一、整体思路
采用分层的思想,面向对象的编程思想。
1、怎样在LCD上显示一个文件
2、如何组织代码
分层的结构
main--draw--XXX_manager--fb.c等
二、分层编写-底层实现
1、显示部分代码编写
- show_file\display\fb.c
- show_file\display\disp_manager.c
- show_file\include\config.h
- show_file\include\disp_manager.h
- show_file\draw\draw.c
先写fb.c 一面向对象编程思想
设置构造一个结构体
结构体需要有哪些成员呢:
显示部分,一定有一个显示函数,FB要显示就要初始化,所以有一个fb初始化函数,换页的时候我们要进行清屏操作,要有一个清屏函数,所以要有3个函数。
(1) fb初始化
(2) 显示函数
(3) 清屏函数
只有函数还不全,还需要一些属性,如定义一个名字“fb”,X坐标,Y坐标,多少位表示一个像素等属性。
disp_manager.h中结构体设计如下
- typedef struct DispOpr {
- char *name;
- int iXres;
- int iYres;
- int iBpp;
- int (*DeviceInit)(void);
- int (*ShowPixel)(int iPenX, int iPenY, unsigned int dwColor);
- int (*CleanScreen)(unsigned int dwBackColor);
- struct DispOpr *ptNext;
- }T_DispOpr, *PT_DispOpr;
- static T_DispOpr g_tFBOpr = {
- .name = "fb",
- .DeviceInit = FBDeviceInit,
- .ShowPixel = FBShowPixel,
- .CleanScreen = FBCleanScreen,
- };
结构体用到这些函数 ,所以事先声明一下,都是static所以只能在本文件中使用,外面想用只能通过上一层。
- static int FBDeviceInit(void);
- static int FBShowPixel(int iX, int iY, unsigned int dwColor);
- static int FBCleanScreen(unsigned int dwBackColor);
在哪注册?
- int FBInit(void)
- {
- return RegisterDispOpr(&g_tFBOpr);
- }
这里就不能写成static了。
注册就是把结构体加入链表中,链表比数组更灵活,大小随意。
一开始链表头是空的,所以让指针指向这个结构体。在注册就让next指向新结构体。
实现三个函数:
注意这里是应用程序所以是一些open,read等函数。
如:g_fd = open(FB_DEVICE_NAME, O_RDWR);
这里不应该把设备名字定死,所以写一个config文件
- #ifndef _CONFIG_H
- #define _CONFIG_H
- #include <stdio.h>
- #define FB_DEVICE_NAME "/dev/fb0"
- #define COLOR_BACKGROUND 0xE7DBB5 /* 泛黄的纸 */
- #define COLOR_FOREGROUND 0x514438 /* 褐色字体 */
- #define DBG_PRINTF(...)
- //#define DBG_PRINTF printf
- #endif /* _CONFIG_H */
DBG_PRINTF:这个宏可以控制打印开关。
显示做好了,但是我们显示内容在哪呢?需要设置显示字体,得到显示的点阵。如显示ASCII还是ABK,还是freetype。同理写出这部分代码。
代码:
fb.c:重点是结构
- #include <config.h>
- #include <disp_manager.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <fcntl.h>
- #include <sys/ioctl.h>
- #include <sys/mman.h>
- #include <linux/fb.h>
- #include <string.h>
- static int FBDeviceInit(void);
- static int FBShowPixel(int iX, int iY, unsigned int dwColor);
- static int FBCleanScreen(unsigned int dwBackColor);
- static int g_fd;
- static struct fb_var_screeninfo g_tFBVar; //可变参数
- static struct fb_fix_screeninfo g_tFBFix; //固定参数
- static unsigned char *g_pucFBMem; //内存映射
- static unsigned int g_dwScreenSize; //FB屏幕大小
- static unsigned int g_dwLineWidth; //一行宽度:一行的像素*像素位数/8字节
- static unsigned int g_dwPixelWidth; //每个像素占据多少字节:BPP/8=2字节(一个像素占据2字节)
- static T_DispOpr g_tFBOpr = {
- .name = "fb",
- .DeviceInit = FBDeviceInit,
- .ShowPixel = FBShowPixel,
- .CleanScreen = FBCleanScreen,
- };
- static int FBDeviceInit(void)
- {
- int ret;
- g_fd = open(FB_DEVICE_NAME, O_RDWR);
- if (0 > g_fd)
- {
- DBG_PRINTF("can't open %s\n", FB_DEVICE_NAME);
- }
- ret = ioctl(g_fd, FBIOGET_VSCREENINFO, &g_tFBVar);
- if (ret < 0)
- {
- DBG_PRINTF("can't get fb's var\n");
- return -1;
- }
- ret = ioctl(g_fd, FBIOGET_FSCREENINFO, &g_tFBFix);
- if (ret < 0)
- {
- DBG_PRINTF("can't get fb's fix\n");
- return -1;
- }
- g_dwScreenSize = g_tFBVar.xres * g_tFBVar.yres * g_tFBVar.bits_per_pixel / 8;
- g_pucFBMem = (unsigned char *)mmap(NULL , g_dwScreenSize, PROT_READ | PROT_WRITE, MAP_SHARED, g_fd, 0);
- if (0 > g_pucFBMem)
- {
- DBG_PRINTF("can't mmap\n");
- return -1;
- }
- g_tFBOpr.iXres = g_tFBVar.xres;
