imgui_freetype: Add support for colored glyphs. Font: add support for untinted glyphs (#3369)

Amend 9499afd with missing static inline.

docs/CHANGELOG.txt

@@ -53,10 +53,13 @@ Other Changes:
     other than compiling misc/freetype/imgui_freetype.cpp and linking with FreeType.
   - Use '#define IMGUI_ENABLE_STB_TRUETYPE' if you somehow need the stb_truetype rasterizer to be
     compiled in along with the FreeType one, otherwise it is enabled by default.
+- imgui_freetype: Added support for colored glyphs as supported by Freetype 2.10+ (for .ttf using CPAL/COLR 
+  tables only). Enable the ImGuiFreeTypeBuilderFlags_LoadColor on a given font. Atlas always output directly
+  as RGBA8 in this situation. Likely to make sense with IMGUI_USE_WCHAR32. (#3369) [@pshurgal]
 - Fonts: Fixed CalcTextSize() width rounding so it behaves more like a ceil. This is in order for text wrapping
   to have enough space when provided width precisely calculated with CalcTextSize().x. (#3776)
   Note that the rounding of either positions and widths are technically undesirable (e.g. #3437, #791) but
-  variety of code is currently on it so we are first fixing current behavior before we'll eventually chhnge it.
+  variety of code is currently on it so we are first fixing current behavior before we'll eventually change it.
 - ImDrawList: Fixed AddCircle()/AddCircleFilled() with (rad > 0.0f && rad < 1.0f && num_segments == 0). (#3738)
   Would lead to a buffer read overflow.
 - Backends: Win32: Dynamically loading XInput DLL instead of linking with it, facilite compiling with

imgui.h

@@ -2504,8 +2504,9 @@ struct ImFontConfig
 // (Note: some language parsers may fail to convert the 31+1 bitfield members, in this case maybe drop store a single u32 or we can rework this)
 struct ImFontGlyph
 {
-    unsigned int    Codepoint : 31;     // 0x0000..0xFFFF
+    unsigned int    Colored : 1;        // Flag to indicate glyph is colored and should generally ignore tinting (make it usable with no shift on little-endian as this is used in loops)
-    unsigned int    Visible : 1;        // Flag to allow early out when rendering
+    unsigned int    Visible : 1;        // Flag to indicate glyph has no visible pixels (e.g. space). Allow early out when rendering.
+    unsigned int    Codepoint : 30;     // 0x0000..0x10FFFF
     float           AdvanceX;           // Distance to next character (= data from font + ImFontConfig::GlyphExtraSpacing.x baked in)
     float           X0, Y0, X1, Y1;     // Glyph corners
     float           U0, V0, U1, V1;     // Texture coordinates

imgui_draw.cpp

@@ -3065,6 +3065,7 @@ void ImFont::AddGlyph(const ImFontConfig* cfg, ImWchar codepoint, float x0, floa
     ImFontGlyph& glyph = Glyphs.back();
     glyph.Codepoint = (unsigned int)codepoint;
     glyph.Visible = (x0 != x1) && (y0 != y1);
+    glyph.Colored = false;
     glyph.X0 = x0;
     glyph.Y0 = y0;
     glyph.X1 = x1;
@@ -3315,6 +3316,8 @@ void ImFont::RenderChar(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
     const ImFontGlyph* glyph = FindGlyph(c);
     if (!glyph || !glyph->Visible)
         return;
+    if (glyph->Colored)
+        col |= ~IM_COL32_A_MASK;
     float scale = (size >= 0.0f) ? (size / FontSize) : 1.0f;
     pos.x = IM_FLOOR(pos.x);
     pos.y = IM_FLOOR(pos.y);
@@ -3377,6 +3380,8 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
     ImDrawIdx* idx_write = draw_list->_IdxWritePtr;
     unsigned int vtx_current_idx = draw_list->_VtxCurrentIdx;
 
+    const ImU32 col_untinted = col | ~IM_COL32_A_MASK;
+
     while (s < text_end)
     {
         if (word_wrap_enabled)
@@ -3482,14 +3487,17 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
                     }
                 }
 
