282 lines
9.8 KiB
C++
282 lines
9.8 KiB
C++
//-----------------------------------------------------------------------------
|
|
// Routines to read a TrueType font as vector outlines, and generate them
|
|
// as entities, since they're always representable as either lines or
|
|
// quadratic Bezier curves.
|
|
//
|
|
// Copyright 2016 whitequark, Peter Barfuss.
|
|
//-----------------------------------------------------------------------------
|
|
#include <ft2build.h>
|
|
#include FT_FREETYPE_H
|
|
#include FT_OUTLINE_H
|
|
#include FT_ADVANCES_H
|
|
|
|
/* Yecch. Irritatingly, you need to do this nonsense to get the error string table,
|
|
since nobody thought to put this exact function into FreeType itsself. */
|
|
#undef __FTERRORS_H__
|
|
#define FT_ERRORDEF(e, v, s) { (e), (s) },
|
|
#define FT_ERROR_START_LIST
|
|
#define FT_ERROR_END_LIST { 0, NULL }
|
|
|
|
struct ft_error {
|
|
int err;
|
|
const char *str;
|
|
};
|
|
|
|
static const struct ft_error ft_errors[] = {
|
|
#include FT_ERRORS_H
|
|
};
|
|
|
|
extern "C" const char *ft_error_string(int err) {
|
|
const struct ft_error *e;
|
|
for(e = ft_errors; e->str; e++)
|
|
if(e->err == err)
|
|
return e->str;
|
|
return "Unknown error";
|
|
}
|
|
|
|
/* Okay, we're done with that. */
|
|
#undef FT_ERRORDEF
|
|
#undef FT_ERROR_START_LIST
|
|
#undef FT_ERROR_END_LIST
|
|
|
|
#undef HAVE_STDINT_H /* no thanks, we have our own config.h */
|
|
|
|
#include "solvespace.h"
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Get the list of available font filenames, and load the name for each of
|
|
// them. Only that, though, not the glyphs too.
|
|
//-----------------------------------------------------------------------------
|
|
TtfFontList::TtfFontList() {
|
|
FT_Init_FreeType(&fontLibrary);
|
|
}
|
|
|
|
TtfFontList::~TtfFontList() {
|
|
FT_Done_FreeType(fontLibrary);
|
|
}
|
|
|
|
void TtfFontList::LoadAll() {
|
|
if(loaded) return;
|
|
|
|
for(const std::string &font : GetFontFiles()) {
|
|
TtfFont tf = {};
|
|
tf.fontFile = font;
|
|
if(tf.LoadFromFile(fontLibrary))
|
|
l.Add(&tf);
|
|
}
|
|
|
|
// Sort fonts according to their actual name, not filename.
|
|
std::sort(&l.elem[0], &l.elem[l.n],
|
|
[](const TtfFont &a, const TtfFont &b) { return a.name < b.name; });
|
|
|
|
// Filter out fonts with the same family and style name. This is not
|
|
// strictly necessarily the exact same font, but it will almost always be.
|
|
TtfFont *it = std::unique(&l.elem[0], &l.elem[l.n],
|
|
[](const TtfFont &a, const TtfFont &b) { return a.name == b.name; });
|
|
l.RemoveLast(&l.elem[l.n] - it);
|
|
|
|
// TODO: identify fonts by their name and not filename, which may change
|
|
// between OSes.
|
|
|
|
loaded = true;
|
|
}
|
|
|
|
void TtfFontList::PlotString(const std::string &font, const std::string &str,
|
|
SBezierList *sbl, Vector origin, Vector u, Vector v)
|
|
{
|
|
LoadAll();
|
|
|
|
TtfFont *tf = std::find_if(&l.elem[0], &l.elem[l.n],
|
|
[&](const TtfFont &tf) { return tf.FontFileBaseName() == font; });
|
|
|
|
if(!str.empty() && tf != &l.elem[l.n]) {
|
|
tf->PlotString(str, sbl, origin, u, v);
|
|
} else {
|
|
// No text or no font; so draw a big X for an error marker.
