700字范文 > 【正点原子I.MX6U-MINI应用篇】6 嵌入式Linux在LCD屏幕上显示字符

【正点原子I.MX6U-MINI应用篇】6 嵌入式Linux在LCD屏幕上显示字符

时间：2019-11-22 17:58:15

一、原始方式：取模显示字符

LCD显示屏是由width * height个像素点构成的，显示字符，一个非常容易想到的方法便是对字符取模，然后在LCD屏上打点显示字符；如果大家以前学习过单片机，想必接触过一些显示屏，譬如 oled、或者其它一些点阵式的显示屏，其实这些显示屏显示字符的原理都是一样的，如下所示：

我们可以通过一些字符取模软件获取到字符的子模；所谓子模，其实就是一个二维数组，用于表示字符点阵中，哪些小方块应该要填充颜色、哪些小方块不填充颜色。譬如上图果字符点阵，这是一个宽度为64（64 个小方块）、高度为 86（86 个小方块）的字符点阵，我们会使用一个二维数组来表示这个字符点阵：

unsigned char arr[86][8];

也就是一个86行8列的unsigned char类型数组，数组存储的其实就是字符的位图数据，字符点阵中的每一个小方块对应一个 bit 位，因为一行一共有64个小方块、也就对应8个字节（8 * 8 = 64）；将填充颜色的方块使用1表示、不填充颜色的方块使用0来表示，所以一个小方块刚好可以使用一个bit 位来描述。

