[Spice-devel] [vdagent-win PATCH v12 3/6] Write code to decode PNG format

[Frediano Ziglio]

> > On 25 Jul 2017, at 20:01, Frediano Ziglio < fziglio at redhat.com > wrote:
> 

> > > On Mon, Jul 24, 2017 at 01:39:35PM +0100, Frediano Ziglio wrote:
> > 
> 

> > > > +size_t PngCoder::convert_to_dib(uint8_t *out_buf, const uint8_t *data,
> > > 
> > 
> 
> > > > size_t size)
> > > 
> > 
> 
> > > > +{
> > > 
> > 
> 

> > > [...]
> > 
> 

> > > > + const unsigned int width = png_get_image_width(png, info);
> > > 
> > 
> 
> > > > + const unsigned int height = png_get_image_height(png, info);
> > > 
> > 
> 
> > > > + const size_t stride = compute_dib_stride(width, out_bits);
> > > 
> > 
> 
> > > > + const size_t image_size = stride * height;
> > > 
> > 
> 
> > > > + const int palette_colors = [=]() {
> > > 
> > 
> 

> > > If you want to use a function, then give it a name, if you don't want to
> > 
> 
> > > use a function, then this can just go in convert_to_dib() body rather
> > 
> 
> > > than through a lambda (I know the latter means removing the 'const’).
> > 
> 

> Removing the ‘const’? Why?

> > Lambdas are functions.
> 

> I believe Christophe is objecting to using a lambda whereas all other
> computations use named functions. But frankly, here, I would have
> written:

> const int palette_colors =
> out_bits > 8 ? 0
> : bits == 2 ? 4
> : 1 << out_bits;

This was exactly the previous version, just my version has some additional comments 
to make more readable. 

> Not that I don’t like lambdas, but here, it’s a lot of additional syntactic
> noise.

> Out of curiosity, I submitted both variants of the code to g++, and got
> exactly the same generated code.

> > I personally think the purpose of that code was clear even without
> 
> > a name.
> 
> > Using a "standard" function requires to declare parameters and pass
> 
> > them manually, something that lambda capture can do automatically.
> 

> > > Christophe
> > 
> 

> > By the way, got new version with more old style code.
> 

Frediano 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/spice-devel/attachments/20170726/f8d1891f/attachment-0001.html>