linux应用项目（一）数码相框（2）数码相框之freetype实现矢量字体的显示

上一节我们通过点阵数组实现了字母的显示：http://blog.csdn.net/fengyuwuzu0519/article/details/72877318

现在我们通过freetype这个框架在PC和单板LCD上分别实现矢量字体的显示。

一、PC上矢量字体的显示

（1）矢量字体：存储一些关健点，然后通过贝塞尔曲线连接。





（2）显示实现过程



（3）如何写代码



（4）分析源码自带的例子

/* 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 25 degrees     */
target_height = HEIGHT;

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

error = FT_New_Face( library, argv[1], 0, &face ); /* 打开字体文件argv[1]  create face object */
/* error handling omitted */

#if 0
/* use 50pt at 100dpi */
error = FT_Set_Char_Size( face, 50 * 64, 0,
100, 0 );                /* 设置字符大小   set character size */

/* pixels = 50 /72 * 100 = 69  */
//50*64/64/72（多少英寸）   *100       100：每个英寸有多少个像素点
#else
FT_Set_Pixel_Sizes(face, 24, 0);    //24像素大小 类似于点阵里点的个数。高度=宽度=24
#endif
/* error handling omitted */

slot = face->glyph;     //取出关键点后存在face里的glyph里面

/* 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 (0,40)：lcd    relative to the upper left corner  */
pen.x = 0 * 64;
pen.y = ( target_height - 40 ) * 64; //此处是笛卡尔坐标。原点在左下角
//lcd里原点在左上角 x‘=x  y’=hight-y

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

/* load glyph image into the slot (erase previous one) */
error = FT_Load_Char( face, text
, FT_LOAD_RENDER );// FT_Load_Char：找到；取出；转换为位图；=那三个函数
if ( error )                                          //FT_LOAD_RENDER： glyph立刻转换为位图
//text：unicode ascii编码
continue;                 /* ignore errors */

/* now, draw to our target surface (convert position) */
draw_bitmap( &slot->bitmap,                            //draw_bitmap：打印出来    bitmap里面含有点阵存到image数组中
slot->bitmap_left,
target_height - slot->bitmap_top );

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

show_image();                                              //打印image数组

FT_Done_Face    ( face );
FT_Done_FreeType( library );

return 0;
}

/* EOF */

（5）freetype文件的编译需要库，所以需要提前编译freetype产生编译freetype函数的环境。生成响应的库。

安装配置freetype_PC

tar xjf freetype-2.4.10.tar.bz2

mv freetype-2.4.10   freetype-2.4.10_pc

cd freetype-2.4.10_pc/

./configure

make

sudo make install








（6）编译

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




（7）执行

./example1  ./simsun.ttc  abc

在（0，,40）显示







（8）显示文字









（9）找编码太麻烦了

  #include<wchar.h>

//intchinese_str[] = {0x97e6, 0x4e1c, 0x5c71, 0x0067};

 //char *str = "韦东山";

 wchar_t *chinese_str = L"韦东山g";

 unsigned int *p = (wchar_t *)chinese_str;



gcc -finput-charset=GBK-fexec-charset=UTF-8 -o example1 example1.c -I /usr/local/include/freetype2 -lfreetype -lm

（10）增加打印信息



gcc -finput-charset=GBK-fexec-charset=UTF-8 -o example1 example1.c -I /usr/local/include/freetype2 -lfreetype -lm

二、ARM上显示矢量字体

（1）交叉编译freetype库文件

tar xjf freetype-2.4.10.tar.bz2

./configure --host=arm-linux

make

make DESTDIR=$PWD/tmp install



把tmp/usr/local/lib/*  复制到/usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/lib

sudo cp */usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/lib -d -rf

把tmp/usr/local/include/*  复制到/usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/usr/include

cp */usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/usr/include -rf







（2）编译在串口输出。

arm-linux-gcc -finput-charset=GBK -oexample1 example1.c  -lfreetype -lm













（3）修改代码在LCD上显示矢量字体

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

#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H

#define FONTDATAMAX 4096

static const unsigned char fontdata_8x16[FONTDATAMAX] = {
};

int fd_fb;
struct fb_var_screeninfo var;	/* Current var */
struct fb_fix_screeninfo fix;	/* Current fix */
int screen_size;
unsigned char *fbmem;
unsigned int line_width;
unsigned int pixel_width;

int fd_hzk16;
struct stat hzk_stat;
unsigned char *hzkmem;

/* color : 0x00RRGGBB */
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 int *pen_32;

unsigned int red, green, blue;

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

switch (var.bits_per_pixel)
{
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 surport %dbpp\n", var.bits_per_pixel);
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))
{
/* show */
lcd_put_pixel(x+7-b, y+i, 0xffffff); /* 白 */
}
else
{
/* hide */
lcd_put_pixel(x+7-b, y+i, 0); /* 黑 */
}
}
}
}

void lcd_put_chinese(int x, int y, unsigned char *str)
{
unsigned int area  = str[0] - 0xA1;
unsigned int where = str[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))
{
/* show */
lcd_put_pixel(x+j*8+7-b, y+i, 0xffffff); /* 白 */
}
else
{
/* hide */
lcd_put_pixel(x+j*8+7-b, y+i, 0); /* 黑 */
}

}
}

}
/* 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;

//printf("x = %d, y = %d\n", x, y);

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)
{
unsigned char str[] = "中";
wchar_t *chinese_str = L"繁";

FT_Library	  library;
FT_Face 	  face;
int error;
FT_Vector     pen;
FT_GlyphSlot  slot;
FT_Matrix	  matrix;				  /* transformation matrix */
double        angle;

if (argc != 3)
{
printf("Usage : %s <font_file> <angle>\n", argv[0]);
return -1;
}

fd_fb = open("/dev/fb0", O_RDWR);
if (fd_fb < 0)
{
printf("can't open /dev/fb0\n");
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("can't mmap\n");
return -1;
}

fd_hzk16 = open("HZK16", O_RDONLY);
if (fd_hzk16 < 0)
{
printf("can't open HZK16\n");
return -1;
}
if(fstat(fd_hzk16, &hzk_stat))
{
printf("can't get fstat\n");
return -1;
}
hzkmem = (unsigned char *)mmap(NULL , hzk_stat.st_size, PROT_READ, MAP_SHARED, fd_hzk16, 0);
if (hzkmem == (unsigned char *)-1)
{
printf("can't mmap for hzk16\n");
return -1;
}

/* 清屏: 全部设为黑色 */
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);

/* 显示矢量字体 */
error = FT_Init_FreeType( &library );			   /* initialize library */
/* error handling omitted */

error = FT_New_Face( library, argv[1], 0, &face ); /* create face object */
/* error handling omitted */
slot = face->glyph;

FT_Set_Pixel_Sizes(face, 24, 0);

/* 确定座标:
* lcd_x = var.xres/2 + 8 + 16
* lcd_y = var.yres/2 + 16
* 笛卡尔座标系:
* x = lcd_x = var.xres/2 + 8 + 16
* y = var.yres - lcd_y = var.yres/2 - 16
*/
pen.x = (var.xres/2 + 8 + 16) * 64;
pen.y = (var.yres/2 - 16) * 64;

angle = ( 1.0 * strtoul(argv[2], NULL, 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 );

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

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

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

return 0;
}

arm-linux-gcc -finput-charset=GBK -fexec-charset=GBK -o show_font show_font.c -lfreetype -lm