ImFont: Added AddRemapChar() helper (#609)

imgui.cpp

@@ -537,7 +537,7 @@
  - style: WindowPadding needs to be EVEN needs the 0.5 multiplier probably have a subtle effect on clip rectangle
  - text: simple markup language for color change?
  - font: dynamic font atlas to avoid baking huge ranges into bitmap and make scaling easier.
- - font: helper to add glyph redirect/replacements (e.g. redirect alternate apostrophe unicode code points to ascii one, etc.)
+ - font: fix AddRemapChar() to work before font has been built.
  - log: LogButtons() options for specifying depth and/or hiding depth slider
  - log: have more control over the log scope (e.g. stop logging when leaving current tree node scope)
  - log: be able to log anything (e.g. right-click on a window/tree-node, shows context menu? log into tty/file/clipboard)

imgui.h

@@ -1316,9 +1316,9 @@ struct ImFont
     IMGUI_API ~ImFont();
     IMGUI_API void              Clear();
     IMGUI_API void              BuildLookupTable();
-    IMGUI_API const Glyph*      FindGlyph(unsigned short c) const;
+    IMGUI_API const Glyph*      FindGlyph(ImWchar c) const;
     IMGUI_API void              SetFallbackChar(ImWchar c);
-    float                       GetCharAdvance(unsigned short c) const  { return ((int)c < IndexXAdvance.Size) ? IndexXAdvance[(int)c] : FallbackXAdvance; }
+    float                       GetCharAdvance(ImWchar c) const     { return ((int)c < IndexXAdvance.Size) ? IndexXAdvance[(int)c] : FallbackXAdvance; }
     bool                        IsLoaded() const                    { return ContainerAtlas != NULL; }
 
     // 'max_width' stops rendering after a certain width (could be turned into a 2d size). FLT_MAX to disable.
@@ -1327,6 +1327,10 @@ struct ImFont
     IMGUI_API const char*       CalcWordWrapPositionA(float scale, const char* text, const char* text_end, float wrap_width) const;
     IMGUI_API void              RenderChar(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, unsigned short c) const;
     IMGUI_API void              RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, const ImVec4& clip_rect, const char* text_begin, const char* text_end, float wrap_width = 0.0f, bool cpu_fine_clip = false) const;
+
+    // Private
+    IMGUI_API void              GrowIndex(int new_size);
+    IMGUI_API void              AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst = true); // Makes 'dst' character/glyph points to 'src' character/glyph. Currently needs to be called AFTER fonts have been built.
 };
 
 //---- Include imgui_user.h at the end of imgui.h

imgui_draw.cpp

@@ -1677,14 +1677,8 @@ void ImFont::BuildLookupTable()
 
     IM_ASSERT(Glyphs.Size < 32*1024);
     IndexXAdvance.clear();
-    IndexXAdvance.resize(max_codepoint + 1);
     IndexLookup.clear();
-    IndexLookup.resize(max_codepoint + 1);
+    GrowIndex(max_codepoint + 1);
-    for (int i = 0; i < max_codepoint + 1; i++)
-    {
-        IndexXAdvance[i] = -1.0f;
-        IndexLookup[i] = (short)-1;
-    }
     for (int i = 0; i < Glyphs.Size; i++)
     {
         int codepoint = (int)Glyphs[i].Codepoint;
@@ -1720,6 +1714,36 @@ void ImFont::SetFallbackChar(ImWchar c)
     BuildLookupTable();
 }
 
+void ImFont::GrowIndex(int new_size)
+{
+    IM_ASSERT(IndexXAdvance.Size == IndexLookup.Size);
+    int old_size = IndexLookup.Size;
+    if (new_size <= old_size)
+        return;
+    IndexXAdvance.resize(new_size);
+    IndexLookup.resize(new_size);
+    for (int i = old_size; i < new_size; i++)
+    {
+        IndexXAdvance[i] = -1.0f;
+        IndexLookup[i] = (short)-1;
+    }
+}
+
+void ImFont::AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst)
+{
+    IM_ASSERT(IndexLookup.Size > 0);    // Currently this can only be called AFTER the font has been built, aka after calling ImFontAtlas::GetTexDataAs*() function.
+    int index_size = IndexLookup.Size;
+
+    if (dst < index_size && IndexLookup.Data[dst] == -1 && !overwrite_dst) // 'dst' already exists
+        return;
+    if (src >= index_size && dst >= index_size) // both 'dst' and 'src' don't exist -> no-op
+        return;
+
+    GrowIndex(dst + 1);
+    IndexLookup[dst] = (src < index_size) ? IndexLookup.Data[src] : -1;
+    IndexXAdvance[dst] = (src < index_size) ? IndexXAdvance.Data[src] : 1.0f;
+}
+
 const ImFont::Glyph* ImFont::FindGlyph(unsigned short c) const
 {
     if (c < IndexLookup.Size)