We no longer have to take care of the 8.3 file name limit; this
allows us (a) to introduce longer, meaningful file names, and (b) to
avoid macro names in `#include' lines altogether since some
compilers (most notably Visual C++) doesn't support this properly.
*/*: Replace
#include FOO_H
with
#include <freetype/foo.h>
or something similar. Also update the documentation.
The buffer size FT_MAX_GRAY_SPANS is set to 10 spans, which should be
enough to cover the entire scanline for simple glyphs in most cases:
each slightly slanted edge needs up to two spans, plus a filling span
in-between. This is not new, we used to do it before cb4388783c.
* src/smooth/ftgrays.c (gray_TWorker): Add `spans' and `num_spans'.
(gray_hline, gray_sweep): Implement the span buffering.
(gray_raster_render): Use negative `num_spans' to avoid the direct
mode.
The previous implementation is correct but it is too complex.
The revised algorithm is based on the fact that each split moves
the control points closer to the trisection points on the chord.
The corresponding distances are good surrogates for the curve
deviation from the straight line.
This cubic flattening algorithm is somewhat similar to the conic
algorithm based the distance from the control point to the middle of
the chord. The cubic distances, however, decrease less predictably
but are easy enough to calculate on each step.
* src/smooth/ftgrays.c (gray_render_cubic): Replace the split
condition.
* src/raster/ftraster.c [STANDALONE] (FT_Outline_Get_CBox): Add
function.
[!STANDALONE]: Include FT_OUTLINE_H.
(ft_black_render): Compute CBox and reject glyphs larger than
0xFFFF x 0xFFFF.
* src/smooth/ftgrays.c (gray_raster_render): Reject glyphs larger
than 0xFFFF x 0xFFFF.
This monster commit was created by applying Nikhil's scripts
`docconverter.py' and `markify.py' to all C header and source files,
followed up by minor manual clean-up.
No change in functionality, of course.
I used commit f7419907bc6044b9b7057f9789866426c804ba82 from
https://github.com/nikramakrishnan/freetype-docs.git.
The robust rendering of estra large glyphs came with unbearable cost.
The old way of bisecting should fail but fail faster.
* src/smooth/ftgrays.c (gray_convert_glyph): Switch back to bisecting
in y-direction.
*/* [FT_CONFIG_OPTION_PIC]: Remove all code guarded by this
preprocessor symbol.
*/*: Replace `XXX_GET' macros (which could be either a function in
PIC mode or an array in non-PIC mode) with `xxx' arrays.
* include/freetype/internal/ftpic.h, src/autofit/afpic.c,
src/autofit/afpic.h, src/base/basepic.c, src/base/basepic.h,
src/base/ftpic.c, src/cff/cffpic.c, src/cff/cffpic.h,
src/pshinter/pshpic.c, src/pshinter/pshpic.h, src/psnames/pspic.c,
src/psnames/pspic.h, src/raster/rastpic.c, src/raster/rastpic.h,
src/sfnt/sfntpic.c, src/sfnt/sfntpic.h, src/smooth/ftspic.c,
src/smooth/ftspic.h, src/truetype/ttpic.c, src/truetype/ttpic.h:
Removed.
We used to split large glyphs into horizontal bands and continue
bisecting them still horizontally if that was not enough. This is
guaranteed to fail when a single scanline cannot fit into the
rendering memory pool. Now we bisect the bands vertically so that
the smallest unit is a column of the band height, which is guranteed
to fit into memory.
* src/smooth/ftgrays.c (gray_convert_glyph): Implement it.
At large sizes almost but not exactly horizontal segments can quickly
drain the rendering pool. This patch at least avoids filling the pool
with trivial cells. Beyond this, we can only increase the pool size.
Reported, analyzed, and tested by Colin Fahey.
* src/smooth/ftgrays.c (gray_set_cell): Do not record trivial cells.
* src/smooth/ftgrays.c [STANDALONE] (OVERFLOW_ADD_LONG,
OVERFLOW_SUB_LONG, OVERFLOW_MUL_LONG, NEG_LONG): New macros.
[!STANDALONE]: Include FT_INTERNAL_CALC_H.
(gray_render_cubic): Use those macros where appropriate.
We don't need some divisions if a line segments stays within a single
row or a single column of pixels.
* src/smooth/ftgrays.c (gray_render_line) [FT_LONG64]: Make divisions
conditional.
The algorithm calls `gray_set_cell' at the start of each new contour
or when the contours cross the cell boundaries. Double-checking for
that is wasteful.
* src/smooth/ftgrays.c (gray_set_cell): Remove check for a new cell.
(gray_convert_glyph): Remove initialization introduced by 44b172e88.
* src/smooth/ftgrays.c (gray_move_to): Call `gray_set_cell' directly
instead of...
(gray_start_cell): ... this function, which is removed.
(gray_convert_glyph): Make initial y-coordinate invalid.
It turns out that there is significant cost associated with `FT_Span'
creation and calls to `gray_render_span' because it happerns so
frequently. This removes these steps from our internal use but leaves
it alone for `FT_RASTER_FLAG_DIRECT" to preserve API. The speed gain
is about 5%.
