Raster Can u tell me how to implement pixed based alphablending where alpha channel is in a seperate framebuffer(/dev/fb/2). that is to say. for example,if I draw a rectangle on (/dev/fb/0) using(/dev/fb/2) as its alpha channel, I will look throught the rectangle and see the layer below(/dev/fb/1, a video layer)
Thanks any suggestions is apprieated Jiao ----- Original Message ----- From: "Jiao" <[EMAIL PROTECTED]> To: "Carsten Haitzler (The Rasterman)" <[EMAIL PROTECTED]> Sent: Wednesday, April 26, 2006 9:42 AM Subject: Re: [directfb-dev] Anybody know this? thanks in advance > > ----- Original Message ----- > From: "Carsten Haitzler (The Rasterman)" <[EMAIL PROTECTED]> > To: "Jiao" <[EMAIL PROTECTED]> > Sent: Tuesday, April 25, 2006 2:27 PM > Subject: Re: [directfb-dev] Anybody know this? thanks in advance > > > > On Tue, 25 Apr 2006 13:06:12 +0800 "Jiao" <[EMAIL PROTECTED]> babbled: > > > > > Hi carsten, > > > Thank for your precious help. > > > > > > In my hardware > > > fb1(video) accept yuv data > > > fb0(16bit,RGB 5:6:5 format) > > > fb2 three bits , eight level alphablending > > > I want to find a guide or reference,I notice other gfxdrivers in DFB > > > release, > > > but still not very clear. 1 should I implement fillrectable > > > ,blit,stretchblt > > > with alpha support ? > > > > well the problem is the alpha channel is separate from the pixels, so you > > probably want to implement an ARGB overlay that is emulated in 32bit ARGb > > then > > downrendered to 16bit 565 AND then the alpha plane filled in with the alpha > > channel reduced to 8 bits. that would be what i would do as it would be the > > sanest interface for it - but that's just me. so you use the software 32bit > > ARGB routines for blit, stretchblit etc. on the ARGB overlay (and fb1 being > > a > > yuv plane - same thing) and then track updated regions then at some point > > copy > > those regions to fb1 and fb2 while converting to 16bpp and 3bit alpha > > Thank for your reply.yes, that is what I want to do. that is to say, fill > rectangle and blit with alpha channel support(set alpha(0-255) into 3 bits > corresponding the updated rect),but I don't know if it's a correct way. > since alpha blending between layer, is not same with general alpha blending. > and I have no gfxdrivers in DFB implemented like it. > So if I think, may be I should support alphablending in fuction > (InitLayer, TestRegion,SetRegion) to ,meet our requirements, but I'm not > sure. I'm investigatting it. > > Thank again for your help&May you happy! > > > > > > Best regards > > > Jiao > > > > > > > > > ----- Original Message ----- > > > From: "Carsten Haitzler (The Rasterman)" <[EMAIL PROTECTED]> > > > To: "Jiao" <[EMAIL PROTECTED]> > > > Cc: <[email protected]> > > > Sent: Tuesday, April 25, 2006 10:58 AM > > > Subject: Re: [directfb-dev] Anybody know this? thanks in advance > > > > > > > > > > On Tue, 25 Apr 2006 10:44:29 +0800 "Jiao" <[EMAIL PROTECTED]> babbled: > > > > > > > > > I want to write a gfxdriver, In my hardware, there are three layer, > > > > > vid > > > > > (fb1)--osd(fb0) and an attribute layer(fb2), fb2 is used to control > > > > > alpha > > > > > blending between osd(fb0) and vid layer(fb1), I quite confused about > > > > > how > > > > > to write the gfxdriver, can anybody give me some advice? > > > > > > > > > > Thank in advance > > > > > > > > what is in fb1? a bitmask or unsigned bytes with values (0-7? for 8 > > > > levels > > > > of alpha?) that map pixel for pixel with fb1? > > > > > > > > -- > > > > ------------- Codito, ergo sum - "I code, therefore I am" -------------- > > > > The Rasterman (Carsten Haitzler) [EMAIL PROTECTED] > > > > 裸好多 > > > > Tokyo, Japan (東京 日本) > > > > > > > > > -- > > ------------- Codito, ergo sum - "I code, therefore I am" -------------- > > The Rasterman (Carsten Haitzler) [EMAIL PROTECTED] > > 裸好多 > > Tokyo, Japan (東京 日本) _______________________________________________ directfb-dev mailing list [email protected] http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-dev
