From 3c8831827fc789cda2fe5333910710f4d75547d5 Mon Sep 17 00:00:00 2001
From: Stefan <stefan@die-antwort.eu>
Date: Sun, 15 May 2022 19:16:55 +0200
Subject: Completely hide chart titles if blank
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Before this change, a chart with a blank title would show up in Excel with a default title like “Chart title” or “Diagrammtitel”.

It was not possible to completely hide a chart title: Setting it to an empty space would override Excel’s default, but the empty title did still occupy vertical space.

Per OOXML standard the `title` element is optional, so omitting it if the title is blank looks like the right thing to do and seems to work correctly in Excel.
---
 lib/axlsx/drawing/chart.rb |  2 +-
 test/drawing/tc_chart.rb   | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/axlsx/drawing/chart.rb b/lib/axlsx/drawing/chart.rb
index d3a7e9ff..99b62b64 100644
--- a/lib/axlsx/drawing/chart.rb
+++ b/lib/axlsx/drawing/chart.rb
@@ -189,7 +189,7 @@ module Axlsx
       str << ('<c:date1904 val="' << Axlsx::Workbook.date1904.to_s << '"/>')
       str << ('<c:style val="' << style.to_s << '"/>')
       str << '<c:chart>'
-      @title.to_xml_string str
+      @title.to_xml_string(str) unless @title.empty?
       str << ('<c:autoTitleDeleted val="' << (@title == nil).to_s << '"/>')
       @view_3D.to_xml_string(str) if @view_3D
       str << '<c:floor><c:thickness val="0"/></c:floor>'
diff --git a/test/drawing/tc_chart.rb b/test/drawing/tc_chart.rb
index 302d13cd..58622621 100644
--- a/test/drawing/tc_chart.rb
+++ b/test/drawing/tc_chart.rb
@@ -1,3 +1,5 @@
+$LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../"
+
 require 'tc_helper.rb'
 
 class TestChart < Test::Unit::TestCase
@@ -25,6 +27,8 @@ class TestChart < Test::Unit::TestCase
     @chart.title = @row.cells.first
     assert_equal(@chart.title.text, "one", "the title text was set via cell reference")
     assert_equal(@chart.title.cell, @row.cells.first)
+    @chart.title = ""
+    assert(@chart.title.empty?)
   end
 
   def test_style
@@ -121,4 +125,14 @@ class TestChart < Test::Unit::TestCase
     doc = Nokogiri::XML(@chart.to_xml_string)
     assert_equal("span", doc.xpath("//c:dispBlanksAs").attr("val").value, "did not use the display_blanks_as configuration")
   end
+
+  def test_to_xml_string_for_title
+    @chart.title = "foobar"
+    doc = Nokogiri::XML(@chart.to_xml_string)
+    assert_equal("foobar", doc.xpath("//c:title//c:tx//a:t").text)
+
+    @chart.title = ""
+    doc = Nokogiri::XML(@chart.to_xml_string)
+    assert_equal(0, doc.xpath("//c:title").size)
+  end
 end
-- 
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