My first program that uses the SDL TTF library..and it doesn't work

SDL Development
1

Consider the following C++ program (sorry, not minimal, but still
simple). It runs without assertions being triggered or error messages
being shown but I don’t see any text output at all (the rest works as
expected):
#include <SDL.h>
#include <SDL_ttf.h>
#include <GL/gl.h>

#include
#include
#include

using namespace std;

static int shade_models[] = { GL_FLAT, GL_SMOOTH };

float square_vertices[][2] =
{
{-0.5f, -0.5f},
{-0.5f, 0.5f},
{0.5f, 0.5f},
{0.5f, -0.5f}
};

static SDL_Surface *
obtain_text_surface(const string& fontname, const string& str)
{
int retval = TTF_Init();

assert(retval != -1);

// TODO: Fix font leakage
TTF_Font *font = TTF_OpenFont(fontname.c_str(), 12);

assert(font);

SDL_Color color={0, 0, 0xFF, 0};

return TTF_RenderText_Blended(font, str.c_str(), color);

}

static void
display(SDL_Surface * screen, SDL_Surface *text_surface)
{
glClear(GL_COLOR_BUFFER_BIT);

glBegin(GL_POLYGON);

glColor3ub(0xFF, 0x38, 0x59);
glVertex2fv(square_vertices[0]);

glColor3ub(0xa0, 0x0E, 0x10);
glVertex2fv(square_vertices[1]);

glColor3ub(0x90, 0x90, 0x90);
glVertex2fv(square_vertices[2]);

glColor3ub(0x01, 0x01, 0x20);
glVertex2fv(square_vertices[3]);

glEnd();

SDL_Rect dest = {0,0,0,0};

if (SDL_BlitSurface(text_surface, NULL, screen, &dest) == -1)
{
   cout << "SDL_BlitSurface() failed. SDL_GetError() says: "
        << SDL_GetError() << endl;
}

SDL_GL_SwapBuffers();

}

int
main(int argc, char *argv[])
{
(void)argc;
(void)argv;

int retval = SDL_Init(SDL_INIT_VIDEO);

assert(retval == 0);

SDL_Surface *screen = SDL_SetVideoMode(640, 480, 0, SDL_OPENGL);

assert(screen != NULL);

SDL_WM_SetCaption("Simple 1-3 (using SDL)", NULL);

glShadeModel(GL_FLAT);

SDL_Surface *text_surface =
   obtain_text_surface("arial.ttf", "hello world");

assert(text_surface);

SDL_Event event;
bool run_mainloop = true;

while (run_mainloop == true)
{
   while (SDL_PollEvent(&event))
   {
      switch (event.type)
      {
         case SDL_QUIT:
            run_mainloop = false;

            break;
         case SDL_KEYDOWN:
            switch (event.key.keysym.sym)
            {
               case SDLK_ESCAPE:
               case 'q': /* Catches 'Q' too. */
                  run_mainloop = false;

                  break;
               case 't': /* Catches 'T' too, toggles shade mode. */
                  static int i = 0;

                  glShadeModel(shade_models[++i % 2]);

                  break;
               default:
                  ;
            }

            break;
      }
   }

   display(screen, text_surface);

   SDL_Delay(50);
}

SDL_FreeSurface(text_surface);

SDL_Quit();

}

If I replace the call to TTF_RenderText_Blended() with one to _Solid()
it returns NULL…

Any ideas?

/ E

2

Eric Lilja wrote:

If I replace the call to TTF_RenderText_Blended() with one to _Solid()
it returns NULL…

Any ideas?

There is a bug in the Freetype library which breaks solid text rendering.
It should be fixed in the next release of freetype.

//a