- g_tFBOpr.iYres = g_tFBVar.yres;
- g_tFBOpr.iBpp = g_tFBVar.bits_per_pixel; //设置坐标和多少位表示一个像素
- g_dwLineWidth = g_tFBVar.xres * g_tFBVar.bits_per_pixel / 8;
- g_dwPixelWidth = g_tFBVar.bits_per_pixel / 8;
- return 0;
- }
- //RRGGBB 16: 24转成565
- static int FBShowPixel(int iX, int iY, unsigned int dwColor)
- {
- unsigned char *pucFB;
- unsigned short *pwFB16bpp;
- unsigned int *pdwFB32bpp;
- unsigned short wColor16bpp; /* 565 */
- int iRed;
- int iGreen;
- int iBlue;
- if ((iX >= g_tFBVar.xres) || (iY >= g_tFBVar.yres))
- {
- DBG_PRINTF("out of region\n");
- return -1;
- }
- pucFB = g_pucFBMem + g_dwLineWidth * iY + g_dwPixelWidth * iX;
- pwFB16bpp = (unsigned short *)pucFB;
- pdwFB32bpp = (unsigned int *)pucFB;
- switch (g_tFBVar.bits_per_pixel)
- {
- case 8:
- {
- *pucFB = (unsigned char)dwColor;
- break;
- }
- case 16:
- {
- iRed = (dwColor >> (16+3)) & 0x1f;
- iGreen = (dwColor >> (8+2)) & 0x3f;
- iBlue = (dwColor >> 3) & 0x1f;
- wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;
- *pwFB16bpp = wColor16bpp;
- break;
- }
- case 32:
- {
- *pdwFB32bpp = dwColor;
- break;
- }
- default :
- {
- DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);
- return -1;
- }
- }
- return 0;
- }
- static int FBCleanScreen(unsigned int dwBackColor)
- {
- unsigned char *pucFB;
- unsigned short *pwFB16bpp;
- unsigned int *pdwFB32bpp;
- unsigned short wColor16bpp; /* 565 */
- int iRed;
- int iGreen;
- int iBlue;
- int i = 0;
- pucFB = g_pucFBMem;
- pwFB16bpp = (unsigned short *)pucFB;
- pdwFB32bpp = (unsigned int *)pucFB;
- switch (g_tFBVar.bits_per_pixel)
- {
- case 8:
- {
- memset(g_pucFBMem, dwBackColor, g_dwScreenSize);
- break;
- }
- case 16:
- {
- iRed = (dwBackColor >> (16+3)) & 0x1f;
- iGreen = (dwBackColor >> (8+2)) & 0x3f;
- iBlue = (dwBackColor >> 3) & 0x1f;
- wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;
- while (i < g_dwScreenSize)
- {
- *pwFB16bpp = wColor16bpp;
- pwFB16bpp++;
- i += 2;
- }
- break;
- }
- case 32:
- {
- while (i < g_dwScreenSize)
- {
- *pdwFB32bpp = dwBackColor;
- pdwFB32bpp++;
- i += 4;
- }
- break;
- }
- default :
- {
- DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);
- return -1;
- }
- }
- return 0;
- }
- int FBInit(void)
- {
- return RegisterDispOpr(&g_tFBOpr);
- }
- #include <config.h>
- #include <disp_manager.h>
- #include <string.h>
- static PT_DispOpr g_ptDispOprHead;
- int RegisterDispOpr(PT_DispOpr ptDispOpr)
- {
- PT_DispOpr ptTmp;
- if (!g_ptDispOprHead)
- {
- g_ptDispOprHead = ptDispOpr;
- ptDispOpr->ptNext = NULL;
- }
- else
- {
- ptTmp = g_ptDispOprHead;
- while (ptTmp->ptNext)
- {
- ptTmp = ptTmp->ptNext;
- }
- ptTmp->ptNext = ptDispOpr;
- ptDispOpr->ptNext = NULL;
- }
- return 0;
- }
- void ShowDispOpr(void)
- {
- int i = 0;
- PT_DispOpr ptTmp = g_ptDispOprHead;
- while (ptTmp)
- {
- printf("%02d %s\n", i++, ptTmp->name);
- ptTmp = ptTmp->ptNext;
- }
- }
- PT_DispOpr GetDispOpr(char *pcName)
- {
- PT_DispOpr ptTmp = g_ptDispOprHead;
- while (ptTmp)
- {
- if (strcmp(ptTmp->name, pcName) == 0)
- {
- return ptTmp;
- }
- ptTmp = ptTmp->ptNext;
- }
- return NULL;
- }
- int DisplayInit(void)
- {
- int iError;
- iError = FBInit();
- return iError;
- }
2、字体部分编写
3、编码部分编写
三、分层编写-上层实现
1、draw.c
2、main.c
解析命令-打开文本-显示文本-换页-返回上一页等
- #include <unistd.h>
- #include <stdlib.h>
- #include <stdio.h>
