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fix(svg): split text fallback for symbols and render color emoji glyphs #319

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fix(svg): split text fallback for symbols and render color emoji glyphs #319

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b16fc77
fix: split svg text fallback for symbols and emoji
joeykchen Jun 25, 2026
9ce760a
fix: render svg color emoji glyphs in text
joeykchen Jun 25, 2026
03e8832
fix: address svg emoji review feedback
joeykchen Jun 26, 2026
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3 changes: 3 additions & 0 deletions modules/svg/svg_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,9 @@ void SVGUtils::add_font_face(const String &family, const void *font_data, int le

{
MutexLock lock(svg_font_registry_mutex);
if (svg_named_font_faces.has(family)) {
return;
}
svg_named_font_faces.insert(family, font_bytes);
svg_font_registry_serial++;
}
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12 changes: 12 additions & 0 deletions thirdparty/lunasvg/include/plutovg.h
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Expand Up @@ -849,6 +849,18 @@ PLUTOVG_API void plutovg_font_face_get_metrics(const plutovg_font_face_t* face,
*/
PLUTOVG_API void plutovg_font_face_get_glyph_metrics(plutovg_font_face_t* face, float size, plutovg_codepoint_t codepoint, float* advance_width, float* left_side_bearing, plutovg_rect_t* extents);

/**
* @brief Retrieves embedded SVG glyph data for a specified codepoint when available.
*
* @param face A pointer to a `plutovg_font_face_t` object.
* @param codepoint The Unicode code point of the glyph.
* @param svg Pointer that receives the embedded SVG document owned by the font face.

@fennoai fennoai Bot Jun 26, 2026

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Missing lifetime constraint in API doc: The @param svg line says "owned by the font face" but the pointer is actually an interior pointer into the raw font binary (returned by stbtt_GetGlyphSVG). Callers must not free it, must not modify it, and it becomes invalid once face is destroyed. The current wording does not convey the raw-interior-pointer nature. Suggested addition:

The pointer points directly into the font face's internal data and is valid only for the lifetime of face. The caller must not free or modify it.

* The returned pointer refers to the font face's internal storage, remains valid only for the
* lifetime of `face`, and must not be modified or freed by the caller.
* @return The SVG document length in bytes, or 0 if no embedded SVG glyph exists.
*/
PLUTOVG_API int plutovg_font_face_get_glyph_svg(plutovg_font_face_t* face, plutovg_codepoint_t codepoint, const char** svg);

/**
* @brief Retrieves the path of a glyph and its advance width.
*
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25 changes: 25 additions & 0 deletions thirdparty/lunasvg/source/plutovg-font.c
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Expand Up @@ -256,11 +256,15 @@ static glyph_t* plutovg_font_face_get_glyph(plutovg_font_face_t* face, plutovg_c
unsigned int msb = (codepoint >> 8) & 0xFF;
if(face->glyphs[msb] == NULL) {
face->glyphs[msb] = calloc(GLYPH_CACHE_SIZE, sizeof(glyph_t*));
if(face->glyphs[msb] == NULL)
return NULL;
}

unsigned int lsb = codepoint & 0xFF;
if(face->glyphs[msb][lsb] == NULL) {
glyph_t* glyph = malloc(sizeof(glyph_t));
if(glyph == NULL)
return NULL;
glyph->index = stbtt_FindGlyphIndex(&face->info, codepoint);
glyph->nvertices = stbtt_GetGlyphShape(&face->info, glyph->index, &glyph->vertices);
stbtt_GetGlyphHMetrics(&face->info, glyph->index, &glyph->advance_width, &glyph->left_side_bearing);
Expand All @@ -276,6 +280,13 @@ void plutovg_font_face_get_glyph_metrics(plutovg_font_face_t* face, float size,
{
float scale = plutovg_font_face_get_scale(face, size);
glyph_t* glyph = plutovg_font_face_get_glyph(face, codepoint);
if(glyph == NULL) {
if(advance_width) *advance_width = 0.f;
if(left_side_bearing) *left_side_bearing = 0.f;
if(extents)
extents->x = extents->y = extents->w = extents->h = 0.f;
return;
}
if(advance_width) *advance_width = glyph->advance_width * scale;
if(left_side_bearing) *left_side_bearing = glyph->left_side_bearing * scale;
if(extents) {
Expand All @@ -286,6 +297,18 @@ void plutovg_font_face_get_glyph_metrics(plutovg_font_face_t* face, float size,
}
}

int plutovg_font_face_get_glyph_svg(plutovg_font_face_t* face, plutovg_codepoint_t codepoint, const char** svg)
{
if(svg)
*svg = NULL;
if(face == NULL || svg == NULL)
return 0;
glyph_t* glyph = plutovg_font_face_get_glyph(face, codepoint);
if(glyph == NULL)
return 0;
return stbtt_GetGlyphSVG(&face->info, glyph->index, svg);

@fennoai fennoai Bot Jun 26, 2026

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Null pointer dereference: plutovg_font_face_get_glyph can return NULL if malloc or calloc fails inside the cache-fill path. glyph->index is then dereferenced unconditionally, causing a crash. The existing plutovg_font_face_get_glyph_metrics callers share this pattern (pre-existing), but adding a new public API is a good opportunity to fix it:

glyph_t* glyph = plutovg_font_face_get_glyph(face, codepoint);
if(glyph == NULL)
    return 0;
return stbtt_GetGlyphSVG(&face->info, glyph->index, svg);

}
Comment on lines +300 to +310

@gemini-code-assist gemini-code-assist Bot Jun 26, 2026

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high

If plutovg_font_face_get_glyph returns NULL (e.g., when the codepoint is not supported by the font face), dereferencing glyph->index will cause a null pointer dereference and crash the application. A null check should be added for glyph.

int plutovg_font_face_get_glyph_svg(plutovg_font_face_t* face, plutovg_codepoint_t codepoint, const char** svg)
{
    if(svg)
        *svg = NULL;
    if(face == NULL || svg == NULL)
        return 0;
    glyph_t* glyph = plutovg_font_face_get_glyph(face, codepoint);
    if(glyph == NULL)
        return 0;
    return stbtt_GetGlyphSVG(&face->info, glyph->index, svg);
}


static void glyph_traverse_func(void* closure, plutovg_path_command_t command, const plutovg_point_t* points, int npoints)
{
plutovg_path_t* path = (plutovg_path_t*)(closure);
Expand Down Expand Up @@ -319,6 +342,8 @@ float plutovg_font_face_traverse_glyph_path(plutovg_font_face_t* face, float siz
plutovg_point_t points[3];
plutovg_point_t current_point = {0, 0};
glyph_t* glyph = plutovg_font_face_get_glyph(face, codepoint);
if(glyph == NULL)
return 0.f;
for(int i = 0; i < glyph->nvertices; i++) {
switch(glyph->vertices[i].type) {
case STBTT_vmove:
Expand Down
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