+                // Support for untinted glyphs
+                ImU32 glyph_col = glyph->Colored ? col_untinted : col;
+
                 // We are NOT calling PrimRectUV() here because non-inlined causes too much overhead in a debug builds. Inlined here:
                 {
                     idx_write[0] = (ImDrawIdx)(vtx_current_idx); idx_write[1] = (ImDrawIdx)(vtx_current_idx+1); idx_write[2] = (ImDrawIdx)(vtx_current_idx+2);
                     idx_write[3] = (ImDrawIdx)(vtx_current_idx); idx_write[4] = (ImDrawIdx)(vtx_current_idx+2); idx_write[5] = (ImDrawIdx)(vtx_current_idx+3);
-                    vtx_write[0].pos.x = x1; vtx_write[0].pos.y = y1; vtx_write[0].col = col; vtx_write[0].uv.x = u1; vtx_write[0].uv.y = v1;
+                    vtx_write[0].pos.x = x1; vtx_write[0].pos.y = y1; vtx_write[0].col = glyph_col; vtx_write[0].uv.x = u1; vtx_write[0].uv.y = v1;
-                    vtx_write[1].pos.x = x2; vtx_write[1].pos.y = y1; vtx_write[1].col = col; vtx_write[1].uv.x = u2; vtx_write[1].uv.y = v1;
+                    vtx_write[1].pos.x = x2; vtx_write[1].pos.y = y1; vtx_write[1].col = glyph_col; vtx_write[1].uv.x = u2; vtx_write[1].uv.y = v1;
-                    vtx_write[2].pos.x = x2; vtx_write[2].pos.y = y2; vtx_write[2].col = col; vtx_write[2].uv.x = u2; vtx_write[2].uv.y = v2;
+                    vtx_write[2].pos.x = x2; vtx_write[2].pos.y = y2; vtx_write[2].col = glyph_col; vtx_write[2].uv.x = u2; vtx_write[2].uv.y = v2;
-                    vtx_write[3].pos.x = x1; vtx_write[3].pos.y = y2; vtx_write[3].col = col; vtx_write[3].uv.x = u1; vtx_write[3].uv.y = v2;
+                    vtx_write[3].pos.x = x1; vtx_write[3].pos.y = y2; vtx_write[3].col = glyph_col; vtx_write[3].uv.x = u1; vtx_write[3].uv.y = v2;
                     vtx_write += 4;
                     vtx_current_idx += 4;
                     idx_write += 6;

imgui_internal.h

@@ -2509,7 +2509,8 @@ IMGUI_API void      ImFontAtlasBuildInit(ImFontAtlas* atlas);
 IMGUI_API void      ImFontAtlasBuildSetupFont(ImFontAtlas* atlas, ImFont* font, ImFontConfig* font_config, float ascent, float descent);
 IMGUI_API void      ImFontAtlasBuildPackCustomRects(ImFontAtlas* atlas, void* stbrp_context_opaque);
 IMGUI_API void      ImFontAtlasBuildFinish(ImFontAtlas* atlas);
-IMGUI_API void      ImFontAtlasBuildRender8bppRectFromString(ImFontAtlas* atlas, int atlas_x, int atlas_y, int w, int h, const char* in_str, char in_marker_char, unsigned char in_marker_pixel_value);
+IMGUI_API void      ImFontAtlasBuildRender8bppRectFromString(ImFontAtlas* atlas, int x, int y, int w, int h, const char* in_str, char in_marker_char, unsigned char in_marker_pixel_value);
+IMGUI_API void      ImFontAtlasBuildRender32bppRectFromString(ImFontAtlas* atlas, int x, int y, int w, int h, const char* in_str, char in_marker_char, unsigned int in_marker_pixel_value);
 IMGUI_API void      ImFontAtlasBuildMultiplyCalcLookupTable(unsigned char out_table[256], float in_multiply_factor);
 IMGUI_API void      ImFontAtlasBuildMultiplyRectAlpha8(const unsigned char table[256], unsigned char* pixels, int x, int y, int w, int h, int stride);
 

misc/freetype/imgui_freetype.cpp

@@ -6,6 +6,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2021/01/28: added support for color-layered glyphs via ImGuiFreeTypeBuilderFlags_LoadColor (require Freetype 2.10+).
 //  2021/01/26: simplified integration by using '#define IMGUI_ENABLE_FREETYPE'.
 //              renamed ImGuiFreeType::XXX flags to ImGuiFreeTypeBuilderFlags_XXX for consistency with other API. removed ImGuiFreeType::BuildFontAtlas().
 //  2020/06/04: fix for rare case where FT_Get_Char_Index() succeed but FT_Load_Glyph() fails.
@@ -96,7 +97,7 @@ namespace
     //              |                                   |
     //              |------------- advanceX ----------->|
 
