freetye2 use

  Environment and version: qt ubuntu 16.04 freetype-2.10.0

1. Download

   https://sourceforge.net/projects/freetype/files/freetype2/

2. Unzip the compiler  

　　./configure

　　make

　　sudo make install

3. compiled files stored path

  
  Header file: / usr / local / include / 

library files: / usr / local / lib / 

header file path is problematic, freetype and ft2build.h should be placed outside of freetyp2. So set the header file in the .pro inside path 
set only the first file path does not work, "error appears:. Undefined reference to` FT_Init_FreeType 'wrong 

using .pro file in the right way to add external libraries:

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../usr/local/lib/release/ -lfreetype
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../usr/local/lib/debug/ -lfreetype
else:unix: LIBS += -L$$PWD/../../../../usr/local/lib/ -lfreetype

INCLUDEPATH += $$PWD/../../../../usr/local/include/freetype2
DEPENDPATH += $$PWD/../../../../usr/local/include/freetype2