[Spice-devel] [PATCH spice-server v2 2/6] Handle top down bitmaps dumping

[Frediano Ziglio]

> 
> On Mon, 2016-10-31 at 07:01 -0400, Frediano Ziglio wrote:
> > > 
> > > On Mon, 2016-10-31 at 06:17 -0400, Frediano Ziglio wrote:
> > > > ping
> > > > 
> > > > > 
> > > > > The top down flag can be specified using negative heights.
> > > 
> > > Will the resulting bitmap be upside down ? Or it depends on the
> > > image
> > > viewer ?
> > > 
> > > Pavel
> > > 
> > 
> > According to https://msdn.microsoft.com/en-us/library/windows/deskto
> > p/dd183376(v=vs.85).aspx:
> > 
> > "The height of the bitmap, in pixels. If biHeight is positive, the
> > bitmap is a
> > bottom-up DIB and its origin is the lower-left corner. If biHeight
> > is negative,
> > the bitmap is a top-down DIB and its origin is the upper-left
> > corner."
> > 
> > I don't know how persistent are Microsoft URLs and which license are
> > these information (so: can I put the line above in the commit
> > message?).
> You can quote if you add source, so please put these in the commit log
> 
> > 
> > I could add something like:
> > 
> > "Refer to BITMAPINFOHEADER structure documentation for biHeight
> > field for details."
> > 
> > Frediano
> 
> My question was more about the fact that there could be a reason to
> ignore the topdown flag - to make it more visible to the dev that an
> upside down image was processed. ie before this patch the image would
> be stored upside down, the user would see it when looking on the
> stored bitmap. Now the fact that is upside down will be "hidden" by
> the image viewer.
> 
> It probably depends on the fact how we want to use the DUMP_BITMAP
> 
> I am not nacking the patch, I would just like to know if the "wrong"
> height is intentional.
> 

Hi,
  looks nobody remember if this was intentional or not
(code is really old). On the other side just looking at the
image it's hard to say if it upside-down if this is due to
wrong flag usage or just a different direction.

> Thanks,
> 
> Pavel
> 

Frediano