|
|
SBezier sb;
|
|
sb = SBezier::From(origin, origin.Plus(u).Plus(v));
|
|
sbl->l.Add(&sb);
|
|
sb = SBezier::From(origin.Plus(v), origin.Plus(u));
|
|
sbl->l.Add(&sb);
|
|
}
|
|
}
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Return the basename of our font filename; that's how the requests and
|
|
// entities that reference us will store it.
|
|
//-----------------------------------------------------------------------------
|
|
std::string TtfFont::FontFileBaseName() const {
|
|
std::string baseName = fontFile;
|
|
size_t pos = baseName.rfind(PATH_SEP);
|
|
if(pos != std::string::npos)
|
|
return baseName.erase(0, pos + 1);
|
|
return "";
|
|
}
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Load a TrueType font into memory. We care about the curves that define
|
|
// the letter shapes, and about the mappings that determine which glyph goes
|
|
// with which character.
|
|
//-----------------------------------------------------------------------------
|
|
bool TtfFont::LoadFromFile(FT_Library fontLibrary) {
|
|
FT_Open_Args args = {};
|
|
args.flags = FT_OPEN_PATHNAME;
|
|
args.pathname = &fontFile[0]; // FT_String is char* for historical reasons
|
|
|
|
// We don't use ssfopen() here to let freetype do its own memory management.
|
|
// This is OK because on Linux/OS X we just delegate to fopen and on Windows
|
|
// we only look into C:\Windows\Fonts, which has a known short path.
|
|
if(int fterr = FT_Open_Face(fontLibrary, &args, 0, &fontFace)) {
|
|
dbp("freetype: loading font from file '%s' failed: %s",
|
|
fontFile.c_str(), ft_error_string(fterr));
|
|
return false;
|
|
}
|
|
|
|
if(int fterr = FT_Select_Charmap(fontFace, FT_ENCODING_UNICODE)) {
|
|
dbp("freetype: loading unicode CMap for file '%s' failed: %s",
|
|
fontFile.c_str(), ft_error_string(fterr));
|
|
FT_Done_Face(fontFace);
|
|
return false;
|
|
}
|
|
|
|
name = std::string(fontFace->family_name) +
|
|
" (" + std::string(fontFace->style_name) + ")";
|
|
return true;
|
|
}
|
|
|
|
typedef struct OutlineData {
|
|
Vector origin, u, v; // input parameters
|
|
SBezierList *beziers; // output bezier list
|
|
float factor; // ratio between freetype and solvespace coordinates
|
|
FT_Pos bx; // x offset of the current glyph
|
|
FT_Pos px, py; // current point
|
|
} OutlineData;
|
|
|
|
static Vector Transform(OutlineData *data, FT_Pos x, FT_Pos y) {
|
|
Vector r = data->origin;
|
|
r = r.Plus(data->u.ScaledBy((float)(data->bx + x) * data->factor));
|
|
r = r.Plus(data->v.ScaledBy((float)y * data->factor));
|
|
return r;
|
|
}
|
|
|
|
static int MoveTo(const FT_Vector *p, void *cc)
|
|
{
|
|
OutlineData *data = (OutlineData *) cc;
|
|
data->px = p->x;
|
|
data->py = p->y;
|
|
return 0;
|
|
}
|
|
|
|
static int LineTo(const FT_Vector *p, void *cc)
|
|
{
|
|
OutlineData *data = (OutlineData *) cc;
|
|
SBezier sb = SBezier::From(
|
|
Transform(data, data->px, data->py),
|
|
Transform(data, p->x, p->y));
|
|
data->beziers->l.Add(&sb);
|
|
data->px = p->x;
|
|
data->py = p->y;
|
|
return 0;
|
|
}
|
|
|
|
static int ConicTo(const FT_Vector *c, const FT_Vector *p, void *cc)
|
|
{
|
|
OutlineData *data = (OutlineData *) cc;
|
|
SBezier sb = SBezier::From(
|
|
Transform(data, data->px, data->py),
|
|
Transform(data, c->x, c->y),
|
|
Transform(data, p->x, p->y));
|
|
data->beziers->l.Add(&sb);