-    /// A structure that describe a glyph.
+    // A structure that describe a glyph.
     struct GlyphInfo
     {
         int         Width;              // Glyph's width in pixels.
@@ -104,6 +105,7 @@ namespace
         FT_Int      OffsetX;            // The distance from the origin ("pen position") to the left of the glyph.
         FT_Int      OffsetY;            // The distance from the origin to the top of the glyph. This is usually a value < 0.
         float       AdvanceX;           // The distance from the origin to the origin of the next glyph. This is usually a value > 0.
+        bool        IsColored;
     };
 
     // Font parameters and metrics.
@@ -252,6 +254,7 @@ namespace
         out_glyph_info->OffsetX = Face->glyph->bitmap_left;
         out_glyph_info->OffsetY = -Face->glyph->bitmap_top;
         out_glyph_info->AdvanceX = (float)FT_CEIL(slot->advance.x);
+        out_glyph_info->IsColored = (ft_bitmap->pixel_mode == FT_PIXEL_MODE_BGRA);
 
         return ft_bitmap;
     }
@@ -271,19 +274,15 @@ namespace
                 if (multiply_table == NULL)
                 {
                     for (uint32_t y = 0; y < h; y++, src += src_pitch, dst += dst_pitch)
-                    {
                         for (uint32_t x = 0; x < w; x++)
                             dst[x] = IM_COL32(255, 255, 255, src[x]);
                 }
-                }
                 else
                 {
                     for (uint32_t y = 0; y < h; y++, src += src_pitch, dst += dst_pitch)
-                    {
                         for (uint32_t x = 0; x < w; x++)
                             dst[x] = IM_COL32(255, 255, 255, multiply_table[src[x]]);
                 }
-                }
                 break;
             }
         case FT_PIXEL_MODE_MONO: // Monochrome image, 1 bit per pixel. The bits in each byte are ordered from MSB to LSB.
@@ -305,18 +304,15 @@ namespace
             }
         case FT_PIXEL_MODE_BGRA:
             {
+                // FIXME: Converting pre-multiplied alpha to straight. Doesn't smell good.
                 #define DE_MULTIPLY(color, alpha) (ImU32)(255.0f * (float)color / (float)alpha + 0.5f)
-
                 if (multiply_table == NULL)
                 {
                     for (uint32_t y = 0; y < h; y++, src += src_pitch, dst += dst_pitch)
-                    {
                         for (uint32_t x = 0; x < w; x++)
-                            dst[x] = IM_COL32(
+                        {
-                                DE_MULTIPLY(src[x * 4 + 2], src[x * 4 + 3]),
+                            uint8_t r = src[x * 4 + 2], g = src[x * 4 + 1], b = src[x * 4], a = src[x * 4 + 3];
-                                DE_MULTIPLY(src[x * 4 + 1], src[x * 4 + 3]),
+                            dst[x] = IM_COL32(DE_MULTIPLY(r, a), DE_MULTIPLY(g, a), DE_MULTIPLY(b, a), a);
-                                DE_MULTIPLY(src[x * 4],     src[x * 4 + 3]),
-                                src[x * 4 + 3]);
                         }
                 }
                 else
@@ -324,14 +320,12 @@ namespace
                     for (uint32_t y = 0; y < h; y++, src += src_pitch, dst += dst_pitch)
                     {
                         for (uint32_t x = 0; x < w; x++)
-                            dst[x] = IM_COL32(
+                        {
-                                multiply_table[DE_MULTIPLY(src[x * 4 + 2], src[x * 4 + 3])],
+                            uint8_t r = src[x * 4 + 2], g = src[x * 4 + 1], b = src[x * 4], a = src[x * 4 + 3];
-                                multiply_table[DE_MULTIPLY(src[x * 4 + 1], src[x * 4 + 3])],
+                            dst[x] = IM_COL32(multiply_table[DE_MULTIPLY(r, a)], multiply_table[DE_MULTIPLY(g, a)], multiply_table[DE_MULTIPLY(b, a)], multiply_table[a]);
-                                multiply_table[DE_MULTIPLY(src[x * 4],     src[x * 4 + 3])],
+                        }
-                                multiply_table[src[x * 4 + 3]]);
                     }
                 }
-
                 #undef DE_MULTIPLY
                 break;
             }
@@ -359,6 +353,8 @@ struct ImFontBuildSrcGlyphFT
     GlyphInfo           Info;
     uint32_t            Codepoint;
     unsigned int*       BitmapData;         // Point within one of the dst_tmp_bitmap_buffers[] array
+
+    ImFontBuildSrcGlyphFT() { memset(this, 0, sizeof(*this)); }
 };
 
