On Mon, 02 Jul 2018 10:29:48 -0400 Simon Ser <[email protected]> wrote:
> > On Thu, 12 Apr 2018 09:31:48 +0200 > > Johan Klokkhammer Helsing <[email protected]> wrote: > > > > > Some clients rely on the physical size to determine the physical DPI. > > > With the > > > previous implementation, we would report 1px==1mm, which is a DPI of 25.4, > > > which is incredibly low. > > > > > > The problem is solved by setting a physical size so the DPI is close to 72 > > > instead. If the output is scaled, the DPI is set to the corresponding > > > multiple > > > of 72. > > > > > > This makes the headless backend more usable for automated testing of DPI > > > sensitive functionality such as point sized fonts. > > > > > > Signed-off-by: Johan Klokkhammer Helsing <[email protected]> > > > --- > > > libweston/compositor-headless.c | 16 ++++++++++++---- > > > 1 file changed, 12 insertions(+), 4 deletions(-) > > > > Hi, > > > > this is a good idea, but could you rebase this patch to master? > > > > > > Thanks, > > pq > > Hi, > > Would it make sense to change the protocol to allow compositors to send a zero > physical size in case it isn't relevant? I think it's often full of lies anyway, because usually the reported numbers come directly from EDID. I've heard rumours of something like width=16 height=9 (mm? cm?) etc. when the physical size is unknowable (e.g. a projector) but they still want to send the aspect ratio. If existing toolkits can cope with it, zero would be fine. Whether they do, I really don't know. Something about aspect ratio might need to be taken into account though. We've never really had non-square pixels, so the assumption of square pixels is probably used throughout the stack. If output information implied non-square pixels, does it mean client pixels will be shown equally non-square or are they scaled assuming they are originally square? OTOH, headless reporting a sensible fake size for a fake output is still a good idea in my opinion. Thanks, pq
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