While it is recommended to have an explicit point at each curve
extrema, they might be missing or outline could be rotated. This
leads to excessive bisections in raster to find them. This change
helps to decrease the number of bisections. The scanline
intersections remain monotonous, of course.
* src/raster/ftraster.c (Conic_To, Cubic_To): Check that control
points cross the scanlines to bisect.
This reduces the code duplication.
* src/raster/ftraster.c (Function_Sweep_Span): Change signature.
(Vertical_Sweep_Drop, Horizontal_Sweep_Drop): Focus on pixel setting
and move duplicated the dropout control logic to...
(Draw_Sweep): ... this function and refactor.
(Vertical_Sweep_Span, Horizontal_Sweep_Span): Minor.
This results in noticeable performance improvement.
* src/raster/ftraster.c (Insert_Y_Turns): All bottom y-turns are still
sorted and stored; only the maximum top y-turn is recorded now. The
function is renamed.
(End_Profile): Updated accordingly.
(Convert_Glyph): Reserve space for the top value.
* src/raster/ftraster.c (black_TWorker): Remove the fresh flag.
(New_Profile): Set the starting scanline here based on the current
coordinate and initialize the joint crossing if necessary.
(Line_Up, Bezier_Up): Do not deal with fresh and joint starts at all.
(Line_Down, Bezier_Down): Simplify.
(Conic_To, Cubic_To): Update the current coordinate after each
subsection.
* src/raster/ftraster.c (Line_Up, Bezier_Up): Deal with the scanline
joints directly based on the initial y-coordinate.
(New_Profile, black_TWorker): Remove the boolean flag.
* src/raster/ftraster.c (black_TWorker): Store signed maximum indexes
in both directions instead of unsigned dimensions of the original bitmap.
(*_Sweep_*, Render_Glyph, ft_black_render): Updated all users.
* src/raster/ftraster.c (TProfile): Get rid of `countL`.
(Draw_Sweep): Use `start` for countdown to activation.
(Horizontal_Sweep_Drop, Vertical_Sweep_Drop): Rely on `height` and
`offset` to verify profile ends for the stub detection.
* src/raster/ftraster.c (s/Sort/Increment): Rename this function to
reflect its true purpose, delete exhausted profiles here...
(Draw_Sweep): ... instead of here.
While curving close to a pixel center, vertical and horizontal pass
might split the curve differently and cause a rare dropout. This
makes the split condition invariant of the sweep direction and more
robust.
* src/raster/ftraster.c (Bezier_Up): Modify the split condition.
The jitter exception used to be applied when two neighboring pixels
were barely inside the outline. One the left one was turned on then,
which contradicts the OpenType specifications. Intended to remove
glitches, it caused disappearing lines and was softened by adding an
exception to the exception (#54589).
* src/raster/ftraster.c (Vertical_Sweep_Span): Drop the jitter exception.
* src/raster/ftraster.c (Draw_Sweep): Use y-turns to set the range,
correctly set the initial position, directly loop through y_turns,
and remove a 5-gray remnant at exit.
This is mostly cosmetic and removes a few casts, plus Short is
promoted to Int in calculations anyway.
* src/raster/ftraster.c (Vertical_Sweep_Init, Vertical_Sweep_Span,
Vertical_Sweep_Drop, Horizontal_Sweep_Init, Horizontal_Sweep_Span,
Horizontal_Sweep_Drop, Draw_Sweep): Mostly s/Short/Int/ and remove
casting.
This only helps to delay the pool overflow and bisections to larger
sizes and benefits only very intricate glyphs at reasonable sizes.
* src/raster/ftraster.c (TProfile): Use Int instead of Long or PLong
when it is sufficient.
(New_Profile, End_Profuile, Bezier_Up, Sort): Updated accordingly.
* src/raster/ftraster.c (TProfile): Include the variable array member
and repackage with pointers first.
(New_Profile): Advance the top using the variable array pointer.
These ancient builtins have been supported by clang since 2013. We
condition it somewhat stricter but still around 2017. This is more
portable than `__has_builtin`. Fixes#1260.
* src/raster/ftraster.c (New_Profile): Set important fields only and
delay setting `gProfile` until...
(End_Profile): ... it is checked to be valid here.
(Convert_Glyph): Updated.
This fixes a subtle bug when the last profile in a contour was not
properly short-circuited if it was still empty at `End_Profile`.
We finalize all linking in `Finalize_Profile_List` now and do nothing
else there. The turns are added in `End_Profile`.
* src/raster/ftraster.c (Insert_Y_Turn): Moved up unchanged.
(End_Profile): Take care of turns but set only preliminary linking.
(Finalize_Profile_Table): Take care of linking and null-termination.
(Convert_Glyph): Adjusted accordingly.
* src/raster/ftraster.c (End_Profile): Do not initiate next profile.
(New_Profile): Fully initiate new profile.
(Convert_Glyph): Clean up variables, initialize `fProfile` here.
Alexei Podtelezhnikov