sdlfont.cpp

/*
  font.cpp
  Cone3D SDL font routines.
  Made by Marius Andra 2002
  http://cone3d.gamedev.net

  You can use the code for anything you like.
  Even in a commercial project.
  But please let me know where it ends up.
  I'm just curious. That's all.
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

#include <SDL/SDL.h>

#include "font.h"

// this function draws one part of an image to some other part of an other image
// it's only to be used inside the font.cpp file, so it's not available to any
// other source files (no prototype in font.h)
void fontDrawIMG(SDL_Surface *screen, SDL_Surface *img, int x, int y, int w,
                                                        int h, int x2, int y2)
{
  SDL_Rect dest;
  dest.x = x;
  dest.y = y;
  SDL_Rect src;
  src.x = x2;
  src.y = y2;
  src.w = w;
  src.h = h;
  SDL_BlitSurface(img, &src, screen, &dest);
}

// this function loads in our font file
SDLFont *initFont(char *fontdir, float r, float g, float b, float a)
{
  // some variables
  SDLFont *tempFont;               // a temporary font
  FILE *fp;                        // file pointer - used when reading files
  char tempString[100];            // temporary string
  unsigned char tmp;               // temporary unsigned char
  int width;                       // the width of the font
  SDL_Surface *tempSurface;        // temporary surface

  // find out about the size of a font from the ini file
  sprintf(tempString,"%s/%s",fontdir,"font.ini");
  fp = fopen(tempString, "rb");
  if( fp == NULL )
  {
    return 0;
  }
  fscanf(fp, "%d", &width);
  fclose(fp);

  // let's create our font structure now
  tempFont = new SDLFont;
  tempFont->data = new unsigned char[width*width*4];
  tempFont->width = width;
  tempFont->charWidth = width/16;

  // open the font raw data file and read everything in
  sprintf(tempString,"%s/%s",fontdir,"font.raw");
  fp = fopen(tempString, "rb");
  if( fp != NULL )
  {
    for(int i=0;i<width*width;i++)
    {
      tmp = fgetc(fp);
      tempFont->data[i*4] = (unsigned char)255*(unsigned char)r;
      tempFont->data[i*4+1] = (unsigned char)255*(unsigned char)g;
      tempFont->data[i*4+2] = (unsigned char)255*(unsigned char)b;
      tempFont->data[i*4+3] = (unsigned char)(((float)tmp)*a);
    }
  } else {
    return 0;
  }
  fclose(fp);
  // now let's create a SDL surface for the font
  Uint32 rmask,gmask,bmask,amask;
  #if SDL_BYTEORDER == SDL_BIG_ENDIAN
  rmask = 0xff000000;
  gmask = 0x00ff0000;
  bmask = 0x0000ff00;
  amask = 0x000000ff;
  #else
  rmask = 0x000000ff;
  gmask = 0x0000ff00;
  bmask = 0x00ff0000;
  amask = 0xff000000;
  #endif
  tempSurface = SDL_CreateRGBSurfaceFrom(tempFont->data, width, width,
                              32, width*4, rmask, gmask, bmask, amask);
  tempFont->font = SDL_DisplayFormatAlpha(tempSurface);
  SDL_FreeSurface(tempSurface);

  // let's create a variable to hold all the widths of the font
  tempFont->widths = new int[256];

  // now read in the information about the width of each character
  sprintf(tempString,"%s/%s",fontdir,"font.dat");
  fp = fopen(tempString, "rb");
  if( fp != NULL )
  {
    for(int i=0;i<256;i++)
    {
      tmp = fgetc(fp);
      tempFont->widths[i]=tmp;
    }
  }
  fclose(fp);

  return tempFont;
}

// here we draw the string
void drawString(SDL_Surface *screen, SDLFont *font, int x, int y, char *str, ...)
{
  char string[1024];                  // Temporary string

  va_list ap;                         // Pointer To List Of Arguments
  va_start(ap, str);                  // Parses The String For Variables
  vsprintf(string, str, ap);          // And Converts Symbols To Actual Numbers
  va_end(ap);                         // Results Are Stored In Text

  int len=strlen(string);             // Get the number of chars in the string
  int xx=0;            // This will hold the place where to draw the next char
  for(int i=0;i<len;i++)              // Loop through all the chars in the string
  {
    // This may look scary, but it's really not.
    // We only draw one character with this code.
    // At the next run of the loop we draw the next character.

