fortrangoingonforty/fortty / a7f901b

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Normalize fallback font baseline to fix glyph drift

Store fallback font's ascender and adjust bearing_y when rendering
glyphs from fallback font. This compensates for different font metrics
between primary and fallback fonts, keeping all glyphs on the same
baseline.
Authored by espadonne
SHA
a7f901bdd4772e0479f9be7062f43ab2e787423f
Parents
6d71706
Tree
9040dfd

1 changed file

StatusFile+-
M src/text/font.f90 11 0
src/text/font.f90modified
@@ -19,6 +19,7 @@ module font_mod
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     integer :: cell_height = 0
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     integer :: ascender = 0
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     integer :: descender = 0
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+    integer :: fallback_ascender = 0  ! For baseline alignment with fallback font
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     logical :: loaded = .false.
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     logical :: has_fallback = .false.
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   end type font_t
@@ -194,6 +195,7 @@ contains
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     character(len=*), intent(in) :: path
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     character(len=256) :: c_path
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     integer(c_int) :: err
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+    integer(c_int) :: fb_cell_w, fb_cell_h, fb_asc, fb_desc
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     if (.not. font%loaded) return
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     if (len_trim(path) == 0) return
@@ -209,6 +211,10 @@ contains
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     end if
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     font%has_fallback = .true.
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+
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+    ! Get fallback font metrics for baseline alignment
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+    call fortty_ft_get_metrics(font%ft_face_fallback, fb_cell_w, fb_cell_h, fb_asc, fb_desc)
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+    font%fallback_ascender = fb_asc
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   end subroutine font_load_fallback
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   ! Check if a glyph exists in the primary font
@@ -278,6 +284,11 @@ contains
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     glyph%advance = adv
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     glyph%valid = .true.
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+    ! Normalize baseline: adjust bearing_y for ascender difference between fonts
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+    if (used_fallback) then
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+      glyph%bearing_y = glyph%bearing_y - (font%fallback_ascender - font%ascender)
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+    end if
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+
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   end function font_render_glyph_with_fallback
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   ! Find a font that supports a specific codepoint using fontconfig