* src/smooth/ftgrays.c (gray_render_span): Removed. The code is
migrated to...
(gray_hline): ... here.
Zero coverage is unlikely (1 out of 256) to warrant checking. This
gives 0.5% speed improvement in dendering simple glyphs.
* src/smooth/ftgrays.c (gray_hline, gray_render_span): Remove checks.
This gives 2% speed improvement in rendering simple glyphs.
* src/smooth/ftgrays.c (TPixmap): Reduced pixmap descriptor with a
pointer to its bottom-left and pitch to be used in...
(gray_TWorker): ... here.
(gray_render_span): Move pixmap flow check from here...
(gray_raster_render): .. to here.
This removes unnecessary complexity of span merging and buffering.
Instead, the spans are rendered as they come, speeding up the
rendering by about 5% percents as a result.
* src/smooth/ftgrays.c [FT_MAX_GRAY_SPANS]: Macro removed.
(gray_TWorker): Remove span buffer and related fields.
(gray_sweep, gray_hline): Updated.
* include/freetype/ftimage.h: Remove documentation note about
`FT_MAX_GRAY_SPANS', which was never in `ftoption.h' and is now gone.
Rasterization sub-banding is utilized at large sizes while using
rather small fixed memory pool. Indeed it is possible to make an
educated guess how much memory is necessary at a given size for a
given glyph. It turns out that, for large majority of European glyphs,
you should store about 8 times more boundary pixels than their height.
Or, vice versa, if your memory pool can hold 800 pixels the band
height should be 100 and you should sub-band anything larger than
that. Should you still run out of memory, FreeType bisects the band
but you have wasted some time. This is what has been implemented in
FreeType since the beginning.
It was overlooked, however, that the top band could grow to twice the
default band size leading to unnecessary memory overflows there. This
commit fixes that. Now the bands are distributed more evenly and
cannot exceed the default size.
Now the magic number 8 is really suitable for rather simple European
scripts. For complex Chinese logograms the magic number should be 13
but that is subject for another day.
* src/smooth/ftgrays.c (gray_convert_glyph): Revise sub-banding
protocol.
* src/smooth/ftgrays.c (TArea): Restore original definition as `int'.
(gray_render_line) [FT_LONG64]: Updated.
(gray_convert_glyph): 32-bit band bisection stack should be 32 bands.
(gray_convert_glyph_inner): Trace successes and failures.
This patch restores original `TCoord' definition as `int' so that the
rendering pool is used more efficiently on LP64 platforms (unix).
* src/smooth/ftgrays.c (gray_TWorker, TCell, gray_TBand): Switch some
fields to `TCoord'.
(gray_find_cell, gray_render_scanline, gray_render_line, gray_hline,
gray_sweep, gray_convert_glyph): Updated.
* src/smooth/ftgrays.c (gray_convert_glyph): Do not use volatile
qualifier.
(gray_raster_render): Move span initializations from here.
(gray_sweep): ... to here and remove unused `target' argument.
* src/smooth/ftgrays.c (gray_init_cells): Remove function.
(gray_TWorker): Remove fields that become local variables.
(gray_raster_render): Move rendering buffer declaration from here.
(gray_convert_glyph): ... to here and update accordingly.
Removing the checks from `gray_hline' shaves 1% off rendering speed.
* src/smooth/ftgrays.c [STANDALONE_]: Duplicate `FT_MIN' and `FT_MAX'.
(gray_TWorker): No need to store `clip_box'.
(gray_hline): Remove unnecessary boundary checks.
(gray_convert_glyph): Move boundary checks from here.
(gray_raster_render): ... to here and consolidate.
* src/smooth/ftgrays.c [STANDALONE_]: Duplicate `FT_Outline_Get_CBox'.
(gray_compute_cbox): Remove this function.
(gray_convert_glyph): Update to use `FT_Outline_Get_CBox'.
The convergence of Bézier flatteners is fast with the deviation
from straight line being assymptotically cut 4-fold on each bisection.
This justifies smaller bisection stack size.
* src/smooth/ftgrays.c (gray_TWorker): Remove common `bez_stack'.
(gray_render_conic): Create and use conic `bez_stack'. Move back the
band analysis from...
(gray_conic_to): ... here.
(gray_render_cubic): Create and use cubic `bez_stack'. Move back the
band analysis from...
(gray_cubic_to): ... here.
(gray_move_to): Updated.
A single decrement counter of segments to draw, instead of an array,
contains all the information necessary to decide when to split and
when to draw a conic segment. The number of splits before each draw is
equal to the number of trailing zeros in the counter.
* src/smooth/ftgrays.c (gray_TWorker): Remove `lev_stack'.
(gray_render_conic): Updated to use decrement counter of segments.
* src/smooth/ftgrays.c (gray_render_conic, gray_render_cubic): Move
band clipping from here.
(gray_conic_to, gray_cubic_to): ... to here.
(gray_rander_line, gray_render_scanline): Initialize variables closer
to their use.
Alexei Podtelezhnikov