使用freetype来显示中文汉字和英文字符

这里我们用到了freetype。进入官网http://savannah.nongnu.org/download/freetype/ 中下载最新的版本2.7的源代码和文件。freetype-2.7.tar.gz freetype-doc-2.7.tar.gz

首先我们在使用官方提供的程序在pc上运行一下。需要安装zlib库。

在freetype-doc-2.7.tar.gz文件中的docus目录下的tutorial有一个example.c的源文件。

example.c：

/* example1.c                                                      */
/*                                                                 */
/* This small program shows how to print a rotated string with the */
/* FreeType 2 library.                                             */

#include <stdio.h>
#include <string.h>
#include <math.h>

#include <ft2build.h>
#include FT_FREETYPE_H

#define WIDTH   80
#define HEIGHT  80

/* origin is the upper left corner */
unsigned char image[HEIGHT][WIDTH];

/* Replace this function with something useful. */

void
draw_bitmap( FT_Bitmap*  bitmap,
             FT_Int      x,
             FT_Int      y)
{
  FT_Int  i, j, p, q;
  FT_Int  x_max = x + bitmap->width;
  FT_Int  y_max = y + bitmap->rows;

  for ( i = x, p = 0; i < x_max; i++, p++ )
  {
    for ( j = y, q = 0; j < y_max; j++, q++ )
    {
      if ( i < 0      || j < 0       ||
           i >= WIDTH || j >= HEIGHT )
        continue;

      image[j][i] |= bitmap->buffer[q * bitmap->width + p];
    }
  }
}

void
show_image( void )
{
  int  i, j;

  for ( i = 0; i < HEIGHT; i++ )
  {
    for ( j = 0; j < WIDTH; j++ )
      putchar( image[i][j] == 0 ? ' '
                                : image[i][j] < 128 ? '+'
                                                    : '*' );
    putchar( '\n' );
  }
}

int
main( int     argc,
      char**  argv )
{
  FT_Library    library;
  FT_Face       face;

  FT_GlyphSlot  slot;
  FT_Matrix     matrix;                 /* transformation matrix */
  FT_Vector     pen;                    /* untransformed origin  */
  FT_Error      error;

  char*         filename;
  char*         text;

  double        angle;
  int           target_height;
  int           n, num_chars;

  if ( argc != 3 )
  {
    fprintf ( stderr, "usage: %s font sample-text\n", argv[0] );
    exit( 1 );
  }

  filename      = argv[1];                           /* first argument     */
  text          = argv[2];                           /* second argument    */
  num_chars     = strlen( text );
  angle         = ( 0.0 / 360 ) * 3.14159 * 2;      /* use 0 degrees  旋转     */
  target_height = HEIGHT;

  error = FT_Init_FreeType( &library );              /* initialize library */
  /* error handling omitted */

  error = FT_New_Face( library, filename, 0, &face );/* create face object */
  /* error handling omitted */

  /* use 50pt at 100dpi */
  error = FT_Set_Char_Size( face, 50 * 64, 0,
                            30, 0 );                /* set character size */
  /* error handling omitted */

  slot = face->glyph;

  /* set up matrix */
  matrix.xx = (FT_Fixed)( cos( angle ) * 0x10000L );
  matrix.xy = (FT_Fixed)(-sin( angle ) * 0x10000L );
  matrix.yx = (FT_Fixed)( sin( angle ) * 0x10000L );
  matrix.yy = (FT_Fixed)( cos( angle ) * 0x10000L );

  /* the pen position in 26.6 cartesian space coordinates; */
  /* start at (40,0) relative to the upper left corner  */
  pen.x = 0 * 64;
  pen.y = ( target_height - 40 ) * 64;

  for ( n = 0; n < num_chars; n++ )
  {
    /* set transformation */
    FT_Set_Transform( face, &matrix, &pen );

    /* load glyph image into the slot (erase previous one) */
    error = FT_Load_Char( face, text[n], FT_LOAD_RENDER );
    if ( error )
      continue;                 /* ignore errors */

