** Buffer::change issues
When calling Buffer::changed outside of bv::processUpdateFlags,
-how do we now that the update strategy is set correctly? It is
+how do we know that the update strategy is set correctly? It is
possible to reset the strategy at the end of bv::draw. What would be
a good value? NoScreenUpdate?
On a related note, what is the semantics of a call to
Buffer::changed(false)? What does the caller mean?
-** What happens with FitCursor when the cursor is already OK?
+** How to avoid redraw with FitCursor when the cursor is already OK?
-In this case, we invoke Buffer::change(false) with drawing disabled,
-which means that the paint machinery is invoked to update inset
-positions.
+In this case, we invoke Buffer::change(false) with drawing disabled
+and NoScreenUpdate strategy.
-Actually, this was added as part of the horizontal scrolling GSoC
-work. We need to investigate how costly this is.
+In the draw phase, bv::checkCursorScrollOffset (the horizontal
+scrolling machinery) will change the strategy to FullScreenUpdate if
+the current row needs further scrolling.
+When the update strategy it kept to NoScreenUpdate, there is currently
+a no-draw full repaint, which should not be necessary. It would be
+possible to avoid that if the call to checkCursorScrollOffset was done
+in bv::processUpdateFlags instead of bv::draw.
-* Proposals
+The global idea would be to extend FitCursor to cover also horizontal
+cursor.
-** get rid of pm::insetDimension.
-The information contained there is already in bv::coordCache.
+* Clean-up of drawing code
-Effect: only code simplification.
+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 inset position during metrics phase
+Other changes are only clean-ups.
-This implies to set inset positions relative to outer isnet during
-metrics phase and then in a second loop to descend into insets and
-update positions correctly.
+** When a paragraph ends with a newline, compute correctly the height of the extra row.
+** Rewrite TextMetrics::editXY, checkInsetHit using row information (getPosNearX)?
-Effect: avoid going through the painter machinery when it is not necessary.
+ The helper version should return a Row::Element instead of an InsetTable.
+
+** Remember rtl status in the row object
+
+This will avoid to pass a Paragraph object to methods that do not need it.
+
+** Rewrite RowPainter::paintSelection using row information
+
+Currently it uses some very complicated code. It should be possible to
+reuse the logic of paintStringAndSel.
+
+** Set inset position during metrics phase
+
+In order to do that, a no-paint drawing will be initiated after every
+redoParagraph. This code path will need to be made as fast as possible.
+
+Effect: avoid depending on actual drawing having taken place. In turn,
+it will allow to do drawing on paint events, like any reasonable
+application would do.
+
+** Cleanup after complete metrics
+ Then the following can be done:
+ + remove hack in InsetMathNest::drawSelection
+ + remove painting when not inside in drawParagraph
+ + remove Cursor::inCoordCache?
+
+** Use Row for MathData
+
+It may not be so difficult. Implement x2pos and pos2x from
+the TM:cursorX and TM::getPosNearX, and use them for both text and
+math.
+
+Will the strings display OK if drawing string-wise?
+
+Then it would be possible to streamline drawing with disabled painter.
+
+** Paint directly to screen
+
+Instead of using an intermediary pixmap. I have no idea of how
+difficult it will prove.
+One benefit will be that subpixel aliasing will work again (#9972)
** Merging bv::updateMetrics and tm::metrics
does not try any such optimization. This can be very bad for very tall
insets. We should re-use the bv::updateMetrics logic:
+ transfer all the logic of bv::updateMetrics to tm.
- + Main InsetText should not be special.
-
-** Metrics outside of visible area
+ + Main InsetText should not be special.
-Currently metrics are computed for current visible paet of text, the
-page above and the page below. It should be possible to compute hidden
-rows ony on demand, although it might be a bit slow.
+The difficuly 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.
-There was a proposal to always compute _all_ rows, but this may become
-expensive for large files. This would though help scrolling.
+* Description of current drawing mechanism
-* Two phase drawing
+** Two stage drawing
There are two parts to drawing the work area:
+ the metrics phase computes the size of insets and breaks the
paragraphs into rows. It stores the dimension of insets (both
- normal and math) in bv::coordCache, and the size of normal
- insets in pm::insetDimension.
+ normal and math) in bv::coordCache.
+ the drawing phase draws the contents and caches the inset
positions. Since the caching of positions is useful in itself,
thing we want is to cache inset positions
(Painter::setDrawingEnabled).
-
The machinery is controlled via bv::processUpdateFlags. This method is
called at the end of bv::mouseEventDispatch and in
GuiApplication::dispatch, via the updateCurrentView method. There are
update flag is Update::None.
-* Metrics computation
+** Metrics computation
This is triggered by bv::updateMetrics, which calls tm::redoParagraph for
- + all visible paragraphs
- + paragraph above the screen (up to one page)
- + paragraphs below the screen (up to one page again)
-
-The paragraphs outside of the screen are required to make PageUp/Down
-work.
+all visible paragraphs. Paragraphs above or below the screen (needed
+for page up/down) and computed as needed.
tm::redoParagraph will call Inset::metrics for each inset. In the case
of text insets, this will invoke recursively tm::metrics, which redoes
all the paragraphs of the inset.
-* Drawing the work area.
+** Drawing the work area.
This is done in bv::draw. This method is triggered mainly by
Buffer::changed, which draws all the work areas that show the given buffer.
projects / lyx.git / blobdiff