/头文件/

include <sys/types.h>

include <sys/stat.h>

include <fcntl.h>

include <unistd.h>

include <stdio.h>

include <sys/mman.h>

include <stdlib.h>

/宏定义/

define FILE_PATH "/dev/fb0"

/*
Init_LCD:初始化显示屏
参数为空
返回值 int*
成功 返回映射区域的首地址
失败 返回NULL
*/
int *Init_LCD(int *fd)
{
//1.打开帧缓冲
*fd = open("/dev/fb0",O_RDWR);
if(-1 == *fd)
{

	perror("open fail");
	return NULL;
}
//2.映射
int *plcd = mmap(NULL,800*480*4
		,PROT_READ |  PROT_WRITE,
		MAP_SHARED,*fd,0);
if(MAP_FAILED == plcd)
{
	perror("mmap fail");
	return NULL;
}
return plcd;

}

/*
Uninit_LCD:解初始化屏幕
@fd:帧缓冲的文件描述符
@plcd:
返回值:无
/
void Uninit_LCD(int fd,int plcd)
{
//1.解映射
munmap(plcd,8004804);
//2.关闭帧缓冲
close(fd);
}

void Lcd_draw_point(int x,int y,int color,int *plcd)
{
if(NULL == plcd)
{
printf("error:plcd == NULL\n");
return ;
}
if(x>=0&&x<800&&y>=0&&y<480)
{
(plcd+800y+x) = color;
}
}
void Lcd_draw_matrx(int x,int y,int h,int w,int color,int *plcd)
{
int i,j;
if((x+w)>=0||(x+w)<=880||(y+h)>=0||(y+h)<=880)
for(j=x;j<x+w;j++)
{
for(i=y;i<y+h;i++)
{
Lcd_draw_point(i,j,color,plcd);
}
}
}

/*
Bmp_display:在屏幕的指定的位置显示bmp图片
@bmp_file：图片的路径名
@x0 y0 图片左上角在屏幕上的坐标
@plcd:帧缓冲映射区域的首地址
返回值：
-1 失败
0 成功
*/
int Bmp_display(const char *bmp_file,int x0,int y0,int *plcd)
{
if(plcd == NULL || !(x0>=0&&x0<800&&y0>=0&&y0<480))
{
return -1;
}
//1.打开图片
int fd = open(bmp_file,O_RDONLY);
if(-1 == fd)
{
printf("%s",bmp_file);
perror("open fail");
return -1;
}
//2.判断到底是不是一张bmp图片
char buf[4]={0};
read(fd,buf,2);
if(buf[0]!=0x42 || buf[1]!=0x4D)
{
printf("NOT BMP\n");
close(fd);
return -1;
}
//3.解析图片 宽 高 色深
lseek(fd,0x12,SEEK_SET);
read(fd,buf,4);
int width = buf[3]<<24 | buf[2]<<16 | buf[1]<<8 | buf[0];

lseek(fd,0x16,SEEK_SET);
read(fd,buf,4);
int height = buf[3]<<24 | buf[2]<<16 | buf[1]<<8 | buf[0];

lseek(fd,0x1c,SEEK_SET);
read(fd,buf,2);
short depth = buf[1]<<8 | buf[0];

if(!(depth == 24 || depth == 32))
{
	printf("NOT SUPPORT!\n");
	close(fd);
	return -1;
}

printf("%s:%d*%d depth:%d\n",bmp_file,width,height,depth);
//4.获取像素数组
int line_vaild_bytes=abs(width)*depth/8;
int line_bytes;//一行总字节数=有效字节数+赖子数
int laizi = 0;

if(line_vaild_bytes%4)
{
	laizi = 4 - line_vaild_bytes%4;
}
line_bytes = line_vaild_bytes + laizi;
int total_bytes = line_bytes*abs(height);//整个像素数组的大小

//从文件中读取像素数组
lseek(fd,54,SEEK_SET);
unsigned char piexl[total_bytes];
read(fd,piexl,total_bytes);
//5.在屏幕的对应位置显示即可
unsigned char a,r,g,b;
int color;
int i=0;
int x,y;
//遍历整个像素数组
for(y=0;y<abs(height);y++)
{
	for(x=0;x<abs(width);x++)
	{
		b=piexl[i++];
		g=piexl[i++];
		r=piexl[i++];
		if(depth==32)
		{
			a=piexl[i++];
		}
		else
		{
			a=0;//不透明
		}
		color=a<<24|r<<16|g<<8|b;
		Lcd_draw_point(width>0?x+x0:x0+abs(width)-x-1,
      	height>0?y0+abs(height)-y-1:y0+y,color,plcd);
	}
	//每一行末尾可能存在赖子
	i+=laizi;
}
close(fd);
return 0;

}

标签：return,plcd,Day8,int,fd,ElectronicAlbum,include,buf
来源： https://www.cnblogs.com/jfbk/p/16302897.html