressive encoding is used for the image data.
`Performance`	public	Set for best quality or best speed.
`Scale`	public	A predefined scaling value applied to the image data.
`Smoothing`	public	Indicates if smoothing is applied to the raw image data.

Methods

`InitializeReader`	protected	Initializes the FCL-compatible image reader for the image type.
`InitializeWriter`	protected	Initializes the FCL-compatible Image Writer for the image type.
`FinalizeReader`	protected	Finalizes the FCL Image reader.
`GetReaderClass`	protected	Gets the class reference used to create new instances of the FCL-compatible image reader.
`GetWriterClass`	protected	Gets the class reference used to create new instances of the FCL-compatible image writer.
`GetSharedImageClass`	protected	Gets the class reference used to create new shared image instances in the class.
`Create`	public	Constructor for the class instance.
`Compress`	public	Applies compression settings in the class instance to the image data.
`IsStreamFormatSupported`	public	Indicates if the stream contains a format supported for the image type.
`GetFileExtensions`	public	Gets the file extension(s) supported for the image format.