分类: 嵌入式
2015-08-23 16:37:23
/* example1.c */
15年8月21日20:12:42
/* 代码如下*/
/* 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 <wchar.h>
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_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++ )
{
printf("%02d", 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;
//int chinese_str[] = {0x97e6, 0x4e1c, 0x5c71, 0x0067};
wchar_t *chinese_str = L"闫gif";
unsigned int *p = (wchar_t *)chinese_str;
int i;
FT_BBox bbox;
FT_Glyph glyph;
printf("Unicode : \n");
for (i = 0; i < wcslen(chinese_str); i++)
{
printf(" 0x%x", p[i]);
}
printf("\n");
//return 0;
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 ); /* 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 */
/* error handling omitted */
#else
FT_Set_Pixel_Sizes(face, 24, 0);
#endif
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 (0,40) relative to the upper left corner */
pen.x = 0 * 64;
pen.y = ( target_height - 40 ) * 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);
/* now, draw to our target surface (convert position) */
draw_bitmap( &slot->bitmap,
slot->bitmap_left,
target_height - slot->bitmap_top );
printf("Unicode : 0x%x\n", chinese_str[n]);
printf("originx = %d, originy = %d\n", pen.x/64, pen.y/64);
printf("xMin = %d, xMax = %d, yMin = %d, yMax = %d\n", bbox.xMin, bbox.xMax, bbox.yMin, bbox.yMax);
printf("slot->advance.x/64 = %d, slot->advance.y/64 = %d\n", slot- >advance.x/64, slot->advance.y/64);
/* 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 */
想象一个文字的显示过程:
(1)给定一个文字,‘A’:0x41, “中”:GBK, unicode;可以确定它的编码值;
(2)根据“编码值”,从字体文件中找到对应的“glyph”;
(3)设置字体大小;
(4)用某些函数把glyph里的点缩放为所需的字体大小;
(5)转换为位图点阵;
(6)在LCD上面显示出来。
怎么写代码?
(1)初始化:FT_Init_FreeType()
(2)加载字体face:FT_New_Face()
(3)设置字体大小:FT_Set_Char_Size()
FT_Set_Pixel_Sizes()
(4)根据编码值加载glyph:
1)找到编码值:glyph_index = FT_Get_Char_Index();
2)取出:FT_Load_Glyph();
转换为位图:FT_Render_Glyph();
其中第(4)步,可以简单地用一个函数代替:FT_Load_Char(face, charcode, FT_LOAD_RENDER);
(5)变换,如移动/旋转等:FT_Set_Transform()。
写代码这几步,详细的可以参考《freetype使用帮助.pdf》,上面将的很详细。上面的代码在它的一个例子基础上进行修改,让这个例子可以运行在PC电脑上面。