Calculate width for multiline text

Author: Paxa

ext/fast_excel/text_width_ext.c

@@ -405,6 +405,7 @@ static VALUE
 rb_some_text_width(VALUE text, float default_width, float char_widths[127], float kernings[127][127]) {
   char *text_value = StringValueCStr(text);
 
+  double max = 0;
   double total = 0;
   char ch = 0;
   char nch = 0;
@@ -414,6 +415,11 @@ rb_some_text_width(VALUE text, float default_width, float char_widths[127], floa
     ch = text_value[i];
     nch = text_value[i + 1];
 
+    if (ch == 10) {
+      if (total > max) max = total;
+      total = 0;
+    }
+
     if (ch < 32) continue;
 
     if (ch > 126) {
@@ -425,8 +431,9 @@ rb_some_text_width(VALUE text, float default_width, float char_widths[127], floa
       total += char_widths[ch];
     }
   }
+  if (total > max) max = total;
 
-  return DBL2NUM(total);
+  return DBL2NUM(max);
 }
 
 static VALUE

letters.html

@@ -44,7 +44,7 @@
     canvas.textAlign = 'start';
     canvas.textBaseline = 'alphabetic';
 
-    var textWidth = function getWidth(value) {
+    window.textWidth = function getWidth(value) {
       return canvas.measureText(value).width;
     }
 

test/text_width_test.rb

@@ -18,6 +18,10 @@
   it "should skip system characters" do
     assert_in_delta(FastExcel.arial_text_width(10.chr), 0.0)
   end
+
+  it "should handle multiline text" do
+    assert_in_delta(FastExcel.arial_text_width("More\nThen\nOne Line"), 405.85, 0.1)
+  end
 end
 
 describe "FastExcel Calibri text_width" do