这里我是使用的的是PCtoLCD2002.exe这个软件。获取几个字符的子模，然后在我们的 LCD 屏上去显示这些字符。按照下图的方式设置，就可以生成字模了。

1.1 源码

#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <sys/ioctl.h>#include <string.h>#include <errno.h>#include <string.h>#include <sys/mman.h>#include <linux/fb.h>#define FB_DEV"/dev/fb0"//LCD设备节点static int width; //LCD宽度static int height; //LCD高度static unsigned short *screen_base = NULL;//LCD显存基地址static unsigned char ch_char1[86][8] = {{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0x00,0x00,0xE0,0xFF,0xFF,0x01,0x00,0x00},{0x00,0x00,0xF0,0xFF,0xFF,0x07,0x00,0x00},{0x00,0x00,0xFC,0xFF,0xFF,0x1F,0x00,0x00},{0x00,0x00,0xFF,0xFF,0xF7,0x7F,0x00,0x00},{0x00,0xC0,0xFF,0xFB,0xE7,0xFF,0x01,0x00},{0x00,0xF8,0xFF,0xF9,0xC7,0xFF,0x0F,0x00},{0x00,0xFF,0x7F,0xF8,0x87,0xFF,0x7F,0x00},{0xE0,0xFF,0x3F,0xF8,0x07,0xFE,0xFF,0x07},{0xFC,0xFF,0x1F,0xF8,0x07,0xFC,0xFF,0x1F},{0xFC,0xFF,0x07,0xF8,0x07,0xF8,0xFF,0x1F},{0xF8,0xFF,0x03,0xF8,0x07,0xE0,0xFF,0x0F},{0xF8,0xFF,0x00,0xF8,0x07,0x80,0xFF,0x0F},{0xF0,0x3F,0x00,0xF8,0x07,0x00,0xFE,0x07},{0xF0,0x0F,0x00,0xF8,0x07,0x00,0xF8,0x07},{0xE0,0x01,0x00,0xF8,0x07,0x00,0xC0,0x03},{0x60,0x00,0x00,0xF8,0x07,0x00,0x00,0x03},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"果",0*/};static unsigned char ch_char2[86][8] = {{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0x00,0xF8,0x07,0xC0,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0x7F,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0xFC,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x0F},{0x00,0x00,0xE0,0xFF,0xFF,0x01,0x00,0x00},{0x00,0x00,0xF0,0xFF,0xFF,0x07,0x00,0x00},{0x00,0x00,0xFC,0xFF,0xFF,0x1F,0x00,0x00},{0x00,0x00,0xFF,0xFF,0xF7,0x7F,0x00,0x00},{0x00,0xC0,0xFF,0xFB,0xE7,0xFF,0x01,0x00},{0x00,0xF8,0xFF,0xF9,0xC7,0xFF,0x0F,0x00},{0x00,0xFF,0x7F,0xF8,0x87,0xFF,0x7F,0x00},{0xE0,0xFF,0x3F,0xF8,0x07,0xFE,0xFF,0x07},{0xFC,0xFF,0x1F,0xF8,0x07,0xFC,0xFF,0x1F},{0xFC,0xFF,0x07,0xF8,0x07,0xF8,0xFF,0x1F},{0xF8,0xFF,0x03,0xF8,0x07,0xE0,0xFF,0x0F},{0xF8,0xFF,0x00,0xF8,0x07,0x80,0xFF,0x0F},{0xF0,0x3F,0x00,0xF8,0x07,0x00,0xFE,0x07},{0xF0,0x0F,0x00,0xF8,0x07,0x00,0xF8,0x07},{0xE0,0x01,0x00,0xF8,0x07,0x00,0xC0,0x03},{0x60,0x00,0x00,0xF8,0x07,0x00,0x00,0x03},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"果",0*/};static unsigned char ch_char3[86][8] = {{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x06,0x00},{0x00,0x0C,0x00,0xF8,0x0F,0xC0,0x07,0x00},{0x00,0xFC,0x00,0xF8,0x0F,0xF8,0x07,0x00},{0x00,0xFC,0x07,0xF8,0x0F,0xFC,0x0F,0x00},{0x00,0xFE,0x07,0xF8,0x0F,0xFC,0x0F,0x00},{0x00,0xFE,0x07,0xF8,0x0F,0xF8,0x1F,0x00},{0x00,0xFE,0x07,0xF8,0x0F,0xF8,0x1F,0x00},{0x00,0xFE,0x03,0xF8,0x0F,0xF0,0x1F,0x00},{0x00,0xFF,0x03,0xF8,0x0F,0xF0,0x3F,0x00},{0x00,0xFF,0x03,0xF8,0x0F,0xF0,0x3F,0x00},{0x00,0xFF,0x01,0xF8,0x0F,0xE0,0x7F,0x00},{0x80,0xFF,0x01,0xF8,0x0F,0xE0,0x7F,0x00},{0x80,0xFF,0x01,0xF8,0x0F,0xE0,0x7F,0x00},{0x80,0xFF,0x01,0xF8,0x0F,0xC0,0xFF,0x00},{0xC0,0xFF,0x00,0xF8,0x0F,0xC0,0xFF,0x00},{0xC0,0xFF,0x00,0xF8,0x0F,0xC0,0xFF,0x01},{0xC0,0xFF,0x00,0xF8,0x0F,0x80,0xFF,0x01},{0xE0,0x7F,0x00,0xF8,0x0F,0x80,0xFF,0x01},{0xE0,0x7F,0x00,0xF8,0x0F,0x80,0xFF,0x03},{0xE0,0x7F,0x00,0xF8,0x0F,0x00,0xFF,0x03},{0xF0,0x3F,0x00,0xF8,0x0F,0x00,0xFF,0x03},{0xF0,0x3F,0x00,0xF8,0x0F,0x00,0xFF,0x07},{0xF0,0x3F,0x00,0xF8,0x0F,0x00,0xFE,0x07},{0xF8,0x1F,0x00,0xF8,0x0F,0x00,0xFE,0x0F},{0xF8,0x1F,0x00,0xF8,0x0F,0x00,0xFE,0x0F},{0xF8,0x1F,0x00,0xF8,0x0F,0x00,0xFC,0x0F},{0xFC,0x0F,0x00,0xF8,0x0F,0x00,0xFC,0x1F},{0xFC,0x0F,0x00,0xF8,0x0F,0x00,0xFC,0x1F},{0xFE,0x0F,0x00,0xF8,0x0F,0x00,0xF8,0x1F},{0xFE,0x07,0x00,0xF8,0x0F,0x00,0xF8,0x1F},{0xF0,0x07,0x00