ImFontConfig: Added GlyphMinAdvanceX/GlyphMaxAdvanceX settings useful to make a font appears monospaced, particularly useful for icon fonts. (#1869)

CHANGELOG.txt

@@ -53,6 +53,7 @@ Other Changes:
  - InputTextMultiline(): Fixed double navigation highlight when scrollbar is active. (#787)
  - InputText(): Fixed Undo after pasting large amount of text (Redo will still fail when undo buffers are exhausted, but text won't be corrupted).
  - SliderFloat(): When using keyboard/gamepad and a zero precision format string (e.g. "%.0f"), always step in integer units. (#1866)
+ - ImFontConfig: Added GlyphMinAdvanceX/GlyphMaxAdvanceX settings useful to make a font appears monospaced, particularly useful for icon fonts. (#1869)
  - ImFontAtlas: Added GetGlyphRangesChineseSimplifiedCommon() helper that returns a list of ~2500 most common Simplified Chinese characters. (#1859) [@JX-Master, @ocornut]
  - Examples: GLFW: Made it possible to Shutdown/Init the backend again (by reseting the time storage properly). (#1827) [@ice1000]
  - Misc: Updated stb_textedit from 1.09 + patches to 1.12 + minor patches.

imgui.h

@@ -1699,13 +1699,15 @@ struct ImFontConfig
     int             FontDataSize;           //          // TTF/OTF data size
     bool            FontDataOwnedByAtlas;   // true     // TTF/OTF data ownership taken by the container ImFontAtlas (will delete memory itself).
     int             FontNo;                 // 0        // Index of font within TTF/OTF file
-    float           SizePixels;             //          // Size in pixels for rasterizer.
+    float           SizePixels;             //          // Size in pixels for rasterizer (more or less maps to the resulting font height).
     int             OversampleH;            // 3        // Rasterize at higher quality for sub-pixel positioning. We don't use sub-pixel positions on the Y axis.
     int             OversampleV;            // 1        // Rasterize at higher quality for sub-pixel positioning. We don't use sub-pixel positions on the Y axis.
     bool            PixelSnapH;             // false    // Align every glyph to pixel boundary. Useful e.g. if you are merging a non-pixel aligned font with the default font. If enabled, you can set OversampleH/V to 1.
     ImVec2          GlyphExtraSpacing;      // 0, 0     // Extra spacing (in pixels) between glyphs. Only X axis is supported for now.
     ImVec2          GlyphOffset;            // 0, 0     // Offset all glyphs from this font input.
     const ImWchar*  GlyphRanges;            // NULL     // Pointer to a user-provided list of Unicode range (2 value per range, values are inclusive, zero-terminated list). THE ARRAY DATA NEEDS TO PERSIST AS LONG AS THE FONT IS ALIVE.
+    float           GlyphMinAdvanceX;       // 0        // Minimum AdvanceX for glyphs, set Min to align font icons, set both Min/Max to enforce mono-space font
+    float           GlyphMaxAdvanceX;       // FLT_MAX  // Maximum AdvanceX for glyphs
     bool            MergeMode;              // false    // Merge into previous ImFont, so you can combine multiple inputs font into one ImFont (e.g. ASCII font + icons + Japanese glyphs). You may want to use GlyphOffset.y when merge font of different heights.
     unsigned int    RasterizerFlags;        // 0x00     // Settings for custom font rasterizer (e.g. ImGuiFreeType). Leave as zero if you aren't using one.
     float           RasterizerMultiply;     // 1.0f     // Brighten (>1.0f) or darken (<1.0f) font output. Brightening small fonts may be a good workaround to make them more readable.
@@ -1787,7 +1789,7 @@ struct ImFontAtlas
         void           SetBit(int n)        { UsedChars[n >> 3] |= 1 << (n & 7); }  // Set bit 'c' in the array
         void           AddChar(ImWchar c)   { SetBit(c); }                          // Add character
         IMGUI_API void AddText(const char* text, const char* text_end = NULL);      // Add string (each character of the UTF-8 string are added)
-        IMGUI_API void AddRanges(const ImWchar* ranges);                            // Add ranges, e.g. builder.AddRanges(ImFontAtlas::GetGlyphRangesDefault) to force add all of ASCII/Latin+Ext
+        IMGUI_API void AddRanges(const ImWchar* ranges);                            // Add ranges, e.g. builder.AddRanges(ImFontAtlas::GetGlyphRangesDefault()) to force add all of ASCII/Latin+Ext
         IMGUI_API void BuildRanges(ImVector<ImWchar>* out_ranges);                  // Output new ranges
     };
 

imgui_draw.cpp

@@ -1325,6 +1325,8 @@ ImFontConfig::ImFontConfig()
     GlyphExtraSpacing = ImVec2(0.0f, 0.0f);
     GlyphOffset = ImVec2(0.0f, 0.0f);
     GlyphRanges = NULL;
+    GlyphMinAdvanceX = 0.0f;
+    GlyphMaxAdvanceX = FLT_MAX;
     MergeMode = false;
     RasterizerFlags = 0x00;
     RasterizerMultiply = 1.0f;
@@ -1867,8 +1869,8 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
         const float ascent = ImFloor(unscaled_ascent * font_scale + ((unscaled_ascent > 0.0f) ? +1 : -1));
         const float descent = ImFloor(unscaled_descent * font_scale + ((unscaled_descent > 0.0f) ? +1 : -1));
         ImFontAtlasBuildSetupFont(atlas, dst_font, &cfg, ascent, descent);
-        const float off_x = cfg.GlyphOffset.x;
-        const float off_y = cfg.GlyphOffset.y + (float)(int)(dst_font->Ascent + 0.5f);
+        const float font_off_x = cfg.GlyphOffset.x;
+        const float font_off_y = cfg.GlyphOffset.y + (float)(int)(dst_font->Ascent + 0.5f);
 
         for (int i = 0; i < tmp.RangesCount; i++)
         {
@@ -1883,10 +1885,16 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
                 if (cfg.MergeMode && dst_font->FindGlyphNoFallback((unsigned short)codepoint))
                     continue;
 
