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

[Pavel Grunt]

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.

Thanks,

Pavel

> 
> > > > 
> > > > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > > > ---
> > > >  server/spice-bitmap-utils.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/server/spice-bitmap-utils.c b/server/spice-
> > > > bitmap-
> > > > utils.c
> > > > index 72a9285..439f05d 100644
> > > > --- a/server/spice-bitmap-utils.c
> > > > +++ b/server/spice-bitmap-utils.c
> > > > @@ -269,7 +269,7 @@ void dump_bitmap(SpiceBitmap *bitmap)
> > > >      put_32le(&ptr, bitmap_data_offset);
> > > >      put_32le(&ptr, header_size - 14);
> > > >      put_32le(&ptr, bitmap->x);
> > > > -    put_32le(&ptr, bitmap->y);
> > > > +    put_32le(&ptr, bitmap->flags &
> > > > SPICE_BITMAP_FLAGS_TOP_DOWN ?
> > > > -bitmap->y
> > > > : bitmap->y);
> > > >  
> > > >      put_16le(&ptr, 1); // plane
> > > >      put_16le(&ptr, n_pixel_bits);
> 
>