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CoreText: Get rid of the line height fudge factor

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It was leading to larger line heights than in iTerm on High Sierra with
Menlo. Also as per Apple documentation, line height should be ascent +
descent + leading.
https://developer.apple.com/library/content/documentation/TextFonts/Conceptual/CocoaTextArchitecture/TypoFeatures/TextSystemFeatures.html
This commit is contained in:
Kovid Goyal 2017-12-13 08:22:26 +05:30
parent e0ef563885
commit 47704f24c1
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GPG Key ID: 06BC317B515ACE7C
1 changed files with 3 additions and 7 deletions
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10
kitty/core_text.m
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@ -228,6 +228,7 @@ harfbuzz_font_for_face(PyObject* s) {
void
cell_metrics(PyObject *s, unsigned int* cell_width, unsigned int* cell_height, unsigned int* baseline, unsigned int* underline_position, unsigned int* underline_thickness) {
// See https://developer.apple.com/library/content/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/TypoFeatures/TextSystemFeatures.html
CTFace *self = (CTFace*)s;
#define count (128 - 32)
unichar chars[count+1] = {0};
@ -242,15 +243,10 @@ cell_metrics(PyObject *s, unsigned int* cell_width, unsigned int* cell_height, u
if (w > width) width = w;
}
}
// See https://stackoverflow.com/questions/5511830/how-does-line-spacing-work-in-core-text-and-why-is-it-different-from-nslayoutm
CGFloat leading = MAX(0, self->leading);
leading = floor(leading + 0.5);
CGFloat line_height = floor(self->ascent + 0.5) + floor(self->descent + 0.5) + leading;
CGFloat ascender_delta = (leading > 0) ? 0 : floor(0.2 * line_height + 0.5);
*cell_width = width; *cell_height = (unsigned int)(line_height + ascender_delta);
*cell_width = width;
*cell_height = (unsigned int)floor(self->ascent + self->descent + MAX(0, self->leading) + 0.5);
*underline_position = (unsigned int)self->underline_position;
*underline_thickness = (unsigned int)self->underline_thickness;
// See https://developer.apple.com/library/content/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/TypoFeatures/TextSystemFeatures.html
*baseline = (unsigned int)self->ascent;
}