[cairo] Pango Cairo Rendering Text with Misc Fonts

[robertk54 at aol.com]

I switched to a Linux prototype and have a simple test app which 
renders text on top of an ARGB surface and saves to a .png file.  I am 
still having some issues with rendering text when selecting 
international fonts.  It's almost as if Cairo is using the toy fonts 
but some fonts render good.  The version of Pango I am currently using 
is older and does not support Gravity so I am not trying to render 
vertical text.

Fonts I tried, all render in english and are not very different from 
each other so I do not think they are all good . . .

Century Schoolbook L
Courier
Drugulin CLM
East Syriac Adiabene
Frank Ruehl CLM
KacstDecorative
KacstQura
Kochi Mincho
Lohit Punjabi
Lohit Tamil
Miriam Mono CLM
Mukti Narrow
Serto Batnan
Serto Jerusalem Outline
ZYSong18030

Most of my current test app . . .

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#include <unistd.h>
#include <stdio.h>

#include <pango/pangocairo.h>

#define FOURCIF_WIDTH   704
#define FOURCIF_HEIGHT  476

#if !defined(CAIRO_HAS_FT_FONT)
#error !CAIRO_HAS_FT_FONT
#endif

static cairo_t *m_pCairo=NULL;
static cairo_surface_t *m_pSurface=NULL;
static cairo_surface_t *m_pSurfaceSample=NULL;static double 
m_dXPosStart=0.0;
static double m_dYPosStart=0.0;
static double m_dXPos=0.0;
static double m_dYPos=0.0;
static char *m_pUtf8=NULL;
static char *m_pColor=NULL;
static char *m_pFont=NULL;
static PangoLayout *m_pPangoLayout=NULL;
static PangoFontMap *m_pPangoFontMap=NULL;
static double m_size=12.0;
static double m_r=1.0, m_g=0.0, m_b=0.0, m_a=1.0;
static double m_dTransparency = 0.0;
static int m_iNumFonts;

void ListFonts (void);
void ParseParameters (int argc, char *argv[]);
void SetFont ( const char *font);
void SetRGB (unsigned char r, unsigned char g, unsigned char b, 
unsigned char a);
void HTML40ToRGB(char *HTML40, unsigned char *R, unsigned char *G, 
unsigned char *B);
void AddText (const char *utf8);

int main(int argc, char *argv[])
{
   // Default initial color blue
   unsigned char R = 0;
   unsigned char G = 0;
   unsigned char B = 255;
   unsigned char A = 255;
   double dNorm;

    m_pSurface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 
FOURCIF_WIDTH, FOURCIF_HEIGHT);
   m_pCairo = cairo_create (m_pSurface);
   cairo_set_source_rgba (m_pCairo, R, G, B, A);
   cairo_paint (m_pCairo);
    m_pSurfaceSample = cairo_image_surface_create_from_png 
("sample.png");
    cairo_set_source_surface (m_pCairo, m_pSurfaceSample, 
FOURCIF_WIDTH*0.21, 0);
   cairo_paint (m_pCairo);
   m_pPangoFontMap = pango_cairo_font_map_get_default ();
   m_pPangoLayout = pango_cairo_create_layout (m_pCairo);

   ParseParameters (argc, argv);

   dNorm = m_dTransparency;
   dNorm = (dNorm < 0.0) ? 0.0 : dNorm;
   dNorm = (dNorm > 1.0) ? 1.0 : dNorm;
   A = (unsigned char) ((1.0 - dNorm) * 255.0) & 0xff;

   HTML40ToRGB (m_pColor, &R, &G, &B);
   SetRGB (R, G, B, A);
   SetFont (m_pFont);

   AddText (m_pUtf8);

   g_object_unref (m_pPangoLayout);
   // Write the ARGB surface to a .PNG file so we can view it.
   cairo_surface_write_to_png (m_pSurface, "utf8test-pango.png");
   return 0;
}

void ListFonts ()
{
   PangoFontMap     *pPangoFontMap;
   PangoFontFamily **pPangoFontFamily;
   PangoFontFace   **pPangoFontFace;
   int n_faces;
   int n_families;
   int i;
   int j;

   m_iNumFonts = 0;
   pPangoFontMap = pango_cairo_font_map_get_default ();
    pango_font_map_list_families (pPangoFontMap, &pPangoFontFamily, 
&n_families);
    // Determine the font string and insert into (alpabetically sorted) 
combo list.
   for (i=0; i<n_families; i++)
   {
       pango_font_family_list_faces (pPangoFontFamily[i], 
&pPangoFontFace, &n_faces);
       printf ("%s :: [", pango_font_family_get_name 
(pPangoFontFamily[i]));
      for (j=0; j<n_faces; j++)
      {
          printf ("%s", pango_font_face_get_face_name 
(pPangoFontFace[j]));
         if (j+1 < n_faces) printf (", ");
         m_iNumFonts++;
      }
      printf ("]\n");
   }
   g_free (pPangoFontFace);
   g_free (pPangoFontFamily);
}

void AddText (const char *utf8)
{
   PangoAttrList* pPangoAttrList;
   gchar *text;
   // Get the layout's current attribute list
   pPangoAttrList = pango_layout_get_attributes (m_pPangoLayout);
    
/////////////////////////////////////////////////////////////////////////
/
    // Would be nice to extend the markup language for dynamic 
attributes.
    // These would need to be processed and stripped here, prior to the 
pango_parse_markup call.
    
/////////////////////////////////////////////////////////////////////////
/
   // Update the attribute list from the markup text.
   pango_parse_markup (utf8, -1, 0, &pPangoAttrList, &text, NULL, NULL);
   pango_layout_set_attributes (m_pPangoLayout, pPangoAttrList);
   pango_attr_list_unref (pPangoAttrList);
   pango_layout_set_text (m_pPangoLayout, text, -1);
   // Set the color and position of the cairo context.
   cairo_set_source_rgba (m_pCairo, m_r, m_g, m_b, m_a);
   cairo_save (m_pCairo);
   cairo_move_to (m_pCairo, m_dXPos+m_dXPosStart, m_dYPos+m_dYPosStart);
   // Let the pango layout know of the context changes above.
   pango_layout_context_changed (m_pPangoLayout);
   pango_cairo_update_layout (m_pCairo, m_pPangoLayout);
   pango_cairo_show_layout (m_pCairo, m_pPangoLayout);
   cairo_restore (m_pCairo);
};

void SetFont (const char *font)
{
   PangoFontDescription* pPangoFontDescription=NULL;
   double dSize;

   pPangoFontDescription = pango_font_description_from_string (font);
    dSize = m_size * cairo_image_surface_get_height (m_pSurface) / 100.0 
* PANGO_SCALE;
    pango_font_description_set_absolute_size (pPangoFontDescription, 
dSize);
    pango_layout_set_font_description (m_pPangoLayout, 
pPangoFontDescription);
    printf ("%s : %s : %d : %d\n", font, 
pango_font_description_to_string (pPangoFontDescription), (int) m_size, 
(int) dSize);
   pango_font_description_free (pPangoFontDescription);
   pPangoFontDescription = NULL;
};
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