,0xF8,0x0F,0x00,0xF8,0x03},{0xC0,0x07,0x00,0xF8,0x0F,0x00,0xF0,0x00},{0x00,0x02,0x00,0xF8,0x0F,0x00,0x10,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x0F,0x00,0x00,0x00},{0x00,0x00,0x00,0xFC,0x0F,0x00,0x00,0x00},{0x00,0x40,0x00,0xFE,0x0F,0x00,0x00,0x00},{0x00,0x80,0xFF,0xFF,0x0F,0x00,0x00,0x00},{0x00,0x80,0xFF,0xFF,0x0F,0x00,0x00,0x00},{0x00,0x80,0xFF,0xFF,0x0F,0x00,0x00,0x00},{0x00,0x80,0xFF,0xFF,0x07,0x00,0x00,0x00},{0x00,0x00,0xFF,0xFF,0x07,0x00,0x00,0x00},{0x00,0x00,0xFF,0xFF,0x03,0x00,0x00,0x00},{0x00,0x00,0xFF,0xFF,0x01,0x00,0x00,0x00},{0x00,0x00,0xFF,0xFF,0x00,0x00,0x00,0x00},{0x00,0x00,0xFF,0x3F,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"小",0*/};static unsigned char ch_char4[86][8] = {{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0xC0,0x1F,0x00,0x00,0x00,0x00,0x00},{0x00,0xC0,0x1F,0x00,0x00,0x00,0x00,0x00},{0x00,0xC0,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0x00,0xC0,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0xFF,0xFF,0xFF,0xFF,0x0F},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0x00,0xC0,0x3F,0x00,0x00},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xFF,0xFF,0xFF,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xC3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x1F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xE3,0x0F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xF3,0x0F,0xFE,0xC1,0x3F,0xF8,0x07},{0xF8,0xF3,0x0F,0xFE,0xC1,0x3F,0xFC,0x07},{0xF8,0xF3,0x0F,0xFE,0xC1,0xFF,0xFF,0x07},{0x00,0xF8,0x0F,0xFE,0xC1,0xFF,0xFF,0x07},{0x00,0xF8,0x0F,0xFE,0xC1,0xFF,0xFF,0x03},{0x00,0xF8,0x07,0xFE,0xC1,0xBF,0xFF,0x03},{0x00,0xFC,0x07,0xFE,0xC1,0xBF,0xFF,0x03},{0x00,0xFC,0x07,0xFE,0xC1,0xBF,0xFF,0x01},{0x00,0xFE,0x03,0xFE,0xC1,0xBF,0xFF,0x00},{0x00,0xFF,0x03,0xFE,0xC1,0x3F,0x3F,0x00},{0x00,0xFF,0x03,0x00,0xC0,0x3F,0x00,0x00},{0x80,0xFF,0x01,0x00,0xC0,0x3F,0x00,0x00},{0xC0,0xFF,0x01,0x00,0xC0,0x3F,0x00,0x00},{0xE0,0xFF,0x00,0x00,0xC0,0x3F,0x00,0x00},{0xE0,0xFF,0x00,0x00,0xC0,0x3F,0x00,0x00},{0xC0,0x7F,0x00,0x00,0xC0,0x3F,0x00,0x00},{0x00,0x7F,0x00,0x00,0xC0,0x3F,0x00,0x00},{0x00,0x3E,0x00,0x00,0xC0,0x3F,0x00,0x00},{0x00,0x18,0x00,0x00,0xC0,0x3F,0x00,0x00},{0x00,0x10,0x00,0x00,0xC0,0x3F,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"师",0*/};static unsigned char ch_char5[86][8] = {{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x08,0x00,0x00,0x06,0x00,0x00},{0x00,0x00,0x1E,0x00,0x00,0x1E,0x00,0x00},{0x00,0x80,0x3F,0x00,0x00,0xFF,0x00,0x00},{0x00,0xE0,0x7F,0x00,0x80,0xFF,0x03,0x00},{0x00,0xE0,0x7F,0x00,0x80,0xFF,0x01,0x00},{0x00,0xC0,0xFF,0x00,0xC0,0xFF,0x00,0x00},{0x00,0x80,0xFF,0x01,0xE0,0x7F,0x00,0x00},{0x00,0x00,0xFF,0x01,0xE0,0x3F,0x00,0x00},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0x00,0x00,0x00,0xF8,0x07,0x00,0xFF,0x01},{0xC0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xC0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xC0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xC0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xE0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xE0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xE0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x01},{0xE0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xE0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xE0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xE0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF0,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF0,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF8,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0xF8,