Fonts: Selecting font config source list done by shared code.

imgui.h

@@ -3631,19 +3631,19 @@ struct ImFont
     float                       FallbackAdvanceX;   // 4     // out // FindGlyph(FallbackChar)->AdvanceX
     float                       FontSize;           // 4     // in  // Height of characters/line, set during loading (don't change after loading)
 
-    // [Internal] Members: Hot ~28/40 bytes (for RenderText loop)
+    // [Internal] Members: Hot ~28/36 bytes (for RenderText loop)
     ImVector<ImU16>             IndexLookup;        // 12-16 // out // Sparse. Index glyphs by Unicode code-point.
     ImVector<ImFontGlyph>       Glyphs;             // 12-16 // out // All glyphs.
     int                         FallbackGlyphIndex; // 4     // out // Index of FontFallbackChar
 
-    // [Internal] Members: Cold ~32/40 bytes
+    // [Internal] Members: Cold ~32/40/60 bytes
     // Conceptually Sources[] is the list of font sources merged to create this font.
-    ImFontAtlas*                ContainerAtlas;     // 4-8   // out // What we has been loaded into
-    ImFontConfig*               Sources;            // 4-8   // in  // Pointer within ContainerAtlas->Sources[], to SourcesCount instances
     short                       SourcesCount;       // 2     // in  // Number of ImFontConfig involved in creating this font. Usually 1, or >1 when merging multiple font sources into one ImFont.
     short                       EllipsisCharCount;  // 1     // out // 1 or 3
     ImWchar                     EllipsisChar;       // 2-4   // out // Character used for ellipsis rendering ('...').
     ImWchar                     FallbackChar;       // 2-4   // out // Character used if a glyph isn't found (U+FFFD, '?')
+    ImFontConfig*               Sources;            // 4-8   // in  // Pointer within ContainerAtlas->Sources[], to SourcesCount instances
+    ImFontAtlas*                ContainerAtlas;     // 4-8   // out // What we has been loaded into
     float                       EllipsisWidth;      // 4     // out // Total ellipsis Width
     float                       EllipsisCharStep;   // 4     // out // Step between characters when EllipsisCount > 0
     float                       Scale;              // 4     // in  // Base font scale (~1.0f), multiplied by the per-window font scale which you can adjust with SetWindowFontScale()
@@ -3651,7 +3651,7 @@ struct ImFont
     int                         MetricsTotalSurface;// 4     // out // Total surface in pixels to get an idea of the font rasterization/texture cost (not exact, we approximate the cost of padding between glyphs)
     ImU8                        Used8kPagesMap[(IM_UNICODE_CODEPOINT_MAX+1)/8192/8]; // 1 bytes if ImWchar=ImWchar16, 16 bytes if ImWchar==ImWchar32. Store 1-bit for each block of 4K codepoints that has one active glyph. This is mainly used to facilitate iterations across all used codepoints.
     bool                        LockDisableLoading;
-    ImFontConfig*               LockSingleSrcConfig;
+    short                       LockSingleSrcConfigIdx;
 
     // Methods
     IMGUI_API ImFont();

imgui_draw.cpp

@@ -3394,10 +3394,12 @@ bool ImFontAtlasBuildAddFont(ImFontAtlas* atlas, ImFontConfig* src)
 void ImFontAtlasBuildSetupFontSpecialGlyphs(ImFontAtlas* atlas, ImFontConfig* src)
 {
     ImFont* font = src->DstFont;
+    const int cfg_idx_in_font = (int)(src - font->Sources);
+    IM_ASSERT(cfg_idx_in_font >= 0 && cfg_idx_in_font < font->SourcesCount);
     IM_UNUSED(atlas);
 
     // While manipulating glyphs during init we want to restrict all searches for one source font.
-    font->LockSingleSrcConfig = src;
+    font->LockSingleSrcConfigIdx = (short)cfg_idx_in_font;
 
