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Improve the code that limits scrolling at top/bottom

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The most visible part of this commit is the move of part of
BufferView::updateMetrics to a new TextMetrics::updateMetrics. This
new method makes sure that metrics are known for all visible paragraphs
(starting from anchor), and that the positions of the paragraphs have
been recorded.

This method is called up to 3 times in BufferView::updateMetrics:
* unconditionally, to update all visible metrics,
* then, if the bottom of the document is visible and too high, after
  updating the anchor ypos,
* and similarly if the top of the document is visible and too low.

This fixes for example the case where one jumps to Section 5.3 at the
end of Tutorial and 'scroll_below_document' is false.

Some now redundant code is removed from BufferView::scrollToCursor.

The anchor-setting code in BufferView::draw is not clearly useful, but
left here just in case. It generates a debug warning, though.

Part of bug #12297.
This commit is contained in:
Jean-Marc Lasgouttes 2023-11-17 18:30:37 +01:00
parent 08010c6a5e
commit f15d2ebf38
3 changed files with 85 additions and 62 deletions
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93
src/BufferView.cpp
View File

@ -762,6 +762,7 @@ void BufferView::scrollDocView(int const pixels, bool update)
TextMetrics const & tm = textMetrics(&buffer_.text());
if (tm.first().second->top() - pixels <= height_
&& tm.last().second->bottom() - pixels >= 0) {
LYXERR(Debug::SCROLLING, "small skip");
d->anchor_ypos_ -= pixels;
processUpdateFlags(Update::ForceDraw);
return;
@ -784,6 +785,7 @@ void BufferView::scrollDocView(int const pixels, bool update)
return;
}
LYXERR(Debug::SCROLLING, "search paragraph");
// find paragraph at target position
int par_pos = d->scrollbarParameters_.min;
pit_type i = 0;
@ -1097,8 +1099,6 @@ bool BufferView::scrollToCursor(DocIterator const & dit, ScrollType how)
d->anchor_ypos_ = - offset + row_dim.ascent();
if (how == SCROLL_CENTER)
d->anchor_ypos_ += height_/2 - row_dim.height() / 2;
else if (!lyxrc.scroll_below_document && d->anchor_pit_ == max_pit)
d->anchor_ypos_ = height_ - offset - row_dim.descent();
else if (offset > height_)
d->anchor_ypos_ = height_ - offset - defaultRowHeight();
else
@ -3129,7 +3129,7 @@ void BufferView::updateMetrics(bool force)
return;
Text & buftext = buffer_.text();
pit_type const npit = int(buftext.paragraphs().size());
pit_type const lastpit = int(buftext.paragraphs().size()) - 1;
if (force) {
// Clear out the position cache in case of full screen redraw,
@ -3148,62 +3148,35 @@ void BufferView::updateMetrics(bool force)
if (d->inlineCompletionPos_.fixIfBroken())
d->inlineCompletionPos_ = DocIterator();
if (d->anchor_pit_ >= npit)
if (d->anchor_pit_ > lastpit)
// The anchor pit must have been deleted...
d->anchor_pit_ = npit - 1;
d->anchor_pit_ = lastpit;
if (!tm.contains(d->anchor_pit_))
// Rebreak anchor paragraph.
tm.redoParagraph(d->anchor_pit_);
ParagraphMetrics & anchor_pm = tm.parMetrics(d->anchor_pit_);
// Update metrics around the anchor
tm.updateMetrics(d->anchor_pit_, d->anchor_ypos_, height_);
// make sure than first paragraph of document is not too low
if (d->anchor_pit_ == 0) {
int scrollRange = d->scrollbarParameters_.max - d->scrollbarParameters_.min;
// Complete buffer visible? Then it's easy.
if (scrollRange == 0)
d->anchor_ypos_ = anchor_pm.ascent();
else {
// avoid empty space above the first row
d->anchor_ypos_ = min(d->anchor_ypos_, anchor_pm.ascent());
}
}
anchor_pm.setPosition(d->anchor_ypos_);
LYXERR(Debug::PAINTING, "metrics: " << " anchor pit = " << d->anchor_pit_
<< " anchor ypos = " << d->anchor_ypos_);
// Redo paragraphs above anchor if necessary.
int y1 = d->anchor_ypos_ - anchor_pm.ascent();
// We are now just above the anchor paragraph.
pit_type pit1 = d->anchor_pit_ - 1;
for (; pit1 >= 0 && y1 > 0; --pit1) {
if (!tm.contains(pit1))
tm.redoParagraph(pit1);
ParagraphMetrics & pm = tm.parMetrics(pit1);
y1 -= pm.descent();
// Save the paragraph position in the cache.
pm.setPosition(y1);
y1 -= pm.ascent();
// Check that the end of the document is not too high
int const min_visible = lyxrc.scroll_below_document ? minVisiblePart() : height_;
if (tm.last().first == lastpit && tm.last().second->bottom() < min_visible) {
d->anchor_ypos_ += min_visible - tm.last().second->bottom();
LYXERR(Debug::SCROLLING, "Too high, adjusting anchor ypos to " << d->anchor_ypos_);
tm.updateMetrics(d->anchor_pit_, d->anchor_ypos_, height_);
}
// Redo paragraphs below the anchor if necessary.
int y2 = d->anchor_ypos_ + anchor_pm.descent();
// We are now just below the anchor paragraph.
pit_type pit2 = d->anchor_pit_ + 1;
for (; pit2 < npit && y2 < height_; ++pit2) {
if (!tm.contains(pit2))
tm.redoParagraph(pit2);
ParagraphMetrics & pm = tm.parMetrics(pit2);
y2 += pm.ascent();
// Save the paragraph position in the cache.
pm.setPosition(y2);
y2 += pm.descent();
// Check that the start of the document is not too low
if (tm.first().first == 0 && tm.first().second->top() > 0) {
d->anchor_ypos_ -= tm.first().second->top();
LYXERR(Debug::SCROLLING, "Too low, adjusting anchor ypos to " << d->anchor_ypos_);
tm.updateMetrics(d->anchor_pit_, d->anchor_ypos_, height_);
}
//FIXME: do we want that?
// if updating, remove paragraphs that are outside of screen
/* FIXME: do we want that? It avoids potential issues with old
* paragraphs that should have been recomputed but have not, at
* the price of potential extra metrics computaiton. I do not
* think that the performance gain is high, so that for now the
* extra paragraphs are removed
*/
// Remove paragraphs that are outside of screen
while(tm.first().second->bottom() <= 0) {
//LYXERR0("Forget pit: " << tm.first().first);
tm.forget(tm.first().first);
@ -3213,6 +3186,8 @@ void BufferView::updateMetrics(bool force)
tm.forget(tm.last().first);
}
/* FIXME: if paragraphs outside of the screen are not removed
* above, one has to search for the first visible one here */
// Normalize anchor for next time
if (d->anchor_pit_ != tm.first().first
|| d->anchor_ypos_ != tm.first().second->position()) {
@ -3223,14 +3198,6 @@ void BufferView::updateMetrics(bool force)
d->anchor_ypos_ = tm.first().second->position();
}
LYXERR(Debug::PAINTING, "Metrics: "
<< " anchor pit = " << d->anchor_pit_
<< " anchor ypos = " << d->anchor_ypos_
<< " y1 = " << y1
<< " y2 = " << y2
<< " pit1 = " << pit1
<< " pit2 = " << pit2);
// Now update the positions of insets in the cache.
updatePosCache();
@ -3698,6 +3665,7 @@ void BufferView::draw(frontend::Painter & pain, bool paint_caret)
updateScrollbarParameters();
// Normalize anchor for next time (in case updateMetrics did not do it yet)
// FIXME: is this useful?
pair<pit_type, ParagraphMetrics const *> firstpm = tm.first();
pair<pit_type, ParagraphMetrics const *> lastpm = tm.last();
for (pit_type pit = firstpm.first; pit <= lastpm.first; ++pit) {
@ -3705,9 +3673,10 @@ void BufferView::draw(frontend::Painter & pain, bool paint_caret)
if (pm.bottom() > 0) {
if (d->anchor_pit_ != pit
|| d->anchor_ypos_ != pm.position())
LYXERR(Debug::PAINTING, __func__ << ": Found new anchor pit = " << pit
LYXERR0(__func__ << ": Found new anchor pit = " << pit
<< " anchor ypos = " << pm.position()
<< " (was " << d->anchor_pit_ << ", " << d->anchor_ypos_ << ")");
<< " (was " << d->anchor_pit_ << ", " << d->anchor_ypos_ << ")"
"\nIf you see this message, please report.");
d->anchor_pit_ = pit;
d->anchor_ypos_ = pm.position();
break;