    /* now, draw to our target surface (convert position) */
    draw_bitmap( &slot->bitmap,
                 slot->bitmap_left,
                 target_height - slot->bitmap_top );

    /* increment pen position */
    pen.x += slot->advance.x;
    pen.y += slot->advance.y;
  }

  show_image();

  FT_Done_Face    ( face );
  FT_Done_FreeType( library );

  return 0;
}

/* EOF */

程序中把输出的字符打印在屏幕上，分辨率是640*480，从300,200 处开始显示.这里我为了便于查看就改为了80*80.从40，0处开始显示

编译：

gcc -o example1 example1.c -I /usr/local/include/freetype2/ -lfreetype -lm

运行程序即可。

arm：

首先配置：

./configure --host=arm-linux
make 
make DESTDIR=$PWD/tmp install

将生成的文件拷贝到交叉编译器和开发板文件系统相应的位置。

编译文件：

arm-linux-gcc -o test main.c  -lfreetype -lm

将test和字体文件拷贝到开发板中即可运行程序.

源代码：

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <linux/fb.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <math.h>

#include "show_font.h"
#include <ft2build.h>
#include FT_FREETYPE_H

unsigned char *hzkmem;
unsigned char *fbmem;
unsigned int line_width;
unsigned int pixel_width;

struct fb_var_screeninfo var;

void lcd_put_pixel( int x, int y, unsigned int color )
{
    unsigned char *pen_8 = fbmem +y*line_width + x*pixel_width;
    unsigned short *pen_16;
    unsigned short *pen_32;
    unsigned char red,green,blue;

    pen_16 = (unsigned short *)pen_8;
    pen_32 = (unsigned short *)pen_8;

    switch( pixel_width*8 )
    {
    case 8:
        *pen_8 = color;
        break;

    case 16:
        /* 565 */
        red = (color>>16) & 0xff;
        green = (color>>8) & 0xff;
        blue = (color>>0) & 0xff;
        color = ((red>>3)<<11) | ((green>>2)<<5) |((blue>>3));
        *pen_16 = color;
        break;

    case 32:
        *pen_32 = color;
        break;
    default:
        printf("can't support %ddpp\n",pixel_width*8 );
        break;
    }
}

void lcd_put_ascii( int x, int y, unsigned char c )
{
    unsigned char *dots = (unsigned char *)&fontdata_8x16[c*16];
    int i,b;
    unsigned char byte;

    for( i=0; i< 16; i++ )
    {
        byte = dots[i];
        for( b=7;b>=0;b--)
        {
            if( byte & (1<<b))
            {
                lcd_put_pixel(x+7-b,y+i, 0xffffff );
            }
            else
            {
                lcd_put_pixel(x+7-b,y+i, 0x000000 );
            }
        }
    }

}

void lcd_put_chinese( int x, int y, unsigned char *c )
{
    unsigned int area = c[0] - 0xa1;
    unsigned int where = c[1] - 0xa1;
    unsigned char *dots = hzkmem + (area*94+where)*32;
    unsigned char byte;
    int i,j,b;
    for( i=0; i<16; i++ )
    {
        for( j=0; j<2; j++ )
        {
            byte = dots[i*2+j];
            for( b=7; b>=0; b-- )
            {
                if( byte & (1<<b) )
                    lcd_put_pixel(x+j*8+7-b,y+i, 0xffffff );
                else
                    lcd_put_pixel(x+j*8+7-b,y+i, 0x000000 );
            }
        }
    }
}

void draw_bitmap( FT_Bitmap*  bitmap,
             FT_Int      x,
             FT_Int      y)
{
  FT_Int  i, j, p, q;
  FT_Int  x_max = x + bitmap->width;
  FT_Int  y_max = y + bitmap->rows;

  for ( i = x, p = 0; i < x_max; i++, p++ )
  {
    for ( j = y, q = 0; j < y_max; j++, q++ )
    {
      if ( i < 0      || j < 0       ||
           i >= var.xres || j >= var.yres )
        continue;

