using freetype library with Qt

[saman_artorious]

To render text with OpenGL, I need the FreeType library. I found out that this library is included with Qt 3rd party packages, located in :

/opt/Qt5.0.1/5.0.1/Src/qtbase/src/3rdparty/freetype/include/freetype

/opt/Qt5.0.1/5.0.1/Src/qtbase/src/3rdparty/freetype/include/freetype

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To test if the library is successfully working, I ran the below code snippet:

#include <ft2build.h>
#include FT_FREETYPE_H
 
FT_Library ft;
 
if(FT_Init_FreeType(&ft)) {
  fprintf(stderr, "Could not init freetype library\n");
  return 1;
}

#include <ft2build.h>
#include FT_FREETYPE_H

FT_Library ft;
 
if(FT_Init_FreeType(&ft)) {
  fprintf(stderr, "Could not init freetype library\n");
  return 1;
}

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However, I get the following errors:

/usr/local/include/freetype2/freetype/freetype.h:298: error: 'FT_Pos' does not name a type
/usr/local/include/freetype2/freetype/freetype.h:34: error: #include expects "FILENAME" or <FILENAME>
/usr/local/include/freetype2/freetype/freetype.h:656: error: a function call cannot appear in a constant-expression
.
.
.

/usr/local/include/freetype2/freetype/freetype.h:298: error: 'FT_Pos' does not name a type
/usr/local/include/freetype2/freetype/freetype.h:34: error: #include expects "FILENAME" or <FILENAME>
/usr/local/include/freetype2/freetype/freetype.h:656: error: a function call cannot appear in a constant-expression
.
.
.

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any hints would be appreciable.

Cheers,

[wysota]

Your code is invalid and apart from that you're not including proper files thus it does not work.

[saman_artorious]

Your code is invalid and apart from that you're not including proper files thus it does not work.

Before reading your code, I thought the error was because headers are not included from fresh libraries installed, but rather it includes QT freetype headers. If I want to tell qt not to read its own freetype and read the one installed on the system, how can I do that?

about your post, it is the first time I am dealing with freetype, how can I get a valid code? and what are the proper headers I should add? (by the way I followed this tutorial for the above code file:///home/saman/Desktop/OpenGL%20...en%20world.htm)

[wysota]

it is the first time I am dealing with freetype, how can I get a valid code?

A good place to start would be reading compiler errors and correcting them, starting with e.g. this line:

#include FT_FREETYPE_H

#include FT_FREETYPE_H

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[saman_artorious]

A good place to start would be reading compiler errors and correcting them, starting with e.g. this line:

#include FT_FREETYPE_H

#include FT_FREETYPE_H

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Yes, you are right, I change the include directives with their equivalent header files as such:

//#include FT_CONFIG_CONFIG_H
//#include FT_SYSTEM_H
//#include FT_IMAGE_H
 
#include "freetype2/freetype/ftsystem.h"
#include "freetype2/freetype/config/ftconfig.h"
#include "freetype2/freetype/freetype.h"

//#include FT_CONFIG_CONFIG_H
//#include FT_SYSTEM_H
//#include FT_IMAGE_H

#include "freetype2/freetype/ftsystem.h"
#include "freetype2/freetype/config/ftconfig.h"
#include "freetype2/freetype/freetype.h"

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That solved my problem Wysota, thanks for your hint.
I still have one more quetions regarding this problem, when I changed the headers to their equivalents, there are two type of header, as an example for

//#include FT_IMAGE_H

I can add both:

#include "freetype2/freetype/ftimage.h"

or simply

#include "ftimage.h"

I think this is because, I have this library both on Qt 3rd party and have separately installed it as well. is that correct? So, now how do I know which one is for QWt and which one is what i Installed using apt-get .

[wysota]

Your question is unrelated to Qt. Please post C++ questions in the General Programming forum. If you are having trouble understanding how your compiler works, then a good place to look for information would be to read the compiler manual. Assuming you are using GCC the manual can be found on gcc.gnu.org