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Linux: Automatically increase cell height if the font being used is broken and draws the underscore outside the bounding box

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See #690
This commit is contained in:
Kovid Goyal
2019-05-29 16:04:50 +05:30
parent 4e9dabfb25
commit 1ae32b5742
3 changed files with 53 additions and 24 deletions
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70
kitty/freetype.c
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@@ -75,8 +75,6 @@ set_freetype_error(const char* prefix, int err_code) {
static FT_Library library;
#define CALC_CELL_HEIGHT(self) font_units_to_pixels_y(self, self->height)
static inline int
font_units_to_pixels_y(Face *self, int x) {
return ceil((double)FT_MulFix(x, self->face->size->metrics.y_scale) / 64.0);
@@ -87,11 +85,56 @@ font_units_to_pixels_x(Face *self, int x) {
return ceil((double)FT_MulFix(x, self->face->size->metrics.x_scale) / 64.0);
}
static inline int
get_load_flags(int hinting, int hintstyle, int base) {
int flags = base;
if (hinting) {
if (hintstyle >= 3) flags |= FT_LOAD_TARGET_NORMAL;
else if (0 < hintstyle && hintstyle < 3) flags |= FT_LOAD_TARGET_LIGHT;
} else flags |= FT_LOAD_NO_HINTING;
return flags;
}
static inline bool
load_glyph(Face *self, int glyph_index, int load_type) {
int flags = get_load_flags(self->hinting, self->hintstyle, load_type);
int error = FT_Load_Glyph(self->face, glyph_index, flags);
if (error) { set_freetype_error("Failed to load glyph, with error:", error); return false; }
return true;
}
static inline unsigned int
get_height_for_char(Face *self, char ch) {
unsigned int ans = 0;
int glyph_index = FT_Get_Char_Index(self->face, ch);
if (load_glyph(self, glyph_index, FT_LOAD_DEFAULT)) {
unsigned int baseline = font_units_to_pixels_y(self, self->ascender);
FT_GlyphSlotRec *glyph = self->face->glyph;
FT_Bitmap *bm = &glyph->bitmap;
if (glyph->bitmap_top <= 0 || (glyph->bitmap_top > 0 && (unsigned int)glyph->bitmap_top < baseline)) {
ans = baseline - glyph->bitmap_top + bm->rows;
}
}
return ans;
}
static inline unsigned int
calc_cell_height(Face *self, bool for_metrics) {
unsigned int ans = font_units_to_pixels_y(self, self->height);
unsigned int underscore_height = get_height_for_char(self, '_');
if (for_metrics && global_state.debug_font_fallback && underscore_height > ans) {
printf("Increasing cell height by %u pixels to work around buggy font that renders underscore outside the bounding box\n", underscore_height - ans);
}
return MAX(ans, underscore_height);
}
static inline bool
set_font_size(Face *self, FT_F26Dot6 char_width, FT_F26Dot6 char_height, FT_UInt xdpi, FT_UInt ydpi, unsigned int desired_height, unsigned int cell_height) {
int error = FT_Set_Char_Size(self->face, 0, char_height, xdpi, ydpi);
if (!error) {
unsigned int ch = CALC_CELL_HEIGHT(self);
unsigned int ch = calc_cell_height(self, false);
if (desired_height && ch != desired_height) {
FT_F26Dot6 h = floor((double)char_height * (double)desired_height / (double) ch);
return set_font_size(self, 0, h, xdpi, ydpi, 0, cell_height);
@@ -147,17 +190,6 @@ set_size_for_face(PyObject *s, unsigned int desired_height, bool force, FONTS_DA
return set_font_size(self, w, w, xdpi, ydpi, desired_height, fg->cell_height);
}
static inline int
get_load_flags(int hinting, int hintstyle, int base) {
int flags = base;
if (hinting) {
if (hintstyle >= 3) flags |= FT_LOAD_TARGET_NORMAL;
else if (0 < hintstyle && hintstyle < 3) flags |= FT_LOAD_TARGET_LIGHT;
} else flags |= FT_LOAD_NO_HINTING;
return flags;
}
static inline bool
init_ft_face(Face *self, PyObject *path, int hinting, int hintstyle, FONTS_DATA_HANDLE fg) {
#define CPY(n) self->n = self->face->n;
@@ -236,14 +268,6 @@ repr(Face *self) {
}
static inline bool
load_glyph(Face *self, int glyph_index, int load_type) {
int flags = get_load_flags(self->hinting, self->hintstyle, load_type);
int error = FT_Load_Glyph(self->face, glyph_index, flags);
if (error) { set_freetype_error("Failed to load glyph, with error:", error); return false; }
return true;
}
static inline unsigned int
calc_cell_width(Face *self) {
unsigned int ans = 0;
@@ -260,7 +284,7 @@ void
cell_metrics(PyObject *s, unsigned int* cell_width, unsigned int* cell_height, unsigned int* baseline, unsigned int* underline_position, unsigned int* underline_thickness) {
Face *self = (Face*)s;
*cell_width = calc_cell_width(self);
*cell_height = CALC_CELL_HEIGHT(self);
*cell_height = calc_cell_height(self, true);
*baseline = font_units_to_pixels_y(self, self->ascender);
*underline_position = MIN(*cell_height - 1, (unsigned int)font_units_to_pixels_y(self, MAX(0, self->ascender - self->underline_position)));
*underline_thickness = MAX(1, font_units_to_pixels_y(self, self->underline_thickness));