Added IO.FontFallbackGlyph (default to '?') + UTF-8 test in demo window

imgui.cpp

@@ -320,6 +320,7 @@ ImGuiIO::ImGuiIO()
     FontTexUvForWhite = ImVec2(0.0f,0.0f);
     FontBaseScale = 1.0f;
     FontAllowUserScaling = false;
+    FontFallbackGlyph = (ImWchar)'?';
     PixelCenterOffset = 0.0f;
     MousePos = ImVec2(-1,-1);
     MousePosPrev = ImVec2(-1,-1);
@@ -5577,6 +5578,7 @@ ImVec2 ImBitmapFont::CalcTextSizeA(float size, float max_width, const char* text
 
     const float scale = size / (float)Info->FontSize;
     const float line_height = (float)Info->FontSize * scale;
+    const FntGlyph* fallback_glyph = FindGlyph(GImGui.IO.FontFallbackGlyph);
 
     ImVec2 text_size = ImVec2(0,0);
     float line_width = 0.0f;
@@ -5595,7 +5597,18 @@ ImVec2 ImBitmapFont::CalcTextSizeA(float size, float max_width, const char* text
             text_size.y += line_height;
             line_width = 0;
         }
-        else if (const FntGlyph* glyph = FindGlyph((unsigned short)c))
+        else if (c == '\t')
+        {
+            // FIXME: Better TAB handling needed.
+            if (const FntGlyph* glyph = FindGlyph((unsigned short)' '))
+                line_width += (glyph->XAdvance + Info->SpacingHoriz) * 4 * scale;
+        }
+        else
+        {
+            const FntGlyph* glyph = FindGlyph((unsigned short)c);
+            if (!glyph)
+                glyph = fallback_glyph;
+            if (glyph)
             {
                 const float char_width = (glyph->XAdvance + Info->SpacingHoriz) * scale;
                 //const float char_extend = (glyph->XOffset + glyph->Width * scale);
@@ -5603,11 +5616,6 @@ ImVec2 ImBitmapFont::CalcTextSizeA(float size, float max_width, const char* text
                     break;
                 line_width += char_width;
             }
-        else if (c == '\t')
-        {
-            // FIXME: Better TAB handling needed.
-            if (const FntGlyph* glyph = FindGlyph((unsigned short)' '))
-                line_width += (glyph->XAdvance + Info->SpacingHoriz) * 4 * scale;
         }
     }
 
@@ -5633,6 +5641,7 @@ ImVec2 ImBitmapFont::CalcTextSizeW(float size, float max_width, const ImWchar* t
 
     const float scale = size / (float)Info->FontSize;
     const float line_height = (float)Info->FontSize * scale;
+    const FntGlyph* fallback_glyph = FindGlyph(GImGui.IO.FontFallbackGlyph);
 
     ImVec2 text_size = ImVec2(0,0);
     float line_width = 0.0f;
@@ -5649,7 +5658,18 @@ ImVec2 ImBitmapFont::CalcTextSizeW(float size, float max_width, const ImWchar* t
             text_size.y += line_height;
             line_width = 0;
         }
-        else if (const FntGlyph* glyph = FindGlyph((unsigned short)c))
+        else if (c == '\t')
+        {
+            // FIXME: Better TAB handling needed.
+            if (const FntGlyph* glyph = FindGlyph((unsigned short)' '))
+                line_width += (glyph->XAdvance + Info->SpacingHoriz) * 4 * scale;
+        }
+        else
+        {
+            const FntGlyph* glyph = FindGlyph((unsigned short)c);
+            if (!glyph)
+                glyph = fallback_glyph;
+            if (glyph)
             {
                 const float char_width = (glyph->XAdvance + Info->SpacingHoriz) * scale;
                 //const float char_extend = (glyph->XOffset + glyph->Width * scale);
@@ -5657,11 +5677,6 @@ ImVec2 ImBitmapFont::CalcTextSizeW(float size, float max_width, const ImWchar* t
                     break;
                 line_width += char_width;
             }
-        else if (c == '\t')
-        {
-            // FIXME: Better TAB handling needed.
-            if (const FntGlyph* glyph = FindGlyph((unsigned short)' '))
-                line_width += (glyph->XAdvance + Info->SpacingHoriz) * 4 * scale;
         }
     }
 
