strans/font.c

#include "dat.h"
#include <pango/pangocairo.h>
#include "fn.h"

static PangoFontMap *fontmap;
static PangoContext *context;
static PangoLayout *layout;

static void
textclear(void)
{
	if(layout != nil)
		g_object_unref(layout);
	if(context != nil)
		g_object_unref(context);
	if(fontmap != nil)
		g_object_unref(fontmap);
	layout = nil;
	context = nil;
	fontmap = nil;
}

static void
setfont(void)
{
	PangoFontDescription *font;
	PangoRectangle r;
	int size;

	font = pango_font_description_new();
	pango_font_description_set_family(font, "sans");
	pango_font_description_set_absolute_size(font, Fontsz * PANGO_SCALE);
	pango_layout_set_font_description(layout, font);
	pango_layout_set_text(layout, "Mg", -1);
	pango_layout_get_pixel_extents(layout, nil, &r);
	if(r.height > 0){
		/* Fontsz is the popup row height, not a point size. */
		size = Fontsz * PANGO_SCALE * Fontsz / r.height;
		pango_font_description_set_absolute_size(font, max(size, PANGO_SCALE));
		pango_layout_set_font_description(layout, font);
	}
	pango_font_description_free(font);
}

int
textinit(char **path, int npath)
{
	GError *err;
	int i;

	textclear();
	if(path == nil || npath < 1 || npath > Maxfonts){
		fprint(2, "strans: popup: need 1-%d font files\n", Maxfonts);
		return 0;
	}
	fontmap = pango_cairo_font_map_new();
	if(fontmap == nil){
		fprint(2, "strans: popup: can't initialize PangoCairo\n");
		return 0;
	}
	for(i = 0; i < npath; i++){
		if(path[i] == nil){
			fprint(2, "strans: popup: invalid font file\n");
			textclear();
			return 0;
		}
		err = nil;
		if(!pango_font_map_add_font_file(fontmap, path[i], &err)){
			fprint(2, "strans: popup: can't register font: %s: %s\n",
				path[i], err == nil ? "unknown error" : err->message);
			if(err != nil)
				g_error_free(err);
			textclear();
			return 0;
		}
	}
	pango_cairo_font_map_set_resolution(PANGO_CAIRO_FONT_MAP(fontmap), 96);
	context = pango_font_map_create_context(fontmap);
	if(context != nil)
		layout = pango_layout_new(context);
	if(context == nil || layout == nil){
		fprint(2, "strans: popup: can't create text layout\n");
		textclear();
		return 0;
	}
	pango_layout_set_single_paragraph_mode(layout, TRUE);
	setfont();
	return 1;
}

static int
settext(Str *s)
{
	char utf[Maxutf];
	int n;

	if(layout == nil || s == nil || s->n <= 0)
		return 0;
	n = stoutf(s, utf, sizeof utf);
	pango_layout_set_text(layout, utf, n);
	return n > 0;
}

static void
textextents(PangoRectangle *r)
{
	PangoRectangle ink, logical;
	int x0, y0, x1, y1;

	pango_layout_get_pixel_extents(layout, &ink, &logical);
	x0 = min(ink.x, logical.x);
	y0 = min(ink.y, logical.y);
	x1 = max(ink.x + ink.width, logical.x + logical.width);
	y1 = max(ink.y + ink.height, logical.y + logical.height);
	r->x = x0;
	r->y = y0;
	r->width = max(x1 - x0, 0);
	r->height = max(y1 - y0, 0);
}

int
textwidth(Str *s)
{
	PangoRectangle r;

	if(!settext(s))
		return 0;
	textextents(&r);
	return r.width;
}

void
textdraw(u32int *buf, int w, int h, int x, int y, Str *s)
{
	PangoRectangle r;
	cairo_surface_t *surface;
	cairo_t *cr;
	int stride;

	if(buf == nil || w <= 0 || h <= 0 || !settext(s))
		return;
	stride = cairo_format_stride_for_width(CAIRO_FORMAT_RGB24, w);
	if(stride < 0 || (vlong)stride != (vlong)w * sizeof buf[0])
		return;
	surface = cairo_image_surface_create_for_data((uchar*)buf,
		CAIRO_FORMAT_RGB24, w, h, stride);
	if(cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS){
		cairo_surface_destroy(surface);
		return;
	}
	cairo_surface_mark_dirty(surface);
	cr = cairo_create(surface);
	if(cairo_status(cr) == CAIRO_STATUS_SUCCESS){
		pango_cairo_update_layout(cr, layout);
		textextents(&r);
		/* A fallback face must not paint into another popup row. */
		cairo_rectangle(cr, 0, y, w, Fontsz);
		cairo_clip(cr);
		cairo_move_to(cr, x - r.x, y + (Fontsz - r.height) / 2 - r.y);
		cairo_set_source_rgb(cr, 0, 0, 0);
		pango_cairo_show_layout(cr, layout);
	}
	cairo_destroy(cr);
	cairo_surface_flush(surface);
	cairo_surface_destroy(surface);
}