Font: direct AddText()/RenderText() calls don't need to call strlen() if below clipping region.

Unlikely to meaningful affect anyone but still..

Author: ocornut

imgui_draw.cpp

@@ -1669,8 +1669,7 @@ void ImDrawList::AddText(ImFont* font, float font_size, const ImVec2& pos, ImU32
     // Accept null ranges
     if (text_begin == text_end || text_begin[0] == 0)
         return;
-    if (text_end == NULL)
-        text_end = text_begin + strlen(text_begin);
+    // No need to strlen() here: font->RenderText() will do it and may early out.
 
     // Pull default font/size from the shared ImDrawListSharedData instance
     if (font == NULL)
@@ -1693,7 +1692,7 @@ void ImDrawList::AddText(ImFont* font, float font_size, const ImVec2& pos, ImU32
 
 void ImDrawList::AddText(const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end)
 {
-    AddText(NULL, 0.0f, pos, col, text_begin, text_end);
+    AddText(_Data->Font, _Data->FontSize, pos, col, text_begin, text_end);
 }
 
 void ImDrawList::AddImage(ImTextureID user_texture_id, const ImVec2& p_min, const ImVec2& p_max, const ImVec2& uv_min, const ImVec2& uv_max, ImU32 col)
@@ -4125,15 +4124,15 @@ void ImFont::RenderChar(ImDrawList* draw_list, float size, const ImVec2& pos, Im
 // Note: as with every ImDrawList drawing function, this expects that the font atlas texture is bound.
 void ImFont::RenderText(ImDrawList* draw_list, float size, const ImVec2& pos, ImU32 col, const ImVec4& clip_rect, const char* text_begin, const char* text_end, float wrap_width, bool cpu_fine_clip)
 {
-    if (!text_end)
-        text_end = text_begin + strlen(text_begin); // ImGui:: functions generally already provides a valid text_end, so this is merely to handle direct calls.
-
     // Align to be pixel perfect
     float x = IM_TRUNC(pos.x);
     float y = IM_TRUNC(pos.y);
     if (y > clip_rect.w)
         return;
 
+    if (!text_end)
+        text_end = text_begin + strlen(text_begin); // ImGui:: functions generally already provides a valid text_end, so this is merely to handle direct calls.
+
     const float scale = size / FontSize;
     const float line_height = FontSize * scale;
     const float origin_x = x;