|
|
data->px = p->x;
|
|
data->py = p->y;
|
|
return 0;
|
|
}
|
|
|
|
static int CubicTo(const FT_Vector *c1, const FT_Vector *c2, const FT_Vector *p, void *cc)
|
|
{
|
|
OutlineData *data = (OutlineData *) cc;
|
|
SBezier sb = SBezier::From(
|
|
Transform(data, data->px, data->py),
|
|
Transform(data, c1->x, c1->y),
|
|
Transform(data, c2->x, c2->y),
|
|
Transform(data, p->x, p->y));
|
|
data->beziers->l.Add(&sb);
|
|
data->px = p->x;
|
|
data->py = p->y;
|
|
return 0;
|
|
}
|
|
|
|
static const FT_Outline_Funcs outline_funcs = {
|
|
MoveTo, LineTo, ConicTo, CubicTo, 0, 0
|
|
};
|
|
|
|
void TtfFont::PlotString(const std::string &str,
|
|
SBezierList *sbl, Vector origin, Vector u, Vector v)
|
|
{
|
|
FT_Pos dx = 0;
|
|
for(char32_t chr : ReadUTF8(str)) {
|
|
uint32_t gid = FT_Get_Char_Index(fontFace, chr);
|
|
if (gid == 0) {
|
|
dbp("freetype: CID-to-GID mapping for CID 0x%04x failed: %s; using CID as GID",
|
|
chr, ft_error_string(gid));
|
|
}
|
|
|
|
FT_F26Dot6 scale = fontFace->units_per_EM;
|
|
if(int fterr = FT_Set_Char_Size(fontFace, scale, scale, 72, 72)) {
|
|
dbp("freetype: cannot set character size: %s",
|
|
ft_error_string(fterr));
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Stupid hacks:
|
|
* - if we want fake-bold, use FT_Outline_Embolden(). This actually looks
|
|
* quite good.
|
|
* - if we want fake-italic, apply a shear transform [1 s s 1 0 0] here using
|
|
* FT_Set_Transform. This looks decent at small font sizes and bad at larger
|
|
* ones, antialiasing mitigates this considerably though.
|
|
*/
|
|
if(int fterr = FT_Load_Glyph(fontFace, gid, FT_LOAD_NO_BITMAP | FT_LOAD_NO_HINTING)) {
|
|
dbp("freetype: cannot load glyph (gid %d): %s",
|
|
gid, ft_error_string(fterr));
|
|
return;
|
|
}
|
|
|
|
/* A point that has x = xMin should be plotted at (dx0 + lsb); fix up
|
|
* our x-position so that the curve-generating code will put stuff
|
|
* at the right place.
|
|
*
|
|
* There's no point in getting the glyph BBox here - not only can it be
|
|
* needlessly slow sometimes, but because we're about to render a single glyph,
|
|
* what we want actually *is* the CBox.
|
|
*
|
|
* This is notwithstanding that this makes extremely little sense, this
|
|
* looks like a workaround for either mishandling the start glyph on a line,
|
|
* or as a really hacky pseudo-track-kerning (in which case it works better than
|
|
* one would expect! especially since most fonts don't set track kerning).
|
|
*/
|
|
FT_BBox cbox;
|
|
FT_Outline_Get_CBox(&fontFace->glyph->outline, &cbox);
|
|
FT_Pos bx = dx - cbox.xMin;
|
|
// Yes, this is what FreeType calls left-side bearing.
|
|
// Then interchangeably uses that with "left-side bearing". Sigh.
|
|
bx += fontFace->glyph->metrics.horiBearingX;
|
|
|
|
OutlineData data = {};
|
|
data.origin = origin;
|
|
data.u = u;
|
|
data.v = v;
|
|
data.beziers = sbl;
|
|
data.factor = 1.0f/(float)scale;
|
|
data.bx = bx;
|
|
if(int fterr = FT_Outline_Decompose(&fontFace->glyph->outline, &outline_funcs, &data)) {
|
|
dbp("freetype: bezier decomposition failed (gid %d): %s",
|
|
gid, ft_error_string(fterr));
|
|
}
|
|
|
|
// And we're done, so advance our position by the requested advance
|
|
// width, plus the user-requested extra advance.
|
|
dx += fontFace->glyph->advance.x;
|
|
}
|
|
}
|