strans/font.c

#include "dat.h"
#include <ft2build.h>
#include FT_FREETYPE_H
#include "fn.h"

typedef struct Font Font;
struct Font
{
	FT_Face face;
	int base;
};

static FT_Library lib;
static Font fonts[Maxfonts];
static int nfonts;
static u32int blendtab[2][256];

static u32int
blend(u32int bg, u32int fg, int a)
{
	int r, g, b, inv;

	inv = 255 - a;
	r = ((bg >> 16 & 0xff) * inv + (fg >> 16 & 0xff) * a) / 255;
	g = ((bg >> 8 & 0xff) * inv + (fg >> 8 & 0xff) * a) / 255;
	b = ((bg & 0xff) * inv + (fg & 0xff) * a) / 255;
	return (r << 16) | (g << 8) | b;
}

static int
loadfont(char *path)
{
	FT_Face face;
	Font *f;
	vlong height, pixels;

	if(nfonts >= nelem(fonts))
		return 0;
	if(FT_New_Face(lib, path, 0, &face) != 0){
		fprint(2, "strans: popup: can't load font: %s\n", path);
		return 0;
	}
	height = (vlong)face->ascender - face->descender;
	if(height <= 0 || face->units_per_EM == 0){
		fprint(2, "strans: popup: invalid font metrics: %s\n", path);
		FT_Done_Face(face);
		return 0;
	}
	pixels = (vlong)Fontsz * face->units_per_EM / height;
	if(pixels < 1)
		pixels = 1;
	if(FT_Set_Pixel_Sizes(face, 0, pixels) != 0){
		fprint(2, "strans: popup: can't size font: %s\n", path);
		FT_Done_Face(face);
		return 0;
	}
	f = &fonts[nfonts];
	f->face = face;
	f->base = (vlong)Fontsz * face->ascender / height;
	nfonts++;
	return 1;
}

static void
clearfonts(void)
{
	int i;

	for(i = 0; i < nfonts; i++){
		FT_Done_Face(fonts[i].face);
		fonts[i].face = nil;
	}
	nfonts = 0;
}

int
fontinit(char **path, int npath)
{
	int i, a;

	if(path == nil || npath < 1 || npath > nelem(fonts)){
		fprint(2, "strans: popup: need 1-%d font files\n", nelem(fonts));
		clearfonts();
		return 0;
	}
	if(lib == nil && FT_Init_FreeType(&lib) != 0){
		fprint(2, "strans: popup: can't initialize FreeType\n");
		return 0;
	}
	clearfonts();
	for(i = 0; i < npath; i++){
		if(path[i] == nil || !loadfont(path[i])){
			clearfonts();
			return 0;
		}
	}
	for(a = 0; a < 256; a++){
		blendtab[0][a] = blend(Colbg, Colfg, a);
		blendtab[1][a] = blend(Colsel, Colfg, a);
	}
	return 1;
}

static int
drawglyph(Font *f, u32int *buf, int w, int h, int px, int py)
{
	FT_Bitmap *b;
	FT_GlyphSlot g;
	uchar *row;
	vlong pitch, x0, x1, y0, y1;
	int a, sel, x, xa, xb, y, ya, yb;
	u32int *p;

	g = f->face->glyph;
	b = &g->bitmap;
	if(b->pixel_mode != FT_PIXEL_MODE_GRAY || b->num_grays != 256)
		return 0;
	if(b->width == 0 || b->rows == 0)
		return 1;
	pitch = b->pitch;
	if(pitch < 0)
		pitch = -pitch;
	if(b->buffer == nil || pitch < b->width)
		return 0;
	x0 = (vlong)px + g->bitmap_left;
	y0 = (vlong)py + f->base - g->bitmap_top;
	x1 = x0 + b->width;
	y1 = y0 + b->rows;
	if(x1 <= 0 || y1 <= 0 || x0 >= w || y0 >= h)
		return 1;
	xa = x0 < 0 ? 0 : x0;
	xb = x1 > w ? w : x1;
	ya = y0 < 0 ? 0 : y0;
	yb = y1 > h ? h : y1;
	for(y = ya; y < yb; y++){
		if(b->pitch < 0)
			row = b->buffer + ((vlong)b->rows - 1 - (y - y0)) * pitch;
		else
			row = b->buffer + ((vlong)y - y0) * pitch;
		for(x = xa; x < xb; x++){
			a = row[(vlong)x - x0];
			if(a != 0){
				p = &buf[y * w + x];
				sel = *p == Colsel;
				*p = blendtab[sel][a];
			}
		}
	}
	return 1;
}

void
putfont(u32int *buf, int w, int h, int px, int py, Rune r)
{
	FT_UInt g;
	int f;

	if(buf == nil || w <= 0 || h <= 0)
		return;
	for(f = 0; f < nfonts; f++){
		g = FT_Get_Char_Index(fonts[f].face, r);
		if(g == 0 || FT_Load_Glyph(fonts[f].face, g, FT_LOAD_DEFAULT) != 0 ||
		   FT_Render_Glyph(fonts[f].face->glyph, FT_RENDER_MODE_NORMAL) != 0)
			continue;
		if(drawglyph(&fonts[f], buf, w, h, px, py))
			return;
	}
}