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x07},{0x00,0x00,0xFC,0xFF,0x07,0x00,0xF8,0x07},{0x00,0x00,0xFC,0xFF,0x07,0x00,0xF8,0x07},{0x00,0x00,0xFE,0xFB,0x07,0x00,0xF8,0x07},{0x00,0x00,0xFF,0xFB,0x07,0x00,0xF8,0x07},{0x00,0xC0,0xFF,0xF9,0x07,0x00,0xF8,0x07},{0x00,0xE0,0xFF,0xF8,0x07,0x00,0xFC,0x07},{0x00,0xF0,0xFF,0xF8,0x07,0x00,0xFC,0x07},{0x00,0xF8,0x7F,0xF8,0x07,0x00,0xFF,0x07},{0x00,0xFE,0x3F,0xF8,0xC7,0xFF,0xFF,0x07},{0x80,0xFF,0x1F,0xF8,0xC7,0xFF,0xFF,0x03},{0xC0,0xFF,0x0F,0xF8,0xC7,0xFF,0xFF,0x03},{0xF0,0xFF,0x07,0xF8,0x87,0xFF,0xFF,0x01},{0xFC,0xFF,0x03,0xF8,0x87,0xFF,0xFF,0x01},{0xFF,0xFF,0x01,0xF8,0x87,0xFF,0xFF,0x00},{0xFE,0x7F,0x00,0xF8,0x87,0xFF,0x3F,0x00},{0xFC,0x3F,0x00,0xF8,0x87,0xFF,0x0F,0x00},{0xFC,0x1F,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF8,0x07,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF0,0x03,0x00,0xF8,0x07,0x00,0x00,0x00},{0xF0,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x20,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0xF8,0x07,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"弟",0*/};#define argb8888_to_rgb565(color) ({\unsigned int temp = (color); \((temp & 0xF80000UL) >> 8) | \((temp & 0xFC00UL) >> 5) | \((temp & 0xF8UL) >> 3); \})/********************************************************************* 函数名称： lcd_draw_character* 功能描述：在LCD屏指定位置处(x, y)画字符, 参数color指定字符的颜色指针ch指向字符对应的子模数组、参数w、h分别表示字符的宽度和高度* 输入参数： color* 返回值：无********************************************************************/static void lcd_draw_character(unsigned int x, unsigned int y,const unsigned char *ch, unsigned int w,unsigned int h, unsigned int color){unsigned short rgb565_color = argb8888_to_rgb565(color);//得到RGB565颜色值unsigned long temp;unsigned int end_x, end_y;int j;int columns;/**计算出二维数组有多少列参数w表示的是字符的宽度，1个宽度表示的是1个bit位并不是一个字节，这里要注意，如果宽度不是byte单位的整数倍通常会补零**/columns = w / 8; //1byte=8bitif (0 != w % 8) columns++;/* 对参数进行限定 */if (w < 1 || h < 1) return;if (x >= width || y >= height) return;/* 计算出结束坐标位置 */end_x = x + w - 1;end_y = y + h - 1;/* 对结束坐标位置进行限定 */if (end_x >= width)end_x = width - 1;if (end_y >= height)end_y = height - 1;/* 计算有效宽度 */h = end_y - y + 1;w = end_x - x + 1;/* 打点 */temp = y * width + x; //定位到起点for (y = 0; y < h; y++, temp += width) {for (x = 0, j = 0; x < w; ) {if (*(ch + y * columns + j) & (0x1 << (x % 8)))screen_base[temp + x] = rgb565_color;x++;if (0 == x % 8) j++;}}}int main(void){struct fb_var_screeninfo fb_var = {0};struct fb_fix_screeninfo fb_fix = {0};unsigned long screen_size;int fd;/* 打开framebuffer设备 */fd = open(FB_DEV, O_RDWR);if (0 > fd) {fprintf(stderr, "open error: %s: %s\n", FB_DEV, strerror(errno));exit(EXIT_FAILURE);}/* 获取framebuffer设备信息 */ioctl(fd, FBIOGET_VSCREENINFO, &fb_var);ioctl(fd, FBIOGET_FSCREENINFO, &fb_fix);screen_size = fb_fix.line_length * fb_var.yres;width = fb_var.xres;height = fb_var.yres;/* 内存映射 */screen_base = mmap(NULL, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);if (MAP_FAILED == (void *)screen_base) {perror("mmap error");close(fd);exit(EXIT_FAILURE);}/* LCD背景刷白 */memset(screen_base, 0xFF, screen_size);/* 显示字符 */int x = width * 0.5 - 128;int y = height * 0.5 - 43;lcd_draw_character(x, y, (unsigned char *)ch_char1, 64, 86, 0xFF00FF);lcd_draw_character(x + 64, y, (unsigned char *)ch_char2, 64, 86, 0xFF00FF);lcd_draw_character(x + 128, y, (unsigned char *)ch_char3, 64, 86, 0xFF00FF);lcd_draw_character(x + 192, y, (unsigned char *)ch_char4, 64, 86, 0xFF00FF);lcd_draw_character(x + 256, y, (unsigned char *)ch_char5, 64, 86, 0xFF00FF);/* 退出程序 */munmap(screen_base, screen_size);close(fd);return 0;}