      //image[j][i] |= bitmap->buffer[q * bitmap->width + p];
      lcd_put_pixel(i,j,bitmap->buffer[q * bitmap->width + p]);
    }
  }
}

int main( int argc, char **argv )
{
    int hzk_fd;
    int fd_fb;
    struct fb_fix_screeninfo fix;

    int screen_size;

    FT_Library    library;
    FT_Error      error;
    FT_Face       face;
    FT_Matrix     matrix;                 /* transformation matrix */
    FT_Vector     pen;                    /* untransformed origin  */

    double        angle;

    wchar_t *chinese_char = L"周zhou";

    unsigned char str[]={0xd6,0xd0};
    struct stat hzk_stat;

    fd_fb = open("/dev/fb0",  O_RDWR );
    if( fd_fb<0 )
    {
        perror("oepn failed");
        return -1;
    }

    if( ioctl( fd_fb,  FBIOGET_VSCREENINFO, &var ) )
    {
        printf("can't get var\n");
        return -1;
    }

    if( ioctl( fd_fb,  FBIOGET_FSCREENINFO, &fix ) )
    {
        printf("can't get fix\n");
        return -1;
    }
    line_width = var.xres * var.bits_per_pixel / 8;
    pixel_width = var.bits_per_pixel / 8;

    screen_size = var.xres * var.yres * var.bits_per_pixel / 8;
    fbmem = (unsigned char *)mmap( NULL, screen_size,  PROT_READ | PROT_WRITE, MAP_SHARED,fd_fb,0 );
    if( fbmem == (unsigned char *)-1 )
    {
        printf("mmap is failed\n");
        return -1;
    }

    hzk_fd = open("HZK16",  O_RDONLY );
    if( hzk_fd<0 )
    {
        printf("can't open hzk\n");
        return -1;
    }

    if( fstat(hzk_fd, &hzk_stat))
    {
        printf("can't get fstat\n");
        return -1;
    }

    hzkmem = (unsigned char *)mmap( NULL, hzk_stat.st_size,  PROT_READ, MAP_SHARED,hzk_fd,0 );
    if( hzkmem == (unsigned char *)-1 )
    {
        printf("mmap hzk is failed\n");
        return -1;
    }

    memset( fbmem, 0, screen_size );

    lcd_put_ascii(var.xres/2,var.yres/2,'A' );

    printf("chinese code : %02x  %02x\n", str[0],str[1]);
    lcd_put_chinese( var.xres/2 +8 ,var.yres/2, str );

    if( argc != 2 )
    {
        printf("Usage: %s  <font_file>\n", argv[0]);
        return -1;
    }

    error = FT_Init_FreeType( &library );              /* initialize library */
    /* error handling omitted */

    error = FT_New_Face( library, argv[1], 0, &face ); /* create face object */

    /* use 50pt at 100dpi */
    error = FT_Set_Pixel_Sizes( face, 30, 0 );                /* set character size */

    angle         = ( 0.0 / 360 ) * 3.14159 * 2;      /* use 25 degrees     */
     /* set up matrix */
    matrix.xx = (FT_Fixed)( cos( angle ) * 0x10000L );
    matrix.xy = (FT_Fixed)(-sin( angle ) * 0x10000L );
    matrix.yx = (FT_Fixed)( sin( angle ) * 0x10000L );
    matrix.yy = (FT_Fixed)( cos( angle ) * 0x10000L );

    /* the pen position in 26.6 cartesian space coordinates; */
    /* start at (40,0) relative to the upper left corner  */
    pen.x = (var.xres/2+8+16) * 64;
    pen.y = ( var.yres/2 - 16 ) * 64;

    /* set transformation */
    FT_Set_Transform( face, &matrix, &pen );

    /* load glyph image into the slot (erase previous one) */
    error = FT_Load_Char( face, chinese_char[0], FT_LOAD_RENDER );
    if(error)
    {
        printf("FT_load_char error\n");
        return -1;
    }

    draw_bitmap( &face->glyph->bitmap,
                 face->glyph->bitmap_left,
                 var.yres - face->glyph->bitmap_top );

    return 0;

}

sds