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

# TPortableNetworkGraphic

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

Implements support for the PNG image format.

## Declaration

Source position: graphics.pp line 1505

`type TPortableNetworkGraphic = class(TFPImageBitmap)`
`protected`
`class function GetReaderClass; override;` |  | Gets the class reference used to create new instances of the FCL-compatible image reader.
`class function GetWriterClass; override;` |  | Gets the class reference used to create new instances of the FCL-compatible image reader.
`procedure InitializeWriter(); override;` |  | Configures the writer class instance for the image type.
`class function GetSharedImageClass; override;` |  | Gets the class reference used to create new shared image instances in the class.
`public`
`class function IsStreamFormatSupported(); override;` |  | Determines if the specified stream contains image data supported for the image type.
`class function GetFileExtensions; override;` |  | Returns a list of the file extensions available.
`end;`

## Inheritance

`TPortableNetworkGraphic` |  | Implements support for the PNG image format.
`TFPImageBitmap` |  | Implements a Bitmap using the FPImage reader and writer from the FCL.
`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` |  | Abstract base class used for images in supported image formats.
`TPersistent`
?
`TObject`

## Description

TPortableNetworkGraphic is a TFPImageBitmap descendant which implements support for the PNG (Portable Network Graphics) image format. PNG is a raster graphic file format that supports loss-less data compression. PNG was developed as an improved, non-patented replacement for GIF (Graphics Interchange Format).

PNG supports palette-based images (using 24-bit RGB or 32-bit RGBA colors), grayscale images (with or without alpha channel transparency), and full-color non-palette-based RGB or RGBA images. A PNG file contains a single image in an extensible chunk structure, and uses encoding to compress repetitive pixel values in the image.

PNG image files use the file extension PNG or png, and uses the MIME media type 'image/png'.

## See also

TFPImageBitmap |  | Implements a Bitmap using the FPImage reader and writer from the FCL.