程序中定义了5个二维数组ch_char1、ch_char2、ch_char3、ch_char4、ch_char5，这5个二维数组便是5个中文字符果果小师弟的子模，字符宽度为64、高度为86。在取模的时候，选择从左到右、从上到下这种方式进行取模，上述示例代码便是按照这种方式进行解析的。

1.2 编译程序

我们要想给ARM板编译出程序，需要使用交叉编译工具链，交叉编译的工具链我们已经安装过了，详细请看【正点原子】I.MX6U嵌入式Linux驱动开发指南V1.x.pdf 的第4.3小节。我是用的是arm-linux-gnueabihf交叉编译工具链。使用arm-linux-gnueabihf-gcc -v可以查看交叉编译工具链的版本号。

然后就可以使用下面命令编译出可以在ARM板子上运行的可执行文件了。

arm-linux-gnueabihf-gcc -o show_char show_char.c

1、arm表示这是编译arm架构代码的编译器。2、linux表示运行在linux环境下。3、gnueabihf表示嵌入式二进制接口。4、gcc表示是gcc工具。

这样编译出来的 led程序才可以在ARM板子上运行。执行file show_char命令就可以看出hello是32位LSB的ELF格式文件，目标机架构为ARM，说明这个交叉编译正常，可执行文件可以在ARM板上执行。

1.3 上传程序到开发板执行

开发板启动后通过nfs挂载Ubuntu目录的方式，将相应的文件拷贝到开发板上。简单来说，就是通过NFS在开发板上通过网络直接访问ubuntu虚拟机上的文件，并且就相当于自己本地的文件一样。

开发板想访问/home/zhiguoxin/myproject/alientek_app_development_source这个目录中的文件，就要把/home/zhiguoxin/myproject/alientek_app_development_source挂载到开发板的mnt目录，这样就可以通过nfs来访问/home/zhiguoxin/myproject/alientek_app_development_source了。

因为我的代码都放在/home/zhiguoxin/myproject/alientek_app_development_source这个目录下，所以我们将这个目录作为NFS共享文件夹。设置方法参考移植SQLite3、OpenCV到RV1126开发板上开发人脸识别项目第一章。

Ubuntu IP为192.168.10.100，然后一般都是挂载在开发板的mnt目录下，这个目录是专门用来给我们作为临时挂载的目录。

然后使用MobaXterm软件通过SSH访问开发板。

ubuntu ip:192.168.10.100windows ip:192.168.10.200开发板ip:192.168.10.50

在开发板上执行以下命令：

mount -t nfs -o nolock,vers=3 192.168.10.100:/home/zhiguoxin/myproject/alientek_app_development_source /mnt

就将开饭的mnt目录挂载在ubuntu的/home/zhiguoxin/myproject/alientek_app_development_source目录下了。这样我们就可以在Ubuntu下修改文件，然后可以直接在开发板上执行可执行文件了。当然我这里的/home/zhiguoxin/myproject/和windows之间是一个共享目录，我也可以直接在windows上面修改文件，然后ubuntu和开发板直接进行文件同步了。

然后编译，可以编译成功。

./show_char

此时开发板 LCD 屏上会显示果果小师弟五个中文字符，如下图所示

使用这种方式还是非常简单地，自己取模、自己写函数打点显示，但是很 low！好歹咋们玩的也是操作系统，实际的应用项目一般肯定不会这么干，除非你的程序就是显示那么几个固定的字符。那既然如此，为什么还要给大家介绍这种方式呢？一来是让大家理解字符显示的原理；二来，一些实际的应用项目中可能确实就是这么做的，不同的项目它的需求不同，不能一概而论！

操作系统中通常都会有很多的字体文件，譬如 Windows 系统C:\Windows\Fonts目录下就有很多的字体文件，如下所示：

字体文件的格式也有很多种，譬如otf、ttf、ttc等，Linux系统中，字体文件通常会放在/usr/share/fonts目录下，有了字体文件之后，我们就不需要再对字符进行取模了，它们已经编码进了字体文件中，我们只需要解析字体文件、访问字体文件，从字体文件中读取出字符的位图数据即可！