- #include <config.h>
- #include <draw.h>
- #include <encoding_manager.h>
- #include <fonts_manager.h>
- #include <disp_manager.h>
- #include <string.h>
- /* ./show_file [-s Size] [-f freetype_font_file] [-h HZK] <text_file> */
- int main(int argc, char **argv)
- {
- int iError;
- unsigned int dwFontSize = 16;
- char acHzkFile[128];
- char acFreetypeFile[128];
- char acTextFile[128];
- char acDisplay[128];
- char cOpr;
- int bList = 0;
- acHzkFile[0] = '\0';
- acFreetypeFile[0] = '\0';
- acTextFile[0] = '\0';
- strcpy(acDisplay, "fb");
- while ((iError = getopt(argc, argv, "ls:f:h:d:")) != -1)
- {
- switch(iError)
- {
- case 'l':
- {
- bList = 1;
- break;
- }
- case 's':
- {
- dwFontSize = strtoul(optarg, NULL, 0);
- break;
- }
- case 'f':
- {
- strncpy(acFreetypeFile, optarg, 128);
- acFreetypeFile[127] = '\0';
- break;
- }
- case 'h':
- {
- strncpy(acHzkFile, optarg, 128);
- acHzkFile[127] = '\0';
- break;
- }
- case 'd':
- {
- strncpy(acDisplay, optarg, 128);
- acDisplay[127] = '\0';
- break;
- }
- default:
- {
- printf("Usage: %s [-s Size] [-d display] [-f font_file] [-h HZK] <text_file>\n", argv[0]);
- printf("Usage: %s -l\n", argv[0]);
- return -1;
- break;
- }
- }
- }
- if (!bList && (optind >= argc))
- {
- printf("Usage: %s [-s Size] [-d display] [-f font_file] [-h HZK] <text_file>\n", argv[0]);
- printf("Usage: %s -l\n", argv[0]);
- return -1;
- }
- iError = DisplayInit();
- if (iError)
- {
- printf("DisplayInit error!\n");
- return -1;
- }
- iError = FontsInit();
- if (iError)
- {
- printf("FontsInit error!\n");
- return -1;
- }
- iError = EncodingInit();
- if (iError)
- {
- printf("EncodingInit error!\n");
- return -1;
- }
- if (bList)
- {
- printf("supported display:\n");
- ShowDispOpr();
- printf("supported font:\n");
- ShowFontOpr();
- printf("supported encoding:\n");
- ShowEncodingOpr();
- return 0;
- }
- strncpy(acTextFile, argv[optind], 128);
- acTextFile[127] = '\0';
- iError = OpenTextFile(acTextFile);
- if (iError)
- {
- printf("OpenTextFile error!\n");
- return -1;
- }
- iError = SetTextDetail(acHzkFile, acFreetypeFile, dwFontSize);
- if (iError)
- {
- printf("SetTextDetail error!\n");
- return -1;
- }
- DBG_PRINTF("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
- iError = SelectAndInitDisplay(acDisplay);
- if (iError)
- {
- printf("SelectAndInitDisplay error!\n");
- return -1;
- }
- DBG_PRINTF("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
- iError = ShowNextPage();
- DBG_PRINTF("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
- if (iError)
- {
- printf("Error to show first page\n");
- return -1;
- }
- while (1)
- {
- printf("Enter 'n' to show next page, 'u' to show previous page, 'q' to exit: ");
- do {
- cOpr = getchar();
- } while ((cOpr != 'n') && (cOpr != 'u') && (cOpr != 'q'));
- if (cOpr == 'n')
- {
- ShowNextPage();
- }
- else if (cOpr == 'u')
- {
- ShowPrePage();
- }
- else
- {
- return 0;
- }
- }
- return 0;
- }
getopt(argc, argv, "ls:f:h:d:")
:需要带参数
-l 不需要带参数strncpy(acTextFile, argv[optind], 128);得到文件名
(2)初始化显示、字体、编码--》注册相关结构体
- iError = DisplayInit();
- iError = FontsInit();
- iError = EncodingInit();
OpenTextFile(acTextFile)
(4)打开字体文件
SetTextDetail(acHzkFile, acFreetypeFile, dwFontSize);
(5)根据名字选择初始化一个显示器
SelectAndInitDisplay(acDisplay);
(6)显示第一页或者下一页
ShowNextPage();
(7)等待命令参数,显示下一页,上一页等