+                float char_advance_x_org = pc.xadvance;
+                float char_advance_x_mod = ImClamp(char_advance_x_org, cfg.GlyphMinAdvanceX, cfg.GlyphMaxAdvanceX);
+                float char_off_x = font_off_x;
+                if (char_advance_x_org != char_advance_x_mod)
+                    char_off_x += cfg.PixelSnapH ? (float)(int)((char_advance_x_mod - char_advance_x_org) * 0.5f) : (char_advance_x_mod - char_advance_x_org) * 0.5f;
+
                 stbtt_aligned_quad q;
                 float dummy_x = 0.0f, dummy_y = 0.0f;
                 stbtt_GetPackedQuad(range.chardata_for_range, atlas->TexWidth, atlas->TexHeight, char_idx, &dummy_x, &dummy_y, &q, 0);
-                dst_font->AddGlyph((ImWchar)codepoint, q.x0 + off_x, q.y0 + off_y, q.x1 + off_x, q.y1 + off_y, q.s0, q.t0, q.s1, q.t1, pc.xadvance);
+                dst_font->AddGlyph((ImWchar)codepoint, q.x0 + char_off_x, q.y0 + font_off_y, q.x1 + char_off_x, q.y1 + font_off_y, q.s0, q.t0, q.s1, q.t1, char_advance_x_mod);
             }
         }
     }

misc/fonts/README.txt

@@ -57,6 +57,7 @@ In this document:
 
    ImFontConfig config;
    config.MergeMode = true;
+   config.GlyphMinAdvanceX = 13.0f; // Use if you want to make the icon monospaced
    static const ImWchar icon_ranges[] = { ICON_MIN_FA, ICON_MAX_FA, 0 };
    io.Fonts->AddFontFromFileTTF("fonts/fontawesome-webfont.ttf", 13.0f, &config, icon_ranges);
 

misc/freetype/imgui_freetype.cpp

@@ -9,6 +9,7 @@
 // - v0.53: (2017/10/22) minor inconsequential change to match change in master (removed an unnecessary statement)
 // - v0.54: (2018/01/22) fix for addition of ImFontAtlas::TexUvscale member
 // - v0.55: (2018/02/04) moved to main imgui repository (away from http://www.github.com/ocornut/imgui_club)
+// - v0.56: (2018/06/08) added support for ImFontConfig::GlyphMinAdvanceX, GlyphMaxAdvanceX
 
 // Gamma Correct Blending:
 //  FreeType assumes blending in linear space rather than gamma space.
@@ -324,8 +325,8 @@ bool ImGuiFreeType::BuildFontAtlas(ImFontAtlas* atlas, unsigned int extra_flags)
         const float ascent = font_face.Info.Ascender;
         const float descent = font_face.Info.Descender;
         ImFontAtlasBuildSetupFont(atlas, dst_font, &cfg, ascent, descent);
-        const float off_x = cfg.GlyphOffset.x;
-        const float off_y = cfg.GlyphOffset.y + (float)(int)(dst_font->Ascent + 0.5f);
+        const float font_off_x = cfg.GlyphOffset.x;
+        const float font_off_y = cfg.GlyphOffset.y + (float)(int)(dst_font->Ascent + 0.5f);
 
         bool multiply_enabled = (cfg.RasterizerMultiply != 1.0f);
         unsigned char multiply_table[256];
@@ -356,17 +357,23 @@ bool ImGuiFreeType::BuildFontAtlas(ImFontAtlas* atlas, unsigned int extra_flags)
                 font_face.BlitGlyph(ft_glyph_bitmap, blit_dst, atlas->TexWidth, multiply_enabled ? multiply_table : NULL);
                 FT_Done_Glyph(ft_glyph);
 
+                float char_advance_x_org = glyph_info.AdvanceX;
+                float char_advance_x_mod = ImClamp(char_advance_x_org, cfg.GlyphMinAdvanceX, cfg.GlyphMaxAdvanceX);
+                float char_off_x = font_off_x;
+                if (char_advance_x_org != char_advance_x_mod)
+                    char_off_x += cfg.PixelSnapH ? (float)(int)((char_advance_x_mod - char_advance_x_org) * 0.5f) : (char_advance_x_mod - char_advance_x_org) * 0.5f;
+
                 // Register glyph
                 dst_font->AddGlyph((ImWchar)codepoint, 
-                    glyph_info.OffsetX + off_x, 
-                    glyph_info.OffsetY + off_y, 
-                    glyph_info.OffsetX + off_x + glyph_info.Width, 
-                    glyph_info.OffsetY + off_y + glyph_info.Height,
+                    glyph_info.OffsetX + char_off_x, 
+                    glyph_info.OffsetY + font_off_y, 
+                    glyph_info.OffsetX + char_off_x + glyph_info.Width, 
+                    glyph_info.OffsetY + font_off_y + glyph_info.Height,
                     rect.x / (float)atlas->TexWidth, 
                     rect.y / (float)atlas->TexHeight, 
                     (rect.x + glyph_info.Width) / (float)atlas->TexWidth, 
                     (rect.y + glyph_info.Height) / (float)atlas->TexHeight,
-                    glyph_info.AdvanceX);
+                    char_advance_x_mod);
             }
         }
     }