Отображение JPEGа, хранящегося в базе

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OlegE (2002-03-14 15:42) [2]

TJPEGImage encapsulates a jpeg graphic.

Unit Jpeg

Description

Use TJPEGImage to read and write jpeg compressed image data. TJPEGImage handles the digital compression and decompression of still images for use in computer systems. It uses the data from an instance of TJPEGData, which contains the actual jpeg data source and is never modified. Each jpeg image object may share its TJPEGData object with other instances of a jpeg image by creating copies using the Assign method. The jpeg data source handles reference counting for the jpeg image objects that are linked to it.

TJPEGImage has an internal bitmap that represents the jpeg image. This internal image and the original source of the jpeg image are read only. TJPEGImage has properties that determine how each instance will handle color conversion, compression, decompression, performance, and so on.

The following are characteristics of this object. A TJPEGImage object:

Has no canvas (so it cannot draw onto a canvas). However, TJPEGImage implements the protected Draw method introduced in TGraphic, so it can draw itself on the canvas of another object.
Provides no access to the internal bitmap image that it creates for the JPEG image.
Performs reference counting and handle sharing by means of the TJPEGData object. Multiple instances can refer to the same TJPEGData image. TJPEGData is the actual owner of the file handle to the jpeg data source.

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