X-Git-Url: https://git.lyx.org/gitweb/?a=blobdiff_plain;f=development%2FPAINTING_ANALYSIS;h=a506371965a6b9af49744526520fdca6277959de;hb=7b7322b831f1bd916293b0e20c827db429ed3773;hp=f734edb3b012aea63443808e1aa3fdbf4ecfdab7;hpb=b4294a7b06d1d9436efdde3df6ce4b0732620e9e;p=lyx.git

diff --git a/development/PAINTING_ANALYSIS b/development/PAINTING_ANALYSIS
index f734edb3b0..a506371965 100644
--- a/development/PAINTING_ANALYSIS
+++ b/development/PAINTING_ANALYSIS
@@ -11,7 +11,7 @@ Please keep this file up to date as the code evolves!!!
 Abbreviations:
 bv: BufferView
 pm: ParagraphMetrics
-tm::TextMetrics
+tm: TextMetrics
 
 * Questions / Ideas
 
@@ -20,15 +20,9 @@ following section. Some actions are proposed.
 
 ** 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
 
@@ -40,6 +34,7 @@ a good value? NoScreenUpdate?
 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
@@ -60,13 +55,29 @@ cursor.
 
 * 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
@@ -76,7 +87,7 @@ insets. We should re-use the bv::updateMetrics logic:
  + 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.
 
 
@@ -109,15 +120,22 @@ DecorationUpdate). It triggers a recomputation of the metrics when either:
  + 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
@@ -127,6 +145,12 @@ 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.
 
+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.