On Wed, 10 May 2006 15:07:35 +0800 "Jiao" <[EMAIL PROTECTED]> babbled:
> 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) for every pixel you write to the "color" buffer you need to write the alpha component separately (to the right pixel) in the alpha mask fb. you need to check if it uses pre-multiplied alpha or not though (likely not). > 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) > -- ------------- 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
