Fonts: Fixed crash when manually specifying an EllipsisChar that doesn't exist. (#6480)

docs/CHANGELOG.txt

@@ -73,6 +73,7 @@ Other changes:
 - Menus: Fixed an issue when opening a menu hierarchy in a given menu-bar would allow
   opening another via simple hovering. (#3496, #4797)
 - Fonts: Fixed crash when merging fonts and the first font has no valid glyph. (#6446) [@JaedanC]
+- Fonts: Fixed crash when manually specifying an EllipsisChar that doesn't exist. (#6480)
 - Misc: Added ImVec2 unary minus operator. (#6368) [@Koostosh]
 - Debug Tools: Debug Log: Fixed not parsing 0xXXXXXXXX values for geo-locating on mouse
   hover hover when the identifier is at the end of the line. (#5855)

imgui_draw.cpp

@@ -3200,7 +3200,25 @@ void ImFont::BuildLookupTable()
     SetGlyphVisible((ImWchar)' ', false);
     SetGlyphVisible((ImWchar)'\t', false);
 
-    // Ellipsis character is required for rendering elided text. We prefer using U+2026 (horizontal ellipsis).
+    // Setup Fallback character
+    const ImWchar fallback_chars[] = { (ImWchar)IM_UNICODE_CODEPOINT_INVALID, (ImWchar)'?', (ImWchar)' ' };
+    FallbackGlyph = FindGlyphNoFallback(FallbackChar);
+    if (FallbackGlyph == NULL)
+    {
+        FallbackChar = FindFirstExistingGlyph(this, fallback_chars, IM_ARRAYSIZE(fallback_chars));
+        FallbackGlyph = FindGlyphNoFallback(FallbackChar);
+        if (FallbackGlyph == NULL)
+        {
+            FallbackGlyph = &Glyphs.back();
+            FallbackChar = (ImWchar)FallbackGlyph->Codepoint;
+        }
+    }
+    FallbackAdvanceX = FallbackGlyph->AdvanceX;
+    for (int i = 0; i < max_codepoint + 1; i++)
+        if (IndexAdvanceX[i] < 0.0f)
+            IndexAdvanceX[i] = FallbackAdvanceX;
+
+    // Setup Ellipsis character. It is required for rendering elided text. We prefer using U+2026 (horizontal ellipsis).
     // However some old fonts may contain ellipsis at U+0085. Here we auto-detect most suitable ellipsis character.
     // FIXME: Note that 0x2026 is rarely included in our font ranges. Because of this we are more likely to use three individual dots.
     const ImWchar ellipsis_chars[] = { (ImWchar)0x2026, (ImWchar)0x0085 };
@@ -3221,25 +3239,6 @@ void ImFont::BuildLookupTable()
         EllipsisCharStep = (glyph->X1 - glyph->X0) + 1.0f;
         EllipsisWidth = EllipsisCharStep * 3.0f - 1.0f;
     }
-
-    // Setup fallback character
-    const ImWchar fallback_chars[] = { (ImWchar)IM_UNICODE_CODEPOINT_INVALID, (ImWchar)'?', (ImWchar)' ' };
-    FallbackGlyph = FindGlyphNoFallback(FallbackChar);
-    if (FallbackGlyph == NULL)
-    {
-        FallbackChar = FindFirstExistingGlyph(this, fallback_chars, IM_ARRAYSIZE(fallback_chars));
-        FallbackGlyph = FindGlyphNoFallback(FallbackChar);
-        if (FallbackGlyph == NULL)
-        {
-            FallbackGlyph = &Glyphs.back();
-            FallbackChar = (ImWchar)FallbackGlyph->Codepoint;
-        }
-    }
-
-    FallbackAdvanceX = FallbackGlyph->AdvanceX;
-    for (int i = 0; i < max_codepoint + 1; i++)
-        if (IndexAdvanceX[i] < 0.0f)
-            IndexAdvanceX[i] = FallbackAdvanceX;
 }
 
 // API is designed this way to avoid exposing the 4K page size