Abbreviations:
bv: BufferView
pm: ParagraphMetrics
-tm::TextMetrics
+tm: TextMetrics
* Questions / Ideas
** SinglePar update
-The flag Update::SinglePar is set in many places but never acted on.
-Instead, metrics update is skipped whenever the recorded height of
-current paragraph did not change and Update::Force was not specified.
-Is it better to keep that (which incurs extra work) or to condition it
-on Update::SinglePar? If the first solution is kept, the flag
-SingleParUpdate shall be removed.
-
-Moreover, I fail to see (yet) where the 'single' part of the program
-is acted on.
+This flag only has an effect in the current BufferView and at
+top-level, but I think it is useful in other views too. Doing this
+will require some work on the update pipeline, though.
** Buffer::change issues
On a related note, what is the semantics of a call to
Buffer::changed(false)? What does the caller mean?
+
** How to avoid redraw with FitCursor when the cursor is already OK?
In this case, we invoke Buffer::change(false) with drawing disabled
* Clean-up of drawing code
-The goal is to make painting with drawing disable fast enough that it
-can be used after every metrics computation. Then we can separate real
-drawing from metrics.
+** Set Row::changed() in a finer way
+
+*** singleParUpdate
+
+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
+their position recomputed.
+
+This is also true when scrolling (how to do that?)
+
+*** redoParagraph
-Other changes are only clean-ups.
+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
+a lot the amount of stuff to redraw.
+
+** Put labels and friends in the Row as elements
+
+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.
** When a paragraph ends with a newline, compute correctly the height of the extra row.
+
** Merging bv::updateMetrics and tm::metrics
While the full metrics computation tries hard to limit the number of
+ transfer all the logic of bv::updateMetrics to tm.
+ Main InsetText should not be special.
-The difficuly 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.
+ Update::Force has been specified
+ Update::FitCursor has been specified and there is a need to scroll
the display.
- + the current paragraph, after rebreak, does not have the same height as in
- existing metrics. Note that the Update::SinglePar flag is *never*
- taken into account.
+ + Update::SinglePar has been specified and the current paragraph has
+ not changed height.
+
+If a computation of metrics has taken place, Force is removed from the
+flags and ForceDraw is added instead.
+
+It is OK to call processUpateFlags several times before an update. In
+this case, the effects are cumulative. processUpdateFlags executes the
+metrics-related actions, but defers the actual drawing to the next
+paint event.
The screen is drawn (with appropriate update strategy), except when
update flag is Update::None.
-** Metrics computation
+** Metrics computation (and nodraw drawing phase)
This is triggered by bv::updateMetrics, which calls tm::redoParagraph for
all visible paragraphs. Some Paragraphs above or below the screen (needed
of text insets, this will invoke recursively tm::metrics, which redoes
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.
+
+At the end of the function, bv::updatePosCache is called. It triggers
+a repaint of the document with a NullPainter (a painter that does
+nothing). This has the effect of caching all insets positions.
** Drawing the work area.
projects / lyx.git / blobdiff