> On 22 Oct 2017, at 23:11, Jean-Marc Lasgouttes <lasgout...@lyx.org> wrote: > > Le 21 octobre 2017 14:56:36 GMT+02:00, Patrick De Visschere > <pdvissch...@edpnet.be> a écrit : >> Jean-Marc, >> >> This works because every update is turned into a FullScreenUpdate. >> Right? > > If I understand correctly, it turns every update related to an UpdateRequest > event (something internal to qt) into a full screen update (in the LyX > sense). But I think that these updates (those which create the black screen) > are not the norm. > You can check that by adding some debug information along with the new code > in my patch to see how often it triggers.
With the patch in place, SingleParUpdate in bufferView::draw is never reached.
>
> It would be interesting to set a break on QWindow::requestUpdate and see
> whether to is something we do that triggers this effect.
I did and it’s never triggered.
>> Isn’t this a waste of work?
>>
>> Do you consider this as a permanent solution?
>
> Yes maybe, along with other improvement on our draw code. But I might not
> understand exactly what is happening.
>
>> I’ve tried to solve the problem by using: viewport()->update(0,y,w,h)
>> and thus specifying the proper coordinates.
>
> Which one?
The following gives me the correct coordinates for a simple paragraph (for
tables using top_pit looks better).
void BufferView::rectToUpdate(int *y, int *w, int *h)
{
if(d->update_strategy_ == SingleParUpdate) {
Text & buftext = buffer_.text();
pit_type const bottom_pit = d->cursor_.bottom().pit();
TextMetrics & tm = textMetrics(&buftext);
*h = tm.parMetrics(bottom_pit).height();
*y = tm.parMetrics(bottom_pit).position() -
tm.parMetrics(bottom_pit).ascent();
} else {
*y = 0;
*h = height_;
}
*w = width_;
}
>
>> If I pass the coordinates of the paragraph, I notice that
>> “SingleParUpdate" actually means “SingleRowUpdate". Since only the
>> current paragraph is painted black now, except for the current row.
>
> Interesting. Does this mean that we could somehow disable completely these
> black screen paintings ?
Actually I need the coordinates of the current Row instead of those of the
Paragraph, but sofar I couldn’t find this information. I’m afraid that the
currrent Row of a paragraph is not cached somewhere.
And this does not work yet when making a selection or moving the cursor around.
It will only work if for every update we can pass via viewport()->update(x, y,
w,h) the exact area to be painted later. If it’s too large it will be partially
black and if too small updates will be missed.
>
> The whole situation is not clear to me as you can see.
I’m still having problems with the basics. I thought there existed a document
describing the basics of textMetrics, paragraphMetrics … .
I found something on the wiki but not so much.
>
> JMarc
>
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