#2023 Load from a variable font

WIP, beacsue variable fonts are not yeat included.

1 files changed, 92 insertions, 14 deletions

diff --git a/indra/llrender/llfontfreetype.cpp b/indra/llrender/llfontfreetype.cpp
index 063e308da0..9b00df2bf6 100644
--- a/indra/llrender/llfontfreetype.cpp
+++ b/indra/llrender/llfontfreetype.cpp
@@ -39,6 +39,7 @@
 // For some reason, this won't work if it's not wrapped in the ifdef
 #ifdef FT_FREETYPE_H
 #include FT_FREETYPE_H
+#include FT_MULTIPLE_MASTERS_H
 #endif
 
 #include "lldir.h"
@@ -165,7 +166,7 @@ LLFontFreetype::~LLFontFreetype()
     // mFallbackFonts cleaned up by LLPointer destructor
 }
 
-bool LLFontFreetype::loadFace(const std::string& filename, F32 point_size, F32 vert_dpi, F32 horz_dpi, bool is_fallback, S32 face_n, EFontHinting hinting, S32 flags)
+bool LLFontFreetype::loadFace(const std::string& filename, F32 point_size, F32 vert_dpi, F32 horz_dpi, S32 weight, bool is_fallback, S32 face_n, EFontHinting hinting, S32 flags)
 {
     // Don't leak face objects.  This is also needed to deal with
     // changed font file names.
@@ -191,6 +192,18 @@ bool LLFontFreetype::loadFace(const std::string& filename, F32 point_size, F32 v
     mIsFallback = is_fallback;
     mHinting = hinting;
     mFontFlags = flags;
+    mWeight = weight;
+
+    bool variable_font = false;
+    if (weight >= 0)
+    {
+        variable_font = setVariationAxis("wght", static_cast<F32>(weight));
+
+        // For Inter, also set optical size based on point size
+        // This makes text look better at different sizes
+        setVariationAxis("opsz", point_size);
+    }
+
     F32 pixels_per_em = (point_size / 72.f)*vert_dpi; // Size in inches * dpi
 
     error = FT_Set_Char_Size(mFTFace,    /* handle to face object           */
@@ -252,6 +265,12 @@ bool LLFontFreetype::loadFace(const std::string& filename, F32 point_size, F32 v
         // Ex: Inter SemiBold doesn't have FT_STYLE_FLAG_BOLD and without this style it would be bolded programmatically.
         mStyle |= LLFontGL::BOLD;
     }
+    else if (weight >= 600 && variable_font)
+    {
+        // If the font is heavy enough, consider it bold and avoid programmatic bolding
+        // even if it doesn't have the bold style set.
+        mStyle |= LLFontGL::BOLD;
+    }
 
     if(mFTFace->style_flags & FT_STYLE_FLAG_ITALIC)
     {
@@ -359,12 +378,8 @@ F32 LLFontFreetype::getXKerning(llwchar char_left, llwchar char_right) const
 
     llverify(!FT_Get_Kerning(mFTFace, left_glyph, right_glyph, ft_kerning_unfitted, &delta));
 
-    if (mFTFace->face_flags & FT_FACE_FLAG_SCALABLE)
-    {
-        // Return the X advance
-        return (F32)(delta.x * (1.0 / 64.0));
-    }
-    return (F32)delta.x;
+    // ft_kerning_unfitted mode always returns 26.6 fixed-point values
+    return (F32)(delta.x * (1.0 / 64.0));
 }
 
 F32 LLFontFreetype::getXKerning(const LLFontGlyphInfo* left_glyph_info, const LLFontGlyphInfo* right_glyph_info) const
@@ -379,12 +394,8 @@ F32 LLFontFreetype::getXKerning(const LLFontGlyphInfo* left_glyph_info, const LL
 
     llverify(!FT_Get_Kerning(mFTFace, left_glyph, right_glyph, ft_kerning_unfitted, &delta));
 
-    if (mFTFace->face_flags & FT_FACE_FLAG_SCALABLE)
-    {
-        // Return the X advance
-        return (F32)(delta.x * (1.0 / 64.0));
-    }
-    return (F32)delta.x;
+    // ft_kerning_unfitted mode always returns 26.6 fixed-point values
+    return (F32)(delta.x * (1.0 / 64.0));
 }
 
 bool LLFontFreetype::hasGlyph(llwchar wch) const
@@ -697,7 +708,7 @@ void LLFontFreetype::renderGlyph(EFontGlyphType bitmap_type, U32 glyph_index, ll
 void LLFontFreetype::reset(F32 vert_dpi, F32 horz_dpi)
 {
     resetBitmapCache();
-    loadFace(mName, mPointSize, vert_dpi ,horz_dpi, mIsFallback, 0, mHinting, mFontFlags);
+    loadFace(mName, mPointSize, vert_dpi ,horz_dpi, mWeight, mIsFallback, 0, mHinting, mFontFlags);
     if (!mIsFallback)
     {
         // This is the head of the list - need to rebuild ourself and all fallbacks.
@@ -865,6 +876,73 @@ void LLFontFreetype::setSubImageLuminanceAlpha(U32 x, U32 y, U32 bitmap_num, U32
     }
 }
 
+bool LLFontFreetype::setVariationAxis(const std::string& axis_tag, F32 value)
+{
+    if (!mFTFace)
+        return false;
+
+    // Check if this is a variable font
+    FT_MM_Var* master = nullptr;
+    if (FT_Get_MM_Var(mFTFace, &master) != 0)
+    {
+        // Not a variable font - this is not an error, just silently skip
+        return false;
+    }
+
+    // Find the axis by tag (e.g., "wght" for weight)
+    FT_UInt axis_index = 0;
+    bool found = false;
+    for (FT_UInt i = 0; i < master->num_axis; i++)
+    {
+        // Compare the 4-byte tag
+        if (master->axis[i].tag == FT_MAKE_TAG(axis_tag[0], axis_tag[1], axis_tag[2], axis_tag[3]))
+        {
+            axis_index = i;
+            found = true;
+
+            // Clamp value to valid range for this axis
+            F32 min_val = master->axis[i].minimum / 65536.0f;
+            F32 max_val = master->axis[i].maximum / 65536.0f;
+            value = llclamp(value, min_val, max_val);
+
+            break;
+        }
+    }
+
+    if (!found)
+    {
+        FT_Done_MM_Var(gFTLibrary, master);
+        LL_WARNS_ONCE("FontVariation") << "Axis '" << axis_tag << "' not found in font: " << mName << LL_ENDL;
+        return false;
+    }
+
+    FT_UInt num_coords = master->num_axis;
+    FT_Fixed* coords = new FT_Fixed[num_coords];
+
+    // Get current coordinates
+    FT_Get_Var_Design_Coordinates(mFTFace, num_coords, coords);
+
+    // Update the specific axis
+    coords[axis_index] = (FT_Fixed)(value * 65536.0f);
+
+    // Set all coordinates
+    int error = FT_Set_Var_Design_Coordinates(mFTFace, num_coords, coords);
+
+    delete[] coords;
+    FT_Done_MM_Var(gFTLibrary, master);
+
+    if (error != 0)
+    {
+        LL_WARNS() << "Failed to set variation coordinates for " << axis_tag
+            << " = " << value << " in font: " << mName << LL_ENDL;
+        return false;
+    }
+
+    LL_INFOS("FontVariation") << "Set " << axis_tag << " = " << value
+        << " for font: " << mName << LL_ENDL;
+    return true;
+}
+
 
 namespace ll
 {