     // Setup Fallback character
     // FIXME-NEWATLAS: could we use a scheme where this is lazily loaded?
@@ -3448,8 +3450,7 @@ void ImFontAtlasBuildSetupFontSpecialGlyphs(ImFontAtlas* atlas, ImFontConfig* sr
             font->EllipsisWidth = ImMax(dot_glyph->AdvanceX, dot_glyph->X0 + font->EllipsisCharStep * 3.0f - 1.0f); // FIXME: Slightly odd for normally mono-space fonts but since this is used for trailing contents.
         }
     }
-
-    font->LockSingleSrcConfig = NULL;
+    font->LockSingleSrcConfigIdx = -1;
 }
 
 // Those functions are designed to facilitate changing the underlying structures for ImFontAtlas to store an array of ImDrawListSharedData*
@@ -3809,10 +3810,15 @@ ImFontGlyph* ImFont::BuildLoadGlyph(ImWchar codepoint)
 
     //char utf8_buf[5];
     //IMGUI_DEBUG_LOG("[font] BuildAddGlyph U+%04X (%s)\n", (unsigned int)codepoint, ImTextCharToUtf8(utf8_buf, (unsigned int)codepoint));
-
     ImFontAtlas* atlas = ContainerAtlas;
+
+    // Load from single source or all sources?
+    int srcs_count = (LockSingleSrcConfigIdx != -1) ? 1 : SourcesCount;
+    ImFontConfig* srcs = (LockSingleSrcConfigIdx != -1) ? &Sources[LockSingleSrcConfigIdx] : Sources;
+
+    // Call backend
     const ImFontLoader* font_loader = atlas->FontLoader;
-    if (!font_loader->FontAddGlyph(atlas, this, codepoint))
+    if (!font_loader->FontAddGlyph(atlas, this, srcs, srcs_count, codepoint))
     {
         // Mark index as not found, so we don't attempt the search twice
         BuildGrowIndex(codepoint + 1);
@@ -3937,16 +3943,15 @@ static bool ImGui_ImplStbTrueType_FontSrcContainsGlyph(ImFontAtlas* atlas, ImFon
     return glyph_index != 0;
 }
 
-static bool ImGui_ImplStbTrueType_FontAddGlyph(ImFontAtlas* atlas, ImFont* font, ImWchar codepoint)
+static bool ImGui_ImplStbTrueType_FontAddGlyph(ImFontAtlas* atlas, ImFont* font, ImFontConfig* srcs, int srcs_count, ImWchar codepoint)
 {
     // Search for first font which has the glyph
     ImGui_ImplStbTrueType_FontSrcData* bd_font_data = NULL;
     ImFontConfig* src = NULL;
     int glyph_index = 0;
-    int scan_count = (font->LockSingleSrcConfig != NULL) ? 1 : font->SourcesCount;
-    for (int src_n = 0; src_n < scan_count; src_n++, bd_font_data++)
+    for (int src_n = 0; src_n < srcs_count; src_n++)
     {
-        src = font->LockSingleSrcConfig ? font->LockSingleSrcConfig : &font->Sources[src_n];
+        src = &srcs[src_n];
         bd_font_data = (ImGui_ImplStbTrueType_FontSrcData*)src->FontLoaderData;
         glyph_index = stbtt_FindGlyphIndex(&bd_font_data->FontInfo, (int)codepoint);
         if (glyph_index != 0)
@@ -4369,6 +4374,7 @@ ImFont::ImFont()
 {
     memset(this, 0, sizeof(*this));
     Scale = 1.0f;
+    LockSingleSrcConfigIdx = -1;
 }
 
 ImFont::~ImFont()

imgui_internal.h

@@ -3626,7 +3626,7 @@ struct ImFontLoader
     bool            (*FontSrcInit)(ImFontAtlas* atlas, ImFontConfig* src);
     void            (*FontSrcDestroy)(ImFontAtlas* atlas, ImFontConfig* src);
     bool            (*FontSrcContainsGlyph)(ImFontAtlas* atlas, ImFontConfig* src, ImWchar codepoint);
-    bool            (*FontAddGlyph)(ImFontAtlas* atlas, ImFont* font, ImWchar codepoint);
+    bool            (*FontAddGlyph)(ImFontAtlas* atlas, ImFont* font, ImFontConfig* srcs, int srcs_count, ImWchar codepoint);
 
     ImFontLoader()  { memset(this, 0, sizeof(*this)); }
 };