嵌入式中的软字幕的实现（ARGB1555） freetype的应用

只看该作者 · 2017-10-3 16:06

嵌入式中的软字幕的实现（ARGB1555） freetype的应用

很久没有写笔记了，整理一下资料和大家分享一下
函数的实现功能为字幕（汉字/字母/数字）转换为ARGB1555来数据图像信息

这个功能的实现只要有两点：
1、字幕转换为unicode码
2、unicode码转换为空间信息（相对于取字模）
其他都是一些简单的逻辑的实现了，非常的简单；下面的列子是转换为ARGB1555,(海思字幕只支持这个)同样可以转换rgb888，rgb565，BMP等
后面喜欢怎么玩就怎么玩了;

      //转换数字字母汉字为unicode码
      setlocale(LC_ALL,"");
      mbstowcs(draw_subtitle_info.subtitle_num,draw_subtitle_info.subtitle_buf,strlen(draw_subtitle_info.subtitle_buf));

最后输出的数据可以用7yuv这个软件来查看。

/*
注：这个文件的存储格式必须是utf—8 / utf-8 无 ROM 格式编码
*/
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#include "locale.h"
#include <ft2build.h>
#include <freetype/freetype.h>
#include <freetype/fttrigon.h>
#include <freetype/ftstroke.h>
#define REGION_FONT_WIDTH 720
#define REGION_FONT_HEIGHT 480
#define REGION_FONT_FSIZE (REGION_FONT_WIDTH * REGION_FONT_HEIGHT * 2)
/*像素点结构体，这里是ARGB1555的结构*/
typedef struct {
unsigned int a:1;
unsigned int r:5;
unsigned int g:5;
unsigned int b:5;
} colour_argb_t;
/*绘字幕结构体*/
typedef struct {
char *region_ptr;
char subtitle_buf[128];
wchar_t subtitle_num[128];
unsigned int startx;
unsigned int starty;
unsigned int font_size;
} draw_subtitle_t;
char *UNILangPath = "simfang.ttf";
colour_argb_t colour_argb_front,colour_argb_back;
draw_subtitle_t draw_subtitle_info;
int region_draw_subtitle_func(void)
{
unsigned int psize = draw_subtitle_info.font_size;
int row, pixel;
int i,j,k;
int debug_num = 0;
//转换数字字母汉字为unicode码
setlocale(LC_ALL,"");
mbstowcs(draw_subtitle_info.subtitle_num,draw_subtitle_info.subtitle_buf,strlen(draw_subtitle_info.subtitle_buf));
//printf("subtitle_buf = *%s*\n",draw_subtitle_info.subtitle_buf);
//for(i=0;i<strlen(draw_subtitle_info.subtitle_buf);i++)
// printf("%x\n",draw_subtitle_info.subtitle_num);
FT_Library library;
FT_Face face;
FT_UInt glyph_index;
if(FT_Init_FreeType(&library))
return 11;
if(FT_New_Face(library, UNILangPath,0, &face))
return 12;
//FT_Set_Pixel_Sizes(face, 40,60); //直接设置高宽
if(FT_Set_Pixel_Sizes(face, psize,0))
return 13;
k = 0;
while(1)
{
//查看转换的unicode码转换完了没有，完了就退出循环
if(draw_subtitle_info.subtitle_num[k] <= 0)
{
//printf("%x\n",draw_subtitle_info.subtitle_num[k]);
break;
}
//这里把转码出来的unicode码设置一下
glyph_index = FT_Get_Char_Index(face, draw_subtitle_info.subtitle_num[k++]);
if(glyph_index == 0)
{
return 2;
}
if(FT_Load_Glyph(face,glyph_index,FT_LOAD_DEFAULT))
{
return 3;
}
if(FT_Render_Glyph(face->glyph,FT_RENDER_MODE_MONO))
{
return 4;
}
/*
printf("bitmap_left=%d\n"
"bitmap_top=%d\n"
"bitmap.rows=%d\n"
"bitmap.width=%d\n"
"bitmap.pitch=%d\n"
"bitmap.pixel_mode=%d\n",
face->glyph->bitmap_left,
face->glyph->bitmap_top,
face->glyph->bitmap.rows,
face->glyph->bitmap.width,
face->glyph->bitmap.pitch,
face->glyph->bitmap.pixel_mode);
printf("\n\n");
*/
/*字母在绘制过程中没有办法自动对其，在这里做了一个参考来经行字母对齐*/
if( face->glyph->bitmap_top < (psize+10) )
debug_num = psize + 10 - face->glyph->bitmap_top;
else
debug_num = 0;
/*扫描绘字幕，这样处理的效率是非常的高的，只直接绘制字幕*/
for(row = 0,j = draw_subtitle_info.starty + debug_num; row < face->glyph->bitmap.rows; ++row,++j)
{
for(pixel = 0,i = draw_subtitle_info.startx; pixel < face->glyph->bitmap.width; ++pixel,++i)
{
if(face->glyph->bitmap.buffer[row * face->glyph->bitmap.pitch +pixel/8] & (0xC0 >> (pixel % 8)))
memcpy(draw_subtitle_info.region_ptr+i*2+j*REGION_FONT_WIDTH*2,&colour_argb_front,2);
else
memcpy(draw_subtitle_info.region_ptr+i*2+j*REGION_FONT_WIDTH*2,&colour_argb_back,2);
}
}
//如果这里是一个空格，就把坐标跳过去一个字符单位
if (face->glyph->bitmap.width == 0)
draw_subtitle_info.startx += psize;
else
draw_subtitle_info.startx += face->glyph->bitmap.width + 2;
}
return 0;
}
int main()
{
/*如果是rgb888 数据，只需要取高位数据就可以了 5位*/
/*字体颜色*/
colour_argb_front.a = 0x00;
colour_argb_front.r = 0x1F;
colour_argb_front.g = 0x1F;
colour_argb_front.b = 0x1F;
/*字体背景颜色*/
colour_argb_back.a = 0x00;
colour_argb_back.r = 0x1F;
colour_argb_back.g = 0x00;
colour_argb_back.b = 0x00;
char subtitle_buffer[128] = "2014beijing 创新改变世界北京";
draw_subtitle_info.font_size = 30; //字号的设置
memcpy(draw_subtitle_info.subtitle_buf,subtitle_buffer,strlen(subtitle_buffer));
draw_subtitle_info.region_ptr = (char *)malloc(REGION_FONT_FSIZE);
memset(draw_subtitle_info.region_ptr,0,REGION_FONT_FSIZE);
draw_subtitle_info.startx = 0;
draw_subtitle_info.starty = 0;
/*把字幕画到内存里面，里面会有一个局部扫描的过程，
只绘制了字体的背景，其他背景没有经行绘制，可以先绘制整个背景后再来画字*/
region_draw_subtitle_func();
FILE * fp = fopen("720x576_white.raw","wb");
fwrite(draw_subtitle_info.region_ptr,REGION_FONT_FSIZE,1,fp);
fclose(fp);
free(draw_subtitle_info.region_ptr);
draw_subtitle_info.region_ptr = NULL;
return 0;
}