On Thu, Oct 09, 2003 at 10:53:51PM +0000, Angus Leeming wrote:
> André, how does InsetFormula know when it is being edited?
The current idiom is to test for
mathcursor && mathcursor->formula() == SomeInsetFormulaBasePointer
Far from nice, though.
> Is the test below correct?
>
> void InsetFormula::draw(PainterInfo & pi, int x, int y) const
> {
> // The previews are updated/drawn only when we're not editing the inset.
> bool const editing_inset = mathcursor && mathcursor->formula() == this;
This one? Yes.
> I'm trying to reduce the number of wasted cycles by only initiating the
> creation of the preview once we leave the inset. At the moment previewReady
> is called on every key draw event, but my own tree now has:
>
> bool use_preview = !editing_inset;
> if (use_preview) {
> Buffer const * b_ptr = pi.base.bv ? pi.base.bv->buffer() : 0;
> use_preview = b_ptr && preview_->previewReady(*b_ptr);
> }
>
> which prevents us from checking the preview whilst we're editing the inset.
Should be ok.
> Further,
> bool PreviewedInset::previewReady() const;
> does too much at the moment. Not only does it return whether the preview
> is ready to be displayed, but it also initiates the creation of the preview.
> I'd like to split that into two functions,
> // No side effects
> bool PreviewedInset::previewReady() const;
> // Initiate the generation of the preview.
> void PreviewedInset::update(string const & latex_snippet);
> which seems much cleaner.
Good.
> My question is, where should I call PreviewedInset::update from?
> >From InsetFormula::draw or from InsetFormula::metrics? At the moment
> it is effectively invoked from metrics (since we ask previewReady()?
> from both functions).
>
> I have the feeling, however, that 'metrics' should be a lean and mean
> function so 'draw' is the best place from which to call
> PreviewedInset::update.
There should be 1:1 metrics/draw relation in theory and I don't think we
are too far of right now in practice. In fact, I hope to save a few
calls to metrics at one point of time. So I don't think it really
matters where you put it.
Andre'
