Re: [pygame] BUG: Inconsistent font behavior between Windows and Linux

[Lenard Lindstrom <len-l@xxxxxxxxx>]

Attached is a C version of font_test.py. It takes a font size as its 
only argument. Running the program for both pitch 21 and 210 I get the 
same results as I get for font_test.py.

Lenard


Lenard Lindstrom wrote:
> I can't account for why the numbers match at a pitch of 210, but not 
> 21. I did find the place in SDL_ttf where the dpi is set to the 
> FreeType default of 72. And the post to the FreeType mailing list I 
> referred to earlier, 
> http://lists.nongnu.org/archive/html/freetype-devel/2002-08/msg00020.html, 
> does imply that font size, in pixels, is affected by some operating 
> system provided value. But then this could involve values passed to 
> FreeType or FreeType as a display driver. On Windows there are no 
> explicit Windows api calls, just C library calls. So I don't know what 
> I imply any more. Maybe a C only version of font_test.py will clear 
> some things up.
>
> Lenard
>
>
> Brian Fisher wrote:
> > Lenard, are you saying you think it still may be a dpi problem?
> >
> > cause I think if dpi was the problem in this case, the discrepancy 
> > would scale with font size. But as there is no discrepancy between 
> > the platforms when the font size is 210 (i.e. charlies gentoo matches 
> > your windows box), it seems to me that dpi (or any font scaling 
> > really) is not different, and therefore not the cause here
> >
> > I really think SDL_ttf is fixing the freetype scaling so it doesn't 
> > vary with platform. It would just make sense.
> >
> > did I misunderstand or am I missing something there?
> >
> >
> > On Thu, Sep 4, 2008 at 1:38 PM, Lenard Lindstrom <len-l@xxxxxxxxx 
> > <mailto:len-l@xxxxxxxxx>> wrote:
> >
> >     As for display point size, that may be the case with Windows, but
> >     what about Unix.

#include "SDL/SDL.h"
#include "SDL/SDL_ttf.h"
#include <stdio.h>
#include <stdlib.h>

static int err_tst(int result)
{
  if (result != 0)
  {
    printf("*** %s\n", SDL_GetError());
    return 1;
  }
  return 0;
}

static void print_size(TTF_Font* font, char *text)
{
  int w = -1, h = -1;
  
  TTF_SizeText(font, text, &w, &h);
  printf("(%i, %i)\n", w, h);
}

static void print_metrics(TTF_Font* font, char *text)
{
  int minx = -1, maxx = -1, miny = -1, maxy = -1, advance = -1;
  int add_comma = 0;

  printf("[");
  while (*text != '\0')
  {
    if (add_comma)
    {
      printf(", ");
    }
    add_comma = 1;

    if (TTF_GlyphMetrics(font, (unsigned short) *text, &minx, &maxx,
                         &miny, &maxy, &advance) == -1)
    {
      printf("None");
    }
    else
    {
      printf("(%i, %i, %i, %i, %i)", minx, maxx, miny, maxy, advance);
    }
    ++text;
  }
  printf("]\n");
}

static int print_render(TTF_Font* font, char* astring, unsigned char rgba[3])
{
  SDL_Surface* surf = 0;
  const char *type;
  SDL_Color foreg;

  foreg.r = rgba[0];
  foreg.g = rgba[1];
  foreg.b = rgba[2];

  surf = TTF_RenderText_Blended(font, astring, foreg);
  if (surf == 0)
  {
    return 1;
  }
  type = (surf->flags & SDL_HWSURFACE) ? "HW" : "SW";
  printf("<Surface(%dx%dx%d %s)>\n", surf->w, surf->h,
         surf->format->BitsPerPixel, type);
  SDL_FreeSurface(surf);
  return 0;
}

int main(int argc, char *argv[])
{
  int fontsize = atoi(argv[1]);
  TTF_Font* f = 0;
  int retcode = 1;
  unsigned char black[] = {0, 0, 0};
  int w = -1, h = -1;
  
  // pygame.font.init()
  if (err_tst(TTF_Init()))
  {
    goto quit_0;
  }

  // f = pygame.font.Font("acknowtt.ttf", 21)
  if (fontsize <= 1)
  {
    fontsize = 1;
  }
  f = TTF_OpenFont("acknowtt.ttf", fontsize);
  if (err_tst(f == 0))
  {
    goto quit_1;
  }

  // print f.size("6")
  print_size(f, "6");

  // print f.size("7")
  print_size(f, "7");

  // print
  printf("\n");

  // print f.render("66", True, (0,0,0,255))
  if (print_render(f, "66", black))
  {
    goto quit_2;
  }

  // print f.render("67", True, (0,0,0,255))
  if (print_render(f, "67", black))
  {
    goto quit_2;
  }

  // print
  printf("\n");

  // print f.metrics("66")
  print_metrics(f, "66");

  // print f.metrics("67")
  print_metrics(f, "67");

  retcode = 0;

 quit_2:
  TTF_CloseFont(f);
 quit_1:
  TTF_Quit();
 quit_0:
  return retcode;
}