 struct ImFontBuildSrcDataFT
@@ -396,6 +392,7 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
     atlas->ClearTexData();
 
     // Temporary storage for building
+    bool src_load_color = false;
     ImVector<ImFontBuildSrcDataFT> src_tmp_array;
     ImVector<ImFontBuildDstDataFT> dst_tmp_array;
     src_tmp_array.resize(atlas->ConfigData.Size);
@@ -425,6 +422,7 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
             return false;
 
         // Measure highest codepoints
+        src_load_color |= (cfg.FontBuilderFlags & ImGuiFreeTypeBuilderFlags_LoadColor) != 0;
         ImFontBuildDstDataFT& dst_tmp = dst_tmp_array[src_tmp.DstIndex];
         src_tmp.SrcRanges = cfg.GlyphRanges ? cfg.GlyphRanges : atlas->GetGlyphRangesDefault();
         for (const ImWchar* src_range = src_tmp.SrcRanges; src_range[0] && src_range[1]; src_range += 2)
@@ -476,7 +474,6 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
                     if (entries_32 & ((ImU32)1 << bit_n))
                     {
                         ImFontBuildSrcGlyphFT src_glyph;
-                        memset(&src_glyph, 0, sizeof(src_glyph));
                         src_glyph.Codepoint = (ImWchar)(((it - it_begin) << 5) + bit_n);
                         //src_glyph.GlyphIndex = 0; // FIXME-OPT: We had this info in the previous step and lost it..
                         src_tmp.GlyphsList.push_back(src_glyph);
@@ -595,7 +592,7 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
     // 7. Allocate texture
     atlas->TexHeight = (atlas->Flags & ImFontAtlasFlags_NoPowerOfTwoHeight) ? (atlas->TexHeight + 1) : ImUpperPowerOfTwo(atlas->TexHeight);
     atlas->TexUvScale = ImVec2(1.0f / atlas->TexWidth, 1.0f / atlas->TexHeight);
-    if (extra_flags & ImGuiFreeTypeBuilderFlags_LoadColor)
+    if (src_load_color)
     {
         atlas->TexPixelsRGBA32 = (unsigned int*)IM_ALLOC(atlas->TexWidth * atlas->TexHeight * 4);
         memset(atlas->TexPixelsRGBA32, 0, atlas->TexWidth * atlas->TexHeight * 4);
@@ -670,6 +667,10 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
             float u1 = (tx + info.Width) / (float)atlas->TexWidth;
             float v1 = (ty + info.Height) / (float)atlas->TexHeight;
             dst_font->AddGlyph(&cfg, (ImWchar)src_glyph.Codepoint, x0, y0, x1, y1, u0, v0, u1, v1, info.AdvanceX);
+
+            IM_ASSERT(dst_font->Glyphs.back().Codepoint == src_glyph.Codepoint);
+            if (src_glyph.Info.IsColored)
+                dst_font->Glyphs.back().Colored = true;
         }
 
         src_tmp.Rects = NULL;

misc/freetype/imgui_freetype.h

@@ -44,6 +44,6 @@ namespace ImGuiFreeType
     // Obsolete names (will be removed soon)
     // Prefer using '#define IMGUI_ENABLE_FREETYPE'
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    bool BuildFontAtlas(ImFontAtlas* atlas, unsigned int flags = 0) { atlas->FontBuilderIO = GetBuilderForFreeType(); atlas->FontBuilderFlags = flags; return atlas->Build(); }
+    static inline bool BuildFontAtlas(ImFontAtlas* atlas, unsigned int flags = 0) { atlas->FontBuilderIO = GetBuilderForFreeType(); atlas->FontBuilderFlags = flags; return atlas->Build(); }
 #endif
 }