On Monday 08 July 2002 1:17 pm, Juergen Vigna wrote:
> Angus Leeming wrote:
> > Could you two great minds think of ways of improving the interface to do
> > what we'd like to do. The rest should be hidden inside the
> > implementation.
>
> Well I cannot comment on your implementation (I don't have the time
> to look over it in detail), but I will give you a realtime example
> of what I think and why it should be in BufferView.
>
> Think of being Andre opening your workfile and scrolling till the
> end of the document. What should happens now:
>
> 1. All previews/graphics should be converted to a loadable format
>
> 2. I would like to display the part of the graphics I'm actually in
> and am not interested to wait till all other graphics I passed
> truth are displayed to.
>
> 3. Only the really needed graphics should be loaded and displayed
>
> 4. Who knows about where I am in the document? Yes ONLY LyXText
> which is part of the BufferView and BufferView is generally
> the passed pointer.
>
> 5. BufferView should now after I stopped scrolling for "n" bits
> of defined time request the loading of the graphic segments
> I'm displaying right now. For this it should advise the insets
> actually displayed to load it's graphics and fix it's width
> (if it differs from the saved one which could be).
>
> 6. We have to do a rebreak of the text starting at the first displayed
> paragraph-row.
>
> 7. We have to redraw the screen.
>
> That is how I see it. But please fill in the gaps how you would see
> the whole process and where I'm wrong.
>
> Jug
I don't think you're wrong. I'd just like to implement it so that the Inset
does as little as possible. I think I see how we'd do this, but I need your
help to turn it into working code.
The plan
=======
1. Don't load all image files once they are converted.
2. insets ascertain whether they should use the previewed image with
void InsetFormula::draw(BufferView * bv, LyXFont const & font,
int y, float & xx, bool) const
{
if (preview_->usePreview()) {
pi.pain.image(x + 1, y - a + 1, w - 2, h - 2,
*(preview_->pimage_->image()));
...
}
If we modify this usePreview call, we can use that to invode startLoading,
albeit without the inset knowing anything about this.
Within, InsetFormula::usePreview is:
bool InsetFormula::PreviewImpl::usePreview() const
{
// If the cached grfx::PreviewImage is invalid, update it.
string const snippet = latexString();
if (!pimage_ || snippet != pimage_->snippet()) {
grfx::PreviewLoader & ploader =
grfx::Previews::get().loader(view->buffer());
pimage_ = ploader.preview(snippet);
}
if (!pimage_)
return false;
return pimage_->image();
}
So, we already have the mechanism to trigger the loading of the image. Just
modify PreviewLoader::preview to something like:
PreviewImage const *
PreviewLoader::Impl::preview(string const & latex_snippet, Inset * inset)
const
{
Cache::const_iterator it = cache_.find(latex_snippet);
PreviewImage const * pimage =
(it == cache_.end()) ? 0 : it->second.get();
+ // psuedo code
+ if (pimage && pimage->status() == WaitingToLoad) {
+ // call checkVisibility(inset) in 2 secs time
+ startTimer(2, inset, pimage, &PreviewImage::checkVisibility)
+ }
+
return pimage;
}
void PreviewImage::checkVisibility(Inset * inset)
{
if (!inset || iloader_->status() != WaitingToLoad)
return;
if (!inset->isVisible())
return;
image->startLoading();
}
So,, Jürgen, what should I use for "inset->isVisible()". I have a Buffer & at
my disposal.
Angus
