On 08/13/04 11:28, Ville Syrj�l� wrote: > On Tue, Aug 10, 2004 at 11:10:39PM +0800, Chris Leung wrote: >>BTW, could I write a directfb program such that it will render a video >>provider stream in layer 1 and then make the primary layer above the layer >>1 and display some transparent GUI in primary layer? > > Only if the hardware supports alpha blending between the layers. You must > check the layer capabilities for DLCAPS_ALPHACHANNEL to find out if it's > possible. With DLCAPS_DST_COLORKEY you could use an opaque GUI.
AFAIK, all layers additional to the primary layer are provided by the hardware. And different hardware provides different capabilities when dealing with layers. But one thing I would like to ask is whether the layers have specific order, i.e. is layer 1 on top of layer 0? For CLE266, there are the overlay layer and the underlay layer. Does it mean that the overlay layer cover the primary layer, and the primary cover the underlay? Where can I learn more about the layer support of the hardware? > Usually if the layers' can do what you want you should use them. It > reduces the amount of work the accelerator has to do. Do you refer to the software accelerator or the hardware one? Thanks, Selwyn