    // Remember, the fontDrawIMG function looks like this:
        // void fontDrawIMG(SDL_Surface *screen, SDL_Surface *img, int x, int y,
    //                                         int w, int h, int x2, int y2)

    // We draw onto the screen SDL_Surface a part of the font SDL_Surface.
    fontDrawIMG(
      screen,
      font->font,
    // We draw the char at pos [x+xx,y].
    // x+xx: this function's parameter x + the width of all the characters before
    // this one, so we wouldn't overlap any of the previous characters in the string
    // y: this function's y parameter
      xx+x,
      y,
    // For the width of the to-be-drawn character we take it's real width + 2
      font->widths[string[i]]+2,
    // And for the height we take the height of the character (height of the font/16)
      font->charWidth,
    // Now comes the tricky part
    // The font image DOES consist of 16x16 grid of characters. From left to
    // right in the image, the ascii values of the characters increase:
    // The character at block 0x0 in the font image is the character with the
    // ascii code 0, the character at the pos 1x0 has the ascii code 1, the char
    // at the pos 15x0 has the ascii code 15. And that's the end of the first row
    // Now in the second row on the image, the first character (0x1) has the ascii
    // value 16, the fourth character on the second row of the image (3x1) has the ascii
    // value 19. To calculate the ascii value of the character 3x1, we use the
    // really simple equation: row*[number of thing in one row (=16)]+column pos.
    // So the position 3x1 has the ascii value 1*16+3 = 19. The character in the
    // image at the position 8x12 has the ascii value 12*16+8=200, and so on.
    // But this isn't much of use to us since we KNOW the ascii value of a character,
    // but we NEED to find out it's position on the image.
    // First we'll get the column on the image. For that we'll divide the ascii value
    // with 16 (the number of columns) and get it's remainder (we'll use the modulus
    // operator). We'll do this equation to get the column: [ascii value]%16.
    // Now to get to the position of the column in pixels, we multiply the ascii
    // value by the width of one column ([font image width]/16)
    // And so the equation to get the first pixel of the block becomes:
    // [font image width]%16*[1/16th of the font image width]
    // Now, since all the letters are centered in each cell (1/16th of the image),
    // we need to get the center of the cell. This is done by adding half the width
    // of the cell to the number we got before. And the only thing left to do is to
    // subtract half of the character's real width and we get the x position from where
    // to draw our character on the font map :)
      (string[i]%16*font->charWidth)+((font->charWidth/2)-(font->widths[string[i]])/2),
    // To get the row of the character in the image, we divide the ascii value of
    // the character by 16 and get rid of all the numbers after the point (.)
    // (if we get the number 7.125257.., we remove the .125157... and end up with 7)
    // We then multiply the result with the height of one cell and voila - we get
    // the y position!
      (((int)string[i]/16)*font->charWidth)
    );

    // Now we increase the xx printed string width counter by the width of the
    // drawn character
    xx+=font->widths[string[i]];
  }
}

// This function returns the width of a string
int stringWidth(SDLFont *font,char *str,...)
{
  char string[1024];                  // Temporary string

  va_list ap;                         // Pointer To List Of Arguments
  va_start(ap, str);                  // Parses The String For Variables
  vsprintf(string, str, ap);          // And Converts Symbols To Actual Numbers
  va_end(ap);                         // Results Are Stored In Text

  // Now we just count up the width of all the characters
  int xx=0;
  int len=strlen(string);
  for(int i=0;i<len;i++)
  {
    // Add their widths together
    xx+=font->widths[string[i]];
  }

  // and then return the sum
  return xx;
}

// Clear up
void freeFont(SDLFont *font)
{
  delete [] font->widths;
  delete [] font->data;
  SDL_FreeSurface(font->font);
  delete font;
}

---

generated with doxygen 1.5.3 on Mon Oct 29 18:09:26 2007