@@ -5688,6 +5703,7 @@ void ImBitmapFont::RenderText(float size, ImVec2 pos, ImU32 col, const ImVec4& c
     const float tex_scale_x = 1.0f / (float)Common->ScaleW;
     const float tex_scale_y = 1.0f / (float)(Common->ScaleH);
     const float outline = (float)Info->Outline;
+    const FntGlyph* fallback_glyph = FindGlyph(GImGui.IO.FontFallbackGlyph);
 
     // Align to be pixel perfect
     pos.x = (float)(int)pos.x;
@@ -5712,7 +5728,10 @@ void ImBitmapFont::RenderText(float size, ImVec2 pos, ImU32 col, const ImVec4& c
             continue;
         }
 
-        if (const FntGlyph* glyph = FindGlyph((unsigned short)c))
+        const FntGlyph* glyph = FindGlyph((unsigned short)c);
+        if (!glyph)
+            glyph = fallback_glyph;
+        if (glyph)
         {
             const float char_width = (glyph->XAdvance + Info->SpacingHoriz) * scale;
             //const float char_extend = (glyph->XOffset + glyph->Width * scale);
@@ -6038,6 +6057,22 @@ void ShowTestWindow(bool* open)
             ImGui::TreePop();
         }
 
+        if (ImGui::TreeNode("UTF-8 Text"))
+        {
+            // UTF-8 test (need a suitable font, try extra_fonts/mplus* files for example)
+            // Most compiler appears to support UTF-8 in source code (with Visual Studio you need to save your file as 'UTF-8 without signature')
+            // However for the sake for maximum portability here we are *not* including raw UTF-8 character in this source file, instead we encode the string with with hexadecimal constants.
+            // In your own application please be reasonable and use UTF-8 in the source or get the data from external files. :)
+            //const char* utf8_string = "\xe3\x81\x8b\xe3\x81\x8d\xe3\x81\x8f\xe3\x81\x91\xe3\x81\x93\x20\xe6\x97\xa5\xe6\x9c\xac\xe8\xaa\x9e"; // Japanese text for "Kakikukeo" (Hiragana) followed by "Nihongo" (kanji)
+            ImGui::Text("(CJK text will only appears if the font supports it. Please check in\nthe extra_fonts/ folder if you intend to use non-ASCII characters.\nNote that characters values are preserved even if the font cannot be\ndisplayed, so you can safely copy & paste garbled characters.)");
+            ImGui::Text("Hiragana: \xe3\x81\x8b\xe3\x81\x8d\xe3\x81\x8f\xe3\x81\x91\xe3\x81\x93 (kakikukeko)");
+            ImGui::Text("Kanjis: \xe6\x97\xa5\xe6\x9c\xac\xe8\xaa\x9e (nihongo)");
+            static char buf[32] = "\xe6\x97\xa5\xe6\x9c\xac\xe8\xaa\x9e";
+            ImGui::InputText("UTF-8 input", buf, IM_ARRAYSIZE(buf));
+            ImGui::TreePop();
+        }
+
+
         static int e = 0;
         ImGui::RadioButton("radio a", &e, 0); ImGui::SameLine();
         ImGui::RadioButton("radio b", &e, 1); ImGui::SameLine();

imgui.h

@@ -419,6 +419,7 @@ struct ImGuiIO
     ImVec2      FontTexUvForWhite;          // = (0.0f,0.0f)            // Font texture must have a white pixel at this UV coordinate. Adjust if you are using custom texture.
     float       FontBaseScale;              // = 1.0f                   // Base font scale, multiplied by the per-window font scale which you can adjust with SetFontScale()
     bool        FontAllowUserScaling;       // = false                  // Set to allow scaling text with CTRL+Wheel.
+	ImWchar     FontFallbackGlyph;          // = '?'                    // Replacement glyph is one isn't found.
     float       PixelCenterOffset;          // = 0.0f                   // Try to set to 0.5f or 0.375f if rendering is blurry
 
     //------------------------------------------------------------------