当然，这些复杂的解析过程并不需要我们自己去实现，有很多开源的字体引擎可以帮助我们来处理这些复杂的解析过程，譬如freetype库。

二、FreeType简介

FreeType一个完全免费(开源)的软件字体引擎库，设计小巧、高效、高度可定制且可移植，它提供了统一的接口来访问多种不同格式的字体文件。它提供了一个简单、易于使用且统一的接口来访问字体文件的内容，从而大大简化了这些任务。

请注意，FreeType也称为FreeType 2，以区别于旧的、已弃用的FreeType 1库，Freetype 1库已经不再维护和支持了。

2.1 FreeType移植

开发板出厂系统已经移植好了这些库，但是版本稍微太低了，作为学习者，我们应该要学会自己动手移植，这个是很重要的工作；我们很多的编程工作都是基于别人写好的库、调用库函数来实现应用程序的功能，因为 Linux 软件生态做得非常好，有很多免费、开源的库是可以使用的，不用自己去捣鼓这些东西；所以作为一个嵌入式Linux 软件开发人员，学会移植就显得很重要。

2.2 下载FreeType源码

开发板出厂系统中，FreeType 的版本为 2.6，这个版本稍微有点低，我们选择移植 2.8 版本的 FreeType。进入到https://download./releases/freetype/链接地址，如下所示：

往下翻找到2.8版本，选择freetype-2.8.tar.gz压缩文件.

2.3 交叉编译FreeType源码

将下载好的freetype-2.8.tar.gz压缩文件拷贝到 Ubuntu共享文件夹目录下，如下所示：

在/home/zhiguoxin/linux/tool目录下创建一个名为freetype的目录，把它作为FreeType的安装目录：

回到共享文件夹下，执行命令将freetype-2.8.tar.gz解压开来：

tar -xzf freetype-2.8.tar.gz

解压成功之后便会得到FreeType的源码目录freetype-2.8。

进入到freetype-2.8目录，老规矩，同样是三部曲：配置、编译、安装。首先对交叉编译工具的环境进行初始化，前面章节内容已经提过很多次了，使用交叉编译器之前，必须要对其环境进行初始化（如果当前终端已经初始化过了，则无需再次进行初始化）。

FreeType库基于模块化设计，意味着我们可以对其进行裁剪，将不需要的功能模块从配置中移除，减小库文件的体积；除此之外，FreeType还支持很多配置选项，如果大家想要对FreeType做一些自定义配置或者对其进行裁剪，可以参考FreeType源码目录下docs/CUSTOMIZE文档，该文件对此有比较详细的说明，建议大家看一看，如果有需求的话。docs目录下还有其它很多的说明文档，也都可以读一读。

这里我们简单地配置一下，打开include/freetype/config/ftoption.h文件，如下所示：

vim include/freetype/config/ftoption.h

该文件定义了很多的配置宏，我们可以选择使能或禁用这些配置选项，具体配置哪些功能，大家自己去研究，每一个配置宏都有详细地解释说明。这里我们打开以下两个配置宏：

#define FT_CONFIG_OPTION_SYSTEM_ZLIB#define FT_CONFIG_OPTION_USE_PNG

大家找到这两个宏，默认情况下，这两个都被注释掉了，所以是没有使能的；把这两个宏的注释去掉，使能这两个配置宏。

第一个配置宏表示使用系统安装的zlib库，因为 FreeType支持Gzip压缩文件，会使用到zlib库，zlib之前我们移植好了；第二个配置宏表示支持PNG bitmap位图，因为FreeType可以加载PNG格式的彩色位图字形，需要依赖于libpng 库，这个库前面我们也是移植好了。

配置好之后，保存、退出ftoption.h文件，接着执行如下命令对FreeType工程源码进行配置：

./configure --prefix=/home/zhiguoxin/linux/tool/freetype/ --host=arm-poky-linux-gnueabi --with-zlib=yes --with-bzip2=no --with-png=yes --with-harfbuzz=no ZLIB_CFLAGS="-I/home/zhiguoxin/linux/tool/zlib/include -L/home/zhiguoxin/linux/tool/zlib/lib" ZLIB_LIBS=-lz LIBPNG_CFLAGS="-I/home/zhiguoxin/linux/tool/png/include -L/home/zhiguoxin/linux/tool/png/lib" LIBPNG_LIBS=-lpng