50
src/TextMetrics.cpp
View File

@ -216,6 +216,56 @@ void TextMetrics::newParMetricsUp()
}
void TextMetrics::updateMetrics(pit_type const anchor_pit, int const anchor_ypos,
int const bv_height)
{
LASSERT(text_->isMainText(), return);
pit_type const npit = pit_type(text_->paragraphs().size());
if (!contains(anchor_pit))
// Rebreak anchor paragraph.
redoParagraph(anchor_pit);
ParagraphMetrics & anchor_pm = parMetrics(anchor_pit);
anchor_pm.setPosition(anchor_ypos);
// Redo paragraphs above anchor if necessary.
int y1 = anchor_ypos - anchor_pm.ascent();
// We are now just above the anchor paragraph.
pit_type pit1 = anchor_pit - 1;
for (; pit1 >= 0 && y1 > 0; --pit1) {
if (!contains(pit1))
redoParagraph(pit1);
ParagraphMetrics & pm = parMetrics(pit1);
y1 -= pm.descent();
// Save the paragraph position in the cache.
pm.setPosition(y1);
y1 -= pm.ascent();
}
// Redo paragraphs below the anchor if necessary.
int y2 = anchor_ypos + anchor_pm.descent();
// We are now just below the anchor paragraph.
pit_type pit2 = anchor_pit + 1;
for (; pit2 < npit && y2 < bv_height; ++pit2) {
if (!contains(pit2))
redoParagraph(pit2);
ParagraphMetrics & pm = parMetrics(pit2);
y2 += pm.ascent();
// Save the paragraph position in the cache.
pm.setPosition(y2);
y2 += pm.descent();
}
LYXERR(Debug::PAINTING, "TextMetrics::updateMetrics "
<< " anchor pit = " << anchor_pit
<< " anchor ypos = " << anchor_ypos
<< " y1 = " << y1
<< " y2 = " << y2
<< " pit1 = " << pit1
<< " pit2 = " << pit2);
}
bool TextMetrics::metrics(MetricsInfo const & mi, Dimension & dim, int min_width)
{
LBUFERR(mi.base.textwidth > 0);

4
src/TextMetrics.h
View File

@ -73,6 +73,10 @@ public:
///
void newParMetricsUp();
/// Update metrics up to \c bv_height. Only usable for main text (for now).
void updateMetrics(pit_type const anchor_pit, int const anchor_ypos,
int const bv_height);
/// compute text metrics.
bool metrics(MetricsInfo const & mi, Dimension & dim, int min_width = 0);