On Dec 17, 2007, at 1:34 AM, Werner LEMBERG wrote:
Referenced to ftgray.c's comments, I have compile `ftgrays' with the
_STANDALONE_ macro defined. [...] My question is how to us this
lib after compile it? Anybody would give a usage demo?
I believe that such a demo usage has never been given on the list. In
case someone can provide this I would be glad to add it as a very
simple demo to the ft2demos bundle.
I'm not sure if this is helpful, since I don't define _STANDALONE_, I
use the whole FreeType library; but I do use a callback function with
ft_raster_flag_direct. The following code works with FreeType version
2.1.4 (sorry, haven't updated for a while).
params.flags = ft_raster_flag_aa | ft_raster_flag_direct;
params.gray_spans = WenlinGrayRenderSpan; // callback
wenlinGrayTarget = &ttMap;
FT_Outline_Render(ttEngine, &ftOutline, ¶ms);
static void WenlinGrayRenderSpan(int y, int count, FT_Span* spans,
void *raster)
/* Callback function.
See FT_Raster_Span_Func in ftimage.h, and model gray_render_span
() in ftgrays.c
The original fourth parameter was "PRaster", but that's only
defined in ftgrays.c,
so we just set wenlinGrayTarget to point to the bitmap (same as
raster->target).
The difference from the original function is that we require
that the new value
for a pixel ("coverage") is "darker" (numerically greater) than
the current
value; if not darker, keep the current color. This allows us to
rasterize Hanzi
one stroke at a time; otherwise, the anti-aliasing looks wrong
when strokes overlap. */
{
FT_Bitmap *map = wenlinGrayTarget; // = &raster->target;
size_t scanlineOffset, offsetLimit;
/* First of all, compute the scanline offset. */
if (map->pitch >= 0) {
if (y + 1 > map->rows) {
return;
}
scanlineOffset = (map->rows - 1 - y) * map->pitch;
}
else {
scanlineOffset = y * (0 - map->pitch);
}
/* Make it bomb-proof, don't write outside bitmap! */
offsetLimit = map->width * map->rows;
if (scanlineOffset >= offsetLimit) {
SorryGenericWarning("WenlinGrayRenderSpan");
return;
}
for ( ; count > 0; count--, spans++) {
uc c = spans->coverage;
if (c) {
size_t ofs = scanlineOffset + spans->x;
size_t len = spans->len;
if (ofs + len <= offsetLimit) {
while (len--) {
// This test is unique to the Wenlin version.
if (c > map->buffer[ofs]) {
map->buffer[ofs] = c;
}
++ofs;
}
}
}
}
} // WenlinGrayRenderSpan
文林 Wenlin Institute, Inc.Software for Learning Chinese
E-mail: [EMAIL PROTECTED] Web: http://www.wenlin.com
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