这个配置命令很长，简单地提一下，具体的细节大家可以执行./configure --help查看配置帮助信息。

–prefix选项指定FreeType库的安装目录；–host选项设置为交叉编译器名称的前缀;–with-zlib=yes表示使用 zlib；–with-bzip2=no表示不使用bzip2库；–with-png=yes表示使用libpng库；–with-harfbuzz=no表示不使用harfbuzz库。ZLIB_CFLAGS选项用于指定zlib的头文件路径和库文件路径，根据实际安装路径填写；ZLIB_LIBS选项指定链接的zlib库的名称；LIBPNG_CFLAGS选项用于指定libpng的头文件路径和库文件路径，根据实际安装路径填写；LIBPNG_LIBS选项用于指定链接的libpng库的名称。

配置完成之后接着执行make编译，编译完成之后执行make install安装即可！

makemake install

2.4 安装目录下的文件

进入到 FreeType 安装目录下，如下所示：

如果要使用FreeType库，我们需要在应用程序源码中包含include/freetype2目录下的ft2build.h头文件，除此之外，还需要包含另一个头文件 FT_FREETYPE_H，这是一个用宏定义的头文件，其实就是include/freetype2/freetype/freetype.h 头文件。

所以，在我们的应用程序一般是这样写：

#include <ft2build.h>#include FT_FREETYPE_H

2.5 移植到开发板

接下来将编译得到的动态链接库文件拷贝到开发板 Linux 系统/usr/lib 目录，在拷贝之前，需将/usr/lib 目录下原有的 FreeType 库文件删除掉，执行下面这条命令：

rm -rf /usr/lib/libfreetype.*

删除之后，再将编译得到的库文件拷贝到开发板/usr/lib目录，拷贝lib目录下的库文件时，需要注意符号链接的问题，不能破坏原有的符号链接；可以将lib目录下的所有文件打包成压缩包的形式，譬如进入到lib目录，执行命令：

