diff options
Diffstat (limited to 'src/gui/font.h')
| -rw-r--r-- | src/gui/font.h | 66 |
1 files changed, 48 insertions, 18 deletions
diff --git a/src/gui/font.h b/src/gui/font.h index 4410bb7c..b38f822a 100644 --- a/src/gui/font.h +++ b/src/gui/font.h @@ -1,6 +1,7 @@ -// Tiny C shim over FreeType, so gui.zig only imports the stable renderer API. -// The implementation owns FreeType's library and face objects and keeps the -// caller's font bytes borrowed for the face lifetime. +// Tiny C shim over FreeType and HarfBuzz, so gui.zig only imports the stable +// renderer API. The implementation owns FreeType's library and face objects +// and HarfBuzz's font and buffer, and keeps the caller's font bytes borrowed +// for the face lifetime. #ifndef UI_FONT_H #define UI_FONT_H #include <stdint.h> @@ -20,27 +21,56 @@ UIFont *ui_font_new(const uint8_t *data, int32_t len); // font has no PostScript table. Borrowed for the UIFont lifetime. const char *ui_font_name(UIFont *f); -// Whether the selected Unicode charmap maps `cp` to a real glyph. Glyph zero is -// the face's .notdef box and deliberately does not count for fallback choice. -int ui_font_has_glyph(UIFont *f, int32_t cp); +// The glyph the selected Unicode charmap maps `cp` to. Glyph zero is the +// face's .notdef box: the codepoint is missing, which is what fallback choice +// asks. +uint32_t ui_font_glyph(UIFont *f, int32_t cp); -// The size token is a pixel height. Metrics and rasterization both configure -// FreeType at that size, so hinted advances, baseline and bitmaps stay in step. -float ui_font_scale_for_height(UIFont *f, float px); +// `px` is the pixel height. Metrics and rasterization both configure FreeType +// at that size, so hinted advances, baseline and bitmaps stay in step. void ui_font_cell_metrics(UIFont *f, float px, int32_t *cell_w, int32_t *cell_h, int32_t *ascent); -// Rasterize `cp` into `out` as a hinted grayscale cell mask (`stride` bytes per -// row). The origin is the baseline `ascent` pixels from the top. Pixels outside -// the glyph are zero. Missing codepoints render the face's .notdef glyph. -// `bold` emboldens the outline before rendering (synthetic bold, same advance). -// Returns 1 when the glyph produced coverage, 0 for blank/error. -int ui_font_raster(UIFont *f, float px, int32_t cp, int bold, uint8_t *out, - int32_t stride, int32_t cell_w, int32_t cell_h, - int32_t ascent); +// What one grid cell draws: `slice` of the glyph `glyph` rasterized across +// `span` cells with its own cell `lead` cells from the left. A plain cell is +// its own glyph, lead 0, span 1, slice 0. +typedef struct { + uint32_t glyph; + uint8_t lead; + uint8_t span; + uint8_t slice; +} UIShapedCell; + +// The longest glyph strip a ligature may claim, in cells. +#define UI_MAX_SPAN 8 + +// Whether a lookup of the font's ligature features (liga, calt, clig, rlig, +// rclt) could replace `glyph`. When it cannot, shaping leaves the glyph alone +// and its cell needs no shaping at all. +int ui_font_substitutes(UIFont *f, uint32_t glyph); + +// One cell per codepoint of `cps`, all in this face, shaped by HarfBuzz with +// the font's ligature features (a run with no glyph ui_font_substitutes +// reports comes back nominal without it). A substituted glyph whose ink +// reaches over neighbouring cells that draw nothing of their own (a +// ligature's spacers, or the cells a merged cluster swallowed) claims them as +// a strip. Otherwise, and for anything the grid cannot place (several glyphs +// in one cell, positioned marks), each cell is its nominal glyph. +void ui_font_shape(UIFont *f, float px, int32_t cell_w, const uint32_t *cps, + int32_t n, UIShapedCell *out); + +// Rasterize `glyph` into `out` as a hinted grayscale mask of `width` x +// `height` (`stride` bytes per row). The glyph's advance is centered in the +// `cell_w` pixels that start at `cell_x`, and its baseline is `ascent` pixels +// from the top; ink outside the mask is clipped. `bold` emboldens the outline +// before rendering (synthetic bold, same advance). Returns 1 when the glyph +// produced coverage, 0 for blank/error. +int ui_font_raster(UIFont *f, float px, uint32_t glyph, int bold, uint8_t *out, + int32_t stride, int32_t width, int32_t height, + int32_t cell_x, int32_t cell_w, int32_t ascent); // Center bitmap ink bounds, independent of advance and baseline bearings. -int ui_font_raster_centered(UIFont *f, float px, int32_t cp, int bold, +int ui_font_raster_centered(UIFont *f, float px, uint32_t glyph, int bold, uint8_t *out, int32_t stride, int32_t width, int32_t height); |