anne/lyx_mirror
1
0
Fork 0
mirror of https://git.lyx.org/repos/lyx.git synced 2024-11-09 18:31:04 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Update PAINTING_ANALYSIS

Browse Source
This commit is contained in:
Jean-Marc Lasgouttes 2023-11-20 17:24:09 +01:00
parent 2449693301
commit a23522073c
1 changed files with 42 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
development/PAINTING_ANALYSIS
View File

@ -3,7 +3,7 @@ Understanding the painting process
This file tries to describe the state of the metrics/painting This file tries to describe the state of the metrics/painting
mechanism, and identify the improvements that could be made. The first mechanism, and identify the improvements that could be made. The first
section can be read alone, although the context for them is really sections can be read alone, although the context for them is really
given in the following ones. given in the following ones.
Please keep this file up to date as the code evolves!!! Please keep this file up to date as the code evolves!!!
@ -20,9 +20,10 @@ following section. Some actions are proposed.
** SinglePar update ** SinglePar update
This flag only has an effect in the current BufferView and at This flag only has an effect in the current BufferView, but I think it
top-level, but I think it is useful in other views too. Doing this is useful in other views too. Doing this will require some work on the
will require some work on the update pipeline, though. update pipeline, though.
** Buffer::change issues ** Buffer::change issues
@ -53,17 +54,16 @@ The global idea would be to extend FitCursor to cover also horizontal
cursor. cursor.
* Clean-up of drawing code * TODO Clean-up of drawing code
** Set Row::changed() in a finer way ** Set Row::changed() in a finer way
*** singleParUpdate *** singleParUpdate
When the height of the current paragraph changes, there is no need for When the height of the current paragraph changes, there is no need for
a full screen update. Only the rows after the current one need to have a full screen update (at top level, at least). Only the rows after the
their position recomputed. current one need to have their position recomputed.
This is also true when scrolling (how to do that?)
*** redoParagraph *** redoParagraph
@ -71,13 +71,16 @@ It should be possible to check whether the new row is the same as the
old one and keep its changed() status in this case. This would reduce old one and keep its changed() status in this case. This would reduce
a lot the amount of stuff to redraw. a lot the amount of stuff to redraw.
** Put labels and friends in the Row as elements ** Put labels and friends in the Row as elements
It should not be necessary to access the Paragraph object to draw. It should not be necessary to access the Paragraph object to draw.
Adding the static elements to Row is a lot of work, but worth it IMO. Adding the static elements to Row is a lot of work, but worth it IMO.
** When a paragraph ends with a newline, compute correctly the height of the extra row. ** When a paragraph ends with a newline, compute correctly the height of the extra row.
** Merging bv::updateMetrics and tm::metrics ** Merging bv::updateMetrics and tm::metrics
While the full metrics computation tries hard to limit the number of While the full metrics computation tries hard to limit the number of
@ -89,6 +92,12 @@ insets. We should re-use the bv::updateMetrics logic:
The difficulty for a tall table cell for example, is that it may be The difficulty for a tall table cell for example, is that it may be
necessary to break the whole contents to know the width of the cell. necessary to break the whole contents to know the width of the cell.
Also, the anchor is relative to the outer paragraph, which means that
for a very long inset it is necessary to rebreak until the contents
that needs to be shown (to compute the heights).
All in all, this is difficult to get right. This is less important now
that SinglePar updates work in nested insets.
* Description of current drawing mechanism * Description of current drawing mechanism
@ -99,10 +108,12 @@ There are three parts to drawing the work area:
+ the metrics phase computes the size of insets and breaks the + the metrics phase computes the size of insets and breaks the
paragraphs into rows. It stores the dimension of insets (both paragraphs into rows. It stores the dimension of insets (both
normal and math) in bv::coordCache. normal and math) in bv::coordCache and the vertical position of the
top-level paragraphs.
+ the nodraw drawing phase paints the screen (see below) with a null + the nodraw drawing phase paints the screen (see below) with a null
painter. The only useful effect is to store the inset positions. painter. The only useful effect is to store the positions of
visible insets.
+ an update() signal is sent. This in turn will trigger a paint + an update() signal is sent. This in turn will trigger a paint
event, and the actual screen painting will happen then. event, and the actual screen painting will happen then.
@ -115,18 +126,18 @@ whether this is correct.
Depending on the Update::flags passed to the method, it sets an update Depending on the Update::flags passed to the method, it sets an update
strategy in (NoScreenUpdate, SingleParUpdate, FullScreenUpdate, strategy in (NoScreenUpdate, SingleParUpdate, FullScreenUpdate,
DecorationUpdate). It triggers a recomputation of the metrics when either: DecorationUpdate). It triggers a call to updateMetrics when either:
+ Update::Force has been specified + Update::Force has been specified
+ Update::FitCursor has been specified and there is a need to scroll + Update::FitCursor has been specified and there is a need to scroll
the display. the display.
+ Update::SinglePar has been specified and the current paragraph has + Update::SinglePar has been specified and the current paragraph has
not changed height. changed height.
If a computation of metrics has taken place, Force is removed from the If a computation of metrics has taken place, Force is removed from the
flags and ForceDraw is added instead. flags and ForceDraw is added instead.
It is OK to call processUpateFlags several times before an update. In It is OK to call processUpdateFlags several times before an update. In
this case, the effects are cumulative. processUpdateFlags executes the this case, the effects are cumulative. processUpdateFlags executes the
metrics-related actions, but defers the actual drawing to the next metrics-related actions, but defers the actual drawing to the next
paint event. paint event.
@ -137,21 +148,32 @@ update flag is Update::None.
** Metrics computation (and nodraw drawing phase) ** Metrics computation (and nodraw drawing phase)
This is triggered by bv::updateMetrics, which calls tm::redoParagraph for This is done bv::updateMetrics. When the parameter 'force' of this
all visible paragraphs. Some Paragraphs above or below the screen (needed method is true, that first thing that is done is to clear the metrics
for page up/down) and computed as needed. caches to start from a clean slate.
Then, starting upwards then downwards from the anchor paragraph
(anchor_pit_) and its vertical position (anchor_ypos_),
tm::updateMetrics every visible paragraph whose metrics is not know
(all of them when force==true) is recomputed using tm::redoParagraph.
tm::redoParagraph will call Inset::metrics for each inset. In the case tm::redoParagraph will call Inset::metrics for each inset. In the case
of text insets, this will invoke recursively tm::metrics, which redoes of text insets, this will invoke recursively tm::metrics, which redoes
all the paragraphs of the inset. all the paragraphs of the inset. Then, a single big row is created in
tm::tokenizeParagraph, which is later broken in multiple rows by
tm::breakParagraph.
Then, a single big row is created in tm::tokenizeParagraph, which is If it turns out that the top or bottom margin are incorrect (paragraphs
later broken in multiple rows by tm::breakParagraph. are too high/low), tm::updateMetrics will be called again with fixed
values of anchor_ypos_ (this does not incur much extra work).
At the end of the function, bv::updatePosCache is called. It triggers At the end of bv::updateMetrics, bv::updatePosCache is called. It triggers
a repaint of the document with a NullPainter (a painter that does a repaint of the document with a NullPainter (a painter that does
nothing). This has the effect of caching all insets positions. nothing). This has the effect of caching all insets positions.
This way of working means that scrolling can be achieved by just
updating anchor_ypos_ and calling bv::processUpdateFlags(Update::ForceDraw).
** Drawing the work area. ** Drawing the work area.
This is done in bv::draw. This method is triggered by a paint event, This is done in bv::draw. This method is triggered by a paint event,