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font: initial support for double-width *and* color emoji glyphs

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Fonts are now loaded with FT_LOAD_COLOR and we recognize and support
the FT_PIXEL_MODE_BGRA pixel mode.

This is mapped to a CAIRO_FORMAT_ARGB32 surface, that is blitted
as-is (instead of used as a mask like we do for gray and mono glyphs).

Furthermore, since many emojis are double-width, we add initial
support for double-width glyphs.

These are assumed to always be utf8. When PRINT:ing an utf8 character,
we check its width, and add empty "spacer" cells after the cell with
the multi-column glyph.

When rendering, we render the columns in each row backwards. This
ensures the spacer cells get cleared *before* we render the glyph (so
that we don't end up erasing part of the glyph).

Finally, emoji fonts are usually bitmap fonts with *large*
glyphs. These aren't automatically scaled down. I.e. even if we
request a glyph of 13 pixels, we might end up getting a 100px glyph.

To handle this, fontconfig must be configured to scale bitmap
fonts. When it is, we can look at the 'scalable' and 'pixelsizefixup'
properties, and use these to scale the rendered glyph.
This commit is contained in:
Daniel Eklöf 2019-07-31 18:03:35 +02:00
parent 748a1f229c
commit 858a0d9906
No known key found for this signature in database
GPG key ID: 5BBD4992C116573F
5 changed files with 110 additions and 60 deletions
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30
render.c
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@ -139,6 +139,7 @@ static void
render_cell(struct terminal *term, cairo_t *cr,
struct cell *cell, int col, int row, bool has_cursor)
{
if (cell->attrs.clean)
return;
@ -215,12 +216,31 @@ render_cell(struct terminal *term, cairo_t *cr,
struct font *font = attrs_to_font(term, &cell->attrs);
const struct glyph *glyph = font_glyph_for_utf8(font, cell->c);
if (glyph != NULL) {
cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
if (glyph == NULL)
return;
cairo_save(cr);
cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
double fixup = glyph->pixel_size_fixup;
cairo_translate(
cr,
x + glyph->left / fixup,
y + term->fextents.ascent - glyph->top * fixup);
cairo_scale(cr, fixup, fixup);
if (cairo_image_surface_get_format(glyph->surf) == CAIRO_FORMAT_ARGB32) {
/* Glyph surface is a pre-rendered image (typically a color emoji...) */
cairo_set_source_surface(cr, glyph->surf, 0, 0);
cairo_paint(cr);
} else {
/* Glyph surface is an alpha mask */
//assert(glyph->pixel_size_fixup == 1.);
cairo_set_source_rgb(cr, fg.r, fg.g, fg.b);
cairo_mask_surface(
cr, glyph->surf, x + glyph->left, y + term->fextents.ascent - glyph->top);
cairo_mask_surface(cr, glyph->surf, 0, 0);
//cr, glyph->surf, x + glyph->left, y + term->fextents.ascent - glyph->top);
}
cairo_restore(cr);
}
static void
@ -284,7 +304,7 @@ grid_render_scroll_reverse(struct terminal *term, struct buffer *buf,
static void
render_row(struct terminal *term, cairo_t *cr, struct row *row, int row_no)
{
for (int col = 0; col < term->cols; col++)
for (int col = term->cols - 1; col >= 0; col--)
render_cell(term, cr, &row->cells[col], col, row_no, false);
}