在2440开发板液晶上显示两行字

用到了freetype库

下面是测试代码：

/* example1.c                                                      *//*                                                                 *//* This small PRogram shows how to print a rotated string with the *//* FreeType 2 library.                                             */#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 <ft2build.h>#include FT_FREETYPE_H#include FT_GLYPH_H//#define WIDTH   var.xres//80//#define HEIGHT  var.yres//80///////* origin is the upper left corner *///unsigned char image[HEIGHT][WIDTH];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;/* 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;		}	}}/* Replace this function with something useful. */voiddraw_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]);    }  }}intmain( 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           n; int bbox_ymax=0,bbox_ymin=1000;	FT_BBox bbox;	FT_Glyph  glyph;   wchar_t *chinese_str = L"朋哥哥gif";    wchar_t *chinese_str1 = L"无敌朋哥";  if ( argc != 2 )  {    fprintf ( stderr, "usage: %s font/n", argv[0] );    exit( 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;	}	  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 );              /* initialize library */  /* error handling omitted */  error = FT_New_Face( library, argv[1], 0, &face ); /* create face object */  /* error handling omitted */#if 0  /* use 50pt at 100dpi */  error = FT_Set_Char_Size( face, 50 * 64, 0,                            100, 0 );                /* set character size */	/* pixels = 50 /72 * 100 = 69  */#else	FT_Set_Pixel_Sizes(face, 24, 0);#endif  /* 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 );	/* 清屏: 全部设为黑色 */	memset(fbmem, 0, screen_size);	  /* the pen position in 26.6 cartesian space coordinates; */  /* start at (100,100) relative to the upper left corner  */  pen.x = 100 * 64;  pen.y = ( var.yres - 100 ) * 64;  for ( n = 0; n < wcslen(chinese_str); n++ )  {    /* set transformation */    FT_Set_Transform( face, &matrix, &pen );    /* load glyph image into the slot (erase previous one) */    error = FT_Load_Char( face, chinese_str[n], FT_LOAD_RENDER );    if ( error )      continue;                 /* ignore errors */    error = FT_Get_Glyph( face->glyph, &glyph );		if (error)		{			printf("FT_Get_Glyph error!/n");			return -1;		}    FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_TRUNCATE, &bbox );        if(bbox_ymax < bbox.yMax)    	bbox_ymax =bbox.yMax;    if(bbox_ymin > bbox.yMin)    	bbox_ymin =bbox.yMin;    /* now, draw to our target surface (convert position) */    draw_bitmap( &slot->bitmap,                 slot->bitmap_left,                 var.yres - slot->bitmap_top );    /* increment pen position */    pen.x += slot->advance.x;//    pen.y += slot->advance.y;  }    printf("the second line/n");  printf("the line_box_ymax = %d ,line_box_ymin = %d /n",bbox_ymax,bbox_ymin);    /* the pen position in 26.6 cartesian space coordinates; */  /* start at (100,100) relative to the upper left corner  */  pen.x = 100 * 64;  pen.y = ( var.yres - (bbox_ymax-bbox_ymin+100) ) * 64;  for ( n = 0; n < wcslen(chinese_str1); n++ )  {    /* set transformation */    FT_Set_Transform( face, &matrix, &pen );    /* load glyph image into the slot (erase previous one) */    error = FT_Load_Char( face, chinese_str1[n], FT_LOAD_RENDER );    if ( error )      continue;                 /* ignore errors */    error = FT_Get_Glyph( face->glyph, &glyph );		if (error)		{			printf("FT_Get_Glyph error!/n");			return -1;		}    FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_TRUNCATE, &bbox );        if(bbox_ymax < bbox.yMax)    	bbox_ymax =bbox.yMax;    if(bbox_ymin > bbox.yMin)    	bbox_ymin =bbox.yMin;    /* now, draw to our target surface (convert position) */    draw_bitmap( &slot->bitmap,                 slot->bitmap_left,                 var.yres - slot->bitmap_top );    /* increment pen position */    pen.x += slot->advance.x;//    pen.y += slot->advance.y;  }    FT_Done_Face    ( face );  FT_Done_FreeType( library );printf("the end/n");  return 0;}/* EOF */
交叉编译：
arm-linux-gcc -o mycode1 mycode1.c -lfreetype -lm -Wall -finput-charset=GBK
注意代码中 ，下面这两个变量定义后，一定要记得初始化。
int bbox_ymax=0,bbox_ymin=1000;
若不初始化，写成  int  bbox_ymax , bbox_ymin ;
则第二行显示不出字，添加打印程序后才发现错误。
/mnt # ./mycode1 ./simsun.ttc the second linethe line_box_ymax = 191 ,line_box_ymin = -1224855552 the end
 由上面打印信息，很明显看出来 line_box_ymin = -1224855552 ，是变量没有初始化的问题。