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Re: [ft] Drawing unfilled shapes with FreeType2
From: |
Werner LEMBERG |
Subject: |
Re: [ft] Drawing unfilled shapes with FreeType2 |
Date: |
Sun, 09 Nov 2014 12:40:30 +0100 (CET) |
>> What about using `FT_Stroker_ParseOutline' after transformation of the
>> outline?
>
> I've tried that of course but it doesn't make a difference and I
> don't understand why.
There were some errors in your code, fixed in the attachment, together
with some comments.
Werner
#include <stdio.h>
#include <math.h>
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H
#include FT_OUTLINE_H
#include FT_SYNTHESIS_H
#include FT_STROKER_H
static FT_Library freetype_library = NULL;
#define WIDTH 320
#define HEIGHT 240
// desired stroke thickness in pixels
#define STROKE_THICKNESS 8
#define setvector(pv, px, py) \
(pv).x = ((int) (px)) << 6; \
(pv).y = ((int) (py)) << 6;
#define Float2Fixed(fl) ((FT_Fixed)((fl)*65536.0f))
#define writew(fp, w) \
tmpword = (w); \
fwrite(&tmpword, 2, 1, (fp));
#define writel(fp, l) \
tmplong = (l); \
fwrite(&tmplong, 4, 1, (fp));
int main(int argc,
char *argv[])
{
FT_Stroker stroker;
FT_UInt points, contours;
FT_Outline outline;
FT_BBox bbox;
FT_Bitmap bm;
FT_Vector v;
FT_Matrix m;
FT_Pos bbox_xMin, bbox_yMin;
int x, y;
int xmin, ymin, xmax, ymax;
int pixelwidth, pixelheight, bytewidth;
unsigned char *buf, *ptr;
unsigned char *linebuf;
unsigned short tmpword;
unsigned long tmplong;
FILE *fp;
FT_Init_FreeType(&freetype_library);
memset(&outline, 0, sizeof(FT_Outline));
FT_Outline_New(freetype_library, 1024, 512, &outline);
// It would be more efficient to directly construct an FT_Outline object
// instead of doing that with a zero-radius stroker -- the latter produces
// three additional overlapping points per point.
FT_Stroker_New(freetype_library, &stroker);
setvector(v, 0, 0);
FT_Stroker_BeginSubPath(stroker, &v, 1);
FT_Stroker_LineTo(stroker, &v);
setvector(v, 0, 0);
FT_Stroker_LineTo(stroker, &v);
setvector(v, 0, HEIGHT);
FT_Stroker_LineTo(stroker, &v);
setvector(v, WIDTH, HEIGHT);
FT_Stroker_LineTo(stroker, &v);
setvector(v, WIDTH, 0);
FT_Stroker_LineTo(stroker, &v);
setvector(v, 0, 0);
FT_Stroker_LineTo(stroker, &v);
FT_Stroker_EndSubPath(stroker);
// Construct an outline from the stroker.
FT_Stroker_GetBorderCounts(stroker,
FT_STROKER_BORDER_LEFT,
&points,
&contours);
outline.n_points = 0;
outline.n_contours = 0;
FT_Stroker_ExportBorder(stroker,
FT_STROKER_BORDER_LEFT,
&outline);
// Transform the outline.
m.xx = Float2Fixed(1.0);
m.xy = Float2Fixed(0.0);
m.yx = Float2Fixed(0.0);
m.yy = Float2Fixed(0.5);
FT_Outline_Transform(&outline, &m);
// Redo the stroking operation, this time with a non-zero radius.
FT_Stroker_Set(stroker,
(int) ((double) STROKE_THICKNESS * 32.0),
FT_STROKER_LINECAP_ROUND,
FT_STROKER_LINEJOIN_ROUND,
0);
FT_Stroker_ParseOutline(stroker, &outline, 0);
// Again construct an outline from the stroker.
FT_Stroker_GetCounts(stroker,
&points,
&contours);
outline.n_points = 0;
outline.n_contours = 0;
FT_Stroker_Export(stroker, &outline);
FT_Stroker_Done(stroker);
FT_Outline_Get_BBox(&outline, &bbox);
bbox_xMin = bbox.xMin;
bbox_yMin = bbox.yMin;
FT_Outline_Translate(&outline, -bbox_xMin, -bbox_yMin);
// Directly manipulating the bbox is much cheaper than calling
// `FT_Outline_Get_BBox' again.
bbox.xMin = 0;
bbox.yMin = 0;
bbox.xMax -= bbox_xMin;
bbox.yMax -= bbox_yMin;
xmin = bbox.xMin >> 6;
ymin = bbox.yMin >> 6;
xmax = bbox.xMax >> 6;
ymax = bbox.yMax >> 6;
if (bbox.xMax & 0x3f)
xmax++;
if (bbox.yMax & 0x3f)
ymax++;
pixelwidth = xmax - xmin;
pixelheight = ymax - ymin;
buf = calloc(pixelwidth * pixelheight, 1);
memset(&bm, 0, sizeof(FT_Bitmap));
bm.rows = pixelheight;
bm.width = pixelwidth;
bm.pitch = pixelwidth;
bm.buffer = buf;
bm.num_grays = 256;
bm.pixel_mode = FT_PIXEL_MODE_GRAY;
FT_Outline_Get_Bitmap(freetype_library, &outline, &bm);
fp = fopen("dump.bmp", "wb");
bytewidth = pixelwidth * 3 + pixelwidth % 4;
linebuf = malloc(bytewidth);
writew(fp, 0x4D42);
writel(fp, bytewidth * pixelheight + 54);
writel(fp, 0);
writel(fp, 0x36);
writel(fp, 0x28);
writel(fp, pixelwidth);
writel(fp, pixelheight);
writew(fp, 1);
writew(fp, 24);
writel(fp, 0);
writel(fp, 0);
writel(fp, 0);
writel(fp, 0);
writel(fp, 0);
writel(fp, 0);
ptr = buf + pixelheight * pixelwidth;
for (y = 0; y < pixelheight; y++)
{
unsigned char *l = linebuf;
ptr -= pixelwidth;
for (x = 0; x < pixelwidth; x++)
{
unsigned long rgb = ptr[x] * 65793;
*l++ = (unsigned char) (rgb & 0x0000ff);
*l++ = (unsigned char) ((rgb & 0x00ff00) >> 8);
*l++ = (unsigned char) ((rgb & 0xff0000) >> 16);
}
fwrite(linebuf, bytewidth, 1, fp);
}
fclose(fp);
free(linebuf);
free(buf);
FT_Outline_Done(freetype_library, &outline);
FT_Done_FreeType(freetype_library);
return 0;
}