[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] Reference for unit 'Graphics' (#lcl)

TJPEGImage

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

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

Declaration

Source position: graphics.pp line 1628

type TJPEGImage = class(TFPImageBitmap)

protected

  procedure InitializeReader(); override;

  

  procedure InitializeWriter(); override;

  

  procedure FinalizeReader(); override;

  

  function GetReaderClass; override;

  

  function GetWriterClass; override;

  

  function GetSharedImageClass; override;

  

public

  constructor Create; override;

  function GetFileExtensions; override;

  property CompressionQuality: TJPEGQualityRange; [rw]

  

Determine the compression quality for this image

  property GrayScale: Boolean; [r]

  

Is this a grayscale image?

  property ProgressiveEncoding: Boolean; [r]

  

Is progressive encoding used for this JPEG?

  property Performance: TJPEGPerformance; [rw]

  

Set for best quality or best speed

end;

Inheritance

TJPEGImage

  

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

|

TFPImageBitmap

  

A class of Bitmap using the FPImage reader and writer (ie customised for FreePascal)

|

TCustomBitmap

  

TCustomBitMap - the base class for TBitmap

|

TRasterImage

  

TRasterImage - base class for a number of graphic controls, including TCustomBitmap and TCustomIcon, which use a raster of dots to display graphic information

|

TGraphic

  

Base class for dealing with Graphic images

|

TPersistent

|

TObject

Description

JPEG images are very commonly used for storing digital photographs. They can represent detailed colour photos using a high degree of compression, resulting in very efficient storage, though with some loss of quality.

The properties CompressionQuality (an integer between 1 and 100, with 100 representing the best quality) and Performance (an enumerated variable with two states: BestQuality or BestSpeed ie compression) can be used to determine the balance between efficiency of storage and quality of picture.

The latest version of this document can be found at lazarus-ccr.sourceforge.net.