tar -czf lib.tar.gz ./ libfreetype*

拷贝过去之后，开发板/usr/lib目录下就应该存在这些库文件，如下所示：

scp lib.tar.gz root@192.168.10.50:/home/root/

这里如果使用scp命令不成功，可以用其他的方法拷贝。

然后lib.tar.gz就拷贝到开发板了，然后使用下面命令将其解压至/usr/lib 目录下

tar -xmzf lib.tar.gz -C /usr/lib

然后使用下面命令查看是是否成功拷贝至/usr/lib目录。

ls -l /usr/lib/libfreetype.*

2.6 应用编程

#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <sys/ioctl.h>#include <string.h>#include <errno.h>#include <sys/mman.h>#include <linux/fb.h>#include <math.h> //数学库函数头文件#include <wchar.h>#include <ft2build.h>#include FT_FREETYPE_H#define FB_DEV"/dev/fb0"//LCD设备节点#define argb8888_to_rgb565(color) ({\unsigned int temp = (color); \((temp & 0xF80000UL) >> 8) | \((temp & 0xFC00UL) >> 5) | \((temp & 0xF8UL) >> 3); \})static unsigned int width; //LCD宽度static unsigned int height; //LCD高度static unsigned short *screen_base = NULL;//LCD显存基地址 RGB565static unsigned long screen_size;static int fd = -1;static FT_Library library;static FT_Face face;static int fb_dev_init(void){struct fb_var_screeninfo fb_var = {0};struct fb_fix_screeninfo fb_fix = {0};/* 打开framebuffer设备 */fd = open(FB_DEV, O_RDWR);if (0 > fd) {fprintf(stderr, "open error: %s: %s\n", FB_DEV, strerror(errno));return -1;}/* 获取framebuffer设备信息 */ioctl(fd, FBIOGET_VSCREENINFO, &fb_var);ioctl(fd, FBIOGET_FSCREENINFO, &fb_fix);screen_size = fb_fix.line_length * fb_var.yres;width = fb_var.xres;height = fb_var.yres;/* 内存映射 */screen_base = mmap(NULL, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);if (MAP_FAILED == (void *)screen_base) {perror("mmap error");close(fd);return -1;}/* LCD背景刷成黑色 */memset(screen_base, 0xFF, screen_size);return 0;}static int freetype_init(const char *font, int angle){FT_Error error;FT_Vector pen;FT_Matrix matrix;float rad;//旋转角度/* FreeType初始化 */FT_Init_FreeType(&library);/* 加载face对象 */error = FT_New_Face(library, font, 0, &face);if (error) {fprintf(stderr, "FT_New_Face error: %d\n", error);exit(EXIT_FAILURE);}/* 原点坐标 */pen.x = 0 * 64;pen.y = 0 * 64;//原点设置为(0, 0)/* 2x2矩阵初始化 */rad = (1.0 * angle / 180) * M_PI; //（角度转换为弧度）M_PI是圆周率#if 0 //非水平方向matrix.xx = (FT_Fixed)( cos(rad) * 0x10000L);matrix.xy = (FT_Fixed)(-sin(rad) * 0x10000L);matrix.yx = (FT_Fixed)( sin(rad) * 0x10000L);matrix.yy = (FT_Fixed)( cos(rad) * 0x10000L);#endif#if 1 //斜体水平方向显示的matrix.xx = (FT_Fixed)( cos(rad) * 0x10000L);matrix.xy = (FT_Fixed)( sin(rad) * 0x10000L);matrix.yx = (FT_Fixed)( 0 * 0x10000L);matrix.yy = (FT_Fixed)( 1 * 0x10000L);#endif/* 设置 */FT_Set_Transform(face, &matrix, &pen);FT_Set_Pixel_Sizes(face, 50, 0); //设置字体大小return 0;}static void lcd_draw_character(int x, int y,const wchar_t *str, unsigned int color){unsigned short rgb565_color = argb8888_to_rgb565(color);//得到RGB565颜色值FT_GlyphSlot slot = face->glyph;size_t len = wcslen(str); //计算字符的个数long int temp;int n;int i, j, p, q;int max_x, max_y, start_y, start_x;// 循环加载各个字符for (n = 0; n < len; n++) {// 加载字形、转换得到位图数据if (FT_Load_Char(face, str[n], FT_LOAD_RENDER))continue;start_y = y - slot->bitmap_top; //计算字形轮廓上边y坐标起点位置注意是减去bitmap_topif (0 > start_y) {//如果为负数如何处理？？q = -start_y;temp = 0;j = 0;}else {// 正数又该如何处理??q = 0;temp = width * start_y;j = start_y;}max_y = start_y + slot->bitmap.rows;//计算字形轮廓下边y坐标结束位置if (max_y > (int)height)max_y = height;for (; j < max_y; j++, q++, temp += width) {start_x = x + slot->bitmap_left; //起点位置要加上左边空余部分长度if (0 > start_x) {p = -start_x;i = 0;}else {p = 0;i = start_x;}max_x = start_x + slot->bitmap.width;if (max_x > (int)width)max_x = width;for (; i < max_x; i++, p++) {// 如果数据不为0，则表示需要填充颜色if (slot->bitmap.buffer[q * slot->bitmap.width + p])screen_base[temp + i] = rgb565_color;}}//调整到下一个字形的原点x += slot->advance.x / 64; //26.6固定浮点格式y -= slot->advance.y / 64;}}int main(int argc, char *argv[]){/* LCD初始化 */if (fb_dev_init())exit(EXIT_FAILURE);/* freetype初始化 */if (freetype_init(argv[1], atoi(argv[2])))exit(EXIT_FAILURE);/* 在LCD上显示中文 */int y = height * 0.25;lcd_draw_character(50, 100, L"欢迎各位帅哥美女进小弟的博客", 0x000000);lcd_draw_character(50, y+100, L"祝大哥别人不发你还发,永远都是企业家", 0x9900FF);lcd_draw_character(50, 2*y+100, L"祝美女人见人爱，花见花开", 0xFF0099);lcd_draw_character(50, 3*y+100, L"微信公众号：果果小师弟", 0x9932CC);/* 退出程序 */FT_Done_Face(face);FT_Done_FreeType(library);munmap(screen_base, screen_size);close(fd);exit(EXIT_SUCCESS);}

编译方法

source /opt/fsl-imx-x11/4.1.15-2.1.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi # 设置环境变量${CC} -o freetype_test freetype_test.c -I/home/zhiguoxin/linux/tool/freetype/include/freetype2 -L/home/zhiguoxin/linux/tool/freetype/lib -lfreetype -L/home/zhiguoxin/linux/tool/zlib/lib -lz -L/home/zhiguxoin/linux/tool/png/lib -lpng -lm

编译完成就可以在板子上执行可执行文件了。