Alpha blending..

[chethana]

Hi ,

If any one knows about Alpha blending can please give me the details...?? why
Alpha blending is used??

Is their any layering approach is their in QT?? Suppose in one layer map is their and in another layer concentric circle are their .. Both of these layer overlapped on each other .. and it should mimic the appearance as a single layer.. ??

Does Alpha blending relates to layer Approach ??? If any one knows about it please send the reply....

[wysota]

If any one knows about Alpha blending can please give me the details...?? why
Alpha blending is used??
Alpha blending is used to provide transparency effects. When two colours are blended together the final pixel colour (and its alpha component) is computed according to the blending function.

Is their any layering approach is their in QT?? Suppose in one layer map is their and in another layer concentric circle are their .. Both of these layer overlapped on each other .. and it should mimic the appearance as a single layer.. ??
Does Alpha blending relates to layer Approach ??? If any one knows about it please send the reply....

I think it'll be best if you take a look at these:
http://doc.trolltech.com/qq/qq17-compositionmodes.html
http://doc.trolltech.com/4.3/qpainter.html#composition-modes
http://doc.trolltech.com